THERMAL TREATED COMPONENT WIRE MATERIAL, THERMAL TREATED COMPONENT STEEL WIRE, THERMAL TREATED COMPO

专利摘要:
Abstract: "Thermally untreated component wire material, thermally untreated component steel wire and thermally untreated component and its production method". The present invention relates to a wire material used for the production of a thermally untreated component whose tensile strength is 900mpa to 1300mpa, containing by weight%: c: 0.20? at 0.50 ?, si: 0.05? at 2.0 ', mn: 0.20? 1.0 ', being limited to contain p: 0.030? or less, s: 0.030? or less, n: 0.005? or less, f1 defined by the following expression (1) is less than 0.60, with the balance being made of f and the inevitable impurities, where the metal structure contains a perlite structure of 64? (ç?) ? 52? most in a fraction of volume, with the balance being made of one type or two between a proeutectoid ferrite structure and a bainite structure, the average grain diameter of the perlite structure in a region from the surface layer to 0.1 d is 15 µm or less when the diameter of the wire material is adjusted to be d, e (average grain diameter of the perlite structure in the region from the surface layer to 0.1 d) / (average grain diameter of the structure within a range from 0.25 d to the center) is less than 1.0. f1 = c (?)? si (?)? 24? mn (?)? 6 ... (1)
公开号:BR112014003823B1
申请号:R112014003823-6
申请日:2012-08-23
公开日:2019-04-02
发明作者:Makoto Okonogi；Shingo Yamasaki；Akifumi Kawana；Hideaki Gotohda
申请人:Nippon Steel & Sumitomo Metal Corporation；
IPC主号:

专利说明:

