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    • 专利摘要:
    abstract patent of invention: "hot stamped piece of high resistance excellent in anti-corrosion properties after painting and production method". the present invention relates to a high strength hot stamped part in which the propagation of fractures that form in the coating layer at the time of hot stamping when hot stamping an aluminum coated steel sheet is suppressed and the post-paint anti-corrosion property is excellent even without the addition of special ingredient elements that suppress the formation of fractures in an aluminum coating layer. a high-strength hot-stamped part that excels in post-painting anti-corrosion properties whose high-strength, hot-stamped coat has an alloy coating layer that includes an al-fe intermetallic composite phase on the steel sheet surface, where the layer alloy coating is comprised of phases of a plurality of intermetallic compounds, the average linear intersection length of a phase containing al: 40 to 65% by mass between the phases of the plurality of intermetallic compounds is 3 to 20? m, the value mean thickness of the al-fe alloy coating layer is 10 to 50 µm, and the ratio of the average thickness value to the standard deviation of the thickness of the al-fe coating layer satisfies the following relationship: 0 <deviation thickness standard / average thickness value? 0.15.
    公开号:BR112013025401B1
    申请号:R112013025401-7
    申请日:2012-03-30
    公开日:2020-05-12
    发明作者:Jun Maki；Kazuhisa Kusumi；Masayuki Abe；Masao Kurosaki
    申请人:Nippon Steel Corporation；
    IPC主号:
    专利说明:

    Descriptive Report on the Invention Patent for HIGH RESISTANCE HOT PRINTED PIECE AND THE SAME PRODUCTION METHOD.
    Technical Field [0001] The present invention relates to a piece coated with high strength aluminum which is excellent in anti-corrosion properties after painting which is produced by forming by pressing at a high temperature, that is, by hot stamping, and it is suitable for members where strength is required such as auto parts and other structural members, and refers more specifically to a high strength part that is formed by hot stamping that has suppressed the propagation of fractures that form in the coating layer aluminum when hot stamping high strength steel sheet coated with aluminum and which is excellent in anti-corrosion properties after painting, and a production method of it.
    Background of the Technique [0002] In recent years, in steel sheet applications for automotive use (for example, automobile columns, door impact beams. Bumper beams, etc.) and the like, a steel sheet has been desired in which both high strength and high forming capacity are achieved. As a means of dealing with this, there is TRIP (transmission-induced plasticity) steel that uses the transformation into residual austenite martensite. Using this TRIP steel, it is possible to produce high strength steel plate that is excellent in forming capacity and that has a strength class of 1000 MPa or something, but guaranteeing the forming capacity with very resistant steel plate high resistance even higher, for example 1500 MPa or more, was difficult.
    Petition 870190104452, of 10/16/2019, p. 10/66
    2/47 [0003] In view of this situation, the forming method that was most recently focused on as a method to guarantee high strength and high forming capacity has been hot stamping (also called hot pressing, hot stamping, tempering of the die, press quench, etc.). This hot stamping heats the steel sheet up to the austenite region of 800 ° C or more, and then forms it by a matrix when hot to improve the forming capacity of the high-strength steel sheet and, after conforming it , cool it in the pressing mold to temper it and thus obtain a shaped part of the desired quality.
    [0004] Hot stamping is promising as a method for forming members of very high strength, but generally includes a step of heating the steel sheet in the atmosphere. At that time, oxides (scale) form on the surface of the steel plate, so a later step to remove the scale becomes necessary. In this regard, at such a later stage, there was the problem of the need for some measures from the point of view of peeling capacity and environmental load, etc. As a technique to alleviate this problem, the technique of using aluminum-coated steel sheet as a steel sheet for use as a hot stamped member in order to suppress scale formation at the time of heating has been proposed (for example, see PLTs 1 and 2).
    [0005] Aluminum-coated steel sheet is effective for the efficient production of a high-strength piece formed by hot stamping. The aluminum coated steel sheet is generally formed by pressing, and then painted. The aluminum coating layer after heating at the time of hot stamping changes to an intermetallic compound up to the surface. This compound is extremely fragile. If subjected to a severe forming operation by hot stamping, the coating layer
    Petition 870190104452, of 10/16/2019, p. 11/66
    3/47 aluminum fracture breaks easily. In addition, the phases of this intermetallic compound have more electropositive potential than the matrix steel plate, so there was a problem that the corrosion of the steel plate material starts from the fractures as a starting point and the post-painting anticorrosion property falls .
    [0006] To avoid the drop in anti-corrosion properties in postpainting due to the formation of fractures in the aluminum coating layer, it has been proposed to add Mn to this intermetallic compound is extremely effective, so an aluminum coated steel plate that is improved in post-paint anti-corrosion property by adding 0.1% or more of Mn to the aluminum coating layer (for example, see PLT 3).
    [0007] The technique that is described in PLT 3 adds specific ingredient elements to the aluminum coating layer to prevent fractures from forming in the aluminum coating layer, but it is not a technique that prevents the formation of fractures in the aluminum coating layer. aluminum without adding specific ingredient elements to the coating layer.
    [0008] In addition, an aluminum coated steel plate has been proposed where, if elements are added to the matrix steel of the coated steel plate and aluminum to give Ti + 0.1Mn + 0.1Si + 0.1Cr> 0.25, these elements promote the diffusion between Al-Fe so that even if fractures are formed in the aluminum cladding layer, the Fe-Al reaction happens around them and therefore the steel sheet material is prevented from being exposed and the corrosion resistance is improved (see, for example, PLT 4).
    [0009] However, the technique that is described in PLT4 does not try to prevent the formation of fractures in the aluminum cladding layer.
    List of Citations
    Patent Literature
    Petition 870190104452, of 10/16/2019, p. 12/66
    4/47 [00010] PLT 1: Japanese Patent Publication no. 2003-181549A [00011] PLT 2: Japanese Patent Publication No. 2003-49256A [00012] PLT 3: Japanese Patent Publication No. 2003-34855A [00013] PLT 4: Japanese Patent Publication No. 2003-34846A
    Summary of the Invention Technical Problem [00014] The present invention was made in consideration of this situation and its objective is to provide a piece of high strength hot stamped in which the propagation of fractures that form in the aluminum coating layer when the hot stamping of the aluminum coated steel sheet is suppressed and the post-painting anti-corrosion property is excellent even without the addition of special ingredient elements that suppress the formation of fractures in an aluminum coating layer. In addition, it has as its objective the formation of a lubricating film on the surface of the aluminum cladding layer to improve the forming capacity during the hot stamping of the aluminum coated steel sheet and to suppress the formation of fractures in the aluminum coating. In addition, it aims to provide a production method of a high-strength hot-stamped part.
    Solution to the Problem [00015] The inventors engaged in intensive research to solve the above problems and completed the present invention. In general, an aluminum-coated steel sheet for use on a hot-stamped member is formed with a layer of aluminum coating on one or both surfaces of the steel sheet by hot dipping, etc. The aluminum coating layer can contain, in mass%, Si: 2 to 7% according to need and comprises an Al balance and the inevitable impurities.
    Petition 870190104452, of 10/16/2019, p. 13/66
    5/47 [00016] When an aluminum coating layer of the aluminum coated steel plate before hot stamping contains Si, it is comprised of an Al-Si layer and a Fe-Al-Si layer from the layer of surface. To hot-stamp an aluminum-coated steel sheet, the aluminum-coated steel sheet is initially heated to a high temperature to make the steel sheet an austenite phase. In addition, the aluminum coated steel sheet that is converted to austenite is formed by hot pressing, then the shaped aluminum coated steel sheet is cooled. The aluminum-coated steel sheet can be made at a high temperature to make it smooth and facilitate subsequent forming by pressing. In addition, the steel sheet can be heated and cooled so that it is hardened and a mechanical resistance of approximately 1500 MPa is achieved.
    [00017] In the heating stage of this aluminum-coated steel plate for use in a hot-stamped member, inside the aluminum coating layer (when they include Si), the Al-Si and Fe of the steel plate diffuse each other by changing as well as a whole Al-Fe compound (intermetallic compound). At that time, in the compound Al-Fe, a phase containing Si is also partially formed. This compound (intermetallic compound) is extremely fragile. If formed under severe conditions in hot stamping, fractures will form in the aluminum coating layer. In addition, these phases have a more electropositive potential than the matrix steel plate, so the corrosion of the steel plate material will start with fractures as a starting point and the shaped part will be reduced in post-paint anti-corrosion properties. Therefore, the suppression of fractures that form in the aluminum coating layer after hot stamping improves the post-painting anti-corrosion property of the part that is formed by hot stamping.
    Petition 870190104452, of 10/16/2019, p. 14/66
    6/47 [00018] In hot stamping, it is not possible to prevent the formation of fractures in the aluminum cladding layer, but the inventors took note of the fact that it was impossible to stop the spread of fractures in the aluminum cladding layer that formed in the hot stamping inside the aluminum coating layer, the fractures would not reach the matrix steel plate. They found that this would prevent the corrosion of the steel sheet material and prevent a detrimental effect on the post-painting anti-corrosion property of the hot stamped part. The inventors engaged in intensive research in stopping the spread of fractures from an aluminum cladding layer to fractures that formed in the aluminum cladding layer. As a result, they found that by controlling the average linear intersection length of the crystal grains of an intermetallic compound phase containing Al at 40 to 65% between the crystal grains of the plurality of phases of intermetallic compounds based on Al-Fe that are formed on the surface of the steel sheet (sometimes referred to below simply as average linear intersection length) for 3 to 20 pm, it is possible to stop the spread of fractures that form in the aluminum cladding layer. In addition, they found that by also forming a lubricating film containing ZnO on the surface of the aluminum coating surface layer, it is possible to guarantee a lubricating property at the time of hot stamping and to avoid surface defects and the formation of fractures . In addition, they discovered a steel sheet composition that is suitable for hot stamping.
