HIGH-RESISTANCE COLD LAMINATED STEEL SHEET WITH EXCELLENT STRETCH FLOWING CAPACITY AND PRECISION DRI

专利摘要:
"High strength cold rolled steel sheet having excellent stretching flanging ability and precision punching capacity and method for producing it". The present invention relates to a high strength cold rolled steel sheet having excellent drawing flanging ability and precision punching ability containing predetermined components and the balance being composed of iron and the inevitable impurities, in which in a range from 5/8 to 3/8 in sheet thickness from the surface of the sheet steel, the average value of the pole densities of the orientation group {100} <011> to {223} <110> represented by the respective crystal orientations of {100} <011>, {116} <110>, {114} <110>, {113} <110>, {112} <110>, {335} <110>, and {223} <110> is 6.5 or less, and the crystal orientation pole density {332} <113> is 5.0 or less, and the metal frame contains, in terms of area ratio, more than 5% perlite, the sum bainite and martensite limited to less than 5%, and the balance composed of ferrite.
公开号:BR112014001636B1
申请号:R112014001636-4
申请日:2012-07-27
公开日:2019-03-26
发明作者:Shinichiro Watanabe；Hiroshi Shuto；Nobuhiro Fujita；Tatsuo Yokoi；Riki Okamoto；Kazuaki Nakano
申请人:Nippon Steel & Sumitomo Metal Corporation；
IPC主号:

专利说明:

Technical Field [001] The present invention relates to a high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, and a method for producing it.
[002] This application is based on the claims and benefits of the priority of Japanese Patent Application No. 2011-164383, registered on July 27, 2011, the total content of which is incorporated herein by reference.
Background to the Technique [003] To reduce the emission of carbon dioxide gas from automobiles, a reduction in the weight of the chassis of automotive vehicles was promoted by the use of high-strength steel plates. In addition, to also ensure the safety of a passenger, a high-strength steel plate has been increasingly used for an automotive vehicle chassis in addition to a mild steel plate. To also promote the weight reduction of automotive vehicle chassis from now on, it is necessary to increase the level of resistance in the use of a high-strength steel plate more than the conventional one. However, when a high strength steel sheet is used for an outer panel piece, cutting, embossing, and the like are often applied, and also when a high strength steel sheet is used for a bottom part chassis, working methods accompanied by shear such as drilling are often applied, re
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2/68 resulting in the fact that a steel plate having excellent precision drilling capacity was required. In addition, work such as deburring has also been increasingly performed after shearing, so that the ability to stretch the flanging is also an important work-related property. However, when a steel plate is increased in strength in general, drilling accuracy decreases and the stretching flanging capacity also decreases.
[004] Regarding precision drilling capacity, as in Patent Documents 1 and 2, it is described that drilling is carried out in a soft state and the reach of high strength is achieved by heat treatment and carburization, but the process of production is prolonged, thereby causing an increase in cost. On the other hand, as in Patent Document 3, a method of improving the drilling capacity accurately by coalescing the cementite by annealing is also described, but the range of the flanging capacity in the stretch which is important for the work of the vehicle chassis automotive and similar and precision drilling capacity are not considered.
[005] Regarding the stretching flanging ability to reach high strength, a method of controlling the steel structure of the steel plate to improve local elongation is also described, and Non-Patent Document 1 describes that controlling inclusions, making the structures uniform, and also decreasing the difference in hardness between the structures are effective actions for the ability to bend and the ability to flange in the stretch. In addition, Non-Patent Document 2 describes a method in which the finishing temperature of the hot rolling mill, the reduction ratio and the temperature range of the finishing rolling mill are controlled, the recrystallization of the austenite is promoted, the
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3/68 development of a laminated texture is suppressed, and the crystal orientations are randomized, in order to improve strength, ductility and the ability to flange in the stretch. [006] From Non-Patent Documents 1 and 2 it is conceivable that the metal structure and the laminated texture are made uniform, thus making it possible to improve the flanging capacity in the stretch, but the reach of the precision drilling capacity and the capacity flange stretching is not considered.
Prior Art Document
Patent Document
Patent Document 1: Japanese Patent Publication No. H3-2942
Patent Document 2: Japanese Patent Publication No. H5-14764
Patent Document 3: Japanese Patent Publication No. H2-19173
Non-Patent Document
Non-Patent Document 1: K. Sugimoto et al., [ISIJ International] (2000) Vol. 40, pg. 920
Non-Patent Document 2: Kishida, [Nippon Steel Technical Report] (1999) No. 371, pg. 13
Description of the Invention Problems to be solved by the Invention [007] Thus, the present invention is developed in consideration of the problems described above, and aims to provide a cold-rolled steel sheet having high strength and having excellent stretching flanging capabilities and precision drilling capacity and a production method capable of producing the steel sheet inexpensively and stably.
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Means to Solve the Problems [008] The present inventors have optimized components and conditions for the production of a high-strength cold-rolled steel plate and controlled the steel plate structures, in order to be successful in producing a steel plate having excellent resistance. , stretch flanging capacity and precision drilling capacity. The essence is as follows.
[009] A high strength cold rolled steel sheet having excellent stretch flanging capacity and precision drilling capacity contains:
in mass%,
C: greater than 0.01% to 0.4% or less;
Si: not less than 0.001% or more than 2.5%;
Mn: not less than 0.001% or more than 4%;
P: 0.001 to 0.15% or less;
S: 0.0005 to 0.03% or less;
Al: not less than 0.001% or more than 2%;
N: 0.0005 to 0.01% or less; and the balance being composed of iron and the inevitable impurities, in which in a range of 5/8 to 3/8 in the thickness of the plate from the surface of the steel plate, the average value of the pole densities of the group of orientations {100 } <011> to {223} <110> represented by the respective crystal orientations of {100} <011>, {116} <110>, {114} <110>, {113} <110>, {112} < 110>, {335} <110>, and {223} <110> is 6.5 or less, and the pole density of the {332} <113> crystal orientation is 5.0 or less, and the metal structure contains , in terms of an area ratio, more than 5% perlite, the sum of bainite and martensite limited to
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5/68 less than 5%, and the balance composed of ferrite.
[0010] The high strength cold rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity as per item [1], in which also the expert phase Vickers hardness is no less than 150 HV or more than 300 HV.
[0011] The high strength cold rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity according to item 1, in which also the r value in a direction perpendicular to the rolling direction (rC) is 0 , 70 or more, and the r value in a direction at 30 ° from the rolling direction (r30) is 1.10 or less, and the r value in the rolling direction (rL) is 0.70 or more, and the r value in a direction at 60 ° from the rolling direction (r60) is 1.10 or less.
[0012] The high strength cold rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity as per item 1, also contains:
One or two or more types of elements between,
In mass%,
Ti: not less than 0.001% or more than 0.2%,
Nb: not less than 0.001% or more than 0.2%,
B: not less than 0.0001% nor more than 0.005%, Mg: not less than 0.0001% nor more than 0.01%, Rem: not less than 0.0001% nor more than 0.1%, Ca : not less than 0.0001% nor more than 0.01%, Mo: not less than 0.001% nor more than 1%, Cr: not less than 0.001% nor more than 2%,
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V: not less than 0.001% nor more than 1%,
Ni: not less than 0.001% nor more than 2%, Cu: not less than 0.001% nor more than 2%, Zr: not less than 0.0001% nor more than 0.2%, W: not less than 0.001% no more than 1%, As: no less than 0.0001% nor more than 0.5%, Co: no less than 0.0001% nor more than 1%, Sn: no less than 0.0001% nor more than 0.2%, Pb: not less than 0.001% nor more than 0.1%, Y: not less than 0.001% nor more than 0.1%, and Hf: not less than 0.001% nor more than 0.1% , [0013] The high strength cold rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity according to item 1, in which also when the steel sheet whose thickness is reduced to 1.2 mm with the central portion of the plate thickness adjusted to the center is drilled by a circular drill with Φ 10 mm and a circular mold with 1% clearance, the percentage of the shear surface of a perforated edge surface becomes 90% or more.
[0014] The high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity as per item [1], in which a hot dip galvanized layer or a galvanized layer is provided on the surface by hot immersion on.
[0015] The method of producing a cold-rolled steel sheet of high strength having excellent stretching flanging capacity and precision drilling capacity includes:
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7/68 in a steel bar containing:
in mass%,
C: greater than 0.01% to 0.4% or less;
Si: not less than 0.001% or more than 2.5%;
Mn: not less than 0.001% or more than 4%;
P: 0.001 to 0.15% or less;
S: 0.0005 to 0.03% or less;
Al: not less than 0.001% or more than 2%;
N: 0.0005 to 0.01% or less; and the balance being composed of iron and the inevitable impurities, perform a first hot lamination in which the lamination at a reduction rate of 40% or more is performed once or more in a temperature range of not less than 1000 ° C no more than 1200 ° C;
adjust the diameter of the austenite grain to 200 μΐη or less by the first hot rolling;
perform a second hot lamination in which lamination at a reduction rate of 30% or more is performed in a pass at least once in a temperature region of not less than the temperature T1 determined by Expression (1) below + 30 ° C not more than T1 + 200 ° C;
adjust the total reduction ratio in the second hot rolling to 50% or more;
perform the final reduction at a reduction rate of 30% or more on the second hot rolling and then start the cold pre-rolling cooling in such a way that the waiting time t seconds satisfies Expression (2) below;
adjust the average cooling rate in cold pre-lamination cooling to 50 ° C / s or more and adjust the temperature change
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8/68 ture to fall in a range of not less than 40 ° C or more than 140 ° C;
perform cold rolling at a reduction rate of not less than 40% or more than 80%;
perform the heating up to the temperature range of 750 to 900 ° C and perform for a time of not less than 1 second or greater than 300 seconds;
perform primary post-cold rolling cooling to a temperature region of not less than 580 ° C or more than 750 ° C at an average cooling rate of not less than 1 ° C / s or more than 10 ° C / s ;
perform the hold for not less than 1 second and not more than 1000 seconds on the condition that the rate of temperature decrease becomes 1 ° / C / s or less; and perform secondary post-cold rolling cooling at an average cooling rate of 5 ° C / s or less.
T1 (° C) = 850 + 10 x (C + N) x Mn + 350 x Nb + 250 xTi + 40 x B + 10 x Cr + 100 x Mo + 100 x V ··· Expression (1) [0016] Here, C, N, Mn, Nb, Ti, B, Cr, Mo, and V each represent the element content (% by mass).
t <2.5 x t1 ··· Expression (2).
Here, t1 is obtained by Expression (3) below.
t1 = 0.001 x ((Tf - T1) x P1 / 100) ² - 0.109 x ((Tf - T1) x P1 / 100) + 3.1 ··· Expression (3) [0017] Here, in Expression (3 ) above, Tf represents the temperature of the steel bar obtained after the final reduction at a reduction ratio of 30% or more, and P1 represents the reduction ratio of the final reduction to 30% or more.
[0018] The production method of cold rolled steel sheet of
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9/68 high strength having excellent stretching flanging capacity and precision drilling capacity according to item 7, in which the total reduction ratio in a temperature range of less than T1 + 30 ° C is 30% or less.
[0019] The production method of high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity according to item 7, in which the waiting time t seconds also satisfies Expression (2a) below.
t <t1 ··· Expression (2a) [0020] The production method of high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity according to item 7, in which the waiting t seconds also satisfies Expression (2b) below.
t1 <t <t1 x 2.5 ··· Expression (2b) [0021] The method of producing high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity according to item 7 , in which the cold pre-lamination cooling is initiated between the lamination chairs.
[0022] The production method of high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity according to item 7, also includes:
perform winding at 650 ° C or less to obtain a
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10/68 hot rolled steel sheet after cold pre-lamination cooling and before cold rolling.
[0023] The production method of the high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity according to item 7, in which when the heating is carried out to the temperature range of 750 to 900 ° C after cold rolling, the average heating rate of not less than room temperature or greater than 650 ° C is adjusted to HR1 (° C / s) expressed by Expression (5) below, and the average rate of heating from 650 ° C to 750 to 900 ° C is set to HR2 (° C / s) expressed by Expression (6) below.
HR1> 0.3 ... Expression (5)
HR2 <0.5 x HR1 ... Expression (6) [0024] The production method of high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity as per item 7, also includes:
perform hot-dip galvanizing on the surface.
[0025] The production method of high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity according to item 14, also includes:
carry out a bonding treatment at 450 to 600 ° C after the execution of hot dip galvanizing.
Effect of the Invention [0026] In accordance with the present invention, it is possible to provide
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11/68 a high-strength steel plate having excellent stretching flanging capacity and precision drilling capacity. When this steel plate is used, particularly, the performance when the high strength steel plate is used improves, the cost is decreased, etc., resulting in the fact that the industrial contribution is very important.
Brief Description of the Drawings [0027] FIG. 1 is a view showing the relationship between the average value of pole densities in the orientation group {100} <011> to {223} <110> and the tensile strength χ hole expansion ratio;
[0028] FIG. 2 is a view showing the relationship between the pole density of the {332} <113> orientation group and the tensile strength χ the hole expansion ratio;
[0029] FIG. 3 is a view showing the relationship between the value r in a direction perpendicular to the rolling direction (rC) and the tensile strength χ the hole expansion ratio;
[0030] FIG. 4 is a view showing the relationship between the r value in the direction at 30 ° from the rolling direction (r30) and the tensile strength χ the hole expansion ratio;
[0031] FIG. 5 is a view showing the relationship between the value r in the rolling direction (rL) and the tensile strength χ the hole expansion ratio;
[0032] FIG. 6 is a view showing the relationship between the r value in the 60 ° direction from the rolling direction (r60) and the tensile strength χ the hole expansion ratio;
[0033] FIG. 7 shows the relationship between a hard phase fraction and the percentage of shear surface of a perforated edge surface;
[0034] FIG. 8 shows the relationship between the austenite grain diameter after roughing rolling and the r-value in the perpendicular directionPetition 870180165233, of 12/19/2018, p. 14/83
12/68 lar to the rolling direction (rC);
[0035] FIG. 9 shows the relationship between the austenite grain diameter after roughing rolling and the r value in the direction at 30 ° from the rolling direction (r30);
[0036] FIG. 10 shows the relationship between the number of times of the lamination at 40% or more in the roughing lamination and the austenite grain diameter of the roughing lamination;
[0037] FIG. 11 shows the relationship between the reduction ratio at T1 + 30 to T1 + 150 ° C and the mean pole densities in the {100} <011> to {223} <110> group;
[0038] FIG. 12 is an explanatory view of a continuous hot rolling line;
[0039] FIG. 13 shows the relationship between the reduction ratio at T1 + 30 to T1 + 150 ° C and the pole density of the crystal orientation {332} <113>; and [0040] FIG. 14 shows the relationship between the percentage of surface shear and the χ resistance to the bore expansion ratio of the steels of the present invention and comparative steels.
Mode for Carrying Out the Invention [0041] Hereinafter, the content of the present Invention will be explained in detail.
Crystal orientation [0042] In the present invention, it is particularly important that in the range of 5/8 to 3/8 in the thickness of the plate from the surface of the steel plate, the average value of the pole densities of the orientation group {100} <011> to {223} <110> is 6.5 or less and the pole density of the {332} <113> crystal orientation is 5.0 or less. As shown in FIG. 1, since the average value of the orientation group {100} <011> to {223} <110> when X-ray diffraction is performed in the plate thickness range from 5/8 to 3/8 in the plate thickness The
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13/68 from the surface to obtain the pole densities of the respective orientations, either 6.5 or less (desirably 4.0 or less), the tensile strength χ the hole expansion ratio> 30000 that is required to work a lower part chassis to be required immediately is satisfied. When the average value is greater than 6.5, the anisotropy of the mechanical properties of the steel sheet becomes extremely strong, and also the ability to expand the hole in a certain direction is improved, but the material in a direction other than that deteriorates significantly , resulting in the fact that it becomes impossible to satisfy the tensile strength χ the bore expansion ratio> 30000 that is necessary to work a lower part of the chassis. On the other hand, when the average value becomes less than 0.5, which is difficult to achieve in a common continuous hot rolling process, deterioration of the hole expansion capacity is considered.
[0043] The guidelines {100} <011>, {116} <110>, {114} <110>, {113} <110>, {112} <110>, {335} <110>, and {223 } <110> are included in guidance group {100} <011> to {223} <110>.
[0044] The pole density is synonymous with the random X-ray intensity ratio. The polar density (X-ray random intensity ratio) is a numerical value obtained by measuring the X-ray intensities of a standard sample without accumulation in a specific orientation and a test sample under the same conditions or X-ray diffraction or similar and dividing the X-ray intensity obtained from the test sample by the X-ray intensity of the standard sample. This pole density is measured using X-ray diffraction equipment EBSD (Electron Back Scatterinq Diffraction), or similar. In addition, it can also be measured by an EBSP method (Electron Back Scatterinq Pattern) or an ECP method (Electron Channelinq Pattern). Can be obtained from a tridi texture
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14/68 monthly calculated using a vector method based on a pole figure of {110}, or it can also be obtained from a three-dimensional texture calculated by a series expansion method using a plurality (preferably three or more) pole figures outside the pole figures of {110}, {100}, {211}, and {310}.
[0045] For example, for the pole density of each of the crystal orientations described above, each of the intensities of (001) [1-10], (116) [1-10], (114) [1-10 ], (113) [1-10], (112) [1-10], (335) [110], and (223) [1-10] to a cross section φ2 = 45 ° in three-dimensional texture (ODF) can be used in the state.
[0046] The average value of the pole densities of the orientations group {100} <011> to {223} <110> is the arithmetic mean of the pole densities of the respective orientations described above. When it is impossible to obtain the intensities of all the orientations described above, the arithmetic mean of the pole densities of the respective orientations of {100} <011>, {116} <110>, {114} <110>, {112} <110> , and {223} <110> can also be used as a substitute.