[001] The present invention relates to a thermally untreated component produced from a wire material, used for automotive parts and various industrial equipment having an axial shape such as a screw, a torsion bar, a stabilizer, and whose tensile strength is 900 MPa to 1300 MPa, to a steel wire for the production of the above material, in addition to the wire material to produce the steel wire, and to a method for its production. Note that architectural screws, etc., are included in the machine components that are objects of the present invention. This application is based on Japanese Patent Application No. 2011-184737 registered on August 26, 2011, and claims its priority benefits, the total content of which is incorporated herein by reference. [Background of the Technique] [002] A high strength machine component having a tensile strength of 900 MPa or more is used for a vehicle and various industrial equipment to reduce its weight and size. Conventionally, this type of high strength machine component is produced using steel materials of an alloy steel and a special steel in which bonding elements such as Mn, Cr, Mo, or B are added to a carbon steel for use structural in machines, executing the coalescing annealing after the hot rolling to soften the material, conform in a predetermined form by the execution of the cold forging and forming lamination and, later, to provide resistance by the execution of a process
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2/33 hardening in quick cooling and quenching [003] However, the cost of these steel materials is high because the bonding elements are contained, and their production cost increases due to the annealing softener before it is shaped into a component and hardening processes in quenching and quenching after forming are required.
[004] A technique is known in which the stamping of the wire by rapid cooling, strengthening of precipitation, etc., without the execution of softening annealing and hardening processes in rapid cooling and tempering to provide a predetermined strength. This technique is used for screws, etc., and the screw produced by using this technique is called a thermally untreated screw.
[005] In Patent Document 1, a method of producing the thermally untreated screw is described in which a wire material containing C: 0.15% to 0.30%, Si: 0.03% to 0.55% , Mn: 1.1% to 2.0% is cooled in a boiling water bath, and the stamping process is carried out with an area reduction of 20% to 50%. In this production method, it is possible to omit the coalescing annealing and the hardening processes in the quick cooling and quenching, but the maximum resistance of the screw described in the example is 88 kgf / mm ² , and it cannot be said that this screw has resistance enough, and there is a limit on the high reinforcement.
[006] In Patent Document 2, a cold forging steel containing C: 0.4% to 1.0% is described, whose chemical composition satisfies the specific conditional expression, and whose structure is made of perlite and pseudo perlite. The amount of C in the steel is large, and its cold forging capacity deteriorates compared to a carbon steel for use in structural machinery and an alloy steel for use in structural machinery that are conventionally used for compositing 870180133468, of 24 / 09/2018, p. 6/47
3/33 machine parts, such as screws.
[007] As stated above, a machine component having good cold forging capacity and a strength of 900 MPa or more and a steel wire and wire material to produce the above material cannot be obtained by thermally wire materials not treated according to conventional techniques. [Prior Art Documents] [Patent Documents] [008] Patent Document 1: Japanese Laid-open Patent Publication No. H02-274810 [009] Patent Document 2: Japanese Laid-open Patent Publication No. 2000-144306 [ Description of the Invention] [Problems to be solved by the invention] [0010] The present invention is made in consideration of the problems described above in conventional techniques, and its objective is to provide (a) a high strength machine component capable of being produced at low cost, and which has tensile strength of 900 MPa to1300 MPa, (b) a steel wire used to produce the machine component, and capable of omitting heat treatments such as annealing softener and hardening processes, quick cooling and quenching , (c) a wire material for producing the steel wire, and (d) a production method for producing the above. [Means to Solve Problems] [0011] The present inventors investigated the relationship between the chemical composition and the structure of a steel material to obtain a high strength machine component and the structure of a steel material to obtain a steel component. high strength machine having a tensile strength of 900 MPa or more capable of performing cold forging even if the annealing treatment
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4/33 softener is not performed and without performing the thermal refining process such as hardening in the quick cooling and quenching to achieve the objective stated above. The present invention is made on the basis of metallurgical knowledge obtained by the investigation, and an outline of it is as described below.
[1] [0012] A wire material for a thermally untreated component used to produce a thermally untreated component whose tensile strength is 900 MPa to 1300 MPa, which contains, in weight%:
[0013] C: 0.20% to 0.50%, Si: 0.05% to 2.0%, Mn: 0.20% to 1.0%, being limited to contain P: 0.030% or less, S: 0.030% or less, N: 0.005% or less, F1 defined by Expression (1) below is less than 0.60, with the balance being made up of Fe and the inevitable impurities, [0014] where the metal structure contains a perlite structure of 64 x (C%) + 52% or more in a fraction of volume with the balance made of one or two types of a pro-eutectoid ferrite structure and a bainite structure, [0015] the average grain diameter of the perlite structure in a region from the surface layer to 0.1 D is 15 pm or less when the diameter of the wire material is adjusted to be D, e (the average grain diameter of the perlite structure in the region from the surface layer up to 0.1 D) / (the average grain diameter of the perlite structure in the region from the surface layer from 0.25 D to the center) is less than 1.0.
F1 = C (%) + Si (%) / 24 + Mn (%) / 6 ... (1) [2] [0016] The wire material for the thermally untreated component according to item [1], also contains , in mass%:
[0017] one type or two types or more types of elements between Al:
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5/33
0.003% to 0.050%, Ca: 0.001% to 0.010%, Mg: 0.001% to 0.010%, Zr: 0.001% to 0.010%.
[3] [0018] A method of producing a wire material for a thermally untreated component used for the production of a thermally untreated component whose tensile strength is 900 MPa to 1300 MPa, includes:
[0019] Heat a steel bar containing, in% by mass, C: 0.20% to 0.50%, Si: 0.05% to 2.0%, Mn: 0.20% to 1.0% , being limited to contain P: 0.030% or less, S: 0.030% or less, N: 0.005% or less, F1 defined by expression (1) below is less than 0.60, with the balance being made up of Fe and the inevitable impurities;
[0020] laminar in the form of a wire material;
[0021] winding at a cooling temperature of 800 ° C to
900 ° C;
[0022] cool at a cooling rate of 20 ° C / s to 100 ° C / s from the winding end temperature to 600 ° C, also cool at a cooling rate of 20 ° C / s or less from 600 ° C up to 550 ° C;
[0023] thereafter, keep isothermally in a molten salt tank 1 at 400 ° C to 600 ° C and in a successive molten salt tank 2 at 500 ° C at 600 ° C for 5 seconds at 150 seconds each; and [0024] subsequently cool.
F1 = C (%) + Si (%) / 24 + Mn (%) / 6 ... (1) [4] [0025] A steel wire for a thermally untreated component used for the production of a thermal component untreated whose tensile strength is 900 MPa to 1300 MPa, contains, in mass%:
[0026] C: 0.20% to 0.50%, Si: 0.05% to 2.0%, Mn: 0.20% s 1.0%,
Petition 870180133468, of 9/24/2018, p. 9/47
6/33 being limited to containing P: 0.030% or less, S: 0.030% or less, N: 0.005% or less, F1 defined by Expression (1) below is less than 0.60, with the balance being made from Fe and the inevitable impurities, [0027] where the metallic structure contains a pearlite structure of 64 x (C%) + 52% or more in a fraction of volume with the balance being made of one or two types of a pro-ferrite structure -eutectoid and a bainite structure, [0028] the average grain diameter of the perlite structure in, a region from the surface layer up to 0.1 D is 15 mm or less when the diameter of the steel wire is adjusted to be D , and (average grain diameter of the perlite structure in a region from the surface layer to 0.1 D) / (average grain diameter of the perlite structure in a range from 0.25 D to the center) is less than 1, 0, [0029] the area ratio of the structure made of a perlite block whose aspect ratio is 2.0 or more is 70% or more in relation to the total structure perlite in a region from the surface layer to 1.0 mm in a cross section parallel to an axial direction of the steel wire.
F1 = C (%) + Si (%) / 24 + Mn (%) / 6 ... (1) [5] [0030] The steel wire for the thermally untreated component according to item [4], also contains, in% by mass:
[0031] one type or two or more types of elements between Al: 0.003% to 0.050%, Ca: 0.001% to 0.010%, Mg: 0.001% to 0.010%, Zr: 0.001% to 0.010%.
[6] [0032] A method for producing a steel wire for a thermally untreated component used for the production of a thermally untreated component whose tensile strength is 900 MPa to 1300 MPa, includes:
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7/33 [0033] heat a steel bar containing, in% by mass, C: 0.20% to 0.50%, Si: 0.05% to 2.0%, Mn: 0.20% to 1 , 0%, being limited to contain P: 0.030% or less, S: 0.030% or less, N: 0.005% or less, F1 defined by expression (1) below is less than 0.60, with the balance being made de Fe r the inevitable impurities;
[0034] hot-rolling in the form of a steel wire;
[0035] winding at a winding temperature of 800 ° C to 900 ° C;
[0036] cool at a cooling rate of 20 ° C / s to 100 ° C / s from the winding end temperature to 600 ° C, also cooling at a rate of 20 ° C / s or less than 600 ° C to 550 ° C;
[0037] thereafter, keep isothermally in a molten salt tank 1 at 400 ° C to 600 ° C and a successive molten salt tank 2 at 500 ° C at 600 ° C for 5 seconds at 150 seconds each;
[0038] subsequently to cool; and [0039] subsequently perform the wire stamping at a total area reduction of 15% to 80%.