    [00019] In addition, the inventors have found that the thickness of the Al-Fe alloy coating layer has an effect on the dripping state at the time of spot welding and have found that to obtain a stable spot welding capacity it is necessary to impose
    Petition 870190104452, of 10/16/2019, p. 15/66
    7/47 try to reduce the coating thickness deviation (standard deviation), make the average value of the Al-Fe alloy coating layer thickness 10 to 50 μm, and make the ratio of the average thickness value to the standard deviation of the thickness (thickness standard deviation / mean thickness value) 0.15 or less.
    [00020] The present invention was completed on the basis of these discoveries and has as its essence the following: (1) A high-strength, hot-stamped part that excels in post-painting anti-corrosion properties, [00021] comprising a coating layer of alloy comprising an Al-Fe intermetallic composite phase on the steel plate surface, [00022] the alloy coating layer is comprised of phases of a plurality of intermetallic compounds, [00023] the average linear intersection length of the crystal grains of a phase containing Al: 40 to 65% by mass between the phases of the plurality of intermetallic compounds is 3 to 20 μm, [00024] the average thickness value of the Al-Fe alloy coating layer is 10 to 50 µm, and [ 00025] the ratio of the average thickness value to the thickness standard deviation of the Al-Fe alloy coating layer satisfies the following relationships:
    [00026] 0 <thickness standard deviation / average thickness value <0.15 (2) The hot-stamped high-strength part that is excellent in anti-corrosion properties after painting as shown in item (1) above, characterized by the fact that that the ratio of the mean thickness value to the thickness standard deviation is 0.1 or less.
    (3) The hot-stamped high-strength part that is
    Petition 870190104452, of 10/16/2019, p. 16/66
    8/47 excellent in anti-corrosion properties after painting as presented in item (1) or (2) above, characterized by the fact that the Al-Fe alloy coating layer contains, in mass%, Si: 2 to 7% .
    (4) The hot-stamped high-strength part that is excellent in anti-corrosion properties after painting as shown in items (1) or (2) above characterized by the fact that the layer of the surface film containing ZnO is supplied on the surface the Al-Fe alloy coating layer.
    (5) The hot-stamped, high-strength part that is excellent in post-painting anti-corrosion properties as presented in item (4) above, characterized by the fact that the ZnO content of the surface film layer is converted to Zn mass , 0.3 to 7 g / m per side.
    (6) The hot-stamped high-strength part that is excellent in anti-corrosion properties after painting as presented in item (1) or (2) above characterized by the fact that the steel plate is comprised of chemical ingredients steel plate comprising as ingredients, in% by weight, C: 0.1 to 0.5%, [00027] Si: 0.01 to 0.7%, [00028] Mn: 0.2 to 2.5%, [ 00029] Al: 0.01 to 0.5%, [00030] P: 0.001 to 0.1%, [00031] S: 0.001 to 0.1%, [00032] N: 0.0010% to 0.05 %, and [00033] the balance being Fe and the inevitable impurities.
    (7) The hot-stamped high-strength part that is excellent in anti-corrosion properties after painting, as presented in item (6), characterized by the fact that the steel sheet also comprises, in mass%, one or more elements selected among
    Petition 870190104452, of 10/16/2019, p. 17/66
    9/47 [00034] Cr: more than 0.4 to 3%, [00035] Mo: 0.005 to 0.5%, [00036] B: 0.0001 to 0.01%, [00037] W: 0, 01 to 3%, [00038] V: 0.01 to 2%, [00039] Ti: 0.005 to 0.5%, [00040] Nb: 0.01 to 1% [00041] Ni: 0.01 to 5 %, [00042] Cu: 0.1 to 3%, [00043] Sn: 0.005% to 0.1%, and [00044] Sb: 0.005% to 0.1%.
    (8) A method for producing an aluminum-coated steel sheet for a high-strength hot-stamped part comprising the steps of:
    [00045] supply an aluminum coated steel sheet obtained characterized by [00046] hot rolling a steel comprising chemical ingredients, in% by weight, [00047] C: 0.1 to 0.5%, [00048] Si : 0.01 to 0.7%, [00049] Mn: 0.2 to 2.5%, [00050] Al: 0.01 to 0.5%, [00051] P: 0.001 to 0.1%, [00052] S: 0.001 to 0.1%, [00053] N: 0.0010% to 0.05%, and [00054] the balance being Fe and the inevitable impurities, [00055] cold-rolling the aforementioned rolled steel hot to obtain a cold rolled steel sheet, [00056] heat the aforementioned cold rolled steel sheet in a hot dip line to the annealing temperature of
    Petition 870190104452, of 10/16/2019, p. 18/66
    10/47
    670 to 760 ° C, [00057] keep the aforementioned steel sheet heated in a reduction oven for 60 seconds or less, and [00058] coat the aforementioned steel sheet with aluminum, and [00059] perform hardening lamination on the aforesaid aluminum-coated steel plate to give a rolling rate of 0.5 to 2%;
    [00060] increase the temperature of the aforementioned hardened aluminum-coated steel sheet by a temperature rise rate of 3 to 200 ° C / s, the hot stamping of the aluminum-coated steel sheet under conditions of a Larson- Miller (LMP) expressed by the following formula:
    [00061] LMP = T (20 + logt) [00062] (where, T: heating temperature of the aluminum coated steel sheet (absolute temperature K), t: retention time in the heating oven after reaching the desired temperature ( h)) from 20000 to 23000; and [00063] Carry out the hardening lamination of the aforementioned aluminum-coated steel sheet after hot stamping at 20 to 500 ° C / s cooling rate in the mold.
    (9) The method of producing an aluminum-coated steel sheet for a high-strength hot-stamped part as shown in item (8) above characterized by the fact that steel also comprises, in mass%, one or more elements selected from [00064] Cr: more than 0.4 to 3%, [00065] Mo: 0.005 to 0.5%, [00066] B: 0.0001 to 0.01%, [00067] W: 0, 01 to 3%, [00068] V: 0.01 to 2%,
    Petition 870190104452, of 10/16/2019, p. 19/66
    11/47 [00069] Ti: 0.005 to 0.5%, [00070] Nb: 0.01 to 1% [00071] Ni: 0.01 to 5%, [00072] Cu: 0.1 to 3%, [00073 ] Sn: 0.005% to 0.1%, and [00074] Sb: 0.005% to 0.1%.
    (10) The method of producing an aluminum-coated steel plate for a high-strength hot-stamped part as shown in item (8) or (9) above characterized by the fact that the rate of temperature rise in the hot stamping is 4 to 200 ° C / s. (11) The method for producing an aluminum-coated steel sheet for a high-strength hot-stamped skin as presented in any of items (8) to (10) above, characterized by the fact that in the production step of aluminum coated steel plate, the coating bath for aluminum coating comprises Si in an amount of 7 to 15%, and either the bath temperature or the plate temperature at the bath entrance is 650 ° C or less.
    Advantageous Effects of the Invention [00075] According to the present invention, it is possible to interrupt the fractures that have formed in the coating layer (alloy layer) of the aluminum-coated steel sheet at the time of hot stamping without allowing propagation at the edges of the crystal grains of the coating layer. For this reason, fractures do not reach the surface of the hot-stamped high-strength part and the hot-stamped high-strength part can be improved in anti-corrosion properties after painting. In addition, in the present invention, the surface of the coating layer of the aluminum coated steel sheet is also formed with a layer of lubricating surface film containing ZnO and then the sheet is stamped to
    Petition 870190104452, of 10/16/2019, p. 20/66
    12/47 hot to get the shaped part. Because of this, it is possible to improve the work capacity at the time of hot stamping and it is possible to suppress the formation of fractures, so productivity can be increased.
    [00076] In addition, by reducing the deviation in the coating thickness, the spot welding capacity can be stabilized. In addition, using a steel sheet having the steel ingredients of the present invention, it is possible to obtain a high-strength hot-stamped part that has a tensile strength of 1000 MPa or more ..
    Brief Description of the Drawings [00077] FIG. 1 and a polarizing microphotograph of the structure of an aluminum coating layer in the cross section of a hot stamped part.
    [00078] FIG. 2 is an Al-Fe-Si ternary phase diagram (650 ° C isothermal).
    [00079] FIGS. 3 (a) to (d) are polarizing microphotographs of the structure of an aluminum cladding layer. (a) shows the case of a coating thickness of 40 g / m per side and a temperature rise rate in hot stamping of 5 ° C. (b) shows the case of a coating thickness of 40 g / m per side and a temperature rise rate in hot stamping of 20 ° C. (c) shows the case of a coating thickness of 80 g / m per side and a temperature rise rate in hot stamping of 5 ° C. (d) shows the case of a coating thickness of 80 g / m per side and a temperature rise rate in hot stamping of 20 ° C. In addition, (a) is a view showing the method for finding the average linear intersection length of the crystal grains and the line segment method. It is a view that shows the average linear intersection length discovered of this
    Petition 870190104452, of 10/16/2019, p. 21/66
    13/47 by drawing a line parallel to the surface of the coating layer, counting the number of grain edges that are passed through that line, and dividing the length measured by the number of grain edges. In (a), the average linear intersection length was 12.3 μm.
    [00080] FIG. 4 is a view showing the effects of hot stamping conditions at the time of hot stamping on the average linear intersection length of an intermetallic composite phase containing Al: 40 to 65%. The abscissa shows the Larson-Miller (LMP) parameter of the heating conditions at the time of hot stamping.
    [00081] FIG. 5 is a polarizing micrograph of the structure of the aluminum cladding layer of FIG. 3 where the edges of the crystal grains are drawn to show them clearly.
    [00082] FIG. 6 is a view showing the relationship between the amount of Zn deposition on the surface of the aluminum coated steel sheet and the dynamic friction coefficient.
