Specification
Title of Invention : Plated steel sheet for hot stamping and hot stamping member
Technical field
[0001]
The present invention relates to a plated steel sheet for hot stamping and a hot stamping member.
Background technology
[0002]
In recent years, in order to protect the environment and prevent global warming, there has been a demand to curb the consumption of chemical fuels. This requirement has affected various manufacturing industries. For example, automobiles, which are indispensable for daily life and activities as a means of transportation, are no exception. In the automobile manufacturing industry, there is a demand for improvement in fuel efficiency and the like by reducing the weight of vehicle bodies. However, in the automobile manufacturing industry, it is not permissible to simply reduce the weight of the vehicle body in terms of product quality, and it is necessary to ensure appropriate safety.
[0003]
Many automobile structures are made of steel, especially steel plates, and reducing the weight of these steel plates is important for reducing the weight of the car body. However, as described above, simply reducing the weight of the steel sheet is not permitted, and it is also required to ensure the mechanical strength of the steel sheet. Such steel sheets are required not only in the automobile manufacturing industry but also in various manufacturing industries. Therefore, research and development are being conducted on a steel sheet that can maintain or increase the mechanical strength even if the thickness of the steel sheet is thinner than that of a conventional steel sheet, by increasing the mechanical strength of the steel sheet.
[0004]
In general, materials with high mechanical strength tend to lose shape fixability in bending and other forming processes. Therefore, when processing a material having high mechanical strength into a complicated shape, the processing itself may be difficult. One of the means for solving this moldability problem is the so-called "hot stamping method" (also called hot pressing method, hot pressing method, high temperature pressing method, or die quenching method). The hot stamping method is a method in which a steel sheet to be formed is heated to a high temperature in the austenite region, the steel sheet softened by heating is pressed and formed, and then cooled while restrained in a mold. According to the hot stamping method, the steel sheet is once heated to a high temperature in the austenite region and softened, so it can be easily press-formed, and the mechanical strength of the molded product is increased by the quenching effect of cooling after molding. be able to. Therefore, the hot stamping method makes it possible to obtain a molded article having good shape fixability and high mechanical strength.
[0005]
However, when the hot stamping method is applied to steel sheets, it is necessary to apply anti-corrosion treatment and metal coating to the surface of the member after processing for members that require corrosion resistance. In this case, a surface cleaning process, a surface treatment process, and the like are required, resulting in a decrease in productivity.
[0006]
Patent Document 1 describes an aluminum-based plated steel sheet for hot stamping, which has an Al-based metal coating mainly composed of Al and containing Mg and Si on the surface of the steel.
[0007]
Patent Document 2 relates to automobile members, and describes forming an oxide film with a thickness of 0.05 to 1 μm on the surface of the Al—Fe intermetallic compound layer after hot stamping. Further, in Patent Document 2, an Al-plated steel sheet for hot press is heated so that the oxide film has a predetermined thickness, and an Al-Fe intermetallic compound layer is formed up to the surface layer, so that after electrodeposition coating, It is described that coating film defects and deterioration of adhesion are suppressed, and corrosion resistance after coating is ensured.
prior art documents
patent literature
[0008]
Patent Document 1: Japanese Patent Application Laid-Open No. 2003-034845
Patent Document 2: Japanese Patent Application Laid-Open No. 2009-293078
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0009]
The method described in Patent Document 1 does not provide sufficient corrosion resistance after painting after hot stamping. It is presumed that this is because the compound composition and particle size of the outermost surface do not sufficiently strengthen the affinity with the coating film and the chemical conversion treatment layer thereon.
[0010]
As described in Patent Document 2, even if the structure and thickness of the Al-Fe intermetallic compound layer are controlled, it is difficult to obtain sufficient corrosion resistance after painting. It is presumed that this is because the reduced reactivity between the oxide film and the chemical conversion treatment agent causes a decrease in the adhesion amount of the chemical conversion treatment film.
[0011]
As described above, with the conventional technology, when hot-stamping plated steel sheets into hot-stamped members, it was difficult to ensure sufficient corrosion resistance after painting.
[0012]
The present invention has been made against the background of the above circumstances, and aims to provide a hot stamping member having excellent chemical conversion treatability and corrosion resistance after painting, and a plated steel sheet for hot stamping from which this hot stamping member can be obtained. aim.
Means to solve problems
[0013]
In the manufacturing process of automobiles using plated steel sheets for hot stamping, in which a plating layer and a surface film layer are formed on steel sheets, plated steel sheets for hot stamping are heated and formed in the hot stamping process to form hot stamped parts. Become. Hot stamping parts are made practical by laminating a chemical conversion treatment film represented by a zinc phosphate film on the surface of the part (on the surface film layer), an electrodeposition coating film on the upper layer, and in some cases, a further coating film. provided.
[0014]
In a corrosive environment, an anodic dissolution reaction of aluminum, iron, or an intermetallic compound of aluminum and iron generated in the hot stamping process occurs according to the reaction formulas (1) to (3) below. It is presumed that corrosion products are formed by the corrosion, and the coating film blisters progress.
[0015]
　Al→Al 3++3e -　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　...(1)
　Fe→Fe 2++2e -　　　　　　　　　　　　　　　　　　　(2)
　Fe xAl y→xFe+yAl+(2x+3y)e - (3)
[0016]
The present inventors have found that a plurality of stable valences of +1 or more ( For example, the above problem has been solved by containing a predetermined amount of particles containing an element that can have a valence of +3 and +6, and by controlling the average particle diameter of the particles containing these elements within a predetermined range. Specifically, it contains particles containing one or more elements selected from Group A elements consisting of Sc, V, Mn, Fe, Co, Ce, Nb, Mo and W, A surface having a total content of group A elements of 0.01 to 10.0 g/m 2 and an average particle size of the particles containing the group A elements of 0.05 to 3.0 μm The above problem was solved by forming a coating layer on the plating layer.
[0017]
Group A elements contained in the particles can form oxides with higher valences after hot stamping. As a result, the bias (polarity) of electrons in the oxide becomes higher, and the interaction with the components in the chemical conversion treatment solution, which are also highly polar, such as zinc phosphate, is strengthened, thereby improving the chemical conversion treatability. . The term “improved chemical conversion treatability” means that the adhesion amount of the chemical conversion treatment film increases when the hot stamping member is subjected to the chemical conversion treatment. In addition, when the corrosion resistance after painting is improved, when the hot stamped member is subjected to chemical conversion treatment and the surface on which the coating film is formed with the electrodeposition paint is scratched with a cutter, the swelling width of the coating film in a corrosive environment is small. means to become As the chemical conversion treatability increases and the deposition amount of the chemical conversion coating increases, the adhesion between the chemical conversion coating and the electrodeposition coating increases, and the corrosion resistance after coating improves.
[0018]
In a corrosive environment after the surface coating layer contains particles containing a group A element, a chemical conversion coating such as a zinc phosphate coating is formed on the upper layer, and an electrodeposition coating is further formed on the upper layer. It is also expected to prevent corrosive factors such as and salt from reaching the plated metal.
[0019]
In addition, since the group A element in the inorganic coating is contained in the form of particles, the surface area of the surface coating layer increases, which increases the time required for heating during hot stamping. In addition, since the amount of the group A element that is close to the atmosphere in which moisture or oxygen is present increases, the group A element tends to concentrate on the surface of the surface coating layer 3 . Then, zinc phosphate tends to adhere during chemical conversion treatment after hot stamping, for example, phosphoric acid treatment, and the chemical conversion treatment property is improved, thereby improving adhesion after painting.
[0020]
Although there are unclear points about the mechanism by which the coating adhesion of the hot stamped member improves due to the refinement of the metal structure of the plating layer, the present inventors speculate as follows. By controlling the average crystal grain size of the plating layer to be small, the number of crystal grain boundaries can be increased. As a result, the number of grain boundaries increases even after hot stamping, and the oxide film layer on the surface becomes more uneven, so physical and chemical bonds with the electrodeposition coating film after chemical conversion treatment become stronger. guessed.
[0021]
Group A elements are mainly contained in the oxide film layer in the form of oxides. When the outermost surface (the surface of the oxide film layer) of such a hot stamping member is subjected to chemical conversion treatment, the presence of the oxide of the group A element on the outermost surface of the hot stamping member causes the oxide film layer and the chemical conversion treatment to occur. The pH of the chemical conversion treatment liquid at the interface with the treatment liquid rises. This increases the amount of zinc phosphate crystals precipitated. That is, the so-called chemical convertability is enhanced. In addition, by increasing the amount of zinc phosphate crystals precipitated, the adhesion (paint adhesion) of the electrodeposition coating film to be electrodeposition-coated after the chemical conversion treatment is improved. Corrosion resistance after coating is improved by increasing the adhesion of the electrodeposition coating film.
[0022]
The present invention was made based on the above findings, and the gist thereof is as follows.
(1) A plated steel sheet for hot stamping according to one aspect of the present invention,
with a steel plate,
a plating layer formed on one or both sides of the steel sheet and having an Al content of 60% by mass or more;
and a surface film layer formed on the plating layer,
the thickness t of the plating layer is 10 to 60 μm,
The average crystal grain size of the plating layer in the thickness range from the interface between the plating layer and the surface coating layer to the position 2/3 times the thickness t is 2 t/3 or less and 15.0 μm and