F1 = C (%) + Si (%) / 24 + Mn (%) / 6 ... (1) [7] [0040] A thermally untreated component whose tensile strength is 900 MPa to 1300 MPa, produced by working a steel wire containing, in weight%, C: 0.20% to 0.50%, Si: 0.05% to 2.0%, Mn: 0.20% to 1.0% , being limited to contain P: 0.030% or less, S: 0.030% or less, N: 0.005% or less, F1 defined by expression (1) below is less than 0.60 with the balance being made up of Fe and the unavoidable impurities, [0041] Where the metal structure contains a 64 x (C%) pearlite structure + 52% or more in a fraction of volume, with the balance being made up of one or two types of a pro-eutectoid ferrite structure and a Bainite structure,
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8/33 [0042] The average diameter of the perlite structure in a region from the surface layer up to 0.1 D is 15 mm or less when the diameter of the steel wire is set to be D, e (average grain diameter perlite structure in the region from the surface layer to 0.1 D) / (average grain diameter of the perlite structure in a range from 0.25 D to the center) is less than 1.0, and the [0043] ratio of area of the structure made of perlite whose aspect ratio is 2.0 or more is 70% or more in relation to the entire perlite structure in a region from the surface layer to 1.0 mm in a cross section parallel to the direction axial of the steel wire.
F1 = C (%) + Si (%) / 24 + Mn (%) / 6 ... (1) [8] [0044] The thermally untreated component according to item [7], also contains, in% in pasta:
[0045] one type or two or more types of elements between Al: 0.003% to 0.050%, Ca: 0001% to 0.010%, Mg: 0.001% to 0.010%, Zr: 0.001% to 0.010%.
[9] [0046] A method of producing a thermally untreated component whose tensile strength is 900 MPa to 1300 MPa, includes:
[0047] heat a steel bar containing, in% by mass, C: 0.20% to 0.50%, Si: 0.05% to 2.0%, Mn: 0.20% to 1.0% , being limited to contain P: 0.030% or less, S: 0.030% or less, N: 0.005% or less, F1 defined by expression (1) below is less than 0.60, with the balance being Fe and the inevitable impurities;
[0048] hot rolling in a form of wire material;
[0049] winding at a winding temperature of 800 ° C to
900 ° C;
[0050] cool at a cooling rate of 20 ° C / s to 100 ° C / s from the winding end temperature to 600 ° C, also
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9/33 cooling at a cooling rate of 20 ° C / s or less than βϋϋ'Ό to 550 ° C;
[0051] thereafter, keep isothermally in a molten salt tank 1 at 400 ° C to 600 ° C and a successive molten salt tank 2 at 500 ° C to 600 ° C for 5 seconds at 150 seconds each;
[0052] subsequently cool;
[0053] then perform the wire stamping at a total area reduction of 15% to 80%, and [0054] also perform the cold work.
F1 = C (%) + Si (%) / 24 + Mn (%) / 6 ... (1) [10] [0055] The production method of the thermally untreated component according to item [9], [0056 ] where after the wire stamping is carried out, cold lamination is carried out without carrying out a hot softening treatment.
[11] [0057] The method of producing the thermally untreated component according to item [9] also includes:
[0058] Keep at 200 ° C to 600 ° C for 10 minutes or more after cold work is performed.
[Effect of the Invention] [0059] According to the present invention, it is possible to provide a high strength machine component having a tensile strength of 900 MPa to 1300 MPa contributing to the reduction in the weight and size of a vehicle, various types of industrial equipment and architectural members at low cost.
[Brief Description of the Drawings] [0060] [FIG. 1] - FIG. 1 is a view illustrating the relationship between the tensile strength (TS) and the ratio between the average grain diameter of
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10/33 a perlite structure within a range from the surface layer up to 0.1 D and the average grain diameter of the inner block.
[Mode for Carrying Out the Invention] [0061] The present inventors investigated in detail about the relationship between the chemical composition and the structure of the steel material to obtain the high strength machine component having the tensile strength of 900 MPa or more capable to perform cold forging even if the softening heat treatment is not performed as mentioned above and without performing the thermal refining process such as quenching and tempering. Then, the present inventors continued a total study of the series of production methods related to the heat treatment in the line using the heat retained at the time of the hot rolling of a wire material, and even the subsequent steel wire, a component of machine based on metallurgical knowledge obtained by research to produce the high strength machine component at low cost and reached the following conclusions.
[0062] (x) To provide high strength to a wire material by wire stamping and cold forging, it is effective to change the steel structure into an excellent perlite structure in hardening capacity at work, but the working capacity is low, resistance to deformation is high, and working fractures are easy to occur in the perlite structure.
[0063] (y) To improve the working capacity of the perlite structure, it is effective (y1) to reduce the amount of connection elements, and (y2) to make the grain diameter of the perlite structure in a small surface layer.
[0064] (z) That is, it is possible to greatly improve the cold working capacity of the perlite structure if C (%) + Si (%) / 24 + Mn (%) / 6 is set to be less than 0.60 , and the grain diameter of the perlite
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11/33 in a region from the surface layer up to 0.1 D (D: diameter of the wire material) is adjusted to be 15 mm or less, and the ratio with a grain diameter of the perlite within the material of wire is set to be less than 1.0.
[0065] As determined above, it becomes possible to guarantee the excellent hardening capacity at work, to maintain high strength even if the quenching and tempering processes are not carried out, and to improve the cold forging capacity by improving the chemical composition and the structure of the steel material.
[0066] A steel wire to be a material to obtain the machine component capable of performing cold forging even if the softening heat treatment is not performed, and having high strength without performing the thermal refining processes such as quenching and tempered is one that already has the structure with the characteristics mentioned above in one step of the steel wire, and is effective for working on a component for structural use in machines without performing heat treatment before work.
[0067] In this case, the cold working capacity is deteriorated but the cost of softening annealing and the cost of quenching and quenching after work can be reduced, and therefore the present invention is cost-effective compared to a method conventional production in which coalescing annealing is performed for softening.
[0068] Furthermore, regarding the method of producing the steel material to be the steel wire material, it is possible to obtain the steel material in an almost perfect pearlite structure without adding any expensive connecting elements if immersed in a bath of molten salt made from two tanks right after lamination while using the remaining heat at the time of hot lamination. This production method is the best production method capable of obtaining excellence. 870180133468, of 09/24/2018, p. 15/47
12/33 characteristics of material at low cost.
[0069] That is, the present invention is a series of production methods in which the steel material whose chemical composition is adjusted to be the perlite structure is immersed in the molten salt bath using the remaining heat at the time of hot rolling for obtain the wire material having an almost perfect pearlite structure, and then the wire is stamped at room temperature under a specific condition, an adjustment is made to be the high strength pearlite structure, it is formed into a machine component and, thereafter, heat treatment is carried out at a relatively low temperature to recover its ductility.
[0070] Therefore, according to the present invention, it is possible to produce the machine component whose tensile strength is 900 MPa to 1300 MPa at low cost although it is extremely difficult to produce it according to the conventional production method and knowledge .
[0071] Initially, the reasons for limiting the chemical composition of the steel material (wire material, steel wire, thermally untreated component) of the present invention will be described. From now on, the symbol “%” for the chemical composition means “% by mass”.
[0072] C is added to guarantee a predetermined tensile strength. When its content is less than 0.20%, it is difficult to guarantee the tensile strength of 900 MPa or more; on the other hand, when the content exceeds 0.50%, the cold forging capacity deteriorates and, therefore, the C content is adjusted to be 0.20% to 0.50%. A preferable range to allow both strength and cold forging capacity is 0.35% to 0.48%.
[0073] Si works as a deoxidizing element and has the effect of increasing the tensile strength by reinforcing the solid solution. Quan
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13/33 of its content is less than 0.05%, the effect of the addition is insufficient. When it exceeds 2.0%, the effect of the addition is saturated, the hot ductility deteriorates, failures are easy to occur, and the production capacity is decreased. Consequently, the Si content is adjusted to be 0.05% to 2.0%. A preferable range for production capacity is 0.18% to 0.5%.
[0074] Mn has the effect of increasing the tensile strength of steel after transformation into perlite. When its content is less than 0.20%, the effect of the addition is insufficient, and when the content exceeds 1.0%, the effect of the addition is saturated and, therefore, the Mn range is adjusted to be 0.20% to 1.0%. A more preferable range is 0.50% to 0.8%.
[0075] P and S are unavoidable impurities. These elements segregate at the grain edge to deteriorate the characteristics of resistance to hydrogen embrittlement and, therefore, the lower the content, the better. Consequently, the upper limit is each adjusted by 0.030%. The content is preferably 0.015% or less. The lower limit includes 0 (zero)%, but both P and S are inevitably mixed by at least approximately 0.0005%.