    Description of Configurations [00083] The hot stamped part of the present invention is made of a high-strength layer by coating the surface of the steel sheet with Al, thermally treating the aluminum coated steel sheet obtained to make the coating layer of aluminum form an alloy on the surface and then stamp it.
    [00084] The method of coating aluminum on aluminum coated steel sheet for use in a hot stamped member that is used in the present invention is not particularly limited. For example, the immersion method, first and foremost, and also the electroplating method, the vacuum deposition method, the coating method, etc. can be used, but currently the coating method that is most industrially prevalent is the
    Petition 870190104452, of 10/16/2019, p. 22/66
    14/47 hot immersion method. This method is desirable. Generally, in steel sheet aluminum cladding, an aluminum clad bath containing 7 to 15 wt% Si can be used, but Si need not necessarily be contained. Si acts to suppress the growth of the alloy layer of the aluminum coating at the time of coating. If limited to hot stamping applications, there is little need to suppress the growth of the alloy layer, but in the hot dipping method, a single bath is used to produce products for various applications, then in applications where the working capacity of the aluminum coating is required, the growth of the alloy layer has to be suppressed, so Si is generally included. In the present invention, the amount of Si that is contained in the aluminum coating layer before the aluminum coating layer becomes bonded, as explained later, is the factor governing the average linear intersection length of the Al-Fe alloy. In the present invention, the aluminum coating bath preferably includes Si: 7 to 15%. By heating the aluminum coating layer to make it become bonded at the time of hot stamping, Fe diffuses from the steel plate material in the coating layer and the Si concentration in Al-Fe drops compared to the inside of the aluminum coating layer before hot stamping. If the aluminum-coated bath contains 7 to 15% Si, the Al-Fe alloy layer after hot stamping contains 2 to 7% Si.
    [00085] The steel plate in the hot-stamped high-strength part of the present invention has an Al-Fe alloy layer formed by bonding the aluminum coating to the surface due to annealing at the time of hot stamping. This Al-Fe alloy layer has an average thickness value of 10 to 50 qm. If the thick
    Petition 870190104452, of 10/16/2019, p. 23/66
    15/47 r of this Al-Fe alloy layer is 10 μίτι or more, after the heating step, a sufficient post-paint anti-corrosion property cannot be guaranteed by the aluminum-coated steel sheet for use in the quickly heated hot-stamped member . The greater the thickness, the better in terms of corrosion resistance, but the greater the thickness of the Fe-Al alloy layer, the easier it is for the surface layer to disappear at the time of hot stamping, so the upper limit of the average value of the thickness is made 50 μm or less.
    [00086] In addition, the deviation in the thickness of the Al-Fe alloy layer of a high-strength hot-stamped part affects the stability of the spot welding capability. According to the studies of the invention, the thickness of the Al-Fe alloy layer affects the value of the dripping current. The smaller the thickness deviation, the lower the dripping current as a general trend. For this reason, if the thickness deviation of the Al-Fe alloy layer is large, the value of the dripping current varies easily and, as a result, the appropriate welding current ranges become smaller. Therefore, it is necessary to properly control the thickness deviation of the Al-Fe alloy layer. It was learned that it was necessary to make the ratio of the average value to thickness to the standard deviation of thickness (standard deviation of thickness / average value of thickness) of the Al-Fe coating layer 0.15 or less. Most preferably, the foot ratio is 0.1 or less. By doing this, stable spot welding capacity is achieved.
    [00087] The thickness of the Al-Fe alloy coating layer of a hot-stamped high-strength piece was measured and the standard deviation of the thickness was calculated by the following procedure. Initially, the steel was hot rolled, then cold rolled and was coated with Al by a hot dip line. The entire width of the
    Petition 870190104452, of 10/16/2019, p. 24/66
    16/47 steel sheet was heated and tempered. After that, at the position 50 mm from the two edges in the direction of the width, the center of the width, and the intermediate positions of the positions at 50 mm from the two edges and the center, a total of five locations, specimens of 20x30 mm were withdrawn. The specimens were cut, the cross sections were examined, and the thickness of the front and back were measured. In the cross sections of the specimens, any 10 points were measured for thickness. The mean thickness value and the thickness standard deviation were calculated. In the thickness measurement at that moment, each cross section was polished, then it was etched by 2 to 3% NItal to clear the interface between the Al-Fe alloy layer and the steel plate and the thickness measurement of the coating layer turns on.
    [00088] When the aluminum coating layer of the aluminum coated steel plate before hot stamping contains Si, the layer is comprised of the two layers of Al-Si and Fe-Al-Si layer in that order from the layer surface If the Al-Si layer is heated in the hot stamping step to 900 ° C or something, the Fe diffuses from the steel sheet, the coating layer as a whole changes to a layer of Al-Fe compound , and a layer that partially contains Si in the compound Al-Fe is also formed.
    [00089] It is known that when the aluminum coated steel plate is heated to bond the aluminum coating layer before hot stamping, the Al-Fe alloy layer generally has a five-layer structure. Among these five layers, to form the surface layer of the coated steel sheet, the first layer and the third layer comprise mainly Fe2Al5 and FeAl2. In these layers, the concentrations of Al are approximately 50% by mass. The concentration of Al in the second layer is suitable
    Petition 870190104452, of 10/16/2019, p. 25/66
    17/47 approximately 30% by mass. The fourth layer and the fifth layer can be considered to be layers corresponding to Fe-Al and aFe. The DE Al concentrations in the fourth layer and in the third layer are 15 to 30% by weight and 1 to 15% by weight, that is, wide ranges in the compositions, respectively. The balance was Fe and Si in each layer. These alloy layers had corrosion resistance substantially dependent on the Al content. The higher the Al content, the better the corrosion resistance. Therefore, the first layer and the third layer are the best in corrosion resistance. Note that below the fifth layer is the martensite steel sheet. This is a hardened structure comprised mainly of martensite. In addition, the second layer is a Si-containing layer that cannot be explained from the Fe-Al binary phase diagram. The detailed composition is not clear. The inventors have assumed that this is a phase in which Fe2Al5 and Fe-Al-Si compounds are finely mixed.
    [00090] When such aluminum-coated steel sheet is quickly heated and hot stamped, the structure of the AlFe alloy layer obtained, although depending on the heating conditions at the time of hot stamping, does not present such a clear five-layer structure . This is believed to be because since rapid heating is involved, the amount of diffusion of Fe in the coating layer is small.
    [00091] The Al-Fe alloy layer is formed by the diffusion of Fe in the steel plate material in the aluminum coating, so it has a concentration distribution where the concentration of Fe is high and the concentration of Al is low on the side of the steel sheet of the aluminum coating layer and, in addition, the concentration of Fe-Ai and the concentration of Al increase towards the surface side of the coating layer.
    [00092] Examining the aluminum cladding layer of
    Petition 870190104452, of 10/16/2019, p. 26/66
    18/47 a hot stamped part, since the Al-Fe alloy phase is hard and brittle, fractures form in the coating layer of the hot stamped part. FIG. 1 is a polarizing microphotograph of the structure of an aluminum cladding layer in the cross section of a hot stamped part. As shown in FIG. 1, it was learned that large fractures occur through the crystal grains and reach the matrix, then small fractures are interrupted at the edges of the crystal grains (shown by an arrow).
    [00093] Therefore, the inventors took note of the phenomenon of fractures being interrupted at the edges of the crystal grains and studied in depth the interruption of the propagation of fractures that form in the aluminum cladding layer. As a result, they found that, among the crystal grains of the plurality of layers of intermetallic compounds comprised mainly of Al-Fe that are formed on the surface of the steel, controlling the middle intersection layer of the crystal grains of an intermetallic compound that contain Al: 40 to 65% up to 3 to 20 μίτι in band, it is possible to stop the propagation of fractures that form in the aluminum cladding layer. As explained below, the aforementioned means the length measured in a direction parallel to the surface of the steel sheet. Here, the naturally bound aluminum coating is mainly comprised of Al and Fe, but the aluminum coating also contains Si, so it is comprised mainly of Al-Fe and contains a small amount of Al-Fe-Si.
    [00094] The inventors studied the dominant factors that affect the average linear intersection length of the average linear intersection length of a phase containing Al: 40 to 65%, and so they found that the average linear intersection length of a phase that contains Al: 40 to 65% is greatly affected by the thickness of the coating, the thermal history (rate of temperature rise and
    Petition 870190104452, of 10/16/2019, p. 27/66
    19/47 retention time), the conditions of the aluminum coating (amount of Si, bath temperature, and plate temperature when dipped) and other production conditions of the hot-stamped high-resistance parts. Specifically, the effect of the type of alloy layer after the aluminum coating is particularly great. The thermal history can be controlled using the Larson-Miller (LMP) parameter which is explained below.
    [00095] To reduce the average linear intersection length of a phase containing Al: 40 to 65% after bonding to a finer 3 to 20 μm, it is preferable to form β-AlFeSi as the initial alloy layer at the moment of the aluminum coating. β-AlFeSi is a compound that has a monoclinic crystal structure and is also said to have an AFFeSi composition. In addition, to form β-AlFeSi as an alloy layer after the aluminum coating, it is effective to make the amount of Si in the bath 7 to 15% and the bath temperature 650 ° C or less, or to make the bath temperature 650 to 680 ° C and the inlet plate temperature 650 ° C or less. This is because in the concentration of Si and in the temperature of that region, β-AlFeSi becomes a stable phase.