[0047] Furthermore, due to a similar reason, since the pole density of the crystal orientation {332} <113> of a flat plate in the range of 5/8 to 3/8 in the thickness of the plate from the surface of the steel cap is 5.0 or less (desirably 3.0 or less) as shown in FIG. 2, the tensile strength χ the bore expansion ratio> 30000 that is required to work a part to be required immediately is satisfied. When it is greater than 5.0, the anisotropy of the mechanical properties of the steel sheet becomes extremely strong, and also the ability to bore in only one direction is improved, but the material in a direction other than that deteriorates significantly, resulting in the fact that it becomes impossible to satisfactorily guarantee the tensile strength χ the bore expansion ratio> 30000 that is necessary to work a part
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15/68 bottom of the chassis. On the other hand, when the pole density becomes less than 0.5, which is difficult to achieve in a common continuous hot rolling process, deterioration of the hole expansion capacity is considered.
[0048] The reason why the pole densities of the crystal orientations described above are important for improving the hole expansion capacity is not necessarily obvious, but it is differently related to the sliding behavior of the crystal at the time of the hole expansion work.
[0049] Regarding the sample to be subjected to X-ray diffraction, the steel sheet is reduced in thickness to a predetermined sheet thickness from the surface by mechanical polishing or similar, and the next tension is removed by chemical polishing, electrolytic polishing, or similar, and at the same time, the sample is adjusted according to the method described above in such a way that, in the range of 3/8 to 5/8 in the thickness of the plate, a suitable plane becomes the plane of measurement, and it is measured.
[0050] Obviously, the limitation of pole densities described above is satisfied not only in the vicinity of 1/2 the thickness of the sheet, but also in as many ranges of thickness ranges as possible, and thus the hole expansion capacity is also improved . However, the range of 3/8 to 5/8 in the thickness of the plate from the surface of the steel plate is measured, in order to make it possible to represent the material property of the entire plate. Thus, 5/8 to 3/8 of the plate thickness is prescribed as the measuring range.
[0051] Incidentally, the crystal orientation represented by {hkl} <uvw> means that the normal direction to the plane of the steel plate is parallel to <hkl> and the rolling direction is parallel to <uvw>. In relation to the crystal orientation, normally, the vertical orientation to the plate plane is represented by [hkl] or {hkl} and the parallel orientation
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The direction of lamination is represented by (uvw) or <uvw>. {hkl} and <uvw> are generic terms for equivalent plans, and [hkl] and (uvw) each indicate an individual crystal plane. That is, in the present invention, a centered body cubic structure is desired, and so, for example, the planes (111), (-111), (1-11), (11-1), (-1-11 ), (-111), (1-1-1), and (-1-1-1) are equivalent to make it impossible to make them different. In such a case, these guidelines are generically referred to as {111}. In an ODF representation, [hkl] (uvw) is also used to represent orientations of other low symmetrical crystal structures, and so it is common to represent each orientation as [hkl] (uvw), but in the present invention, [hkl] (uvw ) and {hkl} <uvw> are synonymous with each other. Measurement of crystal orientation by an X-ray is performed according to the method described in, for example, Cullity, Elements of X-ray Diffraction, new edition (published in 1986, translated by MATSUMURA, Gentaro, published by AGNE Inc. ) on pages 274 to 296.
(r value) [0052] The r value in a direction perpendicular to the rolling direction (rC) is important in the present invention. That is, as a result of serious research, the present inventors have found that good hole expansion capacity cannot always be achieved even when only the pole densities of the various crystal orientations described above are adequate. As shown in FIG. 3, simultaneously with the pole densities described above, rC must be 0.70 or more. The upper limit of rC is not determined in particular, but if (rC) is 1.10 or less, a more excellent hole expansion capacity can be obtained.
[0053] The r value in the 30 ° direction from the rolling direction (r30) is important in the present invention. That is, as a result of careful investigation, the present inventors have found that a
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17/68 good hole expansion capacity cannot always be obtained when X-ray intensities from the various crystal orientations described above are adequate. As shown in FIG. 4, simultaneously with the X-ray intensities described above, r30 needs to be 1.10 or less. The lower limit of r30 is not determined in particular, but if r30 is 0.70 or more, a more excellent hole expansion capacity can be obtained.
[0054] As a result of the refined investigation, the present inventors have also found that in addition to the random X-ray intensity ratios of the various crystal orientations described above, rC, and r30, as shown in FIG. 5 and FIG. 6, the r value in the rolling direction (rL) and the r value in a direction at 60 ° from the rolling direction (r60) and the r value in the rolling direction (rL) and the r value in one direction at 60 ° from the rolling direction (r60) are rL> 0.70 and r60 <1.10 respectively, the tensile strength x the bore expansion ratio> 30000 is best satisfied.
[0055] The upper limit of the rL value described above and the lower limit value of the r60 value are not determined in particular, but if rL is 1.00 or less and r60 is 0.90 or more, a more bore expansion capacity excellent can be obtained.
[0056] The r-values described above are assessed by a tensile test using a J IS No. 5 tensile specimen. The tensile stress only has to be assessed in a range of 5 to 15% in the case of a sheet of high-strength steel normally, and in a uniform elongation range. By the way, it has been known that texture and r values are generally correlated with each other, but in the present invention, the limitation already described in the pole densities of the crystal orientations and the limitation in r values are not synonymous with each other, and unless both limitations are met simultaneously, good expansion capacity cannot be achieved.
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Metallic Structure [0057] Next, the metallic structure of the steel sheet of the present invention will be explained. The metallic structure of the steel sheet of the present invention contains, in terms of area ratio, more than 5% perlite, the sum of bainite and martensite limited to less than 5%, and the composite balance of ferrite. In high strength steel plate, to increase its strength, a complex structure obtained by providing a second high strength phase in a ferrite phase is often used. The structure is usually composed of ferrite-perlite, ferrite-bainite, ferrite-martensite, or the like, and while the fraction of the second phase is determined, as there are more transformation phases at low temperature each having the second hard phase whose hardness is severe, the strength of the steel plate improves. However, the harder the low temperature transformation phase, the more prominent the difference in ferrite ductility, and during drilling, the stress concentrations of the ferrite and the low temperature transformation phase occur, so that the fracture surface appears in a perforated portion and thus the accuracy of the perforation deteriorates.
[0058] Particularly, when the sum of the bainite and martensite fractions becomes 5% or more in terms of area ratio, as shown in FIG. 7, the percentage of shear surface being a rough precision drilling pattern of high strength steel sheet falls below 90%. In addition, when the perlite fraction becomes 5% or less, the resistance decreases to fall below 500 MPa being the standard for high strength cold rolled steel sheet. Thus, in the present invention, the sum of the bainite and martensite fractions is adjusted to less than 5%, the perlite fraction is adjusted to be greater than 5%, and the balance is adjusted to ferrite. Bainite and martensite can also be 05. Thus, as a metallic structure
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19/68 ca of the steel sheet of the present invention, a shape made of perlite and ferrite, a shape containing perlite and ferrite, and also one of bainite and martensite, and a shape containing perlite and ferrite and also both between bainite and martensite are designed.
[0059] Incidentally, when the fraction of perlite becomes larger, the resistance increases, but the percentage of the surface shear decreases. The perlite fraction is desirably less than 30%. Even if the perlite fraction is 30%, 90% or more of the surface shear percentage can be achieved, but as long as the perlite fraction is less than 30%, 95% or more of the surface shear percentage can be achieved and the precision drilling capacity improves even more.
Vickers hardness of the perlite phase [0060] The hardness of the perlite phase affects the tensile and precision drilling properties. As the Vickers hardness of the perlite phase increases, the strength improves, but when the Vickers hardness of the perlite phase exceeds 300 HV, the precision drilling deteriorates. In order to achieve a good balance of hole expansion capacity and precision drilling, the Vickers hardness of the pearlite phase is adjusted to not less than 150 HV or more than 300 HV. Incidentally, Vickers hardness is measured using microVickers measuring equipment.
[0061] In addition, in the present invention, the precision drilling capacity of the steel sheet is assessed by the percentage of surface shear of a perforated edge surface [= length of the shear surface / (length of the shear surface + length fracture of the surface)]. The steel plate whose thickness is reduced to 1.2 mm with a central portion of the plate thickness adjusted to the center is drilled by a circular drill with Φ 10 mm and a circular mold with 1% clearance, and are
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20/68 measurements were made of the length of the shear surface and the length of the surface fracture in relation to the total circumference of the surface of the perforated edge. Then, the minimum value of the length of the shear surface across the circumference of the perforated edge surface is used to define the percentage of surface shear.
[0062] Incidentally, the central portion of the plate's thickness is more likely to be affected by central segregation. It is conceivable that if the steel sheet has predetermined precision drilling capacity in the central portion of the sheet thickness, the precision drilling capacity can be satisfied for the entire sheet thickness.
[0063] Chemical components of the steel sheet [0064] The following will explain the reasons for limiting the chemical components of the high-strength cold-rolled steel sheet of the present invention. Incidentally,% of a grade is% by mass.
C: greater than 0.01 to 0.4% [0065] C is an element that contributes to increase the strength of the base material, but it is also an element that generates iron-based carbides such as cementite (Fe3C) to be the starting point of the fracture when expanding the hole. When the C content is 0.01% or less, it is not possible to obtain the effect of improving the resistance by reinforcing the structure by a transformation phase at low temperature. When greater than 0.4%, the central segregation becomes prominent and the amount of iron-based carbides such as cementite (Fe3C) is increased to be the starting point for fractures in a secondary surface shear at the time of drilling, resulting in the fact that the drilling capacity deteriorates. Therefore, the C content is limited to the range greater than
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21/68
0.01% to 0.4% or less. In addition, when balance with ductility is considered together with improved strength, the C content is desirably 0.20% or less.
Si: 0.001 to 2.5% [0066] Si is an element that contributes to increase the strength of the base material and also has a role as a deoxidizing material for molten steel, and thus foot added according to need. As for the Si content, when 0.001% or more is added, the effect described above is presented, but when more than 2.5% are added, the effect of contributing to increase the resistance is saturated. Therefore, the Si content is limited to the range of not less than 0.001% or more than 2.5%. In addition, when more than 0.1% Si is added, Si, with the increase in its content, suppresses the precipitation of iron-based carbides such as cementite in the material structure and contributes to improving strength and improving capacity hole expansion. In addition, when Si exceeds 1%, the effect of suppressing the precipitation of iron-based carbides is saturated. Thus, the desirable range of Si content is more than 0.1 to 1%.
Mn: 0.01 to 4% [0067] Mn is an element that contributes to improve the strength by reinforcing the solid solution and reinforcing the quench and is added as needed. When the Mn content is less than 0.01%, this effect cannot be achieved, and when more than 4% are added, this effect is saturated. For this reason, the Mn content is limited to a range of not less than 0.01% or more than 4%. In addition, to suppress the occurrence of hot fractures by S, when elements other than Mn are not sufficiently added, the amount of Mn that allows the content of Mn ([Mn]) and the content of S ([S]) satisfying [Mn] / [S]> 20 in mass% is desirably added. In addition, Mn is an element that, with the increase in its content, expands the
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22/68 temperature from the austenite region to a low temperature side, improves the hardening capacity, and facilitates the formation of a transformation structure in continuous cooling with excellent deburring. When the Mn content is less than 1%, this effect is not easily seen, and thus 1% or more is desirably added.
P: 0.001 to 0.15% or less [0068] P is an impurity contained in cast iron, and is an element that is segregated at the grain edges and decreases toughness with an increase in its content. For this reason, the most desirable P content is the lowest possible, and when more than 0.15% is contained, P adversely affects the workability and the welding capacity, and so P is adjusted to 0.15% or any less. Particularly, when the hole expansion capacity and the welding capacity are considered, the P content is desirably 0.02% or less. The lower limit is set to 0.001% applicable to current common refineries (including secondary refineries).
S: 0.0005 to 0.03% or less [0069] S is an impurity contained in cast iron, and it is an element that not only causes fractures when hot rolling, but also generates an A-based inclusion that deteriorates the ability to expand the hole when its content is very high. For this reason, the S content should be decreased as much as possible, but as the S content is 0.03% or less, it falls within a tolerable range, so the S content is adjusted to 0 , 03% or less. However, it is desirable that the S content, when the bore expansion capacity to such an extent is necessary, is preferably 0.01% or less, and is more preferably 0.005% or less. The lower limit is set to 0.0005% applicable to the current common refining (including secondary refining).
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23/68
Al: 0.001 to 2% [0070] For the deoxidation of molten steel in a steel refining process, 0.001% or more of Al needs to be added, but the upper limit is adjusted to 2% because an increase in cost is caused. In addition, when Al is added in very large quantities, non-metallic inclusions are increased to cause ductility and toughness to deteriorate, so that the Al content is desirably 0.06% or less. It is also desirably 0.04% or less. In addition, to obtain the effect of suppressing the precipitation of iron-based carbide such as cementite in the material structure, similarly to Si, 0.016% or more are desirably added. Thus, the content of Al is desirably not less than 0.016% or more than 0.04%.
N: 0.0005 to 0.01% or less [0071] The N content should be decreased as much as possible, but once it is 0.01% or less, it falls within a tolerable range. In terms of resistance to aging, however, the N content is also desirably adjusted to 0.005% or less. The lower limit is set to 0.0005% applicable to the current common refining (including secondary refining).
[0072] In addition, as elements that have been used so far to control inclusions and to make precipitates thin so that the hole expansion capacity can be improved, one type or two types or more types of elements between Ti, Nb, B, Mg, REM, Ca, Mo, Cr, V, W, Zr, Cu, Ni, As, Co, Sn, Pb, Y, and Hf can be contained. [0073] Ti, Nb, and B improve the material through mechanisms for fixing carbon and nitrogen, reinforcing precipitation, controlling the structure, and the like, so that, as needed, 0.001% of Ti, 0.001% of Nb, and 0.0001% or more of B are desirably added. The Ti content is preferably 0.01%, and the Ti content
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24/68 Nb is preferably 0.005% or more. However, even when they are added excessively, no significant effect is achieved to the contrary, causing the working capacity and production capacity to deteriorate, so that the upper limit of Ti is adjusted to 0.2%, the upper limit of Nb is adjusted to 0.2%, and the upper limit of N is adjusted to 0.005%. The B content is preferably 0.003% or less.
[0074] Mg, Rem, and Ca are important additive elements to render inclusions harmless. The lower limit of each element is set to 0.0001%. As its preferred lower limits, Mg is preferably 0.0005%, Rem is preferably 0.001%, and Ca is preferably 0.0005%. On the other hand, its excessive additions lead to deterioration of cleanliness, so that the upper limit of Mg is adjusted to 0.01%, the upper limit of Rem is adjusted to 0.1%, and the upper limit of Ca is adjusted to 0.01%. The Ca content is preferably 0.01% or less.
[0075] Mo, Cr, Ni, W, Zr, and As each have the effect of increasing mechanical strength and improving the material, so that according to the need, 0.001% or more of each element between Mo , Cr, Ni, and W is desirably added, and 0.0001% or more of each element between Zr and As is desirably added. As its lower limits, the Mo content is preferably 0.01%, the Cr content is preferably 0.01%, the NI content is preferably 0.05% and the W content is preferably 0.01%. However, when they are added excessively, on the contrary the working capacity is deteriorated, so that the upper limit of Mo is adjusted by 1.0%, the upper limit of Cr is adjusted by 2.0%, the upper limit of NI is adjusted at 2.0%, the upper limit of W is adjusted at 1.0%, the upper limit of Zr is adjusted at 0.2%, and the upper limit of As is adjusted at 0.5%. The Zr content is preferably 0.05% or less.
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25/68 [0076] V and Cu, similarly to Nb and Ti, are additive elements that are effective in reinforcing precipitation, have a smaller deterioration margin of local ductility attributable to reinforcement by adding these elements, and are more effective than Nb and Ti when high strength and better hole expansion capacity are required. Therefore, the lower limits of V and Cu are adjusted to 0.001%. They are each preferably 0.01% or more. Excessive additions lead to deterioration of work capacity, so that the upper limit of V is adjusted by 1.0% and the upper limit of Cu is adjusted by 2.0%. V is preferably 0.5% or less.
[0077] Co significantly increases the transformation point from γ to a, so as to be an effective element when a hot rolling to an Are point or less is directed in particular. To achieve this effect, the lower limit is set to 0.0001%. It is preferably 0.001% or more. However, when it is very large, the welding capacity deteriorates, so the upper limit is adjusted to 1.0%. It is preferably 0.1% or less.