[0076] N deteriorates the ability to work cold due to the dynamic aging stress and, therefore, the lower its content, the better, so the upper limit is adjusted to 0.005%. The content is preferably 0.004% or less. The lower limit includes “0” (zero)%, but is inevitably mixed by at least approximately 0.0005%. [0077] When the relational expression (1) of the levels of C, Si, and Mn: F1 = C (%) + Si (%) / 24 + Mn (%) / 6 becomes 0.60 or more, the resistance deformation increases and the cold working capacity deteriorates and therefore F1 is adjusted to be less than 0.60.
[0078] C, Si, and Mn are elements that improve resistance. F1 is an expression that restricts the total amount of C, Si, and Mn considering the degree of contribution to the improvement of resistance.
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14/33 [0079] In the present invention, Al can be contained by 0.003% to 0.050%. Al works as a deoxidizing element, and in addition, forms AlN to reduce the solid N solution, and suppresses the dynamic aging stress. AlN acts as a fixing particle to refine the crystal grains and improve the ability to work cold.
[0080] When its content is less than 0.003%, there is no effect of the addition, and when the content exceeds 0.050% the effect of the addition is saturated, and the production capacity deteriorates, and therefore the Al content is adjusted to be 0.003% to 0.050%. It is preferably 0.008% to 0.0045%.
[0081] In the present invention, one type or two or more types of elements can be contained between Ca: 0.001% to 0.010%, Mg: 0.001% to 0.010%, Zr: 0.001% to 0.010% as deoxidizing elements, and form sulfides such as CaS, MgS to fix the solid solution of S and has the effect of improving the characteristics of resistance to hydrogen embrittlement.
[0082] Cr, Mo, Ni, Ti, Nb and V increase the resistance, deteriorate the capacity of cold working and, therefore, their levels need to be reduced. Note that when the amount contained as impurities is less than 0.60 at a value of C (%) + Si (%) / 24 + Mn (%) / 6 + (Cr (%) + Mo (%)) / 5 + Ni (%) / 40 + (Ti (%) + Nb (%) + V (%)) / 5, the effect on cold working capacity is small and therefore Cr, Mo, Ni, Ti, Nb and V are allowed within a range of less than 0.60 in the amount shown above. The value shown above is preferably 0.58 or less.
[0083] Note that O inevitably exists in the form of an oxide of Al, Ca and / or Mg in steel. When the amount of O is large, a crude oxide can be generated, which can cause a fatigue fracture and, therefore, its content is preferably 0.01% or less. Note that O is inevitably mixed by at least approximately 0.001%.
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15/33 [0084] In the present invention, a steel bar having the chemical composition shown above needs to be hot rolled to transform it into a steel material (wire material, steel wire, thermally untreated component) having a specific microstructure. The following are the reasons for limiting the microstructure of the steel material, (wire material, steel wire, thermally untreated component).
[0085] The pearlite structure is a structure having excellent hardening characteristics at work. When the volume fraction is less than 64 x (C%) + 52%, the work hardening at the time of stamping and at the time of cold forging becomes small, the resistance is reduced, and work fractures are easy to occur at the time of cold forging because a part of the non-pearl structure becomes the starting point of the fracture. Consequently, the lower limit of the volume fraction of the perlite structure is adjusted to be 64 x (C%) + 52%.
[0086] It is possible to contain a pro-eutectoid ferrite structure and a bainite structure as a remaining structure different from the perlite structure. A martensite structure is not contained because fractures at the time of stamping the wire and at the time of cold forging are easy to occur and the characteristics of resistance to hydrogen embrittlement are deteriorated.
[0087] The volume fraction of the perlite structure is discovered, for example, by photographing the cross section C of the wire material (a cross section perpendicular to the longitudinal direction of the wire material) at a magnification of 1000 times by using a scanning electron microscope, and for performing image analysis. For example, in cross section C of the wire material, a 125 pm x 95 pm region is photographed in each of the regions in the vicinity of a surface layer (surface) of the wire material.
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16/33 wire, a 1/4 D part (a part held by 1/4 of a D diameter of the wire material from the surface of the wire material towards the center of the wire material), and a part 1 / 2 D (the central part of the wire material). The area ratio of a structure contained in a microscopic observation surface (cross section C) is equal to the volume fraction of the structure and, therefore, the area ratio obtained by image analysis is the volume fraction of the structure. Note that the volume fractions of the perlite structures of the steel wire and the thermally untreated component are defined in a similar way.
[0088] When the average grain diameter of the perlite structure in a range from the surface layer to 0.1 D exceeds 15 mm, working fractures are easy to occur at the time of cold forging and, therefore, the upper limit the average grain diameter is adjusted to be 15 mm.
[0089] When (average grain diameter of the perlite structure in the region from the surface layer to 0.1 D) / (average grain diameter of the perlite structure in a range from 0.25 D to the center) and makes 1, 0 or more, working fractures are easy to occur and therefore the ratio of average grain diameters is adjusted to less than 1.0. Its preferable upper limit is 0.90.
[0090] Next, in the present invention, the area ratio of a structure made of perlite whose aspect ratio is 2.0 or more in a region from the surface layer to 1.0 mm in the cross section that is parallel to the axial direction of the steel wire is 70% or more in relation to the entire pearlite structure in the steel wire obtained by stamping the wire material. The relationship between the tensile strength (TS) and the ratio of the average grain diameter of the perlite structure in the range from the surface layer to 0.1 D and the average diameter of the internal grain is illustrated in Fig. 1. In the drawing, a black square means a case of a steel material whose chemical composition is out of
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17/33 range of the present invention and F1 is 0.6 or more.
[0091] In the drawing, a black triangle represents a case of a steel wire whose chemical composition is within the range of the present invention, but whose fraction of volume of the structure made of perlite whose aspect ratio is 2.0 or more is less that 70% in relation to the entire perlite structure to be outside the range of the present invention, and ♦ represents the case of a steel wire whose chemical composition is within the range of the present invention, and whose volume fraction of the structure made of perlite whose aspect ratio is 1.0 or more is 70% or more in relation to the entire pearlite structure.
[0092] The average grain diameter can be measured using, for example, an EBSP (Electron Back Scattering Pattern) equipment. Specifically, a region of 275 mm x 165 mm is measured in each strip from the surface layer to 0.1 D and in the strip from 1/4 D (a part 1/4 of the diameter D of a steel wire from the surface of the steel wire towards the center of the steel wire) to the 1/2 D part (the central part of the steel wire) in the cross section of the wire material perpendicular to the longitudinal direction of the wire material .
[0093] An edge where the disorientation becomes 10 ° or more from the crystal orientation map of a bcc structure measured by the EBSP equipment is adjusted to be the grain edge of the block. The equivalent circle diameter of a grain is defined as the grain diameter of the block, and its average volume is defined as the average grain diameter.
[0094] The thermally untreated component is a machine component in which heat treatments such as softening annealing and the quenching and tempering process are not carried out, and resistance is provided by work effects such as wire stamping and forging. Here, it is the machine component whose
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18/33 area reduction since the initial cross section is 10% or more. [0095] The following describes a production method for the steel material (the wire material, the steel wire, the thermally untreated component). A steel bar made of a predetermined chemical composition is heated, then hot rolled in a wire state and, later, it is wound in a ring state. The winding temperature is set at 800 ° C to 90 ° C, and is cooled at a cooling rate of 20 ° C / s to 100 ° C / s from the winding end temperature to 600 ° C, in addition to This is cooled at a cooling rate of 20 ° C / s or less than 600 ° C to 550 ° C.
[0096] The coiling temperature affects the grain of the pearlite to the transformation. When the winding temperature exceeds 900 ° C, the grain diameter of the perlite of the wire material after hot rolling becomes a raw grain to exceed 15 mm a part of the surface layer, and the cold forging capacity is deteriorated. When the winding temperature is less than 800 ° C, the volume fraction of the pro-eutectoid ferrite structure of the structure after transformation increases, and the volume fraction of the perlite structure becomes less than 64 x (C%) + 52% . Consequently, the winding temperature is adjusted to 800 ° C to 900 ° C.
[0097] When the cooling rate after winding is less than 20 ° C / s, the volume fraction of the pro-eutectoid ferrite structure of the wire material increases and the volume fraction of the perlite structure becomes less than 64 x ( C%) + 52%. Excessive cooling equipment is required to allow a cooling rate of more than 100 ° C / s. Consequently, the cooling rate after winding up to 600 ° C is set at 20 ° C / s to 100 ° C / s.
[0098] When the cooling rate from 600 ° C to 550 ° C exceeds 20 ° C / s, the bainite structure is generated in the structure to deteriorate the capacity of cold forging and, therefore, the upper limit of the rate of
Petition 870180133468, of 9/24/2018, p. 22/47
19/33 cooling from 600C to 550 ° C is set to 20 ° C / s. the lower limit is preferably 1 ° C / s from the point of view of productivity. [0099] Next, the wire material is immersed in the molten salt tank by using the remaining heat at the time of hot rolling to generate the isothermal transformation of perlite.