    [00096] The reason why the average linear intersection length of a phase containing Al: 40 to 65% becomes small when β-AlFeSi forms as an alloy layer after the aluminum coating can be deduced give ternary phase diagram Al -Fe-Si which is shown in FIG. 2. A phase containing Al: 40 to 65% is believed to be a phase that mainly comprises Fe2Al5. The phase of a compound in an alloy layer that is formed by an aluminum coating is a phase that equilibrates with a liquid phase of Al-Si and can take three forms of a phase, a β phase, and a FeAF phase. For example, when a FeAF phase is formed, if Fe diffuses into that compound, it is believed that the FeAF phase will turn into a
    Petition 870190104452, of 10/16/2019, p. 28/66
    20/47 Fe2Alõ phase. In opposition to this, for the β phase to be transformed into a Fe2Al5 phase, it is necessary to go through numerous transformations such as β -> α phase -> FeAh phase -> Fe2Al5 phase. Going through the transformations, crystal grains are formed again, so the greater the transformation that undergoes, the shorter the average linear intersection length tends to become. That is, the average linear intersection length becomes smaller with the α phase than the FeAl3 phase and with the β phase than the α phase.
    [00097] The method of measuring an average linear intersection length in an alloy coating layer is to polish any cross section of a hot stamped part, then etch it by 2 to 3% by volume of Nital and examine the result under a microscope. For the examination, a polarizing microscope was used. The polarization angle is adjusted so that the contrast of the crystal grains becomes the clearest. At that time, the layer of a compound whose contrast appears clear on the side of the surface layer consecutively from the layer of a compound whose contrast appears dark in an Al phase: 40 to 65%. This phase is a phase that has the property of stopping the spread of fracture and is a phase that affects the post-painting anti-corrosion property and the ability to coat work. As shown in FIGs. 3 (a) to (b), in particular when the coating thickness is thin (40 g / m 2 per side), due to the effect of the dark contrast phase, the average linear intersection length of Al: 40 to 65% it is difficult to measure. Therefore, in this description, the average linear intersection length of the crystal grains in the alloy coating layer is defined as the average linear intersection length that is measured in the direction parallel to the surface of the steel sheet. The average linear intersection length is discovered by the line segment method. As shown in FIG. 3 (a), the mean linear intersection length is discreet
    Petition 870190104452, of 10/16/2019, p. 29/66
    21/47 berto drawing a line parallel to the surface of the steel sheet in the coating layer, count the number of grain edges that this line passes through, and divide the length measured by the number of grain edges. It is possible to calculate the grain size from this average linear intersection length, but calculating the grain size requires that the shape of the grains is known. In the steel plate, the crystal grains can be assumed to be spherical, but the intermetallic compounds that are formed on the surface as in the present invention are unknown as to the shape of the crystal grain, so that the average linear intersection length was used.
    [00098] Note that, in the actual measurement, in the polarizing microphotographs of FIGs 3 (a) to (d), the grain edges are not clear, so as shown in FIGS. 5 (a) and (b), the edges of the crystal grains were drawn in the polarization microphotographs of FIGS. 3 (a) and (c) to lighten the edges of the crystal grains.
    [00099] The reason for limiting the average linear intersection length of a phase containing Al: 40 to 65% after the aluminum coating layer is bonded to 3 to 20 gm will be explained. A small grain size is preferable as a fracture stopping property of a phase containing: Al: 40 to 65%, but the steel sheet for use in a hot stamping member must be heated once until austenite region. For this reason, this steel plate is usually heated to 850 ° C or more, so the aluminum coating layer that is bonded in this heating step ends up with crystal grains growing up to 3 gm or more. Therefore, generally making the crystal grain smaller than 3 gm is extremely difficult. If the average linear intersection length exceeds 20 gm and the grain size becomes larger, the aluminum cladding layer falls into working capacity and the spraying phenomenon becomes larger. In addition, the interrupt property
    Petition 870190104452, of 10/16/2019, p. 30/66
    22/47 fracture propagation of a phase containing Al: 40 to 65% no longer works and the fractures can no longer be stopped by the crystal grains.
    [000100] Therefore, in the present invention, the average linear intersection length of a phase containing Al: 40 to 65% has been limited to 3 to 20 gm, preferably it is 5 to 17 gm.
    [000101] In the following, the effects of the conditions of the aluminum coating and the heating conditions at the time of hot stamping at the average linear intersection length will be explained. [000102] FIG. 4 is a view showing the effects of the conditions of the aluminum coating, and the heating conditions at the time of hot stamping at the average linear intersection length. In FIG. 4, the abscissa shows the Larson-Miller (LMP) parameter of the heating conditions at the time of hot stamping.
    [000103] The Larson-Miller (LMP) parameter is expressed by: [000104] LMP = T (20 + logt) [000105] (where, T: absolute temperature (K); t: time (h)).
    [000106] Here, T is the heating temperature of the steel layer, while t is the retention time in the heating oven after reaching the desired temperature. LMP is an indicator that is used in general to treat temperature and time in a unified way in heat treatment and phenomena such as deformation where temperature and time have an effect. This parameter can also be used for the growth of crystal grains. In the present invention, LMP summarizes the effects of temperature and time on the average linear intersection length of the crystal grains, so the heat treatment conditions at the time of hot stamping can be described by this parameter only.
    [000107] The symbols that are described in FIG. 4 will be explained.
    Petition 870190104452, of 10/16/2019, p. 31/66
    23/47
    A and B show aluminum coating conditions. A means a bath at 7% Si at a bath temperature of 660 ° C, while B means a bath at 11% Si at a bath temperature of 640 ° C. These are typical conditions with which an α-AlFeSi phase and a β-AlFeSi phase are produced at the time of the aluminum coating. In addition, 5 ° C / s and 50 ° C / s mean the temperature rise rates at the time of hot stamping. 5 ° C / s corresponds to heating in the usual oven, while 50 ° C / s corresponds to infrared heating, ohmic heating, and other rapid heating. Here, the rate of temperature rise means the rate of average temperature rise from the beginning of the temperature rise to a temperature 10 ° C lower than the desired temperature. Comparing the conditions of aluminum coating A and B, the tendency is that the conformation of an aAlFeSi phase at the time of conditions A, that is, aluminum coating, gives an average linear intersection length greater than conditions B. It was learned that it is necessary to limit the range of heating conditions at the time of hot stamping to a narrower range (LMP = 20000 to 23000). If the LMP is less than 20000, the diffusion of the Al-Si coating layer with the steel sheet is insufficient and a layer of unbound Al-Si remains, so this is not preferred. In addition, in the coating conditions A of FIG. 4, comparing the temperature rise rates of 5 ° C / s and 50 ° C / s, it is shown that even such a narrow range, if the rate of temperature rise in hot stamping increases, the structure becomes thinner . The rate of temperature rise is preferably 4 to 200 ° C / s in range. If the rate of temperature rise is slower than 4 ° C / s, this means that the heating step takes time and means that hot stamping drops in productivity. In addition, if it is faster than 200 ° C / s, controlling the distribution of the
    Petition 870190104452, of 10/16/2019, p. 32/66
    24/47 temperature on the steel sheet becomes difficult. Both are preferred. Establish aluminum cladding conditions and hot stamping conditions that allow the average linear intersection length to be made from 3 to 20 μίτι.
    [000108] As explained above, making the average linear intersection length of the crystal grains of a phase containing Al: 40 to 65% in the layer of intermetallic compounds comprising mainly Al-Fe, which is formed on the steel surface, 3 at 20 μm, it is possible to stop the spread of fractures that form in the coating layer due to hot stamping inside the coating layer. Because of this, it is possible to suppress corrosion of the steel plate hue due to fractures in the coating layer and it is possible to obtain high-strength automotive parts that are excellent in anti-corrosion properties after painting and other hot-stamped parts.
    [000109] The hot-stamped high-strength parts of the present invention may also have a surface containing ZnO on the surface of the alloy coating layer comprised mainly of Al-Fe.
    [000110] The hot-stamped high-strength part of the present invention has extremely hard Al-Fe intermetallic compounds formed in the coating layer of the steel sheet surface at the time of hot stamping. For this reason, work defects are formed on the surface of the shaped part due to contact with the mold at the time of forming by pressing on the hot stamping. There is a problem with these work defects due to fractures in the coating layer. The inventors have found that by forming a surface film that has excellent lubricating capacity on the surface of the aluminum cladding layer, it is possible to eliminate the work defects of a part
    Petition 870190104452, of 10/16/2019, p. 33/66
    25/47 shaped and the occurrence of fractures in the coating layer and found that it is possible to improve the forming capacity at the time of hot stamping and the corrosion resistance of a shaped part.
    [000111] The inventors engaged in intensive studies on a surface film that has a lubricating capacity that is suitable for hot stamping and as a result they found that supplying the surface of the aluminum coating layer with a layer of lubricating surface film containing ZnO (zinc oxide), it is possible to effectively avoid work defects B the surface of the shaped part and fractures in the coating layer.
    [000112] ZnO is included in the surface film layer on one side of the aluminum-coated steel sheet in an amount, converted to Zn mass, from 0.3 to 7 g / m 2 . More preferably, it is included at 0.5 to 4 g / m 2 . If the ZnO content is converted to a mass of Zn 0.1 g / m 2 or more, the effect of improving the lubricity and the effect of preventing segregation (effect of allowing a uniform thickness of the aluminum coating layer ) etc. can be effectively displayed. On the other hand, when the ZnO content exceeds, converted to a mass of Zn, 7 g / m 2 , the total thickness of the aluminum coating layer and the surface film layer become very thick and the welding capacity or the ink adhesion drops.