The surface coating layer contains particles containing one or more elements selected from Group A elements consisting of Sc, V, Mn, Fe, Co, Ce, Nb, Mo and W,
the total content of the group A elements in the surface coating layer is 0.01 to 10.0 g/m2,
The particles containing the group A element have an average particle size of 0.05 to 3.0 μm.
(2) In the plated steel sheet for hot stamping described in (1) above, at least part of the particles containing the group A element may contain O.
(3) The plated steel sheet for hot stamping according to (1) or (2) above,
The surface coating layer further contains particles containing one or more selected from group B elements consisting of Zn, Zr and Ti,
The total content of the B group elements in the surface coating layer may be 0.01 to 10.0 g/m 2 .
(4) The plated steel sheet for hot stamping according to any one of (1) to (3) above, wherein the total content of Ca, Mg, Sr and Ti in the plating layer is , in mass %, may be from 0.01% to 20%.
(5) A hot stamped member according to another aspect of the present invention is a hot stamped member obtained by hot stamping the plated steel sheet for hot stamping according to (1) to (4) above,
The surface has an oxide film layer containing one or more elements selected from Group A elements consisting of Sc, V, Mn, Fe, Co, Ce, Nb, Mo and W, Al, and oxygen.
Effect of the invention
[0023]
According to the above aspect of the present invention, it is possible to provide a hot stamping member having excellent chemical conversion treatability and corrosion resistance after painting, and a plated steel sheet for hot stamping from which this hot stamping member can be obtained.
Brief description of the drawing
[0024]
1 is a cross-sectional view of a plated steel sheet for hot stamping according to the present embodiment;
[Fig. 2] Fig. 2 is a schematic diagram showing a method of measuring the average crystal grain size of the plating layer of the plated steel sheet for hot stamping according to the present embodiment.
MODE FOR CARRYING OUT THE INVENTION
[0025]
　The following are the advantages of the present inventionSuitable embodiments are described in detail.
FIG. 1 is a diagram showing a plated steel sheet 10 for hot stamping (hereinafter sometimes simply referred to as a plated steel sheet) according to this embodiment. A plated steel sheet 10 according to the present embodiment includes a steel sheet 1, a plating layer 2 formed on one or both sides of the steel sheet 1 and containing Al, and a surface coating layer 3 formed on the plating layer 2.
[0026]
(Steel plate 1)
The chemical composition of the steel sheet 1, which is the base material of the plated steel sheet 10 for hot stamping according to this embodiment, is not particularly limited. However, the steel plate 1 according to the present embodiment has high mechanical properties (tensile strength, yield stress, elongation, reduction of area, hardness, impact value, strength against mechanical deformation and fracture such as fatigue strength) after hot stamping. It is desirable to use the resulting steel sheet.
[0027]
In order to obtain high mechanical strength after hot stamping, the chemical composition of the steel sheet 1 is C: 0.10 to 0.60%, Si: 0.01 to 0.60%, Mn: 0.01 to 0.60% by mass. 01-3.00%, P: 0.050% or less, S: 0.050% or less, Al: 1.00% or less, Ti: 0.001-0.100%, B: 0.0001-0. 0100%, N: 0.0100% or less, and the balance being Fe and impurities. In addition, "%" regarding the content of an element means "mass %" unless otherwise specified. Preferred chemical compositions of the steel sheet 1 according to this embodiment are described below.
[0028]
C: 0.10-0.60%
C is included to obtain the desired mechanical strength. If the C content is less than 0.10%, the effect of improving the mechanical strength may not be sufficiently obtained, and the effect of containing C may not be obtained. On the other hand, if the C content exceeds 0.60%, the strength of the steel sheet 1 can be further improved, but the elongation and reduction of area may decrease. Therefore, the C content is preferably 0.10-0.60%. If necessary, the lower limit of the C content may be 0.15% or 0.20%, and the upper limit of the C content may be 0.50% or 0.40%.
[0029]
Si: 0.01-0.60%
Si is a strength-improving element that improves mechanical strength, and like C, it is contained in order to obtain the desired mechanical strength of the steel sheet 1 . If the Si content is less than 0.01%, the effect of improving the strength is difficult to obtain, and the mechanical strength may not be sufficiently improved. On the other hand, since Si is also an easily oxidizable element, when the Si content exceeds 0.60%, wettability is reduced during hot-dip plating due to the influence of Si oxides formed on the surface layer of the steel sheet 1. may decrease and non-plating may occur. Therefore, the Si content is preferably 0.01-0.60%.
[0030]
Mn: 0.01-3.00%
　Mn is a strength-improving element that improves mechanical strength, and is also an element that enhances hardenability. Furthermore, Mn has the effect of preventing hot embrittlement due to S, which is an impurity. If the Mn content is less than 0.01%, the above effects may not be obtained. On the other hand, since Mn is a γ-forming element, if the Mn content exceeds 3.00%, the residual γ phase may become too large and the strength of the hot stamped member may be lowered. Therefore, the Mn content is preferably 0.01 to 3.00%. If necessary, the lower limit of the Mn content may be 0.30% or 0.50%, and the upper limit of the Mn content may be 2.50% or 2.10%.
[0031]
P: 0.050% or less
　P is an element that deteriorates the toughness of the hot stamped member after quenching. In particular, when the P content exceeds 0.050%, the toughness of the hot stamped member may deteriorate significantly. Therefore, the P content is preferably 0.050% or less. Also, the P content is more preferably 0.005% or less.
　P is mixed as an impurity from scrap etc. during the production of molten steel, but there is no need to limit its lower limit, and its lower limit is 0%. However, excessively reducing the P content increases the manufacturing cost. Therefore, the lower limit of the P content may be 0.001% or more, or 0.002% or more.
[0032]
S: 0.050% or less
S is an element that deteriorates the toughness of the hot stamped member after quenching. In particular, if the S content exceeds 0.050%, the toughness of the hot-stamped member may significantly deteriorate. Therefore, the S content is preferably 0.050% or less. Moreover, the S content is more preferably 0.003% or less.
Although S is mixed as an impurity from scrap etc. during the production of molten steel, there is no particular need to limit its lower limit, and its lower limit is 0%. However, excessively reducing the S content increases the manufacturing cost. Therefore, the lower limit of the S content may be 0.001% or more.
[0033]
Al: 1.00% or less
Al is an element that enhances the hardenability of steel and makes it possible to stably secure the strength of hot stamped members after hardening. However, when the Al content exceeds 1.00%, the above effects are saturated and the cost increases. Therefore, the Al content is preferably 1.00% or less. Moreover, in order to obtain the above effect, it is preferable to set the Al content to 0.01% or more.
[0034]
Ti: 0.001-0.100%
　Ti is a strength-enhancing element that improves mechanical strength. If the Ti content is less than 0.001%, the effect of improving strength and the effect of improving oxidation resistance may not be obtained. On the other hand, when Ti is contained excessively, for example, carbides and nitrides are formed, which may soften the steel. In particular, when the Ti content exceeds 0.100%, desired mechanical strength may not be obtained. Therefore, the Ti content is preferably 0.001 to 0.100%.
[0035]
B: 0.0001 to 0.0100%
B has the effect of improving the strength of steel during quenching. If the B content is less than 0.0001%, the strength improvement effect described above may not be sufficiently obtained. On the other hand, if the B content exceeds 0.0100%, inclusions may be formed in the steel, embrittlement of the steel sheet 1, and deterioration of fatigue strength. Therefore, the B content is preferably 0.0001% to 0.0100%.
[0036]
N: 0.0100% or less
　N is an element that deteriorates the toughness of the hot stamped member after quenching. In particular, when the N content exceeds 0.0100%, coarse nitrides are formed in the steel, and the local deformability and toughness of the steel plate 1 are remarkably deteriorated. Therefore, the N content is preferably 0.0100% or less. The lower limit of the N content is not particularly limited, but if the N content is less than 0.0002%, the cost may increase. Therefore, the N content is preferably 0.0002% or more, more preferably 0.0008% or more.
[0037]
In addition to the above elements, the steel sheet 1 according to the present embodiment further contains one or more elements selected from Cr, Ni, Cu, V, Nb, Sn, Mo, W, Ca and REM shown below. may be included.
[0038]
Cr: 0-1.0%
Cr is an element that enhances the hardenability of steel and makes it possible to stably obtain the strength of the hot stamped member after hardening, so it may be contained. In addition, Cr forms FeCr 2 O 4 on the surface of the steel sheet during heat treatment, suppresses scale formation, and plays a role of reducing FeO in the scale. Since this FeCr 2 O 4 serves as a barrier layer and blocks the supply of Fe into the scale, the thickness of the scale can be reduced. If the thickness of the scale is thin, there is also the advantage that the scale is difficult to peel off during hot forming and is easy to peel off during the scale removal treatment after hot stamping. However, when the Cr content exceeds 1.0%, the above effect saturates, causing an increase in cost. Therefore, when Cr is contained, the Cr content is made 1.0% or less. The Cr content is preferably 0.8% or less. In order to obtain the above effects, the Cr content is preferably 0.01% or more, more preferably 0.05% or more.
[0039]
Ni: 0-2.0%
Ni is an element that enhances the hardenability of steel and makes it possible to stably obtain the strength of the hot stamped member after hardening, so it may be contained. However, when the Ni content exceeds 2.0%, the above effects become saturated and the cost increases. Therefore, when Ni is contained, the Ni content is set to 2.0% or less. In order to obtain the above effects, the Ni content is preferably 0.1% or more.
[0040]
Cu: 0-1.0%
Cu may be contained because it is an element that enhances the hardenability of steel and makes it possible to stably obtain the strength of the hot stamped member after hardening. Cu is also an element that improves the pitting corrosion resistance of the steel sheet 1 in a corrosive environment. If the Cu content exceeds 1.0%, the above effects are saturated and the cost increases. Therefore, when Cu is contained, the Cu content is set to 1.0% or less. In order to obtain the above effects, the Cu content is preferably 0.1% or more.
[0041]
V: 0-1.0%
V is an element that enhances the hardenability of steel and makes it possible to stably obtain the strength of the hot stamped member after hardening, so it may be contained. However, when the V content exceeds 1.0%, the above effects become saturated and the cost increases. Therefore, when V is contained, the V content should be 1.0% or less. In order to obtain the above effects, the V content is preferably 0.1% or more.
[0042]
Nb: 0-1.0%
Nb is an element that enhances the hardenability of steel and makes it possible to stably obtain the strength of the hot stamped member after hardening, so it may be contained. However, when the Nb content exceeds 1.0%, the above effects become saturated and the cost increases. Therefore, when Nb is contained, the Nb content is set to 1.0% or less. In order to obtain the above effect, Nb is preferably 0.01% or more.