[00100] After being cooled to 550 ° C, the wire material is immersed in a molten salt tank 1 at 400 ° C at 600 ° C and in a successive molten salt tank 2 at 500 ° C at 600 ° C, and is maintained isothermally for 5 seconds to 150 seconds respectively, and is subsequently cooled to produce the wire material having the microstructure mentioned above.
[00101] When the temperature of the molten salt tank 1 is less than 400 ° C, bainite is generated to deteriorate the capacity of cold forging. When the temperature of the molten salt tank 1 exceeds 600 ° C, the time required for the transformation of perlite becomes long. Consequently, the temperature of the molten salt tank 1 is adjusted from 400 ° C to 600 ° C.
[00102] In the molten salt tank 2 subsequent to the molten salt tank 1, the temperature is adjusted from 500 ° C to 600 ° C to finish the perlite transformation in a minimum time. The immersion time in the molten salt tank is adjusted from 5 seconds to 150 seconds in each tank in order to maintain sufficient temperature and the productivity of the steel material. Cooling after being kept in the molten salt tank for a predetermined time can be water-cooled or remain to cool.
[00103] Note that a similar effect can be obtained using equipment such as a lead tank and a fluidized bed such as the immersion tank instead of the molten salt tank, but the present invention is superior in terms of environmental preservation and cost of production.
Petition 870180133468, of 9/24/2018, p. 23/47
20/33 [00104] To change the wire material produced as determined above on a steel wire having the desired strength and forging capacity by performing the wire stamping, the mode of the perlite structure in a region from the surface layer up to 1.0 mm is important.
[00105] When the volume fraction of the structure made of perlite whose aspect ratio is 2.0 or more is less than 70% in relation to the total perlite structure in the region from the surface layer to 1.0 mm of the steel, the effect of improving the cold forging capacity is not obtained. Consequently, the lower limit of the volume fraction of the structure made of perlite whose aspect ratio is 2.0 or more is adjusted by 70%. The preferable lower limit of the volume fraction of the structure is 80% because the lower the volume fraction of the block whose aspect ratio is less than 2.0, the better.
[00106] When the aspect ratio of the pearlite is less than 2.0, the effect of improving the hot forging capacity is small and, therefore, the lower limit of the aspect ratio is adjusted to 2.0. Note that the aspect ratio is the ratio between the major axis and the minor axis of the grain, and is equal to the ratio between the diameter in the axial direction and the diameter in a direction perpendicular to the axis after the wire is stamped (diameter in the axial direction) / diameter in the direction perpendicular to the axis).
[00107] When stamping the wire, the area reduction is adjusted from 15% to 80%. When the wire stamping area reduction is less than 15%, the work hardening is insufficient and the resistance is small and, therefore, the lower limit of the area reduction is adjusted by 15%. When the reduction in area exceeds 80%, working fractures are easy to occur at the time of cold forging and, therefore, the upper limit of the reduction in area is adjusted by 80%. The preferred area reduction is 20% to 65%. Note that wire stamping can be performed once or several times.
Petition 870180133468, of 9/24/2018, p. 24/47
21/33 [00108] The steel wire obtained as established above is formed into a final machine component, but the heat treatment is not necessarily performed before forming to maintain the microstructure characteristics mentioned above. The steel wire obtained as established above is cold forged (cold working), and thus a thermally untreated component is obtained whose tensile strength is 900 MPa to 1300 MPa. The basis of the present invention is to obtain the thermally untreated component whose tensile strength is 900 MPa or more. When the strength of a component is less than 900 MPa in tensile strength, it is not necessary to apply the present invention. On the other hand, a component exceeding 1300 MPa is difficult to produce by cold forging, and the cost of production increases. Consequently, the tensile strength is adjusted to 900 MPa to 1300 MPa as component strength.
[00109] The tensile strength is preferably 900 MPa to 1250 MPa, more preferably 900 MPa to less than 1200 MPa. The machine component can be kept at 200 ° C to 600 ° C for 10 minutes to 5 hours after being cold forged in the form of the component and then cooled to improve other material characteristics necessary for the machine component such as limit elasticity, yield ratio, or ductility through its high strength as a machine component.
Examples [00110] The following describes examples of the present invention. The conditions in the examples are conditional examples applied to verify the feasibility and effects of the present invention, and the present invention is not limited to the conditional examples. The present invention is capable of applying various conditions within a range that does not depart from the spirit of the invention and achieve the purpose of the invention.
Petition 870180133468, of 9/24/2018, p. 25/47
22/33 [00111] The chemical compositions of the steel materials provided for the example and the values of the expression F1 = (C%) + (Si%) / 24 + (Mn%) / 6 are shown in Table 1. The types steel L, M, N and O are comparative examples outside the range of the present invention.
Petition 870180133468, of 9/24/2018, p. 26/47 [Table 1]
Steel type Ç Si Mn P s N Al Here Mg Zr Cr Mo F1 Grades THE 0.24 0.08 0.84 0.009 0.011 0.0026 0.0410.35B 0.32 0.21 0.66 0.008 0.006 0.0033 0.0420.44Ç 0.34 0.23 0.74 0.011 0.007 0.0028 0.0018 0.47D 0.35 0.09 0.92 0.015 0.012 0.0036 0.032 0.0024 0.52AND 0.37 0.23 0.66 0.014 0.006 0.0034 0.0300.49F 0.38 1.82 0.38 0.013 0.024 0.0037 0.004 0.0021 0.52G 0.41 0.32 0.74 0.009 0.007 0.0030 0.0240.55H 0.44 0.22 0.64 0.013 0.019 0.0036 0.0200.56I 0.46 0.12 0.71 0.008 0.011 0.0029 0.0270.58J 0.48 0.11 0.62 0.014 0.008 0.0034 0.0330.59K 0.49 0.06 0.61 0.012 0.009 0.0037 0.025 0.0014 0.0021 0.59L 0.17 0.26 0.63 0.007 0.014 0.0048 0.0420.29 Ex. Comp. M 0.46 0.06 0.64 0.014 0.007 0.0037 0.032 0.23 0.14 0.59 Ex. Comp. N 0.55 0.18 0.73 0.013 0.011 0.0043 0.0380.68 Ex. Comp. O 0.57 0.06 0.13 0.009 0.026 0.0061 0.0350.59 Ex. Comp.
23/33
Petition 870180133468, of 9/24/2018, p. 27/47
24/33 [00112] Steel bars made of this type of steel are hot rolled in wire materials each having a wire diameter of 8.0 mm to 15.0 mm. After hot rolling, coiling and cooling are performed, and the isothermal transformation process is performed in the molten salt tanks 1, 2 in a rolling line, and then cooled.
[00113] The diameter of each hot rolled wire material, the winding temperature after hot rolling, the cooling rate up to 600 ° C, the cooling rate from 600 ° C to 550 ° C, the temperature of isothermal retention and the isothermal retention time in each of the molten salt tanks 1, 2 are shown in Table 2. The wire stamping is performed for each hot rolled wire material after cooling with the area reductions shown in the Table 2, and heat treatment is performed. The temperatures of the respective heat treatments and the retention times of the heat treatment are shown in Table 2.
Petition 870180133468, of 9/24/2018, p. 28/47 [Table 2]
Level Steel Type Wire diameter (mm) Temp. cooling (° C) Cooling rate up to 600 ° C (° C / s) Cooling rate from 600 ° C to 550 ° C (° C / s ) Temp. of the molten salt tank 1(° C) Retention time of molten salt tank1 (s) Temp. of the molten salt tank 2(° C) Retention time of molten salt tank 2(s) Reduction of wire stamping area (%) Heat treatment temperature (° C) Retention timetion (h) Wire stamping fracture Grades 1 Steel 15.0 820 30 7 450 30 560 55 77.1 200 1Example 2 B 8.0 850 65 18 550 20 570 30 30.6 250 3Example 3 Ç 14.5 840 40 9 510 25 540 45 56.4 200 1Example 4 D 14.5 840 40 9 510 25 540 45 56.4 200 3Example 5 AND 15.0 825 30 7 470 30 550 55 26.6 250 3Example 6 AND 15.0 825 30 7 470 30 550 55 70.1 250 3Example 7 F 14.0 865 35 9 490 35 560 60 53.1 300 1Example 8 G 14.0 865 35 9 490 35 560 60 53.1 200 4Example 9 H 15.0 825 35 8 470 30 550 55 58.2 250 3Example 10 H 15.0 825 1.5 Air blast cooling after winding 58.2 250 3Ex. Comp .; 11 H 15.0 Level 10 LP lot 58.2 250 3Ex. Comp .; 12 I 10.5 845 50 14 480 20 540 30 30.5 250 3Example 13 I 10.5 940 55 14 480 20 540 30 30.5 250 3Ex. Comp .; 14 J 15.0 810 35 9 460 30 540 55 70.1 350 0.5Example 15 J 15.0 810 35 9 460 30 540 55 9.2 250 3Ex. Comp .; 16 J 15.0 810 40 23 320 30 400 55 - - - wire fracture Ex. Comp .; 17 K 8.0 885 74 18 550 20 570 30 44.2 300 1Example 18 L 14.5 850 40 9 520 25 550 45 56.4 250 3Ex. Comp .; 19 M 14.5 850 40 9 520 25 550 45 56.4 250 3Ex. Comp .; 20 N 14.5 850 40 9 520 25 550 45 56.4 250 3Ex. Comp .; 21 O 14.5 850 40 9 520 25 550 45 56.4 250 3Ex. Comp .; 22 I 10.5 750 45 14 480 20 540 30 30.5 250 3Ex. Comp .; 23 K 8.0 885 - - 650 20 570 30 44.2 300 1Ex. Comp .; 24 K 8.0 885 75 18 550 20 650 30 44.2 300 1Ex. Comp .; 25 K 8.0 885 75 18 550 3 570 3 - - - wire fracture Ex. Comp .;
25/33
Petition 870180133468, of 9/24/2018, p. 29/47
26/33 [00114] The metal structure, the volume fraction of the perlite structure, the average grain diameter of the perlite structure in a region from the surface layer to 0.1 D, the average grain diameter of the internal perlite structure ( average grain diameter of the perlite structure in a range of 0.25 D to the center), and the ratio of the average grain diameters between the surface layer and the inner part of each of the wire materials obtained by carrying out the transformation process isothermal in the molten salt tanks 1, 2 and then cooled are shown in Table 3. Note that, in the metallic structure, F represents the pro-eutectoid ferrite, P represents perlite, B represents bainite, and M represents martensite.
Petition 870180133468, of 9/24/2018, p. 30/47 [Table 3]