    [000113] FIG. 6 is a view showing the relationship between the amount of Zn deposition on the surface of the aluminum coated steel sheet and the dynamic friction coefficient. The ZnO content in the surface film layer was changed to assess the lubrication capacity at the time of hot stamping. This lubrication capacity was assessed by the following test. Initially,
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    26/47 tests other than aluminum coated steel sheet which has a layer of ZnO film (150x200 mm) were heated to 900 ° C, and then were cooled to 700 ° C. The test materials were subjected to overhead loads using steel balls. In addition, the steel balls were slid over the test materials. Further, the steel balls were slid out over the test materials. The ratio of the outgoing load / push-in load was the dynamic friction coefficient. The results are shown in FIG. 6. If the dynamic friction coefficient is less than 0.65, it is rated as good. It has been learned that in a region where the amount of Zn deposition is generally 0.7 g / m 2 or more, the dynamic friction coefficient is effectively kept low and the hot lubrication capacity can be improved.
    [000114] The surface film layer containing ZnO can be formed, for example, by applying a paint containing ZnO and baking or drying after application for curing to allow formation on the layer aluminum coating. As a method of applying a ZnO paint, for example, the method of mixing a predetermined organic binder and a ZnO powder dispersion and applying to the surface of the aluminum coating layer, a method of powder paint painting, etc. As a method of cooking and drying after application, for example, a hot air oven, an induction heating oven, an oven with near-infrared rays, or another method or method combining them can be mentioned. At that time, depending on the type of binder that is used for the application, instead of cooking and drying after application, for example, curing by ultraviolet rays or electron rays, etc. it's possible. As a predetermined organic binder, for example, a polyurethane resin or resin can be mentioned
    Petition 870190104452, of 10/16/2019, p. 35/66
    27/47 polyester, etc. However, the method for forming the ZnO surface film layer is not limited to these examples and can be formed by several methods.
    [000115] Such a layer of surface film containing ZnO can improve the lubricity of an aluminum coated steel sheet at the time of hot stamping, then working defects of the coating layer and fractures in the coating layer on the surface of the conformed part can be suppressed.
    [000116] ZnO has a melting point of approximately 1975 ° C or greater compared to the aluminum coating layer (the melting point of aluminum is approximately 660 ° C) etc. Therefore, even when working the steel sheet at, for example, 800 ° C or more such as when working the steel sheet coated by the stamping method, etc., the surface film layer containing this ZnO will not melt . Therefore, even if the heating of the aluminum coated steel sheet causes the aluminum coating layer to melt, the state in which the ZnO surface film layer covers the aluminum coating layer to be maintained, then it is possible to prevent the thickness of the molten aluminum cladding layer becomes uneven. Note that uneven thickness of the aluminum cladding layer of a hot-stamped high-strength part occurs easily, for example, in the case of heating by an oven where the disc is oriented vertically in relation to the direction of gravity or the case of heating by ohmic heating or induction heating. However, this surface film layer can prevent uneven thickness of the aluminum coating layer when such heating is performed and allows the aluminum coating layer to be formed thicker.
    [000117] In this way, a layer of ZnO surface film
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    28/47 has the effects of improving lubrication capacity and making the thickness of the aluminum coating layer uniform, etc. then it can improve the forming capacity at the time of forming by pressing in hot stamping and the resistance to corrosion after forming by pressing.
    [000118] In addition, the aluminum cladding layer can be made uniform in thickness, so it can be quickly heated by ohmic heating or induction heating allowing a higher rate of temperature rise. This is effective in making the average linear intersection length of the crystal grains of an intermetallic composite phase containing Al: 40 to 65% by mass 3 to 20 pm.
    [000119] Furthermore, this layer of ZnO surface film never causes a drop in spot weldability, paint adhesion, post-paint anti-corrosion properties, and other performances. The anti-corrosion property after painting is also improved by the transmission of a layer of surface film.
    [000120] Next, the inventors studied the composition of the ingredients for steel plate to obtain the aluminum coated steel plate for use in a hot-stamped member heated quickly provided with both excellent corrosion resistance and excellent productivity. As a result, since the hot stamping was carried out with the pressing and quenching simultaneously by the mold, they obtained the ingredients for the steel sheet which are explained below from the point of view of the aluminum coated steel sheet for use in hot stamped member containing ingredients that allow easy hardening and thus giving hot stamped parts that have high strength of 1000 MPa or more after hot stamping.
    [000121] The reasons for limiting the ingredients will be explained below
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    29/47 members of the steel plate in the present invention. Note that% of ingredients means% by mass.
    C: 0.1 to 0.5% [000122] The present invention provides a hot stamped coat that has a high strength of 1000 MPa or more after forming. In order to obtain high resistance, the steel has to be cooled quickly after hot stamping to transform it into a structure of mainly martensite. From the point of view of improving the curing capacity, an amount of C of at least 0.1% is required. On the other hand, if the amount of C is very large, the toughness of the steel plate drops noticeably, then the workability drops. For that reason, the amount of C is preferably 0.5% or less.
    Si: 0.01 to 0.7% [000123] Si promotes the reaction between Al and Fe in the coating and has the effect of increasing the heat resistance of the aluminum coated steel sheet. However, Si forms a stable oxide during the recrystallization annealing of the cold rolled steel sheet on the surface of the steel layer, so it is an element that obstructs the properties of the aluminum coating. From this point of view, the upper limit on the amount of Si is 0.7%. However, if the amount of S is less than 0.01%, the fatigue property deteriorates, so this is not preferable. Therefore, the amount of Si is 0.01 to 0.7%.
    Mn: 0.2 to 2.5% [000124] Mn is well known as an element that increases the hardening capacity of the steel sheet. In addition, it is also an element that is necessary to avoid hot embrittlement due to the inevitable entry of S. For this reason, 0.2% or more has to be added. In addition, Mn increases the heat resistance of the steel sheet after coating with aluminum. However,
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    30/47 if more than 2.5% Mn is added, the part that is hot stamped after quenching falls into impact properties, then 2.5% is made the upper limit.
    Al: 001 at 0.5% [000125] Al is suitable as a deoxidizing element, so 0.01% or more can be included. However, if included in a large amount, crude oxides are formed and the mechanical properties of the steel plate are impaired, so the upper limit on the amount of Al is made 0.5%.
    P: 0.001 to 0.1% [000126] P is an impurity element that is inevitably included in the steel plate. However, P is an element of reinforcing the solution. It can increase the strength of the steel sheet relatively inexpensively, so the lower limit on the amount of P was made 0.001%. However, if the amount of addition is recklessly increased, the toughness of the high-strength material is decreased and other harmful effects appear, then the upper limit on the amount of P has been made 0.1%.
    S: 0.001 to 0.1% [000127] S is an element inevitably included. It forms MnS inclusions in steel. If the MnS is large in quantity, the MnS forms the starting point for fractures, obstructs ductility and toughness, and becomes the cause of deteriorating work capacity. Therefore, the amount of S is preferably as low as possible. The upper limit on the amount of S was made 0.1% or less, but reducing the amount of S more than necessary is not preferable from the point of view of production cost, so the lower limit was made 0.001%. [0071]
    N: 0.0010% to 0.05% [000128] N easily agglutinates with Ti or B, so it has to be
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    31/47 controlled so as not to reduce the effects desired by these elements. An amount of N of 0.05% or less is permissible. Preferably, the amount of N is 0.01% or less. On the other hand, the more than necessary reduction puts a massive load on the steel production stage, so 0.0010% must be made the desired lower limit for the amount of N. Next, the ingredients that can be selectively contained in the steel.
    Cr: more than 0.4% to 3% [000129] Cr is also an element that generally increases the hardening capacity. It is used in the same way as Mn, but it also has a separate effect when applying a layer of aluminum coating to the steel plate. If Cr is present, for example, when annealing the steel case after application of the aluminum cladding layer in order to bond the aluminum cladding layer, the cladding layer and the steel plate matrix bond easily with each other . When box annealing of aluminum coated steel sheet is performed, AlN is formed in the aluminum coating layer. AlN suppresses the bonding of the aluminum coating layer and leads to peeling of the coating, but the addition of Cr makes the formation of AlN difficult, and makes it easier to bond the aluminum coating layer. To achieve these effects, the amount of Cr is above 0.4%. However, even if Cr is added in an amount of more than 3%, the effect becomes saturated. In addition, the cost also increases. In addition, the property of the aluminum coating falls. Therefore, the upper limit for the amount of Cr is 3%.
    Mo: 0.005 to 0,% [000130] Mo, like Cr, has the effect of suppressing the formation of AlN which causes flaking of the coating layer, formed at the interface of the coating layer and the matrix steel plate when
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    32/47 box annealing of the aluminum coating layer. In addition, it is a useful element from the point of view of the hardening capacity of the steel sheet. To achieve these effects, an amount of Mo of 0.005% is required. However, even if more than 05% is added, the effect of becoming saturated, then the upper limit of the amount of MO is 0.5%.
    B: 0.0001 to 0.01% [000131] B is also a useful element from the point of view of the hardening capacity of the steel sheet and presents its effect at 0.0001% or more. However, even if 0.01% were added, the effect becomes saturated and, in addition, casting defects and fractures of the steel sheet occur during hot rolling, etc. and the production capacity in that way falls, so the upper limit on the amount of B is 0.01%. Preferably, the amount of B is 0.0003 to 0.005%.
    W: 0.01 to 3% [000132] W is a useful element from the point of view of the hardening capacity of the steel sheet and has its effect at 0.01% or more. However, even if more than 3% are added, the effect becomes saturated and, in addition, the cost also increases, so the upper limit on the amount of W is 3%.
    V: 0.01 to 2% [000133] V, like W, is a useful element from the point of view of the hardening capacity of the steel plate, and has its effect at, 01% or more. However, even if it is added in an amount above 3%, the effect becomes saturated and, in addition, the cost also increases, so the upper limit of the amount of V is 2%.
    Ti: 0.005 to 0.5% [000134] Ti can be added from the point of view of fixing N. In mass%, Ti has to be added in an amount of approx.