[0043]
Sn: 0-1.0%
Sn may be contained in order to improve the pitting corrosion resistance of the steel sheet 1 in a corrosive environment. However, when the Sn content exceeds 1.0%, the grain boundary strength is lowered and the toughness is deteriorated. Therefore, when Sn is contained, the Sn content should be 1.0% or less. In order to obtain the above effects, the Sn content is preferably 0.01% or more.
[0044]
Mo: 0-1.0%
Mo is an element that enhances the hardenability of steel and makes it possible to stably secure the strength of the hot stamped member after hardening, so it may be contained. However, when the Mo content exceeds 1.0%, the above effects become saturated and the cost increases. Therefore, when Mo is contained, the Mo content is set to 1.0% or less. In order to obtain the above effects, the Mo content is preferably 0.1% or more.
[0045]
W: 0-1.0%
W may be contained because it is an element that enhances the hardenability of steel and makes it possible to stably secure the strength of the hot stamped member after hardening. Further, it is also an element that improves the pitting corrosion resistance of the steel sheet 1 in a corrosive environment. However, when the W content exceeds 1.0%, the above effects become saturated and the cost increases. Therefore, when W is contained, the W content should be 1.0% or less. In order to obtain the above effects, the W content is preferably 0.01% or more.
[0046]
Ca: 0-0.01%
Ca is an element that has the effect of refining inclusions in steel and improving toughness and ductility after quenching, so it may be contained. However, when the Ca content exceeds 0.01%, the above effects are saturated and the cost increases. Therefore, when Ca is contained, the Ca content shall be 0.01% or less. The Ca content is preferably 0.004% or less. In order to reliably obtain the above effects, the Ca content is preferably 0.001% or more, more preferably 0.002% or more.
[0047]
REM: 0-0.3%
REM, like Ca, is an element that has the effect of refining inclusions in steel and improving toughness and ductility after quenching, so it may be contained. However, when the REM content exceeds 0.3%, the above effects are saturated., the cost increases. Therefore, when REM is contained, the REM content is made 0.3% or less. The REM content is preferably 0.2% or less. In order to reliably obtain the above effects, the REM content is preferably 0.001% or more, more preferably 0.002% or more.
[0048]
Here, REM refers to a total of 17 elements consisting of Sc, Y and lanthanides, and the REM content means the total content of these elements. REMs are added to molten steel using, for example, Fe--Si--REM alloys, which include, for example, Ce, La, Nd, Pr.
[0049]
Note that the steel sheet 1 according to the present embodiment may contain impurities mixed in during the manufacturing process, etc., in addition to the elements described above. When the plated layer 2 and the surface film layer 3 described later are formed on the steel sheet 1 having the chemical composition described above, a tensile strength of about 1000 MPa or more can be achieved by heating and quenching by a hot stamping method.
[0050]
Although the thickness of the steel plate 1 according to this embodiment is not particularly limited, it is preferably 0.6 to 2.5 mm.
[0051]
(Plating layer 2)
The plating layer 2 according to this embodiment is formed on one side or both sides of the steel sheet 1 described above. The plating layer 2 according to this embodiment contains Al. In the present embodiment, the plated layer containing Al means a plated layer containing 60% or more by mass of Al. As elements other than Al in the plated layer 2, Si, Fe and Zn may be contained by about 0.1 to 20%, 0.1 to 10% and 0.1 to 40%, respectively. The lower limit of the content of each of Si, Fe and Zn is 0%, but the lower limit may be 0.1% as described above. In particular, Si has the effect of improving the slidability of the plating layer 2 by suppressing the growth of an alloy layer of Al and Fe (Al--Fe alloy layer). As for Fe, it is conceivable that the plating layer 2 is contaminated with Fe contained in equipment and the like (for example, in the case of the hot dip plating method, a stainless steel container containing a plating solution, etc.). Zn has the effect of lowering the potential of the plating layer 2 and thereby improving the corrosion resistance of the exposed portion of the base iron. The balance of plating layer 2 consists of less than 0.5% of impurities. Impurities include Cu, Na, K, Co, and the like. It should be noted that the content of each element does not need to be within the above range at all locations of the plating layer 2, and the average chemical composition of the entire plating layer 2 may be within the above range. For this reason, when manufacturing by the hot-dip plating method, the average chemical composition of the plating layer 2 as a whole can be made within the above range by setting the chemical composition of the plating bath within the above range.
[0052]
The thickness t of the plating layer 2 is set to 10 to 60 μm. By setting the thickness t of the plating layer 2 to 10 μm or more, the corrosion resistance of the hot stamped member can be improved. Further, by setting the thickness t of the plating layer to 60 μm or less, the Al—Fe intermetallic compound layer is formed up to or near the outermost layer, which improves the corrosion resistance of the hot stamped member. The thickness t of the plating layer 2 is preferably 13 μm or more or 15 μm or more. Moreover, the thickness t of the plating layer 2 is preferably 55 μm or less, 50 μm or less, or 45 μm or less.
[0053]
The thickness t of the plating layer 2 can be measured, for example, by quantitatively analyzing the cross section of the sample with an FE-EPMA (field emission electron probe microanalyzer).
In this embodiment, a sample having a size of 10 mm×10 mm is cut out from a portion at least 10 mm in the width direction from the edge of the plated steel sheet 10, specifically at a portion at a distance of 15 mm, for example. The embedded polished sample is obtained by embedding the sample in resin and polishing. After carbon is vapor-deposited on the embedded polished sample so as to facilitate electric conduction, the content of each element is quantitatively analyzed by point analysis using FE-EPMA at an acceleration voltage of 10 kV and a magnification of 1500 times or more. A plated layer 2 is defined as a layer in which the Al content in the total of elements excluding carbon by mass is 30% by mass or more. A point analysis is performed every 1 μm perpendicular to the steel sheet from the plated surface toward the center of the plate thickness, and the point where the Al content is less than 30% by mass is judged not to be the plated layer 2 . A set of points where the Al content is 30% by mass or more is defined as the plating layer 2, and the thickness t of the plating layer 2 is obtained.
[0054]
In the thickness range from the interface between the plating layer 2 and the surface film layer 3 to the position of 2/3 times the thickness t (2t/3 position), the average crystal grain size of the plating layer 2 is 2t/3 (μm). or less and 15.0 μm or less. In this thickness range, by setting the average crystal grain size of the plating layer 2 to 2t/3 (μm) or less and 15.0 μm or less, the area of the crystal grain boundary is increased, and the atmosphere such as the atmosphere when hot stamping is heated. The interface area with the gas becomes large. This increases the amount of zinc phosphate crystals precipitated. That is, the so-called chemical convertability is enhanced. In addition, this improves the adhesion of the electrodeposition coating film that is electrodeposition coated after the chemical conversion treatment. By increasing the adhesion of the electrodeposition coating film, the post-coating corrosion resistance of the hot-stamped member is improved.
[0055]
After hot stamping, as described above, the corrosion resistance after painting is improved. It is presumed that the physical and chemical bonds with the electrodeposition coating film after the chemical conversion treatment become stronger because the grain boundaries increase and the oxide film layer on the surface becomes more uneven due to the following conditions. be. As a result, corrosion resistance after painting is improved.
[0056]
The average crystal grain size of the plating layer 2 can be obtained by the following method.
A sample is taken from the plated steel sheet 10 for hot stamping so that the cross section in the thickness direction of the plating layer 2 serves as the observation surface. The collected sample is etched with a 3% nitric acid alcohol solution (nital solution) to expose the grain boundaries, and a scanning electron microscope (SEM) is used to examine the steel sheet from the interface between the plating layer 2 and the surface coating layer 3. An image is captured so that up to 1 is included. For this photograph, as shown in FIG. 2, a line segment having a length of 2t/3 (t=thickness of the plating layer (μm)) in the thickness direction from the interface between the plating layer 2 and the surface film layer (not shown) is drawn. By subtracting, the number of intersections with grain boundaries is defined as n, and the value obtained by dividing the line segment length (2t/3) by n, that is, (2t/3n) is defined as the average crystal grain size. Three such line segments are drawn at arbitrary positions at intervals of 5 μm, such as (a), (b), and (c) in FIG. is the average crystal grain size of the plating layer 2 in the thickness range from the interface between the plating layer 2 and the surface film layer 3 to the position 2/3 times the thickness t (2t / 3 position) .
[0057]
When n is 0, 2t/3n cannot be calculated. However, when n is 0, since the grain size is larger than 2t/3 in the observed image, it is determined that the average crystal grain size is not 2t/3 or less.
Also, in calculating the number n of intersections, JIS G 0551:2013 Appendix C. If a line segment intersects a triple point, as described in 2.2, then n is 1.5 at that point.
[0058]
The plating layer 2 according to this embodiment may be formed on the surface of the steel sheet 1 by, for example, hot dip plating. At least part of the plating layer 2 can be alloyed with Fe in the steel sheet 1 during metal coating in hot dip plating, heating in hot pressing, or the like. Therefore, the plated layer 2 according to this embodiment is not necessarily a single layer having a constant chemical composition, and may include an alloyed layer as appropriate.
[0059]
The plating layer 2 according to the present embodiment preferably contains one or more elements selected from Ca, Mg, Sr and Ti. When the above elements are contained in the plating layer 2, the post-coating corrosion resistance of the hot-stamped (hot-stamped member) is further improved. Although the detailed mechanism is not clear, the above elements have an anticorrosion effect against corrosion products generated during the corrosion test process, so it is possible to delay the arrival of corrosion factors such as water, oxygen, and salt to the plating layer 2. It is considered to be a thing.
[0060]
In order to improve the corrosion resistance after painting after hot stamping (hot stamping member), the total content of Ca, Mg, Sr and Ti is 0.01 to 20% in mass% with respect to the entire plating layer 2. Preferably. More preferably, the total content of the above elements is 0.03 to 10% with respect to the entire plating layer 2 . The upper limit may be 6.0%, 4.0% or 2.0%, and the lower limit may be 0.05%, 0.08% or 0.10%.
[0061]
The plating layer 2 according to this embodiment is, for example, in the form of a hot-dip plating layer.
[0062]
(Method for analyzing plating layer 2)