Level Steel Type Metal structure Lower limit of the fraction of perlite volume (%) Volume fraction of perlite (%) Average perlite grain diameter from the surface layer to 0.1 D (mm) Average grain diameter of the internal perlite structure (mm) Ratio of average grain diameters between the surface layer and the inner layer Volume fraction of perlite whose aspect ratio is 2.0 or more (%) Grades 1 THE F, P, B 67.4 69 10.3 12.6 0.82 77 Example 2 B F, P, B 72.5 76 9.7 12.4 0.78 72 Example 3 Ç F, P, B 73.8 78 10.6 13.5 0.79 74 Example 4 D F, P, B 75.0 78 11.7 12.8 0.91 76 Example 5 AND F, P, B 75.7 80 11.8 14.6 0.81 73 Example 6 AND F, P, B 75.7 80 11.8 14.6 0.81 82 Example 7 F F, P, B 76.3 78 10.9 12.9 0.84 76 Example 8 G F, P, B 78.2 82 11.2 13.4 0.84 74 Example 9 H F, P, B 80.2 86 10.8 12.3 0.88 76 Example 10 H F, P 80.2 68 11.8 11.6 1.20 71 Ex. Comp 11 I F, P 80.2 88 19.7 17.4 1.13 77 Ex. Comp 12 I F, P, B 81.4 88 11.1 13.8 0.80 73 Example 13 I F, P, B 81.4 88 17.2 16.9 1.02 75 Ex. Comp 14 J F, P, B 82.7 88 12.3 14.2 0.87 84 Example 15 J F, P, B 82.7 88 12.3 14.2 0.87 63 Ex. Comp 16 J F, P, B, M 82.7 43 10.6 12.7 0.83 62 Ex. Comp 17 K F, P, B 83.4 90 10.7 13.6 0.79 76 Example 18 L F, P, B 62.9 54 11.7 10.6 1.10 62 Ex. Comp 19 M F, P, B 82.7 90 12.2 13.9 0.88 74 Ex. Comp 20 N F, P, B 87.2 94 13.5 14.9 0.91 76 Ex. Comp 21 O F, P, B 88.5 95 14.2 15.3 0.93 75 Ex. Comp 22 I F, P, B 81.4 71 10.3 12.9 0.80 70 Ex. Comp 23 K F, P, B, M 83.4 72 14.8 15.2 0.97 72 Ex. Comp 24 K F, P, B, M 83.4 69 10.9 13.2 0.83 67 Ex. Comp 25 K F, P, B, M 83.4 39 12.3 13.8 0.89 54 Ex. Comp
27/33
Petition 870180133468, of 9/24/2018, p. 31/47
28/33 [00115] The structures of the steel wires after stamping the wire are the same as the structures shown in Table 3. In Table 3, each ratio of a structure made of pearlite whose aspect ratio is 2.0 is represented or more in relation to the total structure of the pearlite in a region from the surface layer to 1.0 mm in a cross section parallel to the axial direction of the steel wire. In addition, each lower limit of the volume fraction of the perlite structure calculated by 64 x (C%) + 52% is shown in Table 3.
[00116] Each tensile strength in the final machine component obtained by carrying out the cold forging (cold working) of the steel wire, and each cold forging capacity of the steel wire before the heat treatment are shown in Table 4 .
Petition 870180133468, of 9/24/2018, p. 32/47 [Table 4]
Level Steel type Tensile strength (MPa) Deformation resistance (MPa) Compression ratio limit (%) Evaluation Grades Deformation resistance Compression ratio limit 1 steel 1018 893 80 OR MORE GOOD GOOD Example 2 B 917 945 80 OR MORE GOOD GOOD Example 3 Ç 1026 1008 80 OR MORE GOOD GOOD Example 4 D 1091 1017 76 GOOD GOOD Example 5 AND 1156 1047 72 GOOD GOOD Example 6 AND 1214 1089 72 GOOD GOOD Example 7 F 1233 1112 70 GOOD GOOD Example 8 G 1128 1084 72 GOOD GOOD Example 9 H 1179 1082 70 GOOD GOOD Example 10 H 1070 1074 58 GOOD BAD Ex. Comp. 11 H 1185 1098 64 GOOD BAD Ex. Comp. 12 I 1038 1108 72 GOOD GOOD Example 13 I 1046 1112 62 GOOD BAD Ex. Comp. 14 J 1267 1130 70 GOOD GOOD Example 15 J 1008 1110 63 GOOD BAD Ex. Comp. 16 J _{- - - - -} Ex. Comp. 17 K 1174 1124 74 GOOD GOOD Example 18 L 856 837 80 OR MORE GOOD GOOD Ex. Comp. 19 M 1256 1240 62 BAD BAD Ex. Comp. 20 N 1269 1248 70 BAD GOOD Ex. Comp. 21 O 1252 1253 70 BAD GOOD Ex. Comp. 22 I 1030 1002 62 GOOD BAD Ex. Comp. 23 K 1298 1287 52 BAD BAD Ex. Comp. 24 K 1311 1291 50 BAD BAD Ex. Comp. 25 K _{- - - - -} Ex. Comp.
29/33
Petition 870180133468, of 9/24/2018, p. 33/47
30/33 [00117] Tensile strength is assessed using a JA Z 2201 9A specimen and the tensile test is performed using a JIS Z 2241 test method. The forging capacity cold is evaluated by maximum stress (resistance to deformation) and maximum compression ratio (limit of compression ratio) without any fractures using a sample of f5.0 mm x 7.5 mm prepared by machining the wire of steel after stamping the wire, when one end of the sample face is constricted and compressed with a metallic mold having a groove in a concentric state, and machined to a compression ratio of 57.3% corresponding to a distortion of 1.0 .
[00118] When the maximum stress, when the wire is machined at a compression ratio of 57.3%, is 1200 MPa or less, it is considered that the resistance to deformation is excellent, and when the compression ratio without any fractures is 65% or more, the compression ratio limit is considered to be excellent.
[00119] Level 10 is a conventional production method in which the isothermal transformation process is not performed after winding, and is cooled in Stelmor as shown in Table 2, and the volume fraction of the perlite structure is outside the range of present invention.
[00120] Level 11 is a comparative example in which the level 10 wire material produced by cooling at Stelmor is heated to 950 ° C for 10 minutes, and kept in a lead bath at 580 ° C for 100 seconds. The average grain diameter of the perlite structure in the range from the surface layer to 0.1 D, and the ratio of the average grain diameters between the surface layer and the inner layer are outside the range of the present invention.
[00121] Level 13 is an example in which the winding temperature exceeds the upper limit of the present invention. The average diameter
Petition 870180133468, of 9/24/2018, p. 34/47
31/33 grain size of the perlite structure in the range from the surface layer to 0.1 D, and the ratio of the average grain diameters of the surface layer and the inner layer are outside the range of the present invention.
[00122] Level 15 is an example in which the reduction in area in the wire stamping is less than the lower limit of the range of the present invention, and the volume fraction of the perlite structure whose aspect ratio is 2.0 or more does not reach the lower limit of the range of the present invention.
[00123] Level 16 is an example in which the temperature of the molten salt bath is lower than the lower limit of the range of the present invention, and the martensite structure is mixed into the metal structure to be outside the structure of the present invention, in addition the volume fraction of the perlite structure and the volume fraction of the perlite structure whose aspect ratio is 20 or more do not reach the lower limit of the range of the present invention. At level 16 at which the martensite structure is mixed, the stamping capacity deteriorates, and the wire fracture occurred during the stamping of the wire.
[00124] Level 22 is an example in which the winding temperature is less than the lower limit of the range of the present invention. Pro-eutectoid ferrite is generated, and the volume fraction of the pearlite structure is less than the lower limit of the range of the present invention.
[00125] Level 23 is an example in which the temperature of the molten salt bath 1 exceeds the upper limit of the range of the present invention. The martensite structure is mixed with the metallic structure to be outside the structure of the present invention, in addition the volume fraction of the perlite structure is less than the lower limit of the range of the present invention.
[00126] Level 24 is an example in which the temperature of the molten salt bath 2 exceeds the upper limit of the range of the present invention
Petition 870180133468, of 9/24/2018, p. 35/47
32/33 tion. The martensite structure is mixed with the metal structure to be outside the structure of the present invention, in addition, the volume fraction of the perlite structure whose aspect ratio is 2.0 or more does not reach the lower limit of the range of the present invention.
[00127] Level 25 is an example in which the retention times of the molten salt tank 1 and molten salt tank 2 are less than the lower limit of the range of the present invention. The martensite structure is mixed into the metal structure to be outside the structure of the present invention, in addition, the volume fraction of the perlite structure and the volume fraction of the perlite structure whose aspect ratio is 2.0 or more do not reach the lower limit of the range of the present invention. At the level 25 at which the martensite structure is mixed, the wire's embossing capacity deteriorates, and the wire fracture occurred during the wire embossing.
[00128] The mechanical properties of the respective levels are shown in Table 4.
[00129] All compression ratios are less than 65% and poor at level 10 in which the volume fraction of the pearlite structure and the ratio of the average grain diameters between the surface layer and the inner layer are outside the range of the present invention , the level 11 at which the average grain diameter of the structure perlites in the range from the surface layer to 0.1 D and the ratio of the average grain diameters between the surface layer and the inner layer are outside the range of the present invention, the level 13 at which the average grain diameter of the perlite structure in the range of the surface layer up to 0.1 D is outside the range of the present invention, the level 15 at which the ratio of the average diameters between the surface layer and the inner layer is outside the range of the present invention, each of the levels 16 and 24 at which the martensite structure is mixed into the metal structure to be outside the structure of the present invention and the volume fraction of the perlite structure and the fraction of
Petition 870180133468, of 9/24/2018, p. 36/47
33/33 volume of the perlite structure whose aspect ratio is 2.0 or more are outside the range of the present invention, the level 18 at which the volume fraction of the perlite structure and the volume fraction of the perlite structure whose aspect ratio is 2.0 or more are outside the range of the present invention, level 22 at which the volume fraction of the perlite structure is outside, and level 23 at which the martensite structure is mixed into the metal structure to be outside the structure of the present invention , and the volume fraction of the pearlite structure is outside the range of the present invention.
[00130] In each between level 19 using type M steel in which Cr and Mo are outside the range of the present invention, level 20 using type N steel in which C and F1 are outside the range of the present invention invention, and level 21 using type O steel in which C and N are outside the range of the present invention, the stress in the compression ratio of 57.3% exceeds 1200 MPa, and the resistance to deformation is poor.
[00131] It can be seen from the description presented above that the machine component according to the present invention has working capacity in which cold forging is possible even if softening annealing is not carried out, and has the strength of 900 MPa to 1300 MPa even if the quenching and tempering process is not carried out.
[Industrial Applicability] [00132] As mentioned above, according to the present invention it is possible to supply the high strength machine component that contributes to the reduction in the weight and size of a vehicle, various types of industrial equipment, and architectural members at low cost. Consequently, the present invention is applicable in mechanical industries.