[0078] Sn and Pb are effective elements to improve the wetting capacity and the adhesion capacity of a coating property, and 0.0001% and 0.001% or more can be added respectively. Sn is preferably 0.001% or more. However, when they are in higher quantities, a failure at the time of production is likely to occur, and a decrease in toughness is also caused, so that the upper limits are adjusted by 0.2% and 0.1% respectively. Sn is preferably 0.1% or less.
[0079] Y and Hf are effective elements for improving corrosion resistance, and 0.001% to 0.10% can be added. When their levels are less than 0.001% each, no effect is confirmed, and when they are added to exceed 0.10%, ca
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26/68 puncture expansion hole deteriorates, as long as the upper limits are set at 0.10%.
Surface Treatment [0080] Incidentally, the high-strength cold-rolled steel sheet of the present invention may also include, on the surface of the cold-rolled steel sheet explained above, a hot-dip galvanized layer made by a galvanizing treatment by hot dipping, and also a galvanized layer bonded by performing a bonding treatment after galvanizing. Even if these galvanized layers are included, the excellent stretch flanging capacity and the precision drilling capacity of the present invention are not impaired. In addition, even if any of the treated surface layers made of film formation by organic coating, film lamination, treatment with organic salts / inorganic salts, treatment without chromium, etc., is included, the effect of the present invention can be obtained.
Steel sheet production method [0081] Next, the steel sheet production method of the present invention will be explained.
[0082] In order to achieve excellent stretching and precision drilling capacity, it is important to form a texture that is random in terms of pole densities and produce a steel sheet that satisfies the conditions of the r values in the respective directions. Details of the production conditions to satisfy these conditions simultaneously will be described below.
[0083] The production method prior to hot rolling is not particularly limited. That is, subsequent to the melting by a vat oven, an electric oven, or similar, it is only necessary to perform the secondary refining in a varied way, thus carrying out the adjustment in order to have the components described above and then execute the lin
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27/68 gutter by normal continuous casting, or by the conventional casting method, or by casting thin plates, or similar. In the case of continuous casting, it is possible that a cast plate is cooled once to a low temperature and then reheated to then be subjected to hot rolling, or it is also possible that the casting plate is subjected to hot rolling continuously. Scrap can also be used as a raw material.
First hot rolling [0084] A plate extracted from a heating furnace is subjected to a rough rolling process and is initially hot rolled to undergo rough rolling, thus obtaining a rough bar. The steel sheet of the present invention must satisfy the following requirements. First, the grain diameter of the austenite before finishing lamination is important. The grain diameter of the austenite before the finishing lamination is desirably small, and the grain diameter of the austenite of 200 pm or less contributes greatly to making the crystal grains thin and the homogenization of the crystal grains, thus making it possible to disperse finely and evenly the martensite to be formed in a later process.
[0085] To obtain the austenite grain diameter of 200 pm or less before the finishing lamination, it is necessary to perform the lamination at a reduction rate of 40% or more or more in the roughing lamination in a temperature region from 1000 to 1200 ° C.
[0086] The grain diameter of the austenite before the finishing lamination is desirably 100 pm or less, and to obtain this grain diameter, the lamination at 40% or more is performed twice or more. However, when in the roughing lamination the reduction is
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28/68 greater than 70% and lamination is performed more than 10 times, there is a concern that the lamination temperature will decrease or excessive scale will be generated.
[0087] In this way, when the grain diameter of the austenite before the finishing lamination is set to 200 pm or less, the recrystallization of the austenite is promoted in the finishing lamination and, particularly, the rL value and the r30 value are controlled, resulting in the fact that it is effective for improving the hole expansion capacity.
[0088] This is supposed to be because the austenite grain edge after roughing lamination (ie, before finishing lamination) functions as one of the recrystallization cores during the finishing lamination. The diameter of the austenite grain after roughing lamination is confirmed so that a steel sheet part before being subjected to finishing lamination is cooled as quickly as possible (which is cooled to 10 ° C / s or more, for example), and the cross section of the steel sheet is subjected to caustication to make the edges of the austenite grains appear, and the edges of the austenite grains are observed by an optical microscope. On that occasion, at 50 or more magnifications, the diameter of the austenite grain from 20 visual fields or more is measured by image analysis or by the method of counting points.
[0089] In order for rC and r30 to satisfy the predetermined values described above, the diameter of austenite grain after roughing lamination, that is, before finishing lamination, is important. As shown in FIG. 8 and in FIG. 9, the austenite grain diameter before the finishing lamination is desirably small, and it has been found that as long as it is 200 pm or less, rC and r30 satisfy the values described above.
Second hot rolling
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29/68 [0090] After the roughing lamination process (first hot lamination) is completed, a finishing lamination process is initiated with the second hot lamination. The time between the end of the roughing rolling process and the beginning of the finishing rolling process is desirably set to 150 seconds or less.
[0091] In the finishing lamination process (second hot lamination), the start temperature of the finishing lamination is desirably set to 1000 ° C or higher. When the start temperature of the finishing lamination is less than 1000 ° C, in each pass of the finishing lamination, the temperature of the lamination to be applied to the raw bar to be laminated is reduced, the reduction is performed, in a temperature region of non-recrystallization, the texture develops, and thus the isotropy deteriorates.
[0092] Incidentally, the upper limit of the start temperature of the finishing lamination is not limited and particular. However, when it is 1150 ° C or more, a bubble to be the starting point for a scaly rod-shaped scale defect is likely to occur between the base steel sheet and the surface scale prior to finishing lamination and between passes, and thus the start temperature of the finishing laminate is desirably below 1150 ° C.
[0093] In finishing lamination, the temperature determined by the chemical composition of the steel sheet is set to T1, and in a temperature region of not less than T1 + 30 ° C nor more than T1 + 200 ° C, the lamination at 30% or more is performed on a pass at least once. In addition, in the finishing lamination, the total reduction ratio is adjusted to 50% or more. Satisfying this condition, in the range of 5/8 to 3/8 in the thickness of the plate from the surface of the steel plate, the average value of the pole densities of the
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30/68 orientation group {100} <011> to {223} <110> becomes 6.5 or less and the pole density of the crystal orientation {332} <113> becomes 5.0 or less. This makes it possible to guarantee excellent flanging capacity and precision drilling capacity.
[0094] Here, T1 is the temperature calculated by Expression (1) below.
T1 (° C) = 850 + 10 x (C + N) x Mn + 350 x Nb + 250 xTi + 40 x B + 10 x Cr + 100 x Mo + 100 x V ··· Expression (1) [0095] C, N, Mn, Nb, Ti, B, Cr, Mo, and V each represent the content of the element (% by mass). Incidentally, when Ti, B, Cr, Mo, and V are not contained, the calculation is performed in a way that considers Ti, B, Cr, Mo, and V as zero.
[0096] In FIG. 10 and FIG. 11 shows the relationship between the reduction ratio in each temperature region and the pole density in each orientation. As shown in FIG. 10 and FIG. 11, a heavy reduction in the temperature region of not less than T1 + 30 ° C or more than T1 + 200 ° C and a slight reduction in T1 or more and less than T1 + 30 ° C controls the mean value of the pole densities of the orientation group {100} <011> to {223} <110> and the pole density of the crystal orientation {332} <113> in the range 5/8 to 3/8 in the plate thickness from the plate surface steel, and thus the bore expansion capacity of the final product is drastically improved, as shown in Tables 2 and 3 of the Examples to be described later.
[0097] The temperature T1 itself is obtained empirically. The present invention has learned empirically from experiments that recrystallization in the austenite region of each steel is promoted based on temperature T1. In order to obtain a better hole expansion capacity, it is important to accumulate tension through heavy reduction, and the total reduction ratio of 50% or more is essential in the finishing lamination.
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31/68 ment. In addition, it is desired to take a reduction of 70% or more, and on the other hand, if the reduction ratio is greater than 90% is taken, the guarantee of temperature and the addition of excessive lamination is added as a result.
[0098] When the ratio of total reduction in the temperature region of not less than T1 + 30 ° C nor more than T1 + 200 ° C is less than 50%, the rolling tension to be accumulated during hot rolling is not enough and the recrystallization of austenite does not proceed Therefore, the texture develops and the isotropy deteriorates. When the total reduction ratio is 70% or more, a sufficient isotropy can be obtained even if variations applicable to temperature fluctuation or the like are considered. On the other hand, when the total reduction exceeds 90%, it becomes difficult to obtain the temperature range of T1 + 200 ° C or less due to the heat generated by the work, and also the rolling load increases to cause the risk that lamination becomes difficult to perform.
[0099] In finishing lamination, to promote uniform recrystallization caused by the release of accumulated tension, lamination at 30% or more is performed and a pass at least once at not less than T1 + 30 ° C or greater than T1 + 200 ° C.
[00100] Incidentally, in order to promote uniform recrystallization caused by the release of accumulated tension, it is necessary to suppress the amount of work in a region of temperatures from less than T1 + 30 ° C to as small as possible. To achieve this, the reduction ratio below T1 + 30 ° C is desirably 30% or less. In terms of plate thickness accuracy and plate shape, a reduction ratio of 10% or less is desirable. When the hole expansion capacity is also emphasized, the reduction ratio in the temperature region of less than T1 + 30 ° C is desirably 0%.
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32/68 [00101] The finishing lamination is desirably finished at T1 + 30 ° C or more. If the rate of reduction in the temperature region of T1 or more and less than T1 + 30 ° C is large, the recrystallized austenite grains are elongated, and if the retention time is short, the recrystallization does not go far enough to do so the hole expansion capacity deteriorates. That is, in relation to the production conditions of the invention of the present application, by making the austenite uniformly and finely recrystallized in the finishing lamination, the texture of the product is controlled and the hole expansion capacity is improved.
[00102] The lamination ratio can be obtained by the current calculation performances from the lamination load, sheet thickness measurement, and / or the like. The temperature can actually be measured by a thermometer between the chairs, or it can be obtained by calculating simulation considering the heat generated by the work from the line speed, the reduction ratio, and / or the like. Therefore, it is possible to easily confirm whether the lamination prescribed in the present invention is performed or not.
[00103] The hot laminations carried out as above (first and second hot laminations) are finished at a temperature of the transformation point Ar ₃ or higher. When the hot rolling is finished with Ar ₃ or less, the hot rolling becomes a two-stage rolling of austenite and ferrite, and the build-up for the guidance group {100} <011> to {223} <110> becomes strong. As a result, the hole expansion capacity deteriorates significantly.
[00104] To obtain better strength and satisfy the hole expansion> 30000 by adjusting rL in the rolling direction and r60 in the 60 ° direction of the rolling direction to rL> 0.70 and r60 <1.10 respectively, the generation maximum amount of working heat in the
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33/68 moment of the reduction to less than T1 + 30 ° C nor more than T1 + 200 ° C, that is, the margin of the increased temperature (° C) by the reduction is desirably suppressed to 18 ° C or less. To achieve this, cooling between chairs or similar is desirably applied.
Cold pre-lamination cooling [00105] After the final reduction to a reduction ratio of 30% or more is performed in the finishing lamination, the cold pre-lamination cooling is started in such a way that the waiting time t seconds satisfies the Expression (2) below.
t <2.5 x t1 ··· Expression (2)
Here, t1 is obtained by Expression (3) below.
t1 = 0.001 x ((Tf - T1) x P1 / 100) ² - 0.109 x ((Tf - T1) x
P1 / 100) + 3.1 ··· Expression (3) [00106] Here, in Expression (3) above, Tf represents the temperature of a steel bar obtained after the final reduction at a reduction rate of 30% or more, and P1 represents the reduction ratio of the final reduction to 30% or more.
[00107] Incidentally, the final reduction to a reduction ratio of 30% or more indicates the finely executed lamination between laminations whose reduction ratio becomes 30% or more except laminations in a plurality of passes performed in the finishing lamination, the lamination reduction ratio performed in the final step is the final reduction at a reduction ratio of 30% or more. In addition, when between laminations in a plurality of passes performed on the finishing lamination, the reduction ratio of the lamination performed before the final stage is 30% or more and then the lamination performed before the final stage (lamination at a reduction of 30 % or more) is performed, the lamination whose reduction ratio becomes 30% or more is not performed, the lamination performed before the final step (lamination at a reduction ratio of 30% or more) is the
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34/68 final reduction at a reduction rate of 30% or more.
[00108] In the finishing lamination, the waiting time t seconds until the primary pre-cold lamination cooling starts after the final reduction at a reduction ratio of 30% or more is performed greatly affects the grain diameter of the austenite. That is, it greatly affects the grain fraction of equivalent dimensions and the gross grain area ratio of the steel plate.
[00109] When the waiting time t exceeds t1 χ 2.5, the recrystallization is almost complete, but the crystal grains grow significantly and the hardening of the grains advances, and thus the r and elongation values are decreased.
[00110] The waiting time t seconds also satisfies Expression (2a) below, thus making it possible to preferentially suppress the growth of the crystal grains. Consequently, although the recrystallization does not proceed sufficiently, it is possible to sufficiently improve the elongation of the steel sheet and improve the fatigue property simultaneously.
t <t1 ··· Expression (2a) [00111] At the same time, the waiting time t seconds also satisfies Expression (2b) below, so that the recrystallization advances sufficiently and the crystal orientations are random. Therefore, it is possible to sufficiently improve the elongation of the steel sheet and greatly improve the isotropy simultaneously.
t1 <t <t1 χ 2.5 ··· Expression (2b) [00112] Here, as shown in FIG. 12, in a continuous hot rolling line 1, the steel bar (plate) heated to a predetermined temperature in the heating furnace is laminated in a roughing laminator 2 and in a finishing laminate 3 sequentially to be a laminated steel plate hot 4 having a predetermined thickness, and the hot rolled steel sheet
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35/68 is transported on an exit table 5. In the production method of the present invention, in the roughing lamination process (first hot rolling) performed on roughing laminator 2, the lamination at a reduction rate of 40% or more in the temperature range of not less than 1000 ° C or more than 1200 ° C.
[00113] The raw bar laminated to a predetermined thickness in the roughing laminator 2 in this way is then laminated in the finishing laminator (it is subjected to the second hot lamination) through a plurality of laminating chairs 6 of the finishing laminator 3 to be the hot-rolled steel sheet 4. Then, in the finishing laminator 3, rolling at 30% or more is carried out in a pass at least once in the temperature region of not less than the temperature T1 + 30 ° C nor more than T1 + 200 ° C. In addition, in the finishing laminator 3, the total reduction ratio becomes 50% or more.
[00114] In addition, in the finishing lamination process, after the final reduction to a reduction ratio of 30% or more is performed, the cold pre-lamination cooling is started in such a way that the waiting time t seconds satisfies Expression (2) above or Expression (2a) or (2b) above. The initiation of this primary cold pre-lamination cooling is carried out by cooling nozzles between chairs 10 arranged between two of the respective lamination chairs 6 of the finishing laminator 3, or cooling nozzles 11 arranged on the exit table 5.
[00115] For example, when the final reduction at a reduction rate of 30% or more is performed only on the rolling chair 6 arranged in the front step of the finishing laminator 3 (on the left side of FIG. 12, on the front side of the lamination) and lamination whose reduction ratio becomes 30% or more is not carried out on the lamination chair 6 arranged on the rear side of the finishing laminator
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36/68 (on the right side in FIG. 12, on the back side of the lamination), if the start of the primary cold pre-lamination cooling is performed by the cooling nozzles 11 arranged on the output table 5, a case is sometimes caused wherein the waiting time t seconds does not satisfy Expression (2) above or Expressions (2a) and (2b) above. In such a case, the primary cold pre-lamination cooling is initiated by the cooling nozzles between chairs 10 arranged between the respective two chairs of the lamination chairs 6 of the finishing laminator 3.
[00116] In addition, for example, when the final reduction to a reduction ratio of 30% or more is performed on the laminating chair 6 arranged in the rear step of the finishing laminator 3 (on the right side in FIG. 12, on the subsequent lamination), although the start of the primary pre-cold lamination cooling is performed by the cooling nozzles 11 arranged on the output table 5, there is sometimes the case that the waiting time t seconds can satisfy Expression (2) above or Expressions (2a) and (2b) above. In this case, the primary cold pre-lamination cooling can also be initiated by the cooling nozzles 11 arranged on the output table 5. Needless to say, as long as the performance of the final reduction at a reduction rate of 30% or more is completed, the primary cold pre-lamination cooling can also be initiated by the cooling nozzles 10 arranged between the respective two chairs 6 of the finishing laminator 3.