The components of the plating layer 2 in this embodiment are analyzed by the following methods.
In the plated steel sheet 10 according to the present embodiment, the surface film layer 3 described later is formed on the plating layer 2, so the surface film layer 3 is first removed. Specifically, the surface film layer 3 may be removed by polishing. The components of the plating layer 2 exposed on the surface are analyzed by the off-line fluorescent X-ray method described in Annex JB of JIS G 3314:2011.
[0063]
(Surface coating layer 3)
The surface film layer 3 according to the present embodiment is a layer containing a group A element described later, which is formed as an upper layer on the surface of the plating layer 2 described above. The form of the surface film layer 3 according to the present embodiment is typically a paint film or a powder-coated film (powder-baked layer), but is not limited to these forms. .
[0064]
The surface coating layer 3 contains particles containing one or more elements selected from group A elements (Sc, V, Mn, Fe, Co, Ce, Nb, Mo, W). The particles are present in the surface coating layer 3 in the state of particles mainly composed of elemental elements of group A elements or in the form of particles mainly composed of compounds of group A elements (for example, oxides). In the present embodiment, "mainly" may include impurities and the like that are included when the particles are produced. The structure of the particles differs depending on the method of manufacturing the surface coating layer 3 . The detailed configuration will be described later for convenience of explanation.
[0065]
The group A element in the surface coating layer 3 is contained in the following aspects i to v.
i: A mode of particles mainly composed of one simple substance of the A group element.
ii: A mode of particles mainly composed of one simple substance of the group A element and particles mainly composed of another single substance of the group A element.
iii: A mode of particles mainly composed of one type of compounds of group A elements.
iv: A mode of particles mainly composed of one compound of the group A element and particles mainly composed of another compound of the group A element.
v: Modes of particles (one or more types) mainly composed of simple substances of group A elements and particles (one or more types) mainly composed of compounds of group A elements.
[0066]
When the surface coating layer 3 is a coating film, the "particles" in the surface coating layer 3 exist as particles mainly composed of simple substances of group A elements and/or particles mainly composed of compounds of group A elements. Such a surface coating layer 3 is produced by, for example, applying a paint obtained by mixing the above-described particles to an organic binder on the plating layer 2 and drying the applied coating film by heating as necessary. . There is no particular need to limit the organic binder, and known organic binders and the like can be used.
[0067]
When the surface coating layer 3 is manufactured by powder baking, the "particles" in the surface coating layer 3 indicate powder particles. Such a surface film layer 3 is produced by, for example, coating and baking a paint obtained by mixing the above-described powder particles in an organic binder on the plating layer 2 .
[0068]
In the case where the surface coating layer 3 contains particles mainly composed of elemental elements and/or compounds of group A elements, after hot stamping, the surface coating layer 3 reacts with moisture or oxygen at the interface between the surface coating layer 3 and the atmosphere. An oxide of the group A element is formed in the . In the case of elements that can have a plurality of types of stable valences of +1 or more (for example, +3 and +6 valences), such as A group elements, electron bias (polarity) in the oxide becomes high. If a component of the chemical conversion treatment solution having a relatively high polarity, such as zinc phosphate, is deposited on the surface coating layer 3, the interaction between the oxide and the zinc phosphate is strengthened, resulting in a chemical conversion treatment. improve sexuality. In addition, if the chemical treatability is improved,Adhesion between the post-treatment coating and the electrodeposition coating increases, and the corrosion resistance after coating improves. Elements and compounds of group A elements are also expected to have the effect of improving post-coating corrosion resistance by dissolving in water or salt water, which is a corrosion accelerating factor, to form a sparingly soluble compound in a corrosive environment.
[0069]
In the surface coating layer 3, the simple substance of the group A element and/or the compound exists in the state of particles mainly composed of these elements, so the surface coating layer 3 does not contain the particles of the simple substance of the group A element and/or the compound. , the surface area of the surface coating layer 3 is increased. When the surface area of the surface coating layer 3 increases, the time required for heating during hot stamping increases. In addition, since the surface coating layer 3 with a large surface area contains the A group element, compared to the surface coating layer with a small surface area (the above-mentioned particles do not exist), the distance to the atmosphere where moisture or oxygen is present is close. The amount of group elements increases. This makes it easier for the A group element to concentrate on the surface of the surface coating layer 3 after hot stamping. Then, zinc phosphate is likely to adhere to the surface of the surface film layer 3 during chemical conversion treatment after hot stamping, for example, phosphoric acid treatment, thereby improving chemical conversion treatability. This improves the adhesion of the plated steel sheet 10 for hot stamping after coating.
[0070]
The total content of group A elements per 1 m 2 of the surface coating layer 3 according to the present embodiment is 0.01 to 10.0 g as the total content of each group A element per 1 m 2 of the surface coating layer 3. /m2. The total content of each A group element means the total mass of all types of A group elements contained per 1 m 2 of the surface coating layer 3 .
[0071]
For example, when the surface coating layer 3 contains particles containing only Sc as a group A element, the content of the group A element is calculated as follows. When the surface coating layer 3 contains particles mainly composed of an element of Sc, which is a Group A element, or when the surface coating layer 3 contains particles mainly composed of scandium chloride, which is a compound of Sc which is a Group A element, In any case, the content of the group A element per 1 m 2 of the surface coating layer 3 is the content of Sc per 1 m 2 of the surface coating layer 3 . In addition, the above-mentioned "consisting mainly of" means that impurities other than the group A elements, which are mixed during the production of the particles, may be contained. For this reason, "particles mainly composed of simple substance of Sc" refer to particles composed of simple substance of Sc and impurities containing no group A element. In the above example, the case where the surface coating layer 3 contains particles containing only Sc as a group A element was exemplified, but when these particles also contain other group A elements, each A group in the surface coating layer 3 The weight of the element contained per 1 m 2 is calculated, and the sum of the weights is defined as the content of the group A element in the surface coating layer 3 per 1 m 2 .
[0072]
For example, when the surface coating layer 3 contains particles containing Sc and particles containing V as group A elements, the content of the group A elements per 1 m 2 of the surface coating layer 3 is calculated as follows. When the surface coating layer 3 contains particles mainly composed of a simple substance of Sc, which is a group A element, and particles mainly composed of vanadium chloride, which is a compound of V which is a group A element, 1 m 2 of the surface coating layer 3 The content of the group A element per 1 m 2 of the surface coating layer 3 is the total amount of Sc and V contained per 1 m 2 .
[0073]
If the total content of group A elements in the surface coating layer 3 is less than 0.01 g/m 2 , a sufficient amount of oxides of group A elements will not be formed on the surface of the surface coating layer 3 after hot stamping. Insufficient chemical convertibility. Therefore, when the total content of the group A elements in the surface coating layer 3 is less than 0.01 g/m 2 , even if the plated steel sheet 10 is subjected to chemical conversion treatment, the surface of the surface coating layer 3 is subjected to a sufficient amount of chemical conversion treatment. No treated film is formed. As a result, the electrodeposition coating film cannot maintain sufficient adhesion to the chemical conversion coating film 3, resulting in inferior corrosion resistance after coating. Therefore, the total content of group A elements in the surface coating layer 3 is set to 0.01 g/m 2 or more from the viewpoint of maintaining chemical conversion treatability, but from the viewpoint of improving corrosion resistance after painting, it is set to 0.1 g/m 2 or more. , 0.2 g/m 2 or more, or 0.4 g/m 2 or more.
[0074]
On the other hand, if the total content of group A elements in the surface coating layer 3 exceeds 10.0 g/m 2 , the post-coating corrosion resistance will be saturated, causing an increase in cost. Therefore, the total content of group A elements in the surface coating layer 3 of the present embodiment is set to 10.0 g/m 2 or less. Considering the added amount and effect of the group A elements, the total content is 6.0 g/m 2 or less, 3.0 g/m 2 or less, or 2.0 g/m 2 or less from the viewpoint of cost effectiveness. is preferred.
[0075]
The average particle size of the particles containing the group A element in the surface coating layer 3 according to this embodiment is 0.05 to 3.0 μm. When the average particle size of the particles containing the A group element is within the above range, the chemical conversion treatability can be improved while the corrosion resistance of the surface coating layer 3 is maintained.
[0076]
If the average particle diameter of the particles containing the group A element is more than 3.0 μm, the surface area per volume of the particles mainly composed of simple substance of the group A element and/or the particles mainly composed of the compound of the group A element is small. , the surface area of the surface layer 3 becomes insufficient. As a result, the amount of oxides of group A elements formed on the surface of the surface coating layer 3 after hot stamping becomes insufficient, and the chemical conversion treatability of the plated steel sheet 10 is not improved. As a result, the desired corrosion resistance after painting cannot be obtained. From the viewpoint of improving the chemical conversion treatability by increasing the surface area of the surface coating layer 3, the average particle diameter of the particles containing the group A element is 2.0 μm or less, 1.5 μm or less, 1.1 μm or less, or 0.7 μm or less. is preferred, and 0.5 μm or less is particularly preferred. On the other hand, when the average particle diameter is less than 0.05 μm, the surface area of the particles mainly composed of simple substance of group A element and/or particles mainly composed of compound of group A element becomes too large, and they are exposed to corrosive environment. It becomes an intrusion route for water and salt in Therefore, the desired corrosion resistance after painting cannot be obtained. Therefore, the average particle size of the particles containing the A group element is set to 0.05 μm or more. If necessary, it may be 0.07 μm or more, 0.1 μm or more, or 0.2 μm or more.
[0077]
