Title of the invention: Steel plate for hot stamping and hot stamp molded body Technical field [0001] The present invention relates to a steel plate for hot stamping and a hot stamp molded body. Specifically, the present invention relates to a steel plate for hot stamping and a hot stamp molded body having excellent deformation characteristics and corrosion resistance at the time of a collision, which contributes to weight reduction of the vehicle body and improvement of collision safety. This application claims priority based on Japanese Patent Application No. 2019-205439 filed in Japan on November 13, 2019, and the contents thereof are incorporated herein by reference. Background technology [0002] In recent years, the application of high-strength steel sheets has been expanding to car body parts used in automobiles due to the demand for weight reduction of car bodies and improvement of collision safety. Since the vehicle body parts are molded by press molding, improvement of press moldability, particularly improvement of shape freezing property, is an issue. Therefore, the hot stamping method is attracting attention as a method for manufacturing high-strength vehicle body parts having excellent shape accuracy. [0003] In recent years, a technique for applying a tailored blank to the hot stamping method has been studied. The tailored blank is made by joining steel plates having different plate thicknesses, chemical compositions, metal structures, etc. by welding, and the characteristics in one joined blank can be partially changed. For example, the impact can be absorbed by increasing the strength of one portion to suppress deformation and reducing the strength of another portion to deform. [0004] As a technique for applying a tailored blank to the hot stamping method, a tailored blank in which a steel plate (low-strength material) having low strength after hot stamping and a steel plate (high-strength material) having high strength after hot stamping are joined by welding is used. There is a technique to use. As the steel sheet having high strength after hot stamping, for example, a steel sheet as shown in Patent Document 1 can be used. For a steel sheet having low strength after hot stamping, the chemical composition of the steel may be adjusted so that the strength becomes low after cooling the mold by hot stamping. [0005] Parts with low-strength parts manufactured by hot-stamping tailored blanks are often used in the lower part of the center pillar. Corrosion resistance is required for the parts used in the lower part of the center pillar. In the prior art, in order to obtain corrosion resistance in the above-mentioned parts, auxiliary materials such as wax and sealer are used to cover the end face which is easily corroded to ensure the corrosion resistance. However, there are restrictions on the shape of parts in order to apply auxiliary materials. In addition, depending on the shape of the parts, it may not be possible to introduce auxiliary materials, and a part of the vehicle body may be corroded. [0006] Generally, it is known that it is effective to contain Sn in a steel sheet in order to improve corrosion resistance. However, as described in Patent Documents 2 and 3, it is known that since Sn is an easily oxidizing element, it is concentrated on the surface layer of the steel sheet. When Sn is concentrated on the surface layer of the steel sheet, the corrosion resistance of the surface layer of the steel sheet is improved. However, when the corrosion pits are formed deeper than the Sn-enriched layer on the surface layer, the effect of suppressing corrosion by Sn may not be obtained. Further, when exposed to a corroded environment for a long time, the corroded pits may develop to the deep part of the steel sheet, and a portion where the plate thickness is greatly reduced may occur. Prior art literature Patent documents [0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-197213 Patent Document 2: Japanese Patent Application Laid-Open No. 2012-255184 Patent Document 3: Japanese Patent Application Laid-Open No. 2002-206139 Outline of the invention Problems to be solved by the invention [0008] In view of the above problems, the present invention provides a hot stamped body that can obtain excellent corrosion resistance even when exposed to a corrosive environment for a long time, and a steel sheet for hot stamping that can obtain the hot stamped body. The purpose is to do. The present invention also provides a hot stamped body having the strength and ductility desired as a low-strength material for a tailored blank to be hot stamped, and a steel sheet for hot stamping capable of obtaining the hot stamped body. The purpose. Means to solve problems [0009] As described above, even if Sn is contained in the steel sheet in order to improve the corrosion resistance, Sn is concentrated on the surface layer of the steel sheet, and the corrosion pits are more