权利要求:
Claims (11)
[1]
1. Wire material for a thermally untreated component, characterized by the fact that it is used to produce a thermally untreated component whose tensile strength is 900 MPa to 1300 MPa, and contains, in mass%,
C: 0.20% to 0.50%, Si: 0.05% to 2.0%, Mn: 0.20% to 1.0%, being limited to contain P: 0.030% or less, S: 0.030 % or less, N: 0.005% or less, F1 defined by Expression (1) below is less than 0.60, with the balance being made up of Fe and the inevitable impurities, in which the metallic structure contains a pearlite structure of 64 x (C%) + 52% or more in a fraction of volume, with the balance being made up of one or two types of a proeutectoid ferrite structure and a bainite structure, the average grain diameter of the perlite structure in a region from of the surface layer up to 0.1 D is 15 mm or less when the diameter of the wire material is adjusted to be D, e (average grain diameter of the perlite structure in the region from the surface layer to 0.1 D) / (average grain diameter of the perlite structure in a range from 0.25 D to the center) is less than 1.0.
F1 = C (%) + Si (%) / 24 + Mn (%) / 6 ... (1)
[2]
2. Wire material for the thermally untreated component, according to claim 1, characterized by the fact that it also contains, in mass%, one type or two or more types of elements between Al: 0.003% to 0.050%, Ca: 0.001% to 0.010%, Mg: 0.001% to 0.010%, Zr: 0.001% to 0.010%.
[3]
3. Method for producing a wire material for a thermally untreated component used to produce a thermally untreated component whose tensile strength is 900 MPa to 1300 MPa, characterized by the fact that it comprises:
Petition 870180133468, of 9/24/2018, p. 38/47
2/6 heat a steel bar containing, in mass%, C: 0.20% to 0.50%, Si: 0.05% to 2.0%, Mn: 0.20% to 1.0% , being limited to contain P: 0.030% or less, S: 0.030% or less, N: 0.005% or less, F1 defined by expression (1) below is less than 0.60, with the balance being made up of Fe and the inevitable impurities;
hot rolling in the form of a wire material;
wind at a winding temperature of 800 ° C to 900 ° C;
cool at a cooling rate of 20 ° C / s to 100 ° C / s from the winding end temperature to 600 ° C, also cool at a cooling rate of 20 ° C / s from 600 ° C to 550 ° C ;
thereafter, keep isothermally in a molten salt tank 1 at 400 ° C to 600 ° C and a successive molten salt tank 2 at 500 ° C at 600 ° C for 5 seconds at 150 seconds each; and subsequently cool.
F1 = C (%) + Si (%) / 24 + Mn (%) / 6 ... (1)
[4]
4. Steel wire for a thermally untreated component, characterized by the fact that it is used to produce a thermally untreated component whose tensile strength is 900 MPa to 1300 MPa, and contains, in mass%,
C: 0.20% to 0.50%, Si: 0.05% to 2.0%, Mn: 0.20% to 1.0%, being limited to contain P: 0.030% or less, S: 0.030 % or less, N: 0.005% or less, F1 defined by Expression (1) below is less than 0.60, with the balance being made up of Fe and the inevitable impurities, in which the metallic structure contains a pearlite structure of 64 x (C%) + 52% or more in a fraction of volume, with the balance being made of one or two types between a pro eutectoid ferrite structure and a bainite structure, the average grain diameter of the perlite structure in a region from the surface layer up to 0.1 D is 15 pm or less
Petition 870180133468, of 9/24/2018, p. 39/47
3/6 when the steel wire diameter is set to D, e (average grain diameter of the perlite structure in the region from the surface layer to 0.1 D) / (average grain diameter of the perlite structure in a range from 0.25 D to the center) is less than 1.0, and the area ratio of a structure made of a pearlite whose aspect ratio is 2.0 or more is 70% or more in relation to the entire structure perlite in a region from the surface layer to 1.0 mm in a cross section parallel to the axial direction of the steel wire.
F1 = C (%) + Si (%) / 24 + Mn (%) / 6 ... (1)
[5]
5. Steel wire for the thermally untreated component, according to claim 4, characterized by the fact that it also contains, in mass%, one type or two or more types of elements between Al: 0.003% to 0.050%, Ca: 0.001% to 0.010%, Mg: 0.001% to 0.010%, Zr: 0.001% to 0.010%.
[6]
6. Method of producing a steel wire for a thermally untreated component used for the production of a thermally untreated component whose tensile strength is 900 MPa to 1300 MPa, characterized by the fact that it comprises:
heat a steel bar containing, in% by mass, C: 0.20% to 0.50%, Si: 0.05% to 2.0%, Mn: 0.20% to 1.0%, being limited to contain P: 0.030% or less, S: 0.030% or less, N: 0.005% or less, F1 defined by expression (1) below is less than 0.60, with the balance being made up of Fe and the inevitable impurities ;
hot rolling in the form of a wire material;
wind at a winding temperature of 800 ° C to 900 ° C;
cool at a cooling rate of 20 ° C / s to 100 ° C / s from the winding end temperature to 600 ° C, also
Petition 870180133468, of 9/24/2018, p. 40/47
4/6 cool at a cooling rate of 20 ° C / s or less than 600 ° C to 550 ° C;
subsequently, keep isothermally in a molten salt tank 1 at 400 ° C to 600 ° C and in a successive molten salt tank 2 at 500 ° C at 600 ° C for 5 seconds at 150 seconds each, subsequently cooling; and then perform the wire stamping at a total area reduction of 15% to 80%.
F1 = C (%) + Si (%) / 24 + Mn (%) / 6 ... (1)
[7]
7. Thermally untreated component, characterized by the fact that it is produced by cold working a steel wire containing, in mass%, C: 0.20% to 0.50%, Si: 0.05% to 2 , 0%, Mn: 0.20% to 1.0%, being limited to contain P: 0.030% or less, S: 0.030% or less, N: 0.005% or less, F1 defined by expression (1) below is less than 0.60, with the balance being made of Fe and the inevitable impurities, in which the metallic structure contains a pearlite structure of 64 x (C%) + 52% or more in a fraction of volume, with the balance being made of one type or two types of a proeutectoid ferrite structure and a bainite structure, the average grain diameter of the perlite structure in a region from the surface layer up to 0.1 D is 15 mm or less when the diameter of the steel is set to D, e (average grain diameter of the perlite structure in the region from the surface layer to 0.1 D) / (average grain diameter of the perlite structure in a range of 0.25 D to the center other) is less than 1.0.
an area ratio of a structure made of a perlite structure whose aspect ratio is 2.0 or more is 70% or more compared to the entire perlite structure in a region from the surface layer to 1.0 mm in a section transversal parallel to the axial direction of the steel wire, and a tensile strength is 900 MPa to 1300 MPa.
Petition 870180133468, of 9/24/2018, p. 41/47
5/6
F1 = C (%) + Si (%) / 24 + Mn (%) / 6 ... (1)
[8]
8. Thermally untreated component, according to claim 7, characterized by the fact that it also contains, in mass%, one type or two or more types of elements between Al: 0.003% to 0.050%, Ca: 0.001% to 0.010%, Mg: 0.001% to 0.010%, Zr: 0.001% to 0.010%.
[9]
9. Method of producing a thermally untreated component having tensile strength is 900 MPa to 1300 MPa, characterized by the fact that it comprises:
heat a steel bar containing, in% by mass, C: 0.20% to 0.50%, Si: 0.05% to 2.0%, Mn: 0.20% to 1.0%, being limited to contain P: 0.030% or less, S: 0.030% or less, N: 0.005% or less, F1 defined by expression (1) below is less than 0.60, with the balance being made up of Fe and the inevitable impurities ;
hot laminating the wire material into a wire material form;
wind at a winding temperature of 800 ° C to 900 ° C;
cool at a cooling rate of 20 ° C / s to 100 ° C / s from the winding end temperature to 600 ° C, also cooling at a cooling rate of 20 ° C / s or less than 600 ° C at 550 ° C;
afterwards, keep isothermally in a molten salt tank 1 at 400 ° C to 600 ° C and in a successive molten salt tank 2 at 500 ° C at 600 ° C for 5 seconds at 150 seconds each;
subsequently cool down;
then, perform the wire stamping at a total area reduction of 15% to 80%; and also perform cold work.
Petition 870180133468, of 9/24/2018, p. 42/47
6/6
F1 = C (%) + Si (%) / 24 + Mn (%) / 6 ... (1)
[10]
10. Method of production of the thermally untreated component, according to claim 9, characterized by the fact that, after the wire stamping is carried out, cold rolling is carried out without the execution of the thermal softening treatment.
[11]
11. Method of production of the thermally untreated component, according to claim 9, characterized by the fact that it also comprises:
keep at 200 ° C to 600 ° C for 10 minutes or more after cold work is performed.