Among the A group elements, Sc, Mn, Fe, Co, Nb, Mo and W are particularly excellent in corrosion resistance after painting. Although the mechanism is not clear in detail, these elements not only have the effect of improving the chemical conversion treatability, but also adsorb to the plating layer 2 when dissolved in water, which is a corrosive factor, in a corrosive environment. It is presumed that this is due to the excellent corrosion suppression effect of preventing the reactions of the above-described formulas (1) to (3) from occurring. Therefore, only Sc, Mn, Fe, Co, Nb and W may be used as group A elements. If necessary, only specific elements among these elements may be used as group A elements.
[0078]
Examples of compounds of group A elements include oxides, chlorides, sulfides, fluorides, hydroxides, carbides, nitrides, and the like. Specifically, scandium oxide, scandium bromide, scandium chloride, scandium fluoride, scandium hydroxide, silicon carbide, titanium chloride, barium titanate, vanadyl acetylacetonate, vanadium acetylacetonate, vanadyl acetate, vanadyl sulfate, Vanadium oxide, vanadium trioxide, vanadium dioxide, ammonium metavanadate, sodium metavanadate, potassium metavanadate, potassium permanganate, ammonium permanganate, iron oxide, iron nitrate, iron sulfate, iron hydroxide, cobalt chloride, cobalt acetate , cobalt oxide, cerium oxide, cerium chloride, cerium nitrate, cerium sulfate, cerium acetate, cerium oxalate, cerium hydroxide, niobium oxide, potassium niobate, lithium niobate, niobium nitride, molybdenum oxide, ammonium molybdate, molybdic acid Examples thereof include potassium, tungsten oxide, ammonium tungstate, potassium tungstate, tungsten sulfide, and hydrates of the above compounds, but are not limited to these.
[0079]
Since oxygen is preferably contained in the surface coating layer 3, it is preferable that at least a portion of the particles containing the A group element contain oxygen atoms (O). When the particles containing a group A element in the surface coating layer 3 contain oxygen atoms, that is, when the surface coating layer 3 contains particles mainly composed of oxides of group A elements, the chemical conversion treatability of the plated steel sheet 10 is reduced. Get even better. In the present embodiment, the expression that at least a portion of the particles containing the group A element contains oxygen means that 30% or more of the particles containing the group A element in the surface coating layer 3 contain 30% or more of the group A element. It indicates that the particles contain oxygen atoms.
[0080]
Although there are unclear points about the detailed mechanism by which the chemical conversion treatability is further improved when at least part of the particles containing the A group element contain oxygen atoms, the present inventors have found the following: I'm guessing.
[0081]
Particles mainly composed of compounds (oxides) of group A elements contain oxygen atoms with relatively high electronegativity, so that the electron bias in the compounds in the particles becomes higher (the polarity becomes higher). . When the electron bias in the compound in the particle becomes higher, the affinity between the main component in the chemical conversion solution and the similarly highly polar component, such as zinc phosphate, and the compound of the group A element increases, so that the chemical conversion treatment improve sexuality. In addition, the effect of improving the adhesion of the coating film is also expected due to the improvement of the chemical conversion treatability. Furthermore, when at least a portion of the particles containing the group A element contains oxygen atoms, the particles exhibit basicity when the oxygen atoms dissolve in the chemical conversion treatment solution. As a result, the pH of the chemical conversion treatment liquid near the surface of the surface coating layer 3 rises, promoting the deposition of components such as zinc phosphate on the surface of the surface coating layer 3 . As a result, the effect of improving the chemical conversion treatability of the surface coating layer 3 is exhibited. Further, when the particles containing the group A element contain atoms other than oxygen such as sulfur and nitrogen, if the atoms other than oxygen are oxidized by heating during hot stamping, volatile gas is generated and the equipment is damaged. Contamination and deterioration of the working environment are feared. However, when the particles containing the group A element contain oxygen atoms, the amount of gas volatilized by heating during hot stamping is extremely small.
[0082]
The surface coating layer 3 according to the present embodiment contains, in addition to particles mainly composed of the above-mentioned group A elements and/or compounds, one or more group B elements consisting of Zn, Zr and Ti. By containing the particles, the post-coating corrosion resistance after hot stamping can be further improved. This is because the B group element exhibits a barrier function against corrosive factors such as water, oxygen, and salt when the member after hot stamping is exposed to a corrosive environment, and becomes resistant to corrosion. It is from In this embodiment, the particles containing the group B element are present in the surface coating layer 3 in a state in which the compound of the group B element is the main component.
[0083]
In the surface coating layer 3 according to this embodiment, the total content of group B elements consisting of Zn, Zr and Ti is preferably 0.01 to 10.0 g/m 2 . The total content of the B group elements means the total mass of all types of B group elements contained per 1 m 2 of the surface coating layer 3 .
[0084]
For example, when the surface coating layer 3 contains particles containing only Zn as the B group element, the total content of the B group elements is calculated as follows. When the surface coating layer 3 contains particles mainly composed of zinc oxide, which is a compound of Zn, which is a group B element, the total content of the B group elements in the surface coating layer 3 is the content of Zn in the surface coating layer 3. quantity.
[0085]
When the surface coating layer 3 contains particles containing Zn and particles containing Zr as group B elements, the total content of the group B elements in the surface coating layer 3 is calculated as follows. When the surface coating layer 3 contains particles mainly composed of zinc oxide, which is a compound of Zn, which is a group B element, and particles mainly composed of ammonium zirconium carbonate, which is a compound of Zr which is a group B element, the group B element is the sum of the Zn content and the Zr content in the surface coating layer 3 .
[0086]
By setting the total content of the B group elements within the above range, the post-coating corrosion resistance after hot stamping can be further improved. The lower limit of the total content of the B group elements is more preferably0.03 g/m 2 , 0.05 g/m 2 or 0.1 g/m 2 , more preferably 0.2 g/m 2 . The upper limit of the total content of group B elements is more preferably 3.0 g/m 2 , 2.0 g/m 2 or 1.0 g/m 2 , still more preferably 0.8 g/m 2 or 0.8 g/m 2 . 7 g/m2.
[0087]
Compounds of group B elements (Zn, Zr, Ti) include oxides, bromides, chlorides, sulfides, fluorides, hydroxides, carbides and nitrides. Specifically, zinc oxide, zinc chloride, zinc sulfide, zinc fluoride, zinc phosphate, zinc dizinc hydrogen phosphate, zirconium oxide, zirconium fluoride, ammonium hexafluorozirconate (ammonium hexafluorozirconate) ), ammonium zirconium carbonate, titanium oxide, fluorotitanic acid, ammonium hexafluorotitanate, etc., but not limited to these.
[0088]
In the case of containing particles mainly composed of a group A element alone and/or particles mainly composed of a group A element compound and particles mainly composed of a group B element compound, the surface coating layer 3 has the form of a coating. A film or a powder-coated film (powder-baked layer) is typical, but the present invention is not limited to these forms.
[0089]
When the surface coating layer 3 containing a group B element is a coating film, the surface coating layer 3 is a coating containing particles mainly composed of a group A element and/or a compound and particles mainly composed of a compound of a group B element. membrane. This coating film may contain an organic binder in addition to particles mainly composed of a group A element and/or compound and particles mainly composed of a compound of a group B element.
[0090]
When the surface coating layer 3 is a powder baked layer, the surface coating layer 3 is a powder baked layer containing particles mainly composed of a group A element and/or compound and particles mainly composed of a group B element compound. is. Also in this case, the powder baking layer may contain an organic binder.
[0091]
Although the film thickness of the surface film layer 3 according to this embodiment is not particularly limited, it is preferably 0.1 to 2.5 μm. The lower limit of the film thickness may be 0.3 μm, 0.5 μm or 0.8 μm, and the upper limit thereof may be 2.2 μm, 1.8 μm or 1.5 μm.
[0092]
(Method for analyzing surface film layer 3)
When the surface coating layer 3 is a coating film or a baked powder layer, the A group element (or the A group element and B group element) content (total amount of each element) can be measured. Specifically, the intensity of the off-line fluorescent X-ray method is measured within a field of view with a diameter of 30 mm. Next, the mass of each A group element and/or each B group element contained per 1 m 2 is calculated using the intensity and the previously prepared calibration curve for each A group element and/or each B group element. By totaling the mass of each A group element and/or each B group element, the content of the A group element and/or the B group element per 1 m 2 of the surface coating layer 3 can be obtained.
[0093]
The average particle size of the particles mainly composed of a single substance and/or compound of the A group element in the surface coating layer 3 is measured by the following method.
A sample with a size of 20 mm x 20 mm is cut out from a portion at least 10 mm away from the end of the plated steel sheet 10 in the width direction, specifically at a point at a distance of, for example, 15 mm, and the surface of the sample is used as an observation surface. Using a field emission scanning electron microscope (FE-SEM), five or more observation fields of 100 μm×100 μm are observed at an accelerating voltage of 15 kV and a magnification of 10000 times. By analyzing the particles in the observation field using an external energy dispersive analyzer (EDX), it is determined whether the particles are mainly composed of simple substance/compounds of group A elements. . Using the observation photograph of the above observation field, the particle diameter of the particles mainly composed of a simple substance and / or compound of the group A element is determined by the cutting method with a circular test line described in Annex C of JIS G 0551: 2013. Ask. By calculating the average particle size of all the particles mainly composed of the simple substance and/or compound of the group A element in the observation photograph, the particles mainly composed of the simple substance and/or compound of the group A element in the surface coating layer 3 to obtain an average particle size of
[0094]
In the present embodiment, the particles containing the group A element in the surface coating layer 3 (particles mainly composed of a simple substance and/or compound of the group A element) are particles generated by the growth of a single crystal nucleus. There are cases where they exist as primary particles, and there are cases where primary particles aggregate and exist as secondary particles. Therefore, the average particle size of the particles containing the A group element in the present embodiment is obtained by measuring the particle size (primary particle size) of one particle when it exists only as primary particles, and two particles when it exists as secondary particles. It is obtained by measuring the particle size of secondary particles (secondary particle size).