    Petition 870190104452, of 10/16/2019, p. 41/66
    33/47 roughly 3.4 times the amount of N, but N, even if decreased, is present at 10 ppm or something, so the lower limit on the amount of Ti was made 0.005%. In addition, even if Ti is added excessively, the hardening capacity of the steel sheet is dropped or the resistance is also dropped, so the upper limit of the amount of Ti is 0.5%.
    Nb: 0.01 to 1% [000135] Nb, like Ti, can be added from the point of view of fixing N. In mass%, Nb has to be added in an amount of approximately 6.6 times the amount of N, but N, even if decreased, is present at 10'ppm or something, so the lower limit of the amount of Nb was made 0.01%. In addition, even if Nb is added excessively, the hardening capacity of the steel sheet is dropped or the resistance is also dropped, so the upper limit of the amount of Nb is 1%, preferably 0.5%.
    [000136] Furthermore, as ingredients in a steel plate, even if Ni, Cu, Sn Sb, are also included, the effect of the present invention is not obstructed. Ni is a useful element from the point of view of not only the hardening capacity of the steel sheet, but also the low temperature toughness which in turn leads to improved impact resistance. It has this effect at 0.01% or more of Ni. However, even if Ni is added by more than 5%, the effect becomes saturated and the cost increases, so Ni can be added in the range of 0.01 to 5%. Cu is also a useful element from the point of view of not only the hardening capacity of the steel sheet, but also the toughness. It has this effect at 0.1% or more of Cu. However, even if Cu is added by more than 3%, the effect becomes saturated and the cost increases. Not only that, the deterioration of the plate properties and fractures and defects in the steel plate at the time of hot rolling are caused, so Cu
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    34/47 must be added in 001 to 3% in range. In addition, Sn and Sb are both elements that are effective in improving the wetting capacity and the agglutination capacity of the coating in relation to the steel plate. An amount of 0.005% to 0.1% can be added. If both are less than 0.005%, no effect can be recognized, whereas if more than 0.1% is added, defects are easily caused at the time of production and, in addition, a drop in toughness caused, then the upper limit of amount of Sn and the amount of Sb is 0.1%.
    [000137] If both quantities are less than 0.005%, no effect can be recognized, whereas if more than 0.1% is added, defects are easily caused at the time of production and a drop in toughness is also caused, then the upper limits of the amount of Sn and the amount of Sb are 0.1%.
    [000138] Furthermore, the other ingredients are not particularly prescribed. Sometimes, Zr, As and other elements enter from scrap iron, but if in the usual range, they do not affect the properties, of the steel that is used for the present invention.
    [000139] Next, the method of producing a high-strength hot-stamped part will be explained.
    [000140] The aluminum-coated steel sheet for use in a hot-stamped member that is used in the present invention is produced by taking a cold-rolled steel sheet that was obtained by hot-rolling steel, and then rolling it cold, and coating it in a hot-dip line with an annealing temperature of 670 to 760 ° C and a baking time in the reduction form of 60 seconds or less to treat the aluminum coated steel sheet contains Si: 7 to 15%. It is effective to make the skinpass lamination rate after 0.1 to 0.5% aluminum coating.
    [000141] The annealing temperature of the hot dip line
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    35/47 has an effect on the shape of the steel sheet. If the annealing temperature is increased, the steel sheet will distort in the C direction. As a result, when coating with aluminum, the difference in the deposition deposit amounts in the central part of the steel sheet in the direction of the width and close to the edges easily becomes bigger. From that point of view, the annealing temperature is preferably 760 ° C or less. In addition, if the annealing temperature is too low, the temperature of the steel plate when immersed in the aluminum plating bath drops too much and sludge defects are easily caused, then the lower limit of the annealing temperature is 670 ° C.
    [000142] The oven time in the reduction oven affects the properties of the aluminum coating. Si, Cr, Al, and other elements that oxidize more easily than Fe oxidize easily in the reduction furnace on the surface of the steel sheet and obstruct the reaction between the aluminum plating bath and the steel sheet. In particular, if the oven time in the reduction oven is long, this effect becomes noticeable, then the oven time is preferably 60 seconds or less. Note that the lower limit of the oven time is not particularly defined, but 30 seconds or more is preferable.
    [000143] After coating with aluminum, for adjusting the plate, etc., the plate is laminated by skinpass lamination, but the lamination rate at that time affects the bonding of the aluminum coating layer at the time of hot stamping. Due to the lamination, a tension is introduced on the steel sheet and the coating layer. This is believed to be the result of this. If the lamination rate is high, the alloy layer after hot stamping tends to become smaller in crystal grain size, but it is not preferable for the lamination rate to be made very low since fractures are given to the layer alloy that is produced. For this reason, the rate of
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    36/47 lamination is preferably done from 0.1 to 0.5%.
    [000144] In addition, after the aluminum coating, box annealing can be performed to make the aluminum coating layer bonded. At that time, to promote bonding, steel is preferably made up of Cr, Mo, etc. Box annealing is performed, for example, at 650 ° C for 10 hours or so.
    [000145] The aluminum coated steel sheet thus obtained can be heated quickly in the subsequent hot stamping step by a temperature rise rate of 50 ° C / s or more. In addition, rapid heating is effective in making the average linear intersection length of the crystal grains in a phase containing Al: 40 to 65% in the Al-Fe 3 alloy layer at 20 μm. The heating system is not particularly limited. The usual heating oven for an infrared heating system using radiant heat can be used. In addition, it is also possible to use ohmic heating or high frequency induction heating or the other heating system that uses electricity which allows rapid heating at a rate of temperature increase of 60 ° C / s or more.
    [000146] The upper limit of the temperature rise rate is not particularly defined, but when using the above ohmic heating or high frequency induction heating or other heating system, due to the performance of the systems, 300 ° C / s or similar becomes the upper limit.
    [000147] In addition, in this heating step, the peak temperature of the plate is preferably set at 850 ° C or more. The peak temperature of the sheet is tape 850 ° C or more in order to heat the steel sheet to the austenite region and promote sufficient bonding of the aluminum coating layer to that surface.
    [000148] Next, the steel sheet coated with aluminum in the state
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    The heated 37/47 is hot stamped to a predetermined shape between a pair of upper and lower forming molds. After being shaped, it is kept stationary at the bottom pressure neutral point for several d seconds to quench by cooling by contact with the forming molds and thus obtain the hot stamped high strength part of the present invention.
    [000149] The hot stamped part was welded, chemically converted, painted by electroplating, etc. to get the final product. Generally, cationic electrodeposition paint is used. The film thickness becomes 1 to 30 µm or similar. After electroplating painting, an intermediate painting, a top painting, and other paintings are sometimes also applied. .
    Examples [000150] Below, examples will be used to explain the present invention in greater detail.
    Example 1 [000151] After the usual hot rolling and cold rolling steps, a cold rolled steel sheet with steel ingredients as shown in Table 1 (sheet thickness 1.4 mm) was covered by an aluminum coating containing Si by hot immersion. For the aluminum coating by hot dip, a type of non-oxidizing reduction furnace was used. After coating, gas washing was used to adjust the amount of coating deposition to a total for both sides of 160 g / m 2 , then the wire plate cooled. At that time, as a composition of the coating bath, there were: (A): Al-7% Si-2% Fe, bath temperature 660 ° C, and (B): Al-11% Si-2% Fe, bath temperature bath 640 ° C. The conditions of the coating bath correspond to the phases in conditions A and B a of the aluminum coating of FIG. 4. It should be noted that the Fe in the bath is the inevitable Fe that is provided by the coating equipment and
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    38/47 by the plate in the bath. In addition, the annealing temperature was 720 ° C and the oven time in the reduction oven was 45 s. The aluminum-coated steel sheet generally looked good, without defects in coating failure, etc.
    [000152] The specimen thus prepared was evaluated for its anti-corrosion properties after painting. Hot stamping was carried out using means of heating in the usual oven. The temperature rise rate of the aluminum coated steel sheet was approximately 5 ° C / s. A large specimen of 250 x 300 mm was heated in the air. The part had its temperature elevated for more than approximately 3 minutes, and then it was maintained for approximately 1 minute, then it was removed from the forum and cooled to a temperature of approximately 700 ° C, shaped like a hat, and cooled in the mold. At that time, the cooling rate was approximately 200 ° C / s. As shown in Table 2, the heating temperature of the specimen was changed in several ways to control the structure of the aluminum coating layer after bonding.
    [000153] The vertical wall part of the hat-shaped piece was cut to 50x100 mm and evaluated for anti-corrosion properties after painting. The chemical conversion solution PB-SX35 made by Parkerizing used for chemical conversion, so the Powernix 110 cationic electrodeposition paint made by Nippon Paint was painted to give a thickness of approximately 20 qm. After that, a cutter was used to cut this film, so a composite corrosion test defined by the Society of Automobile Engineers of Japan (JASO M61092) was performed for 180 cycles (60 days). The extent of blistering from the cut (maximum blistering width on one side) was measured. At that time, the blister width of the common corrosion-proof steel sheet, ie GA (hot-dip galvanized steel sheet) (deposition amount of 45 g / m 2 on one side)
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    39/47 was 5 mm.
    [000154] The anti-corrosion post-paint property was rated as very good with blistering of 4 mm or less, as good with blistering width of more than 4 mm to 6 mm, and as poor with blistering width of more than 6 mm.
    [000155] Regarding the evaluation of spot welding, this has to be carried out by a flat plate, so a mold formed in a 400 x 500 mm plate was used. The usual means of heating in the oven was used, the steel plate coated with 400 x 500 mm aluminum was heated at a rate of temperature rise of approximately 5 ° C / s in the air, the plate was evaluated for temperature for approximately 3 minutes and then held for approximately 1 minute, and then removed from the oven , cooled in the air to approximately 700 ° C temperature, and then quenched in the mold. 30 mm were cut from the two edges of the coated steel plate, coated with Al in a hot dip line, in the width direction. The rest was used for testing. After hot stamping, the part was quenched, so a 30 x 50 mm weld specimen was cut and measured for the proper welding current range at a pressure of 500 kgf and electrification for 10 cycles (60 Hz) . At this time, the lower limit current was made 4 t (t is the thickness of the plate), while the upper limit current was made spattering. The upper limit current value - lower current value has the appropriate welding current range.