than the Sn-concentrated layer on the surface due to exposure to a corrosive environment for a long time. When it is deeply formed, the effect of suppressing corrosion by Sn may not be obtained. The reason is not clear, but when a Sn-enriched layer is formed, there is a possibility that a Sn-deficient layer is formed in the range from the depth position directly under the Sn-enriched layer to the depth position of about 20 μm from the surface layer. It is considered that the progress of corrosion is promoted by the corrosion pit reaching the Sn-deficient layer. [0010] In order to uniformly disperse Sn in a steel sheet and obtain the effect of suppressing corrosion by Sn even when exposed to a corrosive environment for a long time, the present inventors have a predetermined temperature range during hot rolling. It was found that it is effective to suppress the oxidation time in. Specifically, the present inventors have found that it is effective to suppress the oxidation time in the temperature range of 1050 to 1150 ° C., which corresponds to the temperature range of rough rolling during hot rolling. [0011] Sn is incorporated into the scale at the time of oxidation at a high temperature of 1200 ° C. or higher, so that the concentration on the surface of the steel sheet is unlikely to occur. On the other hand, Sn is concentrated on the ground iron side of the interface between the scale and the ground iron at the time of oxidation in the temperature range of 1050 to 1150 ° C. Therefore, in order not to concentrate Sn on the surface layer of the steel sheet, it is effective not to oxidize for a long time in the above temperature range. [0012] Descaling is performed before each pass of hot rolling. Therefore, in order to control the oxidation time, the present inventors can control the time between rolling and rolling (time between passes) in the temperature range of 1050 to 1150 ° C. for hot rolling. It was found to be effective for controlling time. Then, the present inventors have found that in hot rolling, the surface layer concentration of Sn can be suppressed by setting the maximum pass-to-pass time in the temperature range of 1050 to 1150 ° C. to 120 seconds or less. At the same time, the present inventors have also found that descaling is effective in the temperature range of 1050 to 1150 ° C. [0013] The gist of the present invention made based on the above findings is as follows. (1) The steel sheet for hot stamping according to one aspect of the present invention has a chemical composition of% by mass. C: 0.035 to 0.100%, Si: 0.005 to 0.500%, Mn: 0.10 to 2.00%, Al: 0.010 to 0.080%, Sn: 0.005 to 0.200%, P: 0.030% or less, S: 0.0100% or less, N: 0.0100% or less, Cr: 0 to 1.00%, Mo: 0 to 1.00%, and B: 0 to 0.0050% Containing and Ti: 0.005 to 0.100%, Nb: 0.015 to 0.100%, V: 0.005 to 0.100%, and Zr: 0.005 to 0.100% Containing one or more of the group consisting of The balance consists of Fe and impurities, The Sn concentration in the surface layer region is 0.90 to 1.10 times the Sn concentration at the 1/4 position of the plate thickness in the plate thickness direction from the surface. (2) The steel sheet for hot stamping according to (1) above has a chemical composition of% by mass. Cr: 0.005 to 1.00%, and Mo: 1 or 2 of 0.005 to 1.00% may be contained. (3) The steel sheet for hot stamping according to (1) or (2) above may have a chemical composition of B: 0.0002 to 0.0050% in mass%. (4) The hot stamping steel sheet according to any one of (1) to (3) above may have a plating layer on the surface. (5) In the hot stamping steel sheet according to (4) above, the plating layer may be an Al-based plating layer. (6) The hot stamped body according to another aspect of the present invention has the chemical composition according to any one of (1) to (3) above, and the Sn concentration in the surface layer region of the steel sheet is the steel sheet. It may be 0.90 to 1.10 times the Sn concentration at the position of 1/4 of the plate thickness in the plate thickness direction from the surface of the above. (7) The hot stamp molded product according to (6) above may have a plating layer on the surface. (8) In the hot stamp molded body according to (7) above, the plating layer is an Al-based plating layer, and the Sn concentration in the diffusion layer existing in the Al-based plating layer is in the surface layer region of the steel sheet. It may be 1.05 times or more the Sn concentration. Effect of the invention [0014] According to the above aspect according to the present invention, it has the strength and ductility desired as a low-strength material for a tailored blank to be hot-stamped, and excellent corrosion resistance is obtained even when exposed to a corrosive environment for a long time. It is possible to provide a hot stamped body to be obtained, and a steel plate for hot stamping from which the hot stamped body can be obtained. [0015] According to the