[00117] Then, in this primary cold pre-lamination cooling, the cooling is performed that at an average cooling rate of 50 ° C / s or more, the temperature changes (drop in temperature) becomes no less than 40 ° C no more than 140 ° C.
[00118] When the temperature change is less than 40 ° C, the recrystallized austenite grains grow and the low tenacity has
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37/68 perature deteriorates. The temperature change is adjusted to 40 ° C or more, thus making it possible to suppress the hardening of the austenite grains. When the temperature change is less than 40 ° C, the effect cannot be achieved. On the other hand, when the temperature change exceeds 140 ° C, recrystallization becomes insufficient to make it difficult to obtain a random texture. In addition, an effective ferrite phase for elongation is also not easily obtained and the hardness of the ferrite phase becomes high, and thus the bore expansion capacity also deteriorates. In addition, when the temperature change is greater than 140 ° C, an excess to / beyond the temperature of the Are transformation point is likely to be caused. In this case, even due to the transformation of recrystallized austenite, as a result of pointing out the variant selection, the texture is formed and the isotropy consequently decreases.
[00119] When the average cooling rate in cold pre-lamination cooling is less than 50 ° C / s, as expected, the recrystallized austenite grains grow and the low temperature toughness deteriorates. The upper limit of the average cooling rate is not determined in particular, but in terms of the shape of the steel sheet, 200 ° C / s or less is considered to be adequate.
[00120] Furthermore, as previously explained, to promote uniform recrystallization, the amount of work in the region of temperatures of less than T1 + 30 ° C is desirably as small as possible and the rate of reduction in the region of temperatures of less of T1 + 30 ° C is desirably 30% or less. For example, in the case where in the finishing laminator 3 in the continuous hot rolling line 1 shown in FIG. 12, when passing through one or two or more of the lamination chairs 6 arranged on the side of the front step (on the left side in FIG. 12, on the anterior side of the lamination), the steel sheet is in the region of temperatures of no less
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38/68 than Τ1 + 30 ° C or more than T1 + 200 ° C, and when passing through one or more of the lamination chairs 6 arranged on the side of the subsequent rear step (on the right side in FIG. 12, on the rear side lamination), the steel sheet is in the region of temperatures of less than T1 + 30 ° C, when the steel sheet passes through one or two or more of the lamination chairs 6 arranged on the side of the subsequent rear step, (in the right side in Figure 12, on the back side of the lamination), although the reduction is not performed or is performed, the reduction ratio below T1 + 30 ° C is desirably 30% or less in total. In terms of precision of the thickness and shape of the sheet, the reduction ratio below T1 + 30 ° C is desirably a reduction ratio of 10% or less in total. When isotropy is also obtained, the reduction ratio in the region of temperatures below T1 + 30 ° C is desirably 0%.
[00121] In the production method of the present invention, the lamination speed is not particularly limited. However, when the speed on the finishing lamination side is less than 400 mpm, γ grains grow to be crude, regions in which the ferrite can precipitate to obtain the elongation are reduced, and thus the elongation is liable to deteriorate. Although the upper lamination speed limit is not particularly limited, the effect of the present invention can be obtained, but it is current that the lamination speed is 1800 mpm or less due to equipment restrictions. Therefore, in the finishing lamination process, the lamination speed is desirably not less than 400 mpm or more than 1800 mpm. In addition, in hot rolling, the bars can also be connected after roughing rolling to be subjected to finishing rolling continuously. On that occasion, the raw bars can also be wound in the form of a coil once, stored in a cover that has an insulating function.
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39/68 heat as needed, and unwound again to be joined.
Winding [00122] After being obtained in this way, the hot rolled steel sheet can be wound at 650 ° C or less. When the winding temperature exceeds 650 ° C, the area ratio of the ferrite structure increases and the area ratio of the perlite structure does not become greater than 5%.
Cold rolling [00123] The original hot-rolled steel sheet produced as described above is pickled as needed to be subjected to cold rolling at a reduction rate of not less than 40% or more than 80%. When the reduction ratio is 40% or less, it becomes difficult to cause recrystallization in heating and subsequent retention, resulting in the fraction of grains of equivalent dimensions decreasing, and also the crystal grains after heating become crude. When lamination above 80% is performed, the texture is developed at the time of heating, and thus the anisotropy becomes strong. Therefore, the reduction ratio of cold rolling is adjusted to not less than 40% or more than 80%.
Heating and retention [00124] The steel sheet that has been subjected to cold rolling (a cold rolled steel sheet) is subsequently heated to a temperature range of 750 to 900 ° C and is maintained for no less than 1 second nor for more than 300 seconds in the region of temperatures of 750 to 900 ° C. When the temperature is less than that or the time is less than that, the reverse transformation from ferrite to austenite does not proceed sufficiently, and in the subsequent cooling process, the second phase cannot be achieved, resulting in the fact that sufficient resistance does not can be obtained.
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On the other hand, when the temperature is higher than this or the retention is continued for 300 seconds or more, the crystal grains become raw.
[00125] When the steel sheet after cold rolling is heated to a temperature range of 750 to 900 ° C in this way, an average heating rate of not less than room temperature or more than 650 ° C is set to HR1 (° C / s) expressed by Expression (5) below, and an average rate of more than 650 ° C up to the temperature region of 750 to 900 ° C is adjusted to HR2 (° C / s) expressed by Expression (6 ) below.
HR1> 0.3 ... Expression (5)
HR2 <0.5 χ HR1 ... Expression (6) [00126] Hot rolling is performed under the condition described above, and also cold pre-rolling cooling is performed, thus making crystal grains fine and the randomization of the crystal orientations is achieved. However, due to the cold rolling performed later, the strong texture develops and the texture becomes liable to remain on the steel plate. As a result, the r-values and the elongation of the steel plate decrease and the isotropy decreases. Thus, it is desired to make the texture that developed by cold lamination disappear as much as possible by the proper execution of the heating to be performed after cold lamination. To achieve this, it is necessary to divide the average rate of heating into two stages expressed by Expressions (5) and (6) above.
[00127] The detailed reason why the texture and properties of the steel plate are improved by this two-stage heating is not clear, but it is thought that this effect is related to the recovery of the displacement introduced at the time of the cold rolling and recrystallization. That is, the driving force of the recrystallization to occur in the steel plate by heating is the tension accumulated in the plate
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41/68 steel by cold rolling. When the average rate of heating HR1 in the temperature range of not less than room temperature or more than 650 ° C is small, the displacement introduced by cold rolling recovers and recrystallization does not occur. As a result, the texture that developed at the time of cold rolling remains as it is and properties, such as isotropy, deteriorate. When the average rate of heating HR1 in the temperature range of not less than room temperature nor more than 650 ° C is less than 0.3 ° C / s, the displacement introduced by cold rolling recovers, resulting in the fact that the strong texture formed at the time of cold rolling remains. Therefore, it is necessary to adjust the average rate of heating HR1 in the temperature range of not less than room temperature or more than 650 ° C by 0.3 (° C / s) or more.
[00128] On the other hand, when the average HR2 heating rate of more than 650 ° C up to the temperature range of 750 to 900 ° C is large, the ferrite that exists in the steel sheet after cold rolling does not recrystallize and the ferrite not recrystallized in a state of being worked remains. When the steel containing more than 0.01% C in particular is heated to a two-phase region of ferrite and austenite, the formed austenite blocks the growth of the recrystallized ferrite, and thus the non-recrystallized ferrite becomes more likely to remain. This non-recrystallized ferrite has a strong texture, so as to adversely affect properties such as r values and isotropy, and this non-recrystallized ferrite contains many displacements, thereby drastically deteriorating the elongation. Therefore, in the temperature range of more than 650 ° C to the temperature range of 750 to 900 ° C, the average rate of heating HR2 needs to be 0.5 x HR1 (° C / s) or less.
Primary cooling after cold rolling
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42/68 [00129] After the retention is performed for a predetermined time in the above temperature range, a primary post-cold lamination cooling is performed to a temperature region of not less than 580 ° C or more than 750 ° C at a rate average cooling of not less than 1 ° C / s nor more than 10 ° C / s.
Retention [00130] After primary cooling after cold rolling is completed, retention is performed for no less than 1 second or more than 1000 seconds on the condition that the rate of temperature decrease becomes 1 ° C / s or any less.
Secondary cold post-lamination cooling [00131] After the retention described above, secondary cold post-lamination cooling is performed at an average cooling rate of 5 ° C / s or less. When the average cooling rate of the post-cold rolling secondary cooling is greater than 5 ° C / s, the sum of bainite and martensite becomes 5% or more and the precision drilling capacity decreases, resulting in the fact that it it is not favorable.
[00132] In the cold rolled steel sheet produced as above, a hot dip galvanizing treatment, and also subsequent to the galvanizing treatment, a bonding treatment can also be carried out as needed. The hot dip galvanizing treatment can be carried out on cooling after retention in the temperature region of not less than 750 ° C or more than 900 ° C described above, or it can also be carried out after cooling. On that occasion, hot dip galvanizing treatment and bonding treatment can be carried out by common methods. For example, the bonding treatment is carried out in a temperature range of 450 to 600 ° C. When the bonding treatment temperature is less than 450 ° C, the bond does not advance sufficiently, and when it exceeds
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600 ° C, on the other hand, the connection goes a long way and corrosion resistance deteriorates.
Example [00133] The examples of the present invention will be explained below. Incidentally, the conditions of the examples are example conditions employed to confirm the applicability and effects of the present invention, and the present invention is not limited to those example conditions. The present invention can employ several conditions as long as the objective of the present invention is achieved without departing from the spirit of the invention. The chemical components of the respective steels used in the examples are shown in Table 1. The respective production conditions are indicated in Table 2. In addition, the structural constitutions and mechanical properties of the respective types of steel under the production conditions in Table 2 are shown in Table 3. Incidentally, each data underlined in each Table indicates that the numerical value is outside the range of the present invention or outside the preferred range of the present invention.
[00134] Examination results using steels of the invention A to U and comparative steels to g will be explained, each having the chemical composition shown in Table 1. Incidentally, in Table 1, each numerical value of the chemical compositions means% by mass. In Tables 2 and 3, the letters A to U and the letters a to g that are added to the types of steel indicate that they are components of the steels of the invention A to U and the comparative steels to a g in Table 1 respectively.
[00135] These steels (Invention A to U steels and comparative steels a to g) were casted and then heated as they were in a temperature range of 1000 to 1300 ° C, or were casted to then be heated to a region of has
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44/68 peratures from 1000 to 1300 ° C after being cooled once to room temperature, and afterwards they were subjected to hot rolling, cold rolling, and cooling under the conditions shown in Table 2.
[00136] In hot rolling initially, in roughing rolling which is the first hot rolling, rolling was performed once or more at a reduction rate of 40% or more in a temperature region of not less than 1000 ° Not more than 1200 ° C. However, in relation to types of steel A3, E3, and M2, in roughing rolling, rolling at a reduction rate of 40% or more in one pass was not performed. Table 2 shows, in roughing rolling, the number of times the reduction to a reduction ratio of 40% or more, each reduction ratio (%), and the austenite grain diameter (pm) after the rough rolling ( before finishing lamination). Incidentally, the temperature T1 (° C) and the temperature Ac1 (° C) of the respective types of steel are shown in Table 2.
[00137] After the roughing lamination is finished, the finishing lamination which is the second hot lamination has been carried out. In finishing lamination, lamination at a reduction rate of 30% or more was performed in one pass at least once in a temperature region of not less than T1 + 30 ° C or more than T1 + 200 ° C, and in a temperature range of less than T1 + 30 ° C, the total reduction ratio was adjusted to 30% or less. Incidentally, in finishing lamination, lamination at a rate of reduction of 30% or more in one pass was performed in a final pass in the region of temperatures of not less than T1 + 30 ° C nor more than T1 + 200 ° C.
[00138] However, for steel types A9 and C3, rolling at a reduction rate of 30% or more was not carried out in the region of temperatures of not less than T1 + 30 ° C or more than
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Τ1 + 200 ° C. In addition, in relation to steel type A7, the ratio of total reduction in the temperature range of less than T1 + 30 ° C was greater than 30%.
[00139] In addition, in the finishing lamination, the total reduction ratio was adjusted by 50% or more. However, in relation to steel type C3, the ratio of total reduction in the temperature region of not less than T1 + 30 ° C nor more than T1 + 200 ° C was less than 50%.
[00140] Table 2 shows, in the finishing lamination, the reduction ratio (%) in the final pass in the temperature region of not less than T1 + 30 ° C nor more than T1 + 200 ° C and the reduction ratio in a pass in a step prior to the final pass (ratio of reduction in a pass before the final pass) (%). In addition, Table 2 shows, in the finishing lamination, the total reduction ratio (%) in the temperature region of not less than T1 + 30 ° C nor more than T1 + 200 ° C, the temperature (° C) after the reduction in the final pass in the temperature region of not less than T1 + 30 ° C nor more than T1 + 200 ° C, the maximum amount of working heat generation (° C) at the time of reduction in the temperature region of no less than T1 + 30 ° C nor more than T1 + 200 ° C, and the reduction ratio (%) at the time of reduction in the temperature range of less than T1 + 30 ° C.
[00141] After the final reduction in the temperature region of not less than T1 + 30 ° C nor more than T1 + 200 ° C is carried out on the finishing laminate, the cold pre-laminating cooling was started before a waiting time t seconds exceeding 2.5 χ t1. In cold pre-lamination cooling, the average cooling rate has been adjusted to 50 ° C / s or more. In addition, the temperature change (amount of temperature cooled) in cold pre-lamination cooling has been adjusted to fall within the range of not less than 40 ° C or more than 140 ° C.
[00142] However, in relation to steel types A9 and J2, it cools
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46/68 pre-cold rolling was started after the waiting time of t seconds exceeds 2.5 χ t1 since the final reduction in the temperature region of not less than T1 + 30 ° C nor more than T1 + 200 ° C in finishing lamination. In relation to the type of steel A3, the temperature change (amount of temperature cooled) in the primary cold pre-cold rolling was less than 40 ° C, and in relation to the type of steel B3, the temperature change (amount of temperature chilled) in cold pre-lamination cooling was greater than 140 ° C. Regarding the type of steel A8, the average cooling rate in the cold pre-rolling cooling was less than 50 ° C / s.
[00143] Table 2 shows t1 (seconds) of the respective types of steel, the waiting time t (seconds) for the start of cold pre-lamination cooling since the final reduction in the temperature region of not less than T1 + 30 ° C no more than T1 + 200 ° C in finishing lamination, t / t1, temperature change (amount cooled) (° C) in pre-cold rolling cooling, and the average cooling rate in pre-cold rolling cooling (° C / s).
[00144] After pre-cold lamination cooling, winding was performed at 650 ° C or less, and the original hot-rolled sheets were obtained, each having a thickness of 2 to 5 mm.
[00145] However, in relation to steel types A6 and E3, the winding temperature was greater than 650 ° C. Table 2 shows the cold pre-rolling cold stop temperature (winding temperature) (° C) of the respective types of steel.
[00146] Next, the original hot-rolled sheets were stripped, each, to then be subjected to cold rolling at a reduction rate of not less than 40% or more than 80%. However, in relation to steel types A2, E3, I3, and M2, the reduction rate of cold rolling was less than 40%. In addition, in relation to the type of steel C4, the reduction rate of cold rolling was higher
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47/68 or 80%. Table 2 shows the reduction ratio (%) of the cold rolling of the respective types of steel.
[00147] After cold rolling, heating was carried out to a temperature range of 750 to 900 ° C and the retention was carried out for not less than 1 second or more than 30 seconds. In addition, when the heating was performed up to the temperature range of 750 to 900 ° C, the average rate of heating HR1 of not less than room temperature or more than 650 ° C (° C / s) was set to 0, 3 or more (HR1> 0.3), and the average HR2 heating rate of more than 650 ° C to 750 to 900 ° C (° C / s) has been adjusted to 0.5 x HR1 or less (HR2 <0 , 5 x HR1). Table 2 shows, of the respective types of steel, the heating temperature (annealing temperature), the heating and holding time (time to start the primary cold pre-lamination cooling) (seconds), and the average heating rates HR1 and HR2 (° C / s).