    [000156] Spot welding capacity was rated as good when above the appropriate welding current range 2kA and poor when the appropriate welding current range 2kA or less.
    [000157] In addition, after etching with Nital, the specimen was examined in the cross section and the mean value was found
    Petition 870190104452, of 10/16/2019, p. 48/66
    40/47 of the thickness, the standard deviation of the thickness, (deviation in the thickness of the coating), and the ratio of the average value of the thickness to the standard deviation of the thickness (standard deviation / average) were found for the thickness of the coating. In addition, the structure of the alloy layer was examined and the average linear intersection length of the crystal grains of a phase containing Al: 40 to 65% by mass was measured. At this moment. The specimen was cut from the flange part with little deformation in the hat-shaped part.
    [000158] Note that the mean value of the coating thickness and the standard deviation of the coating thickness were determined by taking samples of 20 x 30 mm specimens in positions 50 mm from the two edges of the steel sheet in the direction of width, center, and intermediate positions between the positions 50 mm from the two edges and the center, that is, a total of five locations. The specimens were cut, examined in the cross section, calculated for thickness in the front and rear, measured for thickness in 10 points, and calculated for the average value of thickness and standard deviation.
    [000159] The conditions of the aluminum coating, the hot stamping conditions, the average linear intersection length, the average thickness value and the results of the evaluation of the post-painting anti-corrosion property and the welding capacity are described in Table 2 .
    [000160] In addition, simultaneously, the cross section hardness was measured by a Vickers hardness meter (load 1 kgf), but hardness values of 420 or more were obtained in all the measured locations.
    Table 1
    Steel ingredients (% by mass) Ç Si Mn Al P s N You B Cr 0.22 0.19 1.24 0.04 0.02 0.014 0.005 0.02 0.003 0.12
    Petition 870190104452, of 10/16/2019, p. 49/66
    41/47
    Table 2
    No. Coating conditions Temp. heating ( 0 C) Retention time(s) Average thickness ofclothing (pm) Standard deviation ofthickness of thedress Standard / mean deviation average linear intersection length (pm) Postpaint anti-corrosion property Spot welding capability Grades 1 THE 850 60 28 2.2 0.08 4 Good Good Ex. Inv. 2 THE 900 60 33 2.4 0.07 7 Very good Good Ex. Inv. 3 THE 950 60 37 2.1 0.06 13 Very good Good Ex. Inv, 4 THE 1000 60 44 2.7 0.06 22 Poor Good Ex. Comp. 5 THE 1050 60 53 2.4 0.05 33 Poor Good Ex. Comp. 6 B 850 60 28 2.3 0.08 4 Good Good Ex. Inv. 7 B 900 60 32 2.3 0.07 5 Very good Good Ex. Inv. 8 B 950 60 35 2.5 0.07 9 Very good Good Ex. Inv. 9 B 1000 60 42 2.6 0.06 15 Very good Good Ex. Inv. 10 B 1050 60 50 2.4 0.05 23 Poor Good Ex. Comp.
    [000161] As shown by the results of the evaluations in Table 2, the specimens of the aluminum coating conditions A and B were both hot stamped under the same conditions, but differences in the structures of the obtained alloy layers (lengths of linear intersections). Examples with large average linear intersection lengths fell relatively low in anti-corrosion properties after painting. The reason is believed to be coating fractures.
    [000 162] That is, examples of the invention were all excellent in corrosion after painting property and weldability by points, but we comparative examples where the average linear intersection length failed to satisfy the requirements of this invention (Nos 4, 5, 10), the post-painting anti-corrosion property was infected. 870190104452, of 10/16/2019, p. 50/66
    42/47 rior.
    [000163] Samples coated with Al by conditions A were used for rapid heating and hardening in a flat plate mold. The heating method used was an infrared heating furnace. The rate of temperature rise at that time was 50 ° C / s. The peak plate temperature and retention conditions were also changed to investigate the structures of the coating layers at that time. The results, and the results of Table 2 are summarized in FIG. 4. It is shown that the average linear intersection length depends on the coating conditions and the heating conditions.
    Example 2 [000164] Cold rolled steel sheets of the various steel ingredients (A to I) that are shown in Table 3 (sheet thickness 1 to 2 mm) were used for aluminum coating in the same way as in Example 1 In this example, the annealing temperature and reduction oven time at that time have been changed. As a composition of the aluminum coating bath, in mass%, Si: 9% and Fe: 2% were contained. The bath temperature was 660 ° C and the deposition after coating was adjusted by the gas cleaning method to a total of two surfaces of 160 g / m 2 . .
    [000165] After this, a method similar to Example 1 was used to set the temperature at the time of hot stamping 950 ° C for hardening. After that, the post-painting anti-corrosion property and the spot welding capacity were evaluated. The evaluation method was the same as in Example 1, Vickers hardness was 420 or more in all cases.
    Petition 870190104452, of 10/16/2019, p. 51/66
    43/47
    Table 3
    Steel ingredients (% by mass)Ç Si Mn Al P s N You B Cr Mo Others THE 0.23 0.24 1.52 0.041 0.067 0.071 0.005 0.092 0.006 - -B 0.21 0.39 0.33 0.041 0.009 0.053 0.003 0.033 0.0091 2,624 0.122Ç 0.24 0.03 2.49 0.038 0.032 0.018 0.004 0.099 0.0063 0.001 0.375D 0.36 0.63 1.81 0.013 0.071 0.053 0.005 0.089 0.0064 0.904 0.295 W: 0.01 AND 0.16 0.21 0.84 0.051 0.023 0.038 0.002 0.020 0.0017 2.3 0.233 Ni: 0.04 F 0.19 0.25 2.25 0.044 0.099 0.063 0.003 0.066 0.0026 2,156 0.255 Cu: 0.02 G 0.19 0.75 1,232 0.067 0.069 0.055 0.004 0.026 0.005 2,604 0.032H 0.30 0.19 0.91 0.03 0.01 0.019 0.003 - - - -I 0.17 0.20 0.85 0.052 0.021 0.028 0.002 0.021 0.0015 2.1 - Ni: 0.04Sb: 0.01
    Table 4
    No. Steel Plate thickness (mm) Has p. annealing temperature ( 0 C) Reduction oven time(s) Average coating thickness (pm) Standard deviation of coating thickness Des-medium standard Average linear intersection length (pm) Postpaint anti-corrosion property Spot welding capability Grades 1 THE 1.2 740 40 28 2.5 0.09 12 Very good Good Ex. Inv. 2 THE 1.6 740 50 29 3.1 0.11 12 Very good Good Ex. Inv. 3 THE 2.0 740 55 29 3.7 0.13 12 Very good Good ERx, Inv. 4 THE 2.0 760 55 29 4.5 0.16 12 Very good Poor Ex.Comp. 5 B 1.6 730 50 28 3.0 0.11 13 Very good Good Ex. Inv. 6 Ç 1.6 710 50 29 2.9 0.10 12 Very good Good Ex. Inv. 7 D 1.6 720 50 29 3.3 0.11 12 Very good Good Ex. Inv. 8 AND 1.6 730 50 28 3.2 0.11 13 Very good Good Ex. Inv. 9 F 1.6 740 50 28 3.0 0.11 12 Very good Good Ex. Inv.
    Petition 870190104452, of 10/16/2019, p. 52/66
    44/47
    10 G 2.0 740 65 28 4.4 0.16 12 Very good Poor Ex.Comp. 11 H 1.2 740 40 28 2.6 0.10 12 Very good Good Ex. Inv. 12 I 1.6 740 50 28 3.2 0.11 12 Very good Good Ex. Inv.
    [000166] In Example 2, the ingredients of the steel used, the thickness of the plate, and the components of the aluminum plating bath were touched. As shown by the results of the evaluation in Table 4, a trend was observed where if the thickness of the sheet becomes greater, the standard deviation of the thickness of the coating becomes greater and, in addition, if the temperature of the annealing becomes greater, the deviation pattern of the coating thickness becomes larger. If the standard deviation is large, the appropriate welding current range is narrow and dripping was easily generated in spot welding. In addition, in a high Si ingredient system such as steel G ingredients, if the furnace time in the reduction furnace is long (65 seconds), coating failure defects that may occur and the anti-corrosion property post-painting drops.
    [000167] That is, as shown by the evaluation results in Table 4, the examples of the invention were all excellent in anti-corrosion properties after painting and spot welding ability, but in a comparative example where the average thickness value ratio for the standard deviation of the thickness (standard deviation / average) exceeds 0.15 (n§ 4), the spot welding capacity was lower. In addition, in a comparative example where the time in the reduction furnace was long and the standard deviation / average ratio exceeded 0.15 (No. 10), both the post-paint anti-corrosion property and the spot welding capacity were lower.
    Example 3 [000168] The coated steel sheets of aluminum paragraphs 2 and 5 of Table 4 of Example 2 were annealed in box to connect the layers of aluminum coating. At this moment, number 2 corresponded to
    Petition 870190104452, of 10/16/2019, p. 53/66
    45/47 steel A ingredients and No. 5 to steel B ingredients. These differed in the amounts of Cr in the steel. At that time, at No. 2 (steel A ingredients), at the time of box annealing, AlN was formed close to the interface of the aluminum cladding layer and the steel plate and the aluminum cladding layer cannot be bonded sufficiently . In No. 5 (steel B ingredients), the connection was possible. Using No. 5, an ohmic heating medium was used to increase the temperature by a rate of temperature rise from 200 ° C / s to 950 ° C, so the plate was hardened without retention. Box annealing caused the aluminum cladding layer to become bonded, so even after the ohmic heating, the thickness of the Al-Fe alloy layer was constant. The post-paint anti-corrosion property and the spot welding ability were assessed by methods similar to those in Example 1 and therefore the post-paint anti-corrosion property was assessed to be very good and the spot welding ability was good. that is, excellent properties were exhibited. Vicker's hardness was also shown to be 482.