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同族专利:

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公开号 | 公开日

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CN103906853A|2014-07-02|

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KR101599163B1|2016-03-02|

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JP5590246B2|2014-09-17|

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CA2845611C|2017-05-30|

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US10287658B2|2019-05-14|

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MX360966B|2018-11-23|

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US20140290806A1|2014-10-02|

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IN2014DN01971A|2015-05-15|

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BR112014003823A2|2017-03-14|

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MX2014002069A|2014-05-30|

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WO2013031640A1|2013-03-07|

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KR20140050110A|2014-04-28|

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JPWO2013031640A1|2015-03-23|

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CN103906853B|2016-01-20|

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法律状态:
2018-06-26| B06A| Patent application procedure suspended [chapter 6.1 patent gazette]|

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2019-01-29| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2019-04-02| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 23/08/2012, OBSERVADAS AS CONDICOES LEGAIS. (CO) 20 (VINTE) ANOS CONTADOS A PARTIR DE 23/08/2012, OBSERVADAS AS CONDICOES LEGAIS |

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2019-11-26| B25D| Requested change of name of applicant approved|Owner name: NIPPON STEEL CORPORATION (JP) |

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2021-06-29| B21F| Lapse acc. art. 78, item iv - on non-payment of the annual fees in time|Free format text: REFERENTE A 9A ANUIDADE. |

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2021-10-19| B24J| Lapse because of non-payment of annual fees (definitively: art 78 iv lpi, resolution 113/2013 art. 12)|Free format text: EM VIRTUDE DA EXTINCAO PUBLICADA NA RPI 2634 DE 29-06-2021 E CONSIDERANDO AUSENCIA DE MANIFESTACAO DENTRO DOS PRAZOS LEGAIS, INFORMO QUE CABE SER MANTIDA A EXTINCAO DA PATENTE E SEUS CERTIFICADOS, CONFORME O DISPOSTO NO ARTIGO 12, DA RESOLUCAO 113/2013. |

优先权:

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申请号 | 申请日 | 专利标题

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JP2011184737|2011-08-26|

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JP2011-184737|2011-08-26|

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