[00148] However, in relation to the type of steel F3, the heating temperature was higher than 900 ° C. Regarding the type of steel N2, the heating temperature was less than 750 ° C. Regarding the type of steel C5, the heating and retention time was less than one second. Regarding the type of steel F2, the warm-up and retention time was greater than 300 seconds. In addition, in relation to steel type B4, the average rate of heating HR1 was less than 0.3 (° C / s). Regarding the type of steel B5, the average rate of heating HR2 (° C / s) was greater than 0.5 x HR1.
[00149] After heating and retention, the primary cooling after cold rolling was carried out to a temperature range of 580 ° C to 750 ° C at an average cooling rate of not less than 1 ° C / s or more than 10 ° C / s. However, in relation to steel type A2, the average cooling rate in the primary cooling after cold rolling was greater than 10 ° C / s. Regarding the type of C6 steel, the average rate
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48/68 cooling in the primary cooling after cold rolling was less than 1 ° C / s. In addition, for steel types A2 and A5, the stop temperature of the primary cold post-cold rolling was less than 580 ° C, and for steel types A3, A4, and M2, the stop temperature primary cooling after cold rolling was greater than 750 ° C. Table 2 shows, of the respective types of steel, the average cooling rate (° C / s) and the cooling stop temperature (° C) in the primary cooling after cold rolling.
[00150] After the primary cold post-lamination cooling is performed, the retention was performed for not less than 1 second or more than 1000 seconds under the condition that the rate of temperature decrease becomes 1 ° C / s or less . Table 2 shows the retention time (time to start the primary cooling after cold rolling) of the respective steels.
[00151] After retention, the post-cold lamination secondary cooling was performed at an average cooling rate of 5 ° C / s or less. However, in relation to the type of steel A5, the average cooling rate of the secondary cooling after cold rolling was greater than 5 ° C / s. Table 2 shows the average cooling rate (° C / s) in the secondary cooling after cold rolling of the respective types of steel.
[00152] Subsequently, the 0.5% skin pass lamination was performed and the material evaluation was performed. Incidentally, in steel type T1, a hot dip galvanizing treatment was carried out. In the steel type U1, a bonding treatment was carried out in a temperature range of 450 to 600 ° C after galvanizing.
[00153] Table 3 shows the area ratios (structural fractions) (%) of ferrite, perlite and bainite + martensite in the metallic structure of the respective types of steel, and the average value of pole densities of the {100} < 011> a {223} <110> and the pole density of
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49/68 {332} <113> crystal orientation in a range of 5/8 to 3/8 in the thickness of the plate from the surface of the steel plate of the respective types of steel. Incidentally, the structural fraction was evaluated by the structural fraction before skin pass lamination. In addition, Table 3 showed, as mechanical properties of the respective types of steel, rC, rL, r30, and r60 with the respective values r, the tensile strength TS (MPa), the elongation percentage El (%), the hole expansion ratio λ (%) as an index of local ductility, TS χ λ, Vickers hardness of HVp perlite, and the percentage of shear surface (%). In addition, it showed the presence or absence of galvanizing treatment.
[00154] Incidentally, a tensile test was based on JIS Z 2241. The hole expansion test was based on the Japan Iron and Steel Federation standard JFS T1001. The pole density of each of the crystal orientations was measured using the EBSP previously described at a 0.5 pm pitch in a region at 3/8 to 5/8 in the plate thickness of a cross section parallel to the direction of lamination. In addition, the r-value in each direction was measured by the method described above. Regarding the percentage of the shear surface, each steel sheet whose thickness was adjusted to 1.2 mm was drilled by a circular drill with a diameter Φ 10 mm and a circular mold with 1% clearance, and then the surface of the perforated edge was measured. vTrs (the transition temperature of the appearance of Charpy fracture) was measured by a Charpy impact test based on JIS Z 2241. The flange capacity in the stretch was determined to be excellent in the case of TS χ λ> 30000, and the capacity Precision drilling was determined to be excellent in the event that the percentage of the shear surface is 90% or more. Low temperature toughness was determined to become poor in the case of vTrs = greater than -40.
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50/68 [00155] As shown in FIG. 14, it was discovered that only those steels that satisfy the conditions prescribed in the present invention have excellent precision drilling capacity and stretching flanging capacity.
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Petition 870180165233, of 12/19/2018, p. 56/83
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- 0.621.06 1.69 00C3 - 2.10 0.40 0.19 0.55 1.86 CXI COLD QUANTITY PRE COLD LAMINATION / ° C 100 the co mi O00 O00 100 100 CXI CD D)00 100 100 210 PRE-COLD LAMINATION COOLING RATE / ° C / s 126 127 100 CD00 LD D) 100 O SI 107 CD00 r. 00 105 REDUCTION REASON IN THE TEMPERATURE REGION OF LESS THAN T1 + 30 ° C /% O O O O O O LDI col O O O O O REDUCTION RATIOT1 +30 TOT1 + 200 ° C /% 100 LD h «- O00 The CD The LD the LD the r. 100 the CD O00 the D) the CD l ⁺ > - p 2 O ã Ο ω HH § O LD CO the co θι CO CO O O The CXI O LD co CO lu ow O r Q><(Λ Q 1- Ψ 5 O << ⁺ δ 0Í Dí Q <LL ⁺ O O the co SI SI SI O O The CXI O LD CO SI 4. . <20 932 893 931 926 930 928 O0000 946 CD00 O 936 000000 924 K ^ ^u ^ hjjQh the LU5LLlQ <lli t, S 0 ^ Q ^I 'MQI ^<<rsl CD r- O 00 00 00- r- LD CD 00 w η O - Es „<<« z E <O t £ Q 2 w J□ K 0 <1- 140 co00 287 the D) LD00 the D) 132 146 O00 145 LD00 LD00 Q -s <2 <<δnÍWQOo ^ SO '· CÉ Dí O O 2 ° The LD 45/40 1 45/45 45/40 45/40 The LD CXI LD 50/50 The LD 45/40 45/40 ^ ãg <g $ <P - CXI HI CXI CXI CXI - - - - CXI CXI STEEL 851 851 851 851 851 851 851 851 851 851 851 851 Ac1 STEEL TYPEA2 coLD CD00 D) m CXI m co < < < < < < < < m
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CONNECTION TEMPERATURE ΓΟ I I I I I I I I I I I I PRESENCE / ABSENCE OF GALVANIZATION ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE co LD LD LD LD l LD LD LD LD LD CO LD i ± i§g [2 | o ^ iãoK ^α «Ê Ô>« 200 200 200 200 200 200 200 200 200 200 200 300 COOLING STOP TEMPERATURE AFTER PRIMARY COLD / ° C The CO CD 480 760 O00 h- 530 O00 CD 681 669 673 690 703 671 LU _L O <£ J- - LDLD LD LD LD LD LD LD LD LD LD O i π ¹ O ¹ | -52 ish-h 30.0 30.0 30.0 100.0 30.0 30.0 30.0 30.0 30.0 100.0 30.0 30.0 • <- -L O^ | jj <ÒLLLI | jjNZo_ [ülí 30 ^ 0 ^ The CD 00 752 802 834 O00 h- 768 854 The h00 853 O00 h- O00 7920.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13 HR1: AVERAGE HEATING RATE OF NO LESS THAN ENVIRONMENTAL TEMPERATURE OR MORE THAN 650 ° C / ° C 0.35 0.4 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 <5 <^ <o - CO O) | col CXI OThe LD CO CD H- The CD The CD 426 420 415 379 328 698 410 437 516 300 424 3351.20 1.20 1.20 1.76 oõ 00 0.36 1.67 2.90 1.20 1.20 1.20 t:TIME TOWAIT/s 0.74 2.05 1.27 2.03 1.95 1.99 0.76 0.67 0.54 0.66 2.23 2.07 STEEL TYPE < S! < 5 < < £ < < m CXI CO With
Petition 870180165233, of 12/19/2018, p. 58/83
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1.50 CM 0.82 1.54 0.25 1.45 in 1.68 0.67 r. 1.43 0.77 0.77 CX [ r. 00 o * 0.77 COLD QUANTITY PRE COLD LAMINATION / ° C 100 100 O00 O00 O00 O00 O00 O00 100 100 O00 O00 O00 O00 O00 O00 PRE-COLD LAMINATION COOLING RATE / ° C / s 130 105 102 r. σ> in σ> 100 CD O> 105 CXI 130 104 162 127 CO O> s CO CD REDUCTION REASON IN THE TEMPERATURE REGION OF LESS THAN T1 + 30 ° C /% O O O O O O O O O O O O O O O O REDUCTION RATIOT1 +30 TOT1 + 200 ° C /% o O> o O> H"-θι the r. the r. the r. r. r. CXI CDr. O00 O00 CXI CD O00 l ⁺ > - p 2 O ã Ο ω HH § in CO in CO h «CO dog θι the CO the CO the CO r. CO dog dog dog O the CO dog O lu ow O r O << ⁺ Õ 0Í Dí Q <LL ⁺ in CO in CO h «CO O l O O O O dog O dog O the CO dog O 4. . <20 901 913 942 920 1084 926 913 916 950 923 925 952 931 930 946 931 ^ ° iujQf'Po LU5LLlQ <LLI , t; S Ü ^ Q ^U mÜÍ ^<<tN r- LD LD 00 LDr- O LD 00 00 COCO COw η O '- E2 „> <<ω z E <Ο κ Q 2 u JQ K 0 <| - r. 00 O O> CO00 CXI 00 ιη00 O00 00 CD 00 oõ the CD o O> o O> 298 o O> o O> Q -s <2 <<δ ^ □ ΐ £ Ι '<ο ^ <§ ^ιηΟ c2 Dí O os ° 45/40 45/40 45/40 45/45 45/45 45/45 45/45 45/45 45/45 45/45 40/40/40 45/45 45/45 1 45/40 45/40CXI CXI CXI CXI CXI CXI CXI CXI CXI CXI CO CXI CXI HI CXI CXI STEEL 851 851 865 865 865 865 865 865 865 865 865 858 858 858 858 858 Ac1 718 718 718 718 718 718 718 718 718 736 736 736 736 736 STEEL TYPE CO in CO O 02 03 04 05 06 Q D2 D3 LLJ CXI LU CO LU LL CXI LL
Petition 870180165233, of 12/19/2018, p. 59/83
57/68
ON TEMPERATURE / ° C I I I I I I I I I I I I I I I I PRESENCE / ABSENCE OF GALVANIZATION ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE LU i O li p tr <<□ (Λ ^LJ LD LD LD LD LD LD LD LD LD LD LD LD LD LD LD LD TIME TO START SECONDARY COOLING AFTER SECONDARY COLD LAMINATION / sec 300 300 300 300 300 300 300 300 300 300 500 200 200 200 300 300 COOLING STOP TEMPERATURE AFTER PRIMARY COLD / ° C 700 677 675 691 714 679 675 670 712 669 654 740 669 676 694 682 LU _L O <T J- - LD LD LD LD LD LD LD O) o LD LD LD LD LD LD LD LD O i π 'O ¹ | -52 30.0 30.0 30.0 30.0 30.0 30.0 LDO 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 350.0 '<- -L O^ LLl ^ ÒcOJLLltSÍm® ' 812 797 856 852 831 837 835 864 815 845 843 846 820 756 852 8610.13 0.23 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 HR1: AVERAGE HEATING RATE OF NO LESS THAN ENVIRONMENTAL TEMPERATURE OR MORE THAN 650 ° C / ° C 0.20 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.35 0.35 0.35The CD The CD CO O CXI CD CO00 LD CD LOO CO O> O> POO O> The LD436 400 450 441 462 453 478 487 496 O00 477 477 518 667 O00 4731.84 1.94 1.20 1.20 1.20 1.06 r- 1.20 1.20 1.20 1.20 1.20 1.20 1.90 1.90 1.90 t:TIME TOWAITIs 2.77 2.34 0.98 1.85 0.30 1.54 2.05 2.00 The 00 o * 1.770.93 0.93 2.31 1.66 1.47 STEEL TYPE m LD CO O CXI O CO O O LD O CD O Q CXI O CO O LLJ CXI LU CO LU LL CXI LL
Petition 870180165233, of 12/19/2018, p. 60/83
58/68
THE HOTEL * 00 O * 2.88 0.98 0.733.14 1.23 2.23 2.28 0.57 0.77 1.29 1.42 1.40 0.65 COLD QUANTITY PRE COLD LAMINATION / ° C CO O00 O00 O00 O00 O00 O00 O00 O00 O00 160 O00 O00 O00 O00 O00 PRE-COLD LAMINATION COOLING RATE / ° C / s 00 O 107 103 h03 104 co03 102 0003 0300 CD00 03 105 co03 hCD 120 105 REDUCTION REASON IN THE TEMPERATURE REGION OF LESS THAN T1 + 30 ° C /% O O O O O O O O O O O O O O O O REDUCTION RATIOT1 +30 TOT1 + 200 ° C /% CXI CD O00 the CD The CD O03 The CD O00 O00 The CD O00 The h «- o h «- The h «- The CD o h «- O00 l ⁺ > - p 2 O ã ο ω h § dog O CO CO CO CO O The co CO the co CO CO LD CO O LD CO O O <(Λ << ⁺ Õ 0Í Dí Q <LL ⁺ dog O CO CO O CO O the co CO the co O CO LD CO SI LD CO O 4. . <20 957 935 872 950 961 922 the CD 00 957 915 913 987 066 950 938 940 965 Sáo ^ j £ § 8 ⁺ 9 <E $ ^{i =} D PK ⁺ ^ ^u ^ hjjQh the LLI LLIN ^ <lli Z> 0 ^ Q ^R 2 'MQI ^<<rsl COCXI CD CD 00 ®l r- 00 00 00 00 O SI O 00 LU Q O '- E2 „> <<ω z E << o 2 δ 5 w 5□ fO <1- ld σ> ld σ> LD03 CO LD 03 122 154 LD00 125 123 CXI CD the CD LD CD 340 LD CD the CD Q -s <2 <<δnÍWQOo ^ SO '· CÉ Dí O o s ° 45/40 45/45 40/45 40/40/40 45/40 The LD The h «- 45/40 The LD The LD 40/40/40 40/40/40 40/40/40 1 40/40/40 40/40/40 ^ ãg <8 $ <P CXI CXI CXI CO CXI - - CXI - - CO CO CO HI CO CO STEEL 858 865 865 865 861 861 861 CD0000 CD0000 CD0000 875 892 892 892 CD0000 CD0000 Ac1 736 716 716 738 723 723 723 722 722 722 00 o h «- 00 o h «- 704 704 704 704 STEEL TYPE CO U- 0 G2 I - ÇXI ÇO "3 CXI “3 CO"3 5 M2 z N2
Petition 870180165233, of 12/19/2018, p. 61/83
59/68
CONNECTION TEMPERATURE rc I I I I I I I I I I I I I I I I PRESENCE / ABSENCE OF GALVANIZATION ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE COOLING RATE AFTER LAMINATION LO LO LO LO LO - LO LO LO LO LO LO LO LO LO LO TIME TO START SECONDARY COOLING AFTER SECONDARY COLD / s 300 200 200 200 300 300 300 300 300 300 500 500 300 300 300 300 COOLING STOP TEMPERATURE AFTER PRIMARY COLD / ° C 679 697 700 686 657 643 630 640 607 642 742 738 710 760 730 630 iw j. O -2 E z «i o gi & LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO O i π 'O ¹ | -52 ish-h 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 '<- -L O^ LÚ <ÒLLLI | jjNZo__ 923 O o CO 787 835 856 813 O0000 775 783 846 857 867 O00 h- The h00 850 7300.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.13 0.13 0.13 0.13 0.13 0.13 0.13 HR1: AVERAGE HEATING RATE OF NO LESS THAN ENVIRONMENTAL TEMPERATURE OR MORE THAN 650 ° C / ° C 0.35 0.35 0.35 0.37 0.35 0.35 0.37 0.37 0.37 0.42 0.42 0.42 0.35 0.35 0.35 0.35 <5 <^ <o - LO LO COO O coi colhLO CD CDCXI LO O ini col O CD466 470 463 434 520 486 521 465 532 456 437 375 450 489 460 4901.90 1.90 1.90 1.90 1.90 1.90 2.20 2.20 4.49 2.20 2.20 2.20 2.20 2.20 2.20 1.57 t:TIME TOWAITIs 1.33 1.59 5.48 1.85 1.39 2.73 6.91 2.71 10.00 5.02 1.25 1.69 2.83 3.12 3.09 1.03 STEEL TYPE CO LL 0 CXI0 I - ÇN ÇO "3 CXI “3 CO"3 5 CXIZ z CXIZ
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0.66 3.99 0.25 0.24 0.14 0.14 0.15 0.24 COLD QUANTITY PRE COLD LAMINATION / ° C CO O00 O00 O00 O00 O00 O00 O00 PRE-COLD LAMINATION COOLING RATE / ° C / s 107 CD O> 00 h «- O> h «- 100 104 CO O> 107 REDUCTION REASON IN THE TEMPERATURE REGION OF LESS THAN T1 + 30 ° C /% O O O O O O O O REDUCTION RATIOT1 +30 TOT1 + 200 ° C /% 100 The CD O00 100 O00 LD O> O00 LD CD 2 ⁺ 1- P 2 O ã Ο ω HH § O CO O O O O O LD CO RAZAODE PASS REDUCTION BEFORE ENDING T1 + 30 UNTILT1 + 200 ° C /% O CO O O O O O CO luí $ ^ w2Q — 1O— · LÜ - =: riCj | <<, oW 982 001 H col 1012 962 996 980 978 972 LLl5LLlQ <LLlTt; SO ^ Q ^u mK ^{<<! N} LD CXI CO O CXI - CXI CXI LU Q O - E5 <W Z E<Ο κ Q D u J□ κ 0 <1- ld h «- 120 o h «- O00 CXI 00 oõ O00 00 CD Q a <2 <<δ ^ QlU <ò '<2i0 ⁰ £ Dí ° 45/45 45/45 45/45 45/45 45/45 45/45 45/45 45/45 ^ ãg <8 $ <g CXI CXI CXI CXI CXI CXI CXI CXI STEEL 903 903 903 852 852 852 852 846 855 1376 851 1154 854 854 853 Ac1 713 713 713 728 716 O00 h «- 715 710 724 712 718 713 713 713 712 STEEL TYPE O CXI O CL σ 5Ξ O TJ Φ M— O)
Petition 870180165233, of 12/19/2018, p. 63/83
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LI- TEMPERATUREGATION / ° C 1 I I I I I NOT EXECUTED 585 COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL PRESENCE / ABSENCE OF GALVANIZATION ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE ABSENCE PRESENCE PRESENCE LD LD LD LD LD LD LD LD ^α «κ Ô>« 300 300 300 200 200 300 200 200 ^Q -tfa ^0: íXm ^- Ol <Ss: Ψ F α- Q ² <□. <£ γ- Ο 748 736 741 749 731 748 730 722 LD LD LD LD LD LD LD LD Ο ¹ κι Ζ ¹ Ο Ê £ * §h * Ê3 · * 30.0 30.0 30.0 30.0 30.0 CO 30.0 30.0 ι - ¹ Ο ^ ύ <· ϊ2ιιιώΝΖ ^ ^ □ .δ ^ ΩοίΟωρ 815 786 850 862 CO co 00 871 766 760 ^ üaO ^ ggO 0.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13 <uj, μ. ** <4 ^w μ XqttQLULUS ^ LUJ: ο 0.35 0.35 0.42 0.37 0.35 0.35 0.35 0.35 <5 <i <o-s in l · - CO in in O CXI The in l · - üs ^Q s ^s = e 475 468 470 482 451 468 458 444 2.20 2.20 2.20 2.20 2.20 2.20 2.20 2.20 t:TIME TOWAIT/s 1.46 8.78 0.56 0.53 0.31 0.31 0.32 0.52 STEEL TYPE O CXI O CL σ 2 «5 ro Ξ O TJ Φ M— O)
Petition 870180165233, of 12/19/2018, p. 64/83
62/68
The <£ 1.09 1.05 1.13 1.21 1.23 1.19 1.15 1.05 1.21 1.08 1.06 1.22 in 0) 1.08 1.06 1.08 O<2 1.09 1.05 1.11 1.13 1.19 1.23 CO 1.09 1.21 1.06 1.04 CO CM 1.23 1.22 1.08 1.06O 00 o 0.72 I'm the 0.65 0.50 0.62 o to o 0.76 0.67 O 0.79 0.64 0.67 0.67 0.72 O 0.67 _l 0.76 0.69 co o I'm the 0.62 I'm the 0.62 O 0.64 O CO o 0.68 0.62 0.61 0.73 0.75 0.69 POLE DENSITY OF CRYSTAL ORIENTATION {332} <113> 2.6 CN co in <o m tó <o saw 3.9 o> tó 2.7 2.0 in O l *. tó 3.4 3.7 Oll in POLE DENSITIES OF THE {112} <110> A {113} <110> ORIENTATION GROUP AND THE CHRISTIAN ORIENTATIONTAL {112} <131> 4.8 05 5.9 00 the waistband CO the »co ' 6.0 CXI r- ' 2.4 2.2 6.5 co ' CO l * - ' 3.5 3.6 co BAINITA FRACTION +MARTENSITE FRACTION/% 0.6 16.2 CO 4.2 20.7 3.4 CX [ CO oCX [ 0.9 4.2 O 3.4 oo_ 4.2 co_ FRACTIONINPERLITE/% 13.7 38.0 17.3 6.7 38.7 19.3 to to CO CO 9.5 14.5 9.2 9.0 19.5 37.4 38.3 FERRITE FRACTION /% 85.7 45.8 79.6 89.1 40.6 77.3 82.7 83.1 87.6 87.2 89.6 81.3 90.1 87.6 78.7 58.4 60.1 TYPEINSTEEL < CXI< ev A4 A5 A6 A7 A8 A9 m B2 B3 B4 B5 O C2 C3
Petition 870180165233, of 12/19/2018, p. 65/83
63/68
NOTE STEEL OF THE PRESENT INVENTION COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION COMPARATIVE STEEL PERCENTAGE OF THE SHARP SURFACE OF A PERFECT EDGE SURFACEBORED (%) the o 40 86 88 46 76 06 05 06 the o the o 00 06 68 86 97 U5 HVp 163 143 124 201 133 142 170 173 the CO 190 227 140 197 208 U5 150 150 <X ω i— 45793 25334 22123 29541 20783 20915 21662 32302 18340 50366 51024 28220 27262 26937 50215 52258 29910 OO the o -90 -30 -110 the o -90 the o -30 the o -90 -120 -20 the o -90 -60 09- -70 (%) Y 90.5 40.6 42.3 43.0 40.2 36.5 41.9 62.0 35.0 86.4 82.6 34.0 43.0 41.0 55.0 57.3 34.3 (%) I3m 00 05 CO 00 COU5 COCO CO O CO U5 U5 TS (Mpa) 506 624 523 687 517 573 517 521 524 546 621 830 634 657 913 912 872 KIND OFSTEEL < CN < ev A4 9V A6 A7 A8 A9 m B2 B3 B4 B5 O C2 C3
Petition 870180165233, of 12/19/2018, p. 66/83
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οΈ CO 1.11 1.04 1.07 1.05 1.04 1.06 1.07 1.03 1.05 1.14 1.23 1.02 1.22 1.02 1.05 1.09 1.09 1.06 1.09 1.09 1.03 οΏ 1.20 HI 1.05 1.05 1.06 1.03 1.05 1.05 1.04 1.05 1.13 1.22 1.03 1.23 1.02 1.07 1.07 1.11 1.07 1.09 1.09 1.020.65 0.65 0.73 0.71 the o 0.72 0.72 0.71 0.58 0.72 0.67 0.63 0.73 0.65 0.72 0.72 0.74 co toO 0.72 0.74 the o 0.74 -I 0.69 0.68 co o 0.74 0.74 0.75 0.73 0.73 0.57 0.72 0.69 0.68 co o 0.62 0.77 0.75 0.77 0.69 0.76 o co o 0.75 o co o POLE DENSITY OF CRYSTAL ORIENTATION {332} <113> co Hi iH 3.5 4.6 4.8 4.6 ω cotosaw5.3 5.4 2.3 co iri 2.5 2.2 CO 5.0 2.7 2.4 4.3 2.0 POLE DENSITIES OF THE {112} <110> A {113} <110> ORIENTATION GROUP AND CRYSTAL ORIENTATION {112} <131> to O 6.0 Hi co O CO in CN CD co Hi r- ' 00 4.8 6.2 05 5.8 oj m oj co 6.5 The oj oj in co_ BAINITE FRACTION + MARTENSITE FRACTION /% 2.8 CO m co ' 3.0 2.7 3.6 0.44.0 oj Hi d l *. o> 3.9 4.0 2.4 0.9 co o 2.0 0.3 5.34.6 FRACTIONINPERLITE/% 33.2 29.4 5.2 37.7 29.5 25.5 6.2 7.5 co 10.7 12.0 25.8 48.6 53.9 34.2 7.0 8.8 12.5 8.9 7.6 O_ 15.3 FERRITE FRACTION /% 64.0 67.5 86.3 59.3 67.8 70.9 93.4 91.4 84.2 87.2 77.8 64.5 47.5 42.1 63.4 92.1 90.4 85.5 90.8 87.1 87.6 the co TYPEINSTEEL C4 C5 C2 Q D2 D3 LLJ E2 E3 LL F2 F3 0 G2 ΞCN CO "5 HI “5 J3 s
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V10N COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION COMPARATIVE STEEL STEEL OF THE PRESENT INVENTION COMPARATIVE STEEL COMPARATIVE STEEL STEEL OF THE PRESENT INVENTION COMPARATIVE STEEL STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION COMPARATIVE STEEL STEEL OF THE PRESENT INVENTION COMPARATIVE STEEL STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION PERCENTAGE OFSHEAR SURFACE OF A PERFORATED EDGE SURFACE (%) poo O05 co co05 the o O the o the o LC5 b- the o 00 CXI1 ^ · O05 CD 05 the o the o 05 the o the co the o O05 HVP 159 U5 156 CXI ΙΌ U5 CXI CD 294 232 176 166 154 137 164 157 The CXI 156 CXI CXI 153 U5 CXI CD ίο CXI <X ω ι— 29328 27331 35994 54601 53923 58835 60317 99009 28296 36707 29793 27188 62444 27404 64875 42941 34500 29309 49259 29779 35178 64045 OO O the CD the b- the b- the co the CD the co the co O O05 O05 the o O O O the CD the co the co the CD The CP the CD O (%) Y 31.4 30.2 42.0 60.2 63.1 63.4 73.2 71.0 36.0 50.7 42.5 40.1 5 31.0 62.2 50.4 46.0 39.5 55.1 35.2 39.0 61.7 (%) I3 The CXI LC5 coCXI 05 05 CD B- B- CO CD CXI CD B- CD co CO B-co a.ω ι— 934 906 857 907 855 928 824 846 786 724 the b- 678 1022 MCO co 1043 852 750 742 894 846 902 1038 KIND OFSTEEL O LC5 O CXI O Q CXI Q CO Q LLJ CXI LU CO LLI LL CXI LL COLL 0 CXI0 ΞCXI CO "5 CXI “5 CO"5
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CO