    Example 4 [000169] The steel in Table 1 of Example 1 was used for coating with aluminum under the conditions of aluminum coating B d Example 1. The steel of Table 1 of Example 1. At that time, the amount of coating deposition was adjusted to a total of both sides from 80 to 160 g / m 2 . In addition, after the aluminum coating, a mixture of finely dispersed aqueous ZnO solution (Nanotech Slurry produced by CI Kasei) and a water soluble urethane resin was coated with a coating cylinder and dried at 80 ° C. At that time, the deposition amounts of the ZnO film were converted to Zn, 0.5 to 3 g / m 2 . These specimens were not stamped and interlocked.
    [000170] As hot stamping conditions at this time
    Petition 870190104452, of 10/16/2019, p. 54/66
    46/47 to, in addition to the heating oven which is shown in Example 1, an infrared heating oven was also used. The retention time in the case of oven heating was also 60 s. Note that the rate of temperature rise in infrared heating was approximately 19 ° C / s. The specimen thus prepared was assessed by the same method as in Example 1. The results of the assessment at that time are shown in Table 5. Vicker's hardness was 420 or more in all cases.
    Table 5
    No. Coating deposit amount (g / m 2 ) Quantity of Zn deposition (g / m 2 ) Heating method Temp. heating (° C) Average coating thickness (pm) Standard deviation of coating thickness Des-standard / methodday Average linear intersection length (pm) Postpaint anti-corrosion property Spot welding capability Grades 1 80 1.0 Oven 900 15 1.1 0.07 9 Verygood Good ExInv. 2 80 1.0 Infrastructurered 950 14 1.2 0.09 11 Verygood Good Ex.Inv. 3 80 2.0 Infrastructurered 950 14 1.1 0.08 11 Verygood Good Ex.Inv. 4 80 3.0 Infrastructurered 950 15 1.3 0.09 10 Verygood Good Ex.Inv. 5 120 0.5 Infrastructurered 900 23 2.0 0.09 11 Verygood Good Ex.Inv. 6 160 0.5 Infrastructurered 900 29 2.4 0.08 12 Verygood Good Ex.Inv. 7 160 1.0 Infrastructurered 900 29 2.3 0.08 12 VerygoodEx.Inv.
    [000171] These tests with a ZnO film presented
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    47/47 excellent post-pinch anti-corrosion property even with a small amount of deposition. In addition, the spot welding capability was also excellent.
    权利要求:
    Claims (10)
    [1]
    1. Hot-stamped high-strength part, characterized by the fact that it comprises an alloy coating layer comprising an Al-Fe intermetallic composite phase on the surface of the steel sheet, said alloy coating layer is comprised of phases of one plurality of intermetallic compounds, the average linear intersection length of crystal grains of a phase containing Al: 40 to 65% by mass between the referred phases of the plurality of intermetallic compounds is 3 to 20 pm, the average value of the thickness of said layer of Al-Fe alloy coating is 10 to 50 pm, and the ratio of the average thickness value to the standard deviation of the thickness of said Al-Fe alloy coating layer satisfies the following relationship:
    0 <thickness standard deviation / mean thickness value <0.15.
    [2]
    2. High-strength hot-stamped part according to claim 1, characterized by the fact that the said ratio of the average thickness value to the standard deviation of the thickness is 0.1 or less.
    [3]
    3. High-strength hot-stamped part according to claim 1 or 2, characterized by the fact that said alloy coating layer contains, in mass%, Si: 2 to 7%.
    [4]
    4. High-strength hot-stamped part according to claim 1 or 2, characterized in that the layer of the surface film containing ZnO is deposited on the surface of said Al-Fe alloy coating layer.
    [5]
    5. High-strength hot-stamped part, according to claim 4, characterized by the fact that the ZnO content of the
    Petition 870190104452, of 10/16/2019, p. 57/66
    2/5 said layer of surface film is converted into Zn mass, 0.3 to 7 g / m 2 per side.
    [6]
    6. High-strength hot-stamped part according to claim 1 or 2, characterized by the fact that said steel plate is comprised of a chemical ingredients steel plate which comprises as ingredients, in mass%,
    C: 0.1 to 0.5%,
    Si: 0.01 to 0.7%,
    Mn: 0.2 to 2.5%,
    Al: 0.01 to 0.5%,
    P: 0.001 to 0.1%,
    S: 0.001 to 0.1%,
    N: 0.0010% to 0.05%, and a balance of Fe and the inevitable impurities.
    [7]
    7. High strength hot stamped part, according to claim 6, characterized by the fact that said steel sheet also comprises, in mass%, one or more elements selected from among
    Cr: more than 0.4 to 3%,
    Mo: 0.005 to 0.5%,
    B: 0.0001 to 0.01%,
    W: 0.01 to 3%,
    V: 0.01 to 2%,
    Ti: 0.005 to 0.5%,
    Nb: 0.01 to 1%
    Ni: 0.01 to 5%,
    Cu: 0.1 to 3%,
    Sn: 0.005% to 0.1%, and
    Sb: 0.005% to 0.1%.
    [8]
    8. Method of production of a steel sheet coated with
    Petition 870190104452, of 10/16/2019, p. 58/66
    3/5 aluminum for a hot-stamped piece of high strength, comprising the steps of:
    supply an aluminum coated steel sheet obtained, characterized by hot rolling a steel comprising chemical ingredients comprising, in% by mass,
    C: 0.1 to 0.5%,
    Si: 0.01 to 0.7%,
    Mn: 0.2 to 2.5%,
    Al: 0.01 to 0.5%,
    P: 0.001 to 0.1%,
    S: 0.001 to 0.1%,
    N: 0.0010% to 0.05%, and the balance being Fe and the inevitable impurities, cold-roll said hot-rolled steel to obtain a hot-rolled steel sheet, heat said cold-rolled steel sheet in a hot-dip line up to an annealing temperature of 670 to 760 ° C, keep said steel sheet heated in a reduction oven for 60 seconds or less, and coat said steel sheet with aluminum, and perform the hardening lamination on said aluminum coated steel sheet to give a lamination rate of 0.5 to 2%, increase the temperature of said hardened aluminum coated steel sheet by an elevation rate of 3 to 200 ° C / s ; hot stamping the aluminum coated steel sheet under conditions of a Larson-Miller (LPM) parameter expressed by the following formula:
    Petition 870190104452, of 10/16/2019, p. 59/66
    4/5
    LMP = T (20 + logt) (where, T: heating temperature of the aluminum coated steel sheet (absolute temperature K), t: retention time in the heating forum after reaching the target temperature (h)) of 20000 at 23000; and cooling said aluminum-coated steel sheet after hot stamping at a cooling rate of 20 to 500 ° C / s in the mold, where in the production step of said aluminum-coated steel sheet, a coating bath for aluminum cladding it comprises Si in an amount of 7 to 15%, and a bath temperature or a plate temperature when entering the bath of 650 ° C or less.
    [9]
    9. Method for the production of an aluminum-coated steel sheet for a high-strength hot-stamped part, according to claim 8, characterized by the fact that said steel also comprises, in mass%, one or more elements selected among
    Cr: more than 0.4 to 3%,
    Mo: 0.005 to 0.5%,
    B: 0.0001 to 0.01%,
    W: 0.01 to 3%,
    V: 0.01 to 2%,
    Ti: 0.005 to 0.5%,
    Nb: 0.01 to 1%
    Ni: 0.01 to 5%,
    Cu: 0.1 to 3%,
    Sn: 0.005% to 0.1%, and
    Sb: 0.005% to 0.1%.
    [10]
    10. Production method of a steel sheet coated with
    Petition 870190104452, of 10/16/2019, p. 60/66
    5/5 aluminum for a high strength hot stamped part according to claim 8 or 9, characterized by the fact that the rate of temperature rise in said hot stamping step is 4 to 200 ° C / s.
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    同族专利:
    公开号 | 公开日
    US8986849B2|2015-03-24|
    MX2013011061A|2013-10-17|
    JPWO2012137687A1|2014-07-28|
    EP2695963A4|2014-11-05|
    RU2563421C2|2015-09-20|
    CA2831305A1|2012-10-11|
    KR101829854B1|2018-02-20|
    US20150191813A1|2015-07-09|
    CN103492605B|2016-07-06|
    BR112013025401A2|2016-12-20|
    CN103492605A|2014-01-01|
    RU2013148805A|2015-05-10|
    KR20160015388A|2016-02-12|
    JP5614496B2|2014-10-29|
    EP2695963B1|2021-11-03|
    KR20130132623A|2013-12-04|
    EP2695963A1|2014-02-12|
    US9644252B2|2017-05-09|
    ZA201307304B|2014-06-25|
    CA2831305C|2016-05-10|
    MX356881B|2018-06-19|
    US20140030544A1|2014-01-30|
    WO2012137687A1|2012-10-11|
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    法律状态:
    2018-04-03| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-07-23| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2019-09-03| B25D| Requested change of name of applicant approved|Owner name: NIPPON STEEL CORPORATION (JP) |
    2020-03-17| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2020-05-12| 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 30/03/2012, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    JP2011081995|2011-04-01|
    JP2011-081995|2011-04-01|
    PCT/JP2012/058655|WO2012137687A1|2011-04-01|2012-03-30|Hot stamp-molded high-strength component having excellent corrosion resistance after coating, and method for manufacturing same|
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