[0095]
In a 100 μm × 100 μm observation field of view of a cross-sectional image taken with a scanning electron microscope image, the average value of the major axis and minor axis of each particle (particles mainly composed of simple substance / or compound of group A element) in the field of view The average particle size is determined by calculating for the particles and calculating their average value.
Primary particles and secondary particles can be distinguished, for example, from a scanning electron microscope image by judging the presence or absence of a boundary (difference in brightness) in the particles, or by measuring an electron diffraction image by a transmission electron microscope. If they have the same crystal orientation, they can be regarded as primary particles, and if they differ, they can be regarded as different primary particles.
[0096]
(hot stamping member)
A hot-stamped member having a tensile strength of about 1000 MPa or more can be obtained by subjecting the plated steel sheet 10 for hot stamping described above to heating and quenching by a hot stamping method. In addition, in the hot stamping method, press working can be performed in a state of being softened at a high temperature, so that molding can be easily performed.
[0097]
Since the plated steel sheet 10 for hot stamping according to the present embodiment contains a group A element in the surface coating layer 3 on the outermost layer side, after hot stamping, at the interface between the surface coating layer 3 and the atmosphere, moisture or oxygen An oxide film layer containing the group A element is formed on the surface film layer 3 by the reaction with . This oxide film layer contains one or more elements selected from group A elements consisting of Sc, V, Mn, Fe, Co, Ce, Nb, Mo and W, Al, and oxygen. That is, the hot stamping member according to the present embodiment has, on the surface, one or more elements selected from group A elements consisting of Sc, V, Mn, Fe, Co, Ce, Nb, Mo and W, and Al and oxygen. In the manufacturing process of automobiles, a hot stamping member has a chemical conversion treatment film represented by a zinc phosphate film on the member surface (on the surface film layer 3), an electrodeposition coating on the upper layer, and in some cases, a further upper layer. A coating film is laminated on the surface. In the group A element, the bias (polarity) of electrons in the oxide is high. If a component of the chemical conversion treatment solution having a relatively high polarity, such as zinc phosphate, is deposited on the surface coating layer 3, the interaction between the oxide and the zinc phosphate is strengthened, resulting in a chemical conversion treatment. improve sexuality. In addition, when the chemical conversion treatability increases, the adhesion between the chemical conversion coating and the electrodeposition coating increases, and the corrosion resistance after coating improves. Elements and compounds of group A elements are also expected to have the effect of improving post-coating corrosion resistance by dissolving in water or salt water, which is a corrosion accelerating factor, to form a sparingly soluble compound in a corrosive environment.
[0098]
(Manufacturing method of plated steel sheet 10 for hot stamping)
A method for manufacturing the plated steel sheet 10 according to this embodiment will be described below.
Using a steel sheet 1 having a predetermined chemical composition, a plating layer 2 is formed on one side or both sides of the steel sheet 1 by, for example, a hot dip plating method. The plating bath temperature should be 550 to 700°C.
[0099]
Particles are sprayed onto the surface of the plating layer 2 immediately after plating is applied to one or both sides of the steel sheet 1 by the above method. By spraying the particles before the plating layer 2 solidifies, the growth of metal crystals in the plating layer is inhibited, and the grain size of the metal crystal particles in the plating layer 2 can be reduced. When the surface film layer 3 is formed on the plating layer 2 by reducing the particle size of the metal crystal grains in the plating layer 2 in this way, the plating layer is affected by the size of the crystal grains of the plating layer 2. The crystal grains of the surface coating layer 3 at the interface with 2 become smaller. As a result, the growth of the crystal grains of the surface coating layer 3 formed on the interface is also inhibited, and along with this, the grain size of the particles (elementary substance and/or compound of the group A element) in the surface coating layer 3 can be reduced. and the surface area of the surface coating layer 3 can be increased. When the surface area of the surface film layer 3 is increased, the chemical conversion treatability is improved during the chemical conversion treatment after hot stamping, and the adhesion after painting is improved.
[0100]
Particles are sprayed onto the surface of the plating layer 2 using metal oxides with an average particle size of 20 μm or less (titanium oxide, magnesium oxide, vanadium oxide, chromium oxide, manganese oxide, cobalt oxide, nickel oxide, copper oxide, zirconium oxide, silicon dioxide , zinc oxide, iron oxide, and aluminum oxide) are preferably sprayed together with a cooling gas at a speed of 30 to 70 m/s. The sprayed particles have the effect of nucleating crystals and simultaneously cooling the molten plated metal. By controlling the average crystal grain size in the plating layer to be small, the number of crystal grain boundaries can be increased. As a result, the number of grain boundaries increases even after hot stamping, and the surface oxide film layer also becomes uneven, so that physical and chemical bonding with the electrodeposition coating film after chemical conversion treatment is strengthened. guessed. If the particle blowing speed is less than 30 m/s, the number of crystal nuclei is reduced. As a result, the crystal grain size becomes large even after hot stamping, and the physical and chemical bonding with the electrodeposition coating film cannot be ensured, resulting in poor paint adhesion and post-paint corrosion resistance. On the other hand, if the particle spraying speed is more than 70 m/s, the number of crystals becomes too large due to the particle spraying, and the crystals become too small. Even if it is added, the rate of dissolution in the corrosion test solution becomes relatively fast, so the paint adhesion and corrosion resistance after painting are poor. In order to uniformly spray the particles onto the surface of the plating layer 2, it is desirable to use a spray nozzle, but the method is not limited to this.
[0101]
Instead of hot dip plating, Al and A group elements are deposited on the surface of the steel sheet 1 by vapor deposition or thermal spraying to form an Al coating layer containing the A group elements, and the steel sheet having this Al coating layer is hot stamped. By doing so, the hot stamped member according to the present embodiment may be manufactured.
[0102]
Also, as an example of the method of forming the Al coating layer, Al may be first deposited on the steel plate 1 by vapor deposition or thermal spraying, and then the Group A element may be deposited. As a result, an Al covering layer composed of the Al layer and the A group element is formed.
[0103]
Further, as another example of the method of forming the Al coating layer, vapor deposition or thermal spraying is performed using a vapor deposition source or thermal spray source containing an A group element, and Al and the A group element are simultaneously attached to the steel plate 1. good too. The proportion of the group A element in the Al coating layer is preferably 0.001% to 30% by mass.
[0104]
After that, as in the case of the plated steel sheet 10 for hot stamping, hot stamping is applied to the steel sheet having the Al coating layer, whereby a hot stamped member can be manufactured from the plated steel sheet for hot stamping.
[0105]
The method for forming the surface film layer 3 is not particularly limited, but the surface film layer 3 can be formed, for example, by the following method.
・Apply a solution or suspension containing particles mainly composed of a group A element element and/or compound (or, in addition, particles mainly composed of a compound of a group B element) to the surface of the plating layer 2. and a method of forming a surface film layer 3 as a coating film by performing a drying treatment as necessary. Here, the solution or suspension preferably contains an organic binder.
On the steel sheet 1 on which the plating layer 2 is formed, powder of particles mainly composed of a single substance and / or compound of a group A element (or, in addition, particles mainly composed of a compound of a group B element) is used to obtain a powder A method of forming the surface film layer 3 as a powder baking layer by painting.
[0106]A solution or suspension containing particles mainly composed of elemental elements and/or compounds of group elements (or, in addition, particles mainly composed of compounds of group B elements) contains, if necessary, a predetermined organic Binders may be mixed. Examples of organic binders include polyurethane-based resins, polyester-based resins, acrylic-based resins, silane coupling agents, and the like. Most of these organic binders disappear during the hot stamp heating process.
[0107]
(Manufacturing method of hot stamping member)
Hot stamping is performed on the plated steel sheet 10 for hot stamping manufactured as described above. In the hot stamping method, after blanking (punching) the hot stamping plated steel sheet 10 as necessary, the hot stamping plated steel sheet 10 is heated and softened. Then, the softened plated steel sheet for hot stamping 10 is press-formed and then cooled (quenched). A hot-stamped member that has been heated and quenched has a high tensile strength of about 1000 MPa or more. As a heating method, infrared heating or the like can be employed in addition to a normal electric furnace or radiant tube furnace.
[0108]
The heating temperature and heating time during hot stamping are preferably 850 to 950°C for 2 minutes or more in the case of an air atmosphere. If the heating time is less than 2 minutes, the tensile strength of the hot stamped part will not be high enough.
[0109]
Although it is not necessary to limit the upper limit of the heating time, it is preferably 10 minutes or less. This is because if the time is longer than 10 minutes, the productivity is lowered, which is economically disadvantageous.
[0110]
By controlling the average crystal grain size in the plating layer to be small, it is possible to increase the number of crystal grain boundaries. As a result, the number of grain boundaries increases even after hot stamping, and the upper layer film also has many grain boundaries or irregularities, so that physical and chemical bonding with the electrodeposition coating film after chemical conversion treatment is strengthened. guessed.
Example
[0111]
Examples of the present invention will be described below, but the conditions in the examples are merely examples adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to these example conditions. do not have. Various conditions can be adopted in the present invention as long as the objects of the present invention are achieved without departing from the gist of the present invention.
[0112]
Table 1 shows the chemical composition of the steel plate used for the hot stamping steel plate of this example.
[0113]
[table 1]