OΈ 1.04 1.02 1.08 1.04 CN 1.02 rco 1.03 1.03 1.03 1.04 1.05 1.08 O<2 to o_ (D CN CD to o_ POO COCD- CD COCD- o o_ O- U5 O_ l ^ o_ with o_ O O IO o CXI l ^ o o l ^ o o CO o o l ^ o 0.54 O O CXI l ^ o O O CXI l ^ o _l CO o 0.73 0.69 0.73 0.59 0.76 0.68 0.76 l ^ l ^ o CXI l ^ o 'dl ^ o CXI l ^ o CXI l ^ o POLE DENSITY OF THE ORIENTATION OFCRYSTAL {332} <113> CN CN CD the in CD CN CD The CNPoo CNCN co CN 05 CN POLE DENSITIESFROM THE {112} <110> TO {113} <110> ORIENTATION GROUP AND THE CRYSTAL ORIENTATION{112} <131> CN CN ΙΌ The CN m O5_ CD in CNCN 05 COCN CD co_ 05 BAINITA FRACTION +MARTENSITE FRACTION/% cd CO CN co_ COCN U3 CD o O the o s 33 FRACTIONINPERLITE/% 1 ^CN CO CD l ^ σ> CD oo Poo CO cd 05 K 05 in41.4 36.6 FERRITE FRACTION /% 83.4 90.8 78.5 91.3 90.4 92.6 93.3 CN CD 83.4 84.6 57.4 61.6 87.6 TYPEINSTEEL CN z CN Z O CN O Ξ σ s ω i— 5 frog Ξ O
Petition 870180165233, of 12/19/2018, p. 69/83
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V10N STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION COMPARATIVE STEEL STEEL OF THE PRESENT INVENTION COMPARATIVE STEEL STEEL OF THE PRESENT INVENTION COMPARATIVE STEEL STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION STEEL OF THE PRESENT INVENTION COMPARATIVE STEEL COMPARATIVE STEEL COMPARATIVE STEEL PERCENTAGE OF THE FLOORING SURFACEA PERFORATED EDGE SURFACE(%) O05 the o 1 ^ · the o O the o POO the o CXI o CO o the o the o 100 HVP sCXI 198 156 236 CXI 185 the CXI 175 353 378 00 CO05 U5 CO <X ω ι— 62504 37412 28500 45149 24430 35964 29765 37252 48441 51559 74455 71833 52385 the o2 O the o The CXI O00 O O00 O the o O05 O O05 O05 -110 (%) Y 60.1 50.9 38.0 59.8 31.2 48.6 39.9 52.1 60.4 65.1 85.8 92.1 70.6 (%) ΊΒCO U5 CO CXI CO 05 U5 CO U5 CO CO The CXI CO αω π the o 735 750 755 783 694 746 673 802 792 999 the CO 742 KIND OFSTEEL CXI z CXI Z O CXI O CL σ s ω i— 5 O
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; TABLE 3 the £ O<2 rC FRACTURE OCCURRED DURING HOT LAMINATION _l POLE DENSITY OF THE ORIENTATION OFCRYSTAL {332} <113> POLE DENSITIESFROM THE {112} <110> TO {113} <110> ORIENTATION GROUP AND THE CRYSTAL ORIENTATION{112} <131> BAINITA FRACTION +MARTENSITE FRACTION/% FRACTIONINPERLITE/% FERRITE FRACTION /% Continued TYPEINSTEEL Ό ΦO)
Petition 870180165233, of 12/19/2018, p. 71/83

权利要求:
Claims (15)
[1]
1. High strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, characterized by the fact that it consists of:
in mass%,
C: greater than 0.01% to 0.4% or less;
Si: not less than 0.001% or more than 2.5%;
Mn: not less than 0.001% or more than 4%;
P: 0.001 to 0.15% or less;
S: 0.0005 to 0.03% or less;
Al: not less than 0.001% or more than 2%;
N: 0.0005 to 0.01% or less; and the balance being composed of iron and the inevitable impurities, in which in a range of 5/8 to 3/8 in the thickness of the plate from the surface of the steel plate, the average value of the pole densities of the group of orientations {100 } <011> to {223} <110> represented by the respective crystal orientations of {100} <011>, {116} <110>, {114} <110>, {113} <110>, {112} < 110>, {335} <110>, and {223} <110> is 6.5 or less, and the pole density of the {332} <113> crystal orientation is 5.0 or less, and the metal structure contains , in terms of area ratio, more than 5% perlite. the sum of bainite and martensite limited to less than 5%, and the composite balance of ferrite.
[2]
2. High strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, according to claim 1, characterized by the fact that also the Vickers hardness of a perlite phase is not less than 150 HV not more than 300 HV.
[3]
3. High-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, according to claim 1, characterized by the fact that the r value also in a perpendicular direction
Petition 870180165233, of 12/19/2018, p. 72/83
2/7 to the rolling direction (rC) is 0.70 or more, the r value in the 30 ° direction from the rolling direction (r30) is 1.10 or less, the r value in the rolling direction (rL) is 0.70 or more, and the r value in a 60 ° direction from the rolling direction (r60) is 1.10 or less.
[4]
4. High-strength cold-rolled steel sheet with excellent stretch-flanging capacity and precision drilling capacity, according to claim 1, characterized by the fact that it also consists of:
one type or two or more types of elements between% by mass,
Ti: not less than 0.001% nor more than 0.2%, Nb: not less than 0.001% nor more than 0.2%, B: not less than 0.0001% nor more than 0.005%, Mg: not less than 0.0001% no more than 0.01%, Rem: no less than 0.0001% nor more than 0.1%, Ca: no less than 0.0001% nor more than 0.01%, Mo: no less than 0.001% or more than 1%, Cr: not less than 0.001% nor more than 2%, V: not less than 0.001% nor more than 1%, Ni: not less than 0.001% or more than 2%, Cu: not less than 0.001% nor more than 2%, Zr: not less than 0.0001% nor more than 0.2%, W: not less than 0.001% nor more than 1%, As: not less than 0.0001% no more than 0.5%, Co: no less than 0.0001% or no more than 1%, Sn: no less than 0.0001% or no more than 0.2%, Pb: no less than 0.001% or no more than 0.1%, Y: not less than 0.001% or more than 0.1%, and Hf: not less than 0.001% or more than 0.1%.
[5]
5. High strength cold rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, according to claim 1, character
Petition 870180165233, of 12/19/2018, p. 73/83
3/7 due to the fact that in addition, when the steel sheet whose thickness is reduced to 1.2 mm with a central portion of the thickness of the sheet adjusted to the center is drilled by a circular 10 mm circular drill and a circular mold with 1% clearance, the percentage of the shear surface of the surface of a perforated edge becomes 90% or more.
[6]
6. High strength cold rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, according to claim 1, characterized by the fact that on the surface, a hot dip galvanized or a hot dip galvanized bonded layer.
[7]
7. Production method of a high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, characterized by the fact that it consists of:
on a steel bar containing:
in mass%,
C: more than 0.01% to 0.4% or less;
Si: not less than 0.001% or more than 2.5%;
Mn: not less than 0.001% or more than 4%;
P: 0.001 to 0.15% or less;
S: 0.0005 to 0.03% or less;
Al: not less than 0.001% or more than 2%;
N: 0.0005 to 0.01% or less; and optionally further comprising one or two or more elements selected from
Ti: not less than 0.001% nor more than 0.2%, Nb: not less than 0.001% nor more than 0.2%, B: not less than 0.0001% nor more than 0.005%, Mg: not less than 0.0001% not more than 0.01%, Rem: not less than 0.0001% nor more than 0.1%,
Petition 870180165233, of 12/19/2018, p. 74/83
4/7
Ca: not less than 0.0001% nor more than 0.01%, Mo: not less than 0.001% nor more than 1%, Cr: not less than 0.001% nor more than 2%, V: not less than 0.001% not more than 1%, Ni: not less than 0.001% nor more than 2%, Cu: not less than 0.001% nor more than 2%, Zr: not less than 0.0001% or more than 0.2%, W : not less than 0.001% nor more than 1%, As: not less than 0.0001% nor more than 0.5%, Co: not less than 0.0001% nor more than 1%, Sn: not less than 0 , 0001% not more than 0,2%, Pb: not less than 0,001% nor more than 0,1%, Y: not less than 0,001% nor more than 0,1% and Hf: not less than 0,001% nor more than 0.1%;
the balance being made up of iron and the inevitable impurities, perform the first hot rolling in which rolling at a reduction rate of 40% or more is performed once or more in a temperature range of not less than 1000 ° C nor more than 1200 ° C;
adjust the austenite grain diameter to 200 pm or less by the first hot rolling;
perform the second hot lamination in which the lamination at a reduction rate of 30% or more is performed in a pass at least once in a temperature region of not less than the temperature T1 determined by Expression (1) below + 30 ° C not more than T1 + 200 ° C;
adjust the total reduction ratio in the second hot rolling to 50% or more;
perform the final reduction at a reduction rate of 30% or more on the second hot rolling and then start the cold pre-rolling cooling in such a way that the waiting time t seconds
Petition 870180165233, of 12/19/2018, p. 75/83
5/7 satisfy Expression (2) below;
adjust the average cooling rate in cold pre-lamination cooling to 50 ° C / s or more and adjust the temperature change to fall within the range of not less than 40 ° C or more than 140 ° C;
perform cold rolling at a reduction rate of not less than 40% or more than 80%;
perform the heating up to the temperature range of 750 to 900 ° C and perform the retention for no less than 1 second or more than 300 seconds;
perform primary post-cold rolling cooling down to a temperature range of not less than 580 ° C, not more than 750 ° C at an average cooling rate of not less than 1 ° C / s or more than 10 ° C / s;
perform the retention for not less than 1 second or more than 1000 seconds on the condition that the rate of decrease in temperature becomes 1 ° C / s or less; and perform secondary post-cold rolling cooling at an average cooling rate of 5 ° C / s or less:
T1 (° C) = 850 + 10 x (C + N) x Mn + 350 x Nb + 250 x Ti + 40 x B + 10 x Cr + 100 x Mo + 100 x V ··· Expression (1) here, C, N, Mn, Nb, Ti, B, Cr, Mo, and V each represent the content of the element (% by mass);
t <2.5 x t1 ··· Expression (2)
Here, t1 is obtained by Expression (3) below;
t1 = 0.001 x ((Tf - T1) x P1 / 100) ² - 0.109 x ((Tf - T1) x P1 / 100) + 3.1 ··· Expression (3) here, in Expression (3) above, Tf represents the temperature of the steel bar obtained after the final reduction at a reduction ratio of 30% or more, and P1 represents the reduction ratio of the final reduction to 30% or more.
[8]
8. Production method of cold rolled steel sheet of
Petition 870180165233, of 12/19/2018, p. 76/83
6/7 high strength having excellent stretching flanging capacity and precision drilling capacity, according to claim 7, characterized by the fact that the total reduction ratio in a temperature range of less than T1 + 30 ° C is 30 % or less.
[9]
9. Production method of high strength cold rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, according to claim 7, characterized by the fact that the waiting time t seconds also satisfies the Expression (2a) below:
t <t1 ··· Expression (2a)
[10]
10. Production method of high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, according to claim 7, characterized by the fact that the waiting time t seconds also satisfies the Expression (2b) below:
t1 <t <t1 χ 2.5 ··· Expression (2b)
[11]
11. Production method of high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, according to claim 7, characterized by the fact that cold pre-lamination cooling is initiated between laminating chairs.
[12]
12. Production method of high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, according to claim 7, characterized by the fact that it also comprises:
perform winding at 650 ° C or less to obtain a hot rolled steel sheet after performing cold pre-lamination cooling and before performing cold rolling.
[13]
13. Production method of cold rolled steel sheet
Petition 870180165233, of 12/19/2018, p. 77/83
7/7 high strength having excellent stretching flanging capacity and precision drilling capacity, according to claim 7, characterized by the fact that when heating is carried out up to the temperature range of 750 to 900 ° C after cold rolling, an average heating rate of not less than room temperature or more than 650 ° C is set to HR1 (° C / s) expressed by Expression (5) below, and an average heating rate of more than 650 ° C to 750 to 900 ° C is set to HR2 (° C / s) expressed by Expression (6) below.
HR1> 0.3 ... Expression (5)
HR2 <0.5 x HR1 ... Expression (6)
[14]
14. Production method of high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, according to claim 7, characterized by the fact that it also comprises:
perform hot dip galvanizing on the surface.
[15]
15. Production method of high-strength cold-rolled steel sheet having excellent stretching flanging capacity and precision drilling capacity, according to claim 14, characterized by the fact that it also comprises:
perform a bonding treatment at 450 to 600 ° C after performing hot dip galvanizing.
Petition 870180165233, of 12/19/2018, p. 78/83
1/8
FIG.1
Tensile strength x bore expansion ratio
Average value of pole densities of the {100} <011> to {223} <110> guidance group
□: Average value of the pole densities of the {100} <011> to {223} <110> and pole density of the {332} <113> orientations are both within the range of claims: Only the pole densities of the group of orientations guidelines {100} <011> to {223} <110> are outside the range of claims ^x : Pole densities of two types of guidance groups are outside the range of claims
2/8
FIG.2
Tensile strength x bore expansion ratio □: Average value of pole densities in the {100} <011> to {223} <110> and pole density of the {332} <113> orientations are both within the range of claims Only the pole densities of the guidance group {100} <011> to {223} <110> are outside the range of claims ^x : The pole densities of two types of guidance groups are outside the range of claims
3/8
F1G.3 rC
O: In FIG. 1 and FIG. 2 the pole densities of the guidance groups are within the claims range and rC 0.70 •: rC <0.70
FIG.4 r30
In FIG. 1 and FIG. 2 the pole densities of the guidance groups are within the range of claims and r30 1.10 ·: r30> 1.10
4/8
FIG.5
FIG.6
O: In FIG. 1 and FIG. 2 the pole densities of the guidance groups are within the claims range and rL 0.70 •: 1L <0.70 r60
O: In FIG. 1 and FIG. 2 the pole densities of the guidance groups are within the range of claims and r60 1.10 ·: R6O> 1. 10
5/8
FIG.7 ο CL
Λ A, t ▲ ▲ A4 ▲ ▲ ▲▲THE. M---------------------------------------------- r --- -------------------------------------------------- ----------------------------------------1--------- -------------------------------------1
10.0.ΰ 5.0 10.0 15.0 20.0 25.0
Sum of bainite fraction and martensite fraction in the structure
O: In FIG. 1 and FIG. 2 the pole densities of the guidance groups are within the claims range and 90% shear surface percentage φ: Shear surface percentage <90%
FIG.8
Diameter of austenite grain after roughing rolling (V m)
O: In FIG. 1 and FIG. 2 the pole densities of the guidance groups are within the claims range and rC 0.70 •: pole densities of two types of guidance groups are outside the claims range
6/8
F1G.9
• « O• ▼7 'i —----------- r ------------- 1 ------------ ”i ------ -------- 1 -------------- rj
Ο 50 100 150 200 250 300 350
Austenite grain diameter after roughing rolling (μ m)
O: In FIG. 1 and FIG. 2 the pole densities of the guidance groups are within the claims range and r30 1.10 • ^: pole densities of two types of guidance groups are outside the claims range
FIG.10
Number of times of rolling at 40% or more in roughing rolling

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法律状态:
2018-09-25| B06A| Notification to applicant to reply to the report for non-patentability or inadequacy of the application according art. 36 industrial patent law|

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2019-01-22| B09A| Decision: intention to grant|

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2019-03-26| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 27/07/2012, OBSERVADAS AS CONDICOES LEGAIS. |

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2019-11-12| B25D| Requested change of name of applicant approved|Owner name: NIPPON STEEL CORPORATION (JP) |

优先权:

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申请号 | 申请日 | 专利标题

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JP2011164383|2011-07-27|

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JP2011-164383|2011-07-27|

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PCT/JP2012/069259|WO2013015428A1|2011-07-27|2012-07-27|High-strength cold-rolled steel sheet with excellent stretch flangeability and precision punchability, and process for producing same|

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