[0114]
A plating layer was formed on one or both sides of the steel sheet shown in Table 1 by hot dip plating. The temperature of the plating bath during hot-dip plating is 550 to 700° C. After the steel sheet is immersed in the plating bath, a metal oxide (aluminum oxide) having an average particle size of 1 to 10 μm is applied to the surface of the plating layer using a spray nozzle. was sprayed under the conditions shown in Tables 2-1 to 3-7. However, for the symbols a1, a4 and a5 in Table 2-3, no spraying was performed. Regarding the spraying, the examples in which the spraying was performed are described as "yes", and the examples in which the spraying was not performed are described as "no".
[0115]
After that, the plating amount was adjusted by the gas wiping method so that the plating amount was 80 g/m 2 per side. At this time, the thickness of the plating layer was as shown in Tables 2-1 to 3-7. Furthermore, as shown in Tables 2-1 to 3-8, a surface coating layer containing particles mainly composed of a single substance of a group A element and / or a compound, or a surface coating layer not containing these, and a single substance of a group A element And/or a plated steel sheet was obtained by forming a surface film layer containing particles mainly composed of a compound and particles mainly composed of a compound of a group B element on the coating layer. In some cases, the composition of the plating layer was changed.
[0116]
Examples containing particles mainly composed of simple substance of group A element (codes A1 to A7) were applied with a roll coater with a paint prepared by dispersing or dissolving particles mainly composed of simple substance of group A element and an organic binder in water. After that, the surface film layer was formed by drying at a final plate temperature of 80°C.
[0117]
Examples including particles mainly composed of compounds of group A elements, or particles mainly composed of compounds of group A elements and particles mainly composed of compounds of group B elements (codes A8 to A51, codes a4, a6, a8 and a10 ~ 12, symbols B1 ~ B85), a compound such as chlorides and oxides of group A elements and an organic binder dispersed or dissolved in water are applied with a roll coater and then dried at a final plate temperature of 80 ° C. Thus, a surface film layer was formed.
[0118]
Examples containing particles mainly composed of simple substances of group A elements and particles composed mainly of compounds of group B elements (codes B86 to B112) are particles mainly composed of simple substances of group A elements and chlorides of group B elements, A surface film layer was formed by applying a paint prepared by dispersing or dissolving a compound such as an oxide and an organic binder in water with a roll coater and then drying at a final plate temperature of 80°C.
[0119]
Examples (references a1 to a3, a7 and a9) containing no particles containing group A elements were coated with a paint prepared by dispersing or dissolving aluminum oxide and an organic binder in water with a roll coater, and then at a final plate temperature of 80 ° C. A surface coating layer was formed by drying. Symbols A52 and A53 in Table 2-2 are a surface coating layer by spraying a paint mixed with particles containing a group A element and powder particles containing an organic binder onto the plating layer and then heating it to 200 ° C. formed.
[0120]
In Tables 2-1 to 2-2, symbols A1 to A7 are invention examples in which surface coating layers containing particles mainly composed of simple substances of group A elements are formed, and symbols A8 to A15 are compounds of group A elements. This is an invention example in which the particles form a surface coating layer that does not contain oxygen, and symbols A16 to A47 are particles mainly composed of compounds containing A group elements and oxygen, and the surface coating layer and symbols A48 to A51 are invention examples in which a surface coating layer containing two or more kinds of particles (particles mainly composed of simple substances and/or compounds) mainly composed of group A elements is formed. . Reference numerals A52 and A53 are invention examples in which a surface coating layer containing powder particles containing an organic binder and molybdenum oxide or tungsten oxide is formed.
[0121]
In the examples (codes A48 to A51) in which a surface coating layer containing two or more kinds of particles mainly composed of a single substance and/or a compound of a group A element is formed, each single substance or each compound has (1), ( 2) Numbers of .
[0122]
Codes a1 to a3, a7 and a9 in Table 2-3 are comparative examples in which a surface coating layer containing no particles mainly composed of a simple substance and/or compound of a group A element is formed, and codes a4, a11 and a12 are , Comparative examples in which the content of group A elements (total amount in terms of elements) was insufficient, symbol a5 is a comparative example in which no surface coating layer was laminated, symbols a6 and a8, the thickness of the plating layer was small. Reference a10 is a comparative example in which the average crystal grain size in the plating layer was large.
[0123]
The symbols B1 to B112 in Tables 3-1 to 3-8 are particles mainly composed of simple substances and / or compounds of group A elements, and particles mainly composed of compounds of group B elements. It is an example of an invention formed. In the examples containing two or more types of particles mainly composed of compounds of group B elements (codes B41 to B85 and B95 to B112), each compound is numbered (1), (2), and so on. The elements constituting the compounds of are described in the table.
References C1 to C24 in Table 4 are invention examples with different plating compositions.
[0124]
The analysis results of the plated steel sheets listed in Tables 2-1 to 4 were obtained by the following methods.
[0125]
(Method for analyzing surface film layer)
The content (total amount in terms of elements) of group A elements (or group A elements and group B elements) in the surface coating layer was measured by the offline fluorescent X-ray method described in JIS G 3314:2011 Annex JB. First, the relationship between the known fluorescent X-ray intensity of the oxide film and its content was prepared in advance as a calibration curve. Since the fluorescent X-ray intensity and the content correspond one-to-one in this calibration curve, the content can be specified when the fluorescent X-ray intensity is determined. Next, the intensity of fluorescent X-rays emitted from a group A element and/or a group B element emitted when a sample having a diameter of 30 mm was irradiated with X-rays was measured. From the calibration curve described above, by calculating the content corresponding to the intensity of this fluorescent X-ray, the content (g / m 2) of each A group element and / or each B group element is calculated, and each A group The content of the group A element and/or the group B element was obtained by calculating the total amount of the element and/or the content (g/m 2 ) of each group B element. The contents of group A elements (or group A elements and group B elements) thus obtained are shown in the table. In addition, when 30% or more of the particles containing the group A element in the surface coating layer contained oxygen atoms, it was described as "present" in the column "contains oxygen atoms".
[0126]
A sample with a size of 20 mm x 20 mm was cut from a portion 10 mm or more away from the edge of the plated steel sheet 10, and the surface of the sample was used as an observation surface. Using a field emission scanning electron microscope (FE-SEM), five fields of observation of 100 μm×100 μm were observed. Using an energy dispersive analyzer (EDX) externally attached to the FE-SEM, the particles in the observation field are analyzed to determine whether the particles are mainly composed of a group A element element / or compound. judged. Elements mainly composed of the particles are described in the column of "Elements" in the table. In addition, if the element that is the main component of the particle is contained in the form of a simple substance, enter "elementary substance" in the column of "elementary substance or compound" in the table, and if the element is contained in the state of a compound, The type of compound is described in the column.
[0127]
In a 100 μm × 1005 μm observation field of view of a cross-sectional image taken with a scanning electron microscope image, the average value of the major axis and minor axis of each particle (particles mainly composed of simple substance / or compound of group A element) in the field of view By calculating the average value of the particles, the average particle size of the particles mainly composed of the element of group A element and/or the compound in the surface coating layer was obtained. The table shows the average particle size of the obtained particles mainly composed of the elemental element and/or the compound of the A group element.
Primary particles and secondary particles were determined from the presence or absence of boundaries (differences in brightness) in the particles from scanning electron microscope images.
[0128]
(Method for analyzing plating layer)
The surface film layer on the plating layer was removed by polishing. The components of the plating layer exposed on the surface were analyzed by the off-line fluorescent X-ray method described in Annex JB of JIS G 3314:2011. The components (plating composition) of the obtained plating layer are shown in the table. The rest of the chemical composition of the plating layer was less than 0.5% impurities. For example, in the table, the chemical component (plating composition) of the plating layer is described as "Al-10%Si", the plating layer contains Al, 10% Si, and less than 0.5% It shows that it consists of impurities.
[0129]
(Method for measuring thickness t of plating layer)
The thickness t of the plating layer was measured by quantitatively analyzing the cross section with an FE-EPMA (Field Emission Electron Probe Microanalyzer). A sample having a size of 10 mm×10 mm was cut from a portion of the plated steel sheet 10 at a distance of 15 mm in the width direction. The embedded polished sample was obtained by embedding the sample in resin and polishing. After carbon was vapor-deposited on the embedding sample so as to facilitate electric conduction, the content of each element was quantitatively analyzed by point analysis using an FE-EPMA magnification at an acceleration voltage of 10 kV and a magnification of 1500 times or more. The point at which the Al content in the total of the elements excluding carbon by mass is 30% by mass is defined as the plating layer. A point analysis is performed every 1 μm perpendicular to the steel sheet from the plated surface toward the center of the plate thickness, and points where the Al content is less than 30% by mass are judged not to be the plated layer. A set of points having an Al content of 30% by mass or more was defined as a plating layer, and the thickness t of the plating layer was measured. The thickness t of the obtained plating layer is described in the column of "plating thickness" in the table.
[0130]
(Method for measuring average grain size of plating layer)
A sample was taken from the plated steel sheet for hot stamping so that the cross section in the thickness direction of the plating layer was the observation surface. The collected sample was diluted with 3% nitric acidCrystal grain boundaries were revealed by etching with a alcohol solution (nital solution), and an image was taken using a scanning electron microscope (SEM) so that the top surface of the plating layer to the steel sheet were included. At this time, by EDX (energy dispersive X-ray analysis), a layer having an Al content of 60% by mass or more was determined to be a plating layer. For this photograph, as shown in FIG. 2, a line segment having a length of 2t/3 (t=thickness of the plating layer (μm)) in the thickness direction from the interface between the plating layer 2 and the surface film layer (not shown) is drawn. The number of intersections with grain boundaries was taken as n, and the value obtained by dividing the line segment length (2t/3) by n, ie, (2t/3n), was taken as the average crystal grain size. Three such line segments are drawn at arbitrary positions at intervals of 5 μm, such as (a), (b), and (c) in FIG. was taken as the average crystal grain size of the plating layer in the thickness range from the interface between the plating layer and the surface film layer to the position 2/3 times the thickness t (2t/3 position).
[0131]
When n is 0, 2t/3n cannot be calculated. However, when n is 0, the grain size is larger than 2t/3 in the observed image, so it was determined that the average crystal grain size is not 2t/3 or less.
Also, in calculating the number n of intersections, JIS G 0551:2013 Appendix C. When a line segment intersects a triple point, as described in 2.2, n was taken as 1.5 at that point.
[0132]
After heating the plated steel sheets listed in Tables 2-1 to 4 at 940°C for 6 minutes, they were molded in a mold and simultaneously cooled in the mold to obtain hot stamped members. Heating was performed in a moist atmosphere with a dew point of 40°C.
The obtained hot-stamped members were examined and evaluated for chemical conversion treatability and post-coating corrosion resistance by the following methods. In addition, the hot stamping member of the example has, on the surface, one or more elements selected from group A elements consisting of Sc, V, Mn, Fe, Co, Ce, Nb, Mo and W, Al, It had an oxide film layer containing oxygen.
[0133]
(1) Chemical convertibility
The hot-stamped member was cut into 150 mm x 70 mm pieces, and the test pieces were chemically treated with a chemical treatment solution (PB-SX35) manufactured by Nihon Parkerizing Co., Ltd., and then the zinc phosphate content was measured using a fluorescent X-ray analyzer. The chemical conversion treatability was evaluated according to the following grades X1 to X4 according to the zinc phosphate content obtained by measurement. When the chemical conversion treatability score was X1, X2, or X3, it was judged as being excellent in chemical conversion treatability and judged to be acceptable. A sample with a chemical conversion treatability score of X4 was determined to be unacceptable because the chemical conversion treatability was poor.
[0134]
[Chemical conversion treatability score based on zinc phosphate content]
　X1: 0.7 g/m2 or more
X2: 0.3 g/m 2 or more and less than 0.7 g/m 2
X3: 0.1 g/m 2 or more and less than 0.3 g/m 2
　X4: less than 0.1 g/m2
[0135]
(2) Corrosion resistance after painting
Cut the hot stamp member into 150 mm × 70 mm, and after chemically treating the test piece with a chemical conversion treatment liquid (PB-SX35) manufactured by Nippon Parkerizing Co., Ltd., apply an electrodeposition paint (Powernics 110) manufactured by Nippon Paint Co., Ltd. The coating was applied to a film thickness of 20 µm and baked at 170°C. The post-coating corrosion resistance of the test piece was examined according to the method specified in Japanese Industrial Standards JIS H 8502. Specifically, each sample was subjected to phosphate conversion treatment and cationic electrodeposition coating (thickness 20 microns), then the coating film was scratched with a cutter, sprayed with 5% salt water for 2 hours, dried for 4 hours, and dried. After 180 cycles of the corrosion test by the neutral salt spray cycle test method, in which one cycle is a wet environment for 2 hours, the width (maximum value on one side) of the paint film blistering from the cut was measured. Corrosion resistance after painting was evaluated according to the following grades Y1 to Y4 according to the measurement results. When the post-painting corrosion resistance score was Y1, Y2 or Y3, the post-painting corrosion resistance was judged to be excellent and passed. When the post-painting corrosion resistance score was Y4, the post-painting corrosion resistance was judged to be poor and was judged to be unacceptable.
[0136]
[Corrosion resistance rating after painting]
Y1: swelling width 0 mm or more, less than 1 mm
Y2: Swelling width of 1 mm or more and less than 2 mm
Y3: Swelling width of 2 mm or more and less than 3 mm
Y4: Swelling width of 3 mm or more
[0137]
The results of evaluation of chemical conversion treatability and post-painting corrosion resistance evaluated by the above methods are shown in the table.
[0138]
[Table 2-1]

[0139]
[Table 2-2]

[0140]
[Table 2-3]

[0141]
[Table 3-1]

[0142]
[Table 3-2]

[0143]
[Table 3-3]

[0144]
[Table 3-4]

[0145]
[Table 3-5]

[0146]
[Table 3-6]

[0147]
[Table 3-7]

[0148]
[Table 3-8]

[0149]
[Table 4]

[0150]
As shown in Tables 2-1 and 2-2, the average particle size and the content of the group A element of the particles mainly composed of a simple substance and/or compound of the group A element in the surface coating layer are within the scope of the present invention. Invention Examples A1 to A53 have excellent chemical conversion treatability and corrosion resistance after painting.
[0151]
On the other hand, Comparative Examples a1 to a12 in Table 2-3 were all inferior in chemical conversion treatability and corrosion resistance after painting. In addition, in the symbol a1, the average crystal grain size of the plating layer in the thickness range from the interface between the plating layer and the surface film layer to 2/3 times the thickness t is "-" because it is more than 2t/3. It means big.
[0152]
In all of Comparative Examples a1 to a3, since the surface film layer was formed by an Al compound that does not belong to the A group elements, the chemical conversion treatability and post-painting corrosion resistance were inferior.
In Comparative Examples a4, a11 and a12, the surface coating layer was formed by a compound of Mo belonging to Group A elements, but the total content of Mo was too small, so the chemical conversion treatability and corrosion resistance after painting were inferior.
[0153]
Comparative Example a5 was inferior in chemical conversion treatability and post-painting corrosion resistance because the surface coating layer contained no group A element.
In Comparative Examples a7 and a9, since the surface film layer was formed by a Cr compound that does not belong to the A group elements, the chemical conversion treatability and post-painting corrosion resistance were inferior.
In Comparative Examples a6 and a9, the thickness of the plating layer was small, so the chemical conversion treatability and the corrosion resistance after painting were inferior.
Comparative Example a10 had a large average crystal grain size in the plating layer, so it was inferior in chemical conversion treatability and corrosion resistance after painting.
[0154]
As shown in Tables 3-1 to 3-8, when the surface coating layer contains particles mainly composed of simple substances and / or compounds of group A elements and particles mainly composed of compounds of group B elements showed comparable or better results in terms of chemical convertability and post-coating corrosion resistance than when the surface coating layer contained only particles mainly composed of a single element and/or compound of a group A element.
[0155]
As shown in Table 4, invention examples C1 to C24, in which any one of Ca, Mg, Sr, and Ti was added to the plating layer, compared to the case where these elements were not added to the plating layer, showed better chemical conversion treatability and coating It was confirmed that the post-corrosion resistance was excellent.
[0156]
Although preferred embodiments and examples of the present invention have been described above, these embodiments and examples are merely examples within the scope of the present invention, and are within the scope of the present invention. Additions, omissions, substitutions, and other changes are possible. That is, the present invention is not limited by the foregoing description, but is limited only by the scope of the appended claims, and can of course be modified within the scope thereof.
Code explanation
[0157]
1 Steel plate
2 Plating layer
3　Surface film layer
10 Galvanized steel sheet for hot stamping

The scope of the claims

[Claim 1]
with a steel plate,
a plating layer formed on one or both sides of the steel sheet and having an Al content of 60% by mass or more;
and a surface film layer formed on the plating layer,
the thickness t of the plating layer is 10 to 60 μm,
The average crystal grain size of the plating layer in the thickness range from the interface between the plating layer and the surface coating layer to the position 2/3 times the thickness t is 2 t/3 or less and 15.0 μm and
The surface coating layer contains particles containing one or more elements selected from Group A elements consisting of Sc, V, Mn, Fe, Co, Ce, Nb, Mo and W,
the total content of the group A elements in the surface coating layer is 0.01 to 10.0 g/m2,
The average particle diameter of the particles containing the A group element is 0.05 to 3.0 μm
A plated steel sheet for hot stamping, characterized by:
[Claim 2]
The plated steel sheet for hot stamping according to claim 1, wherein at least part of the particles containing the group A element contains O.
[Claim 3]
The surface coating layer further contains particles containing one or more selected from group B elements consisting of Zn, Zr and Ti,
The plated steel sheet for hot stamping according to claim 1 or 2, wherein the total content of the B group elements in the surface coating layer is 0.01 to 10.0 g/m2.
[Claim 4]
Any one of claims 1 to 3, wherein the total content of Ca, Mg, Sr and Ti in the plating layer is 0.01 to 20% by mass with respect to the entire plating layer. or the plated steel sheet for hot stamping according to any one of items.
[Claim 5]
A hot stamped member obtained by hot stamping the plated steel sheet for hot stamping according to claims 1 to 4,
Having on the surface an oxide film layer containing one or more elements selected from Group A elements consisting of Sc, V, Mn, Fe, Co, Ce, Nb, Mo and W, Al, and oxygen A hot stamping member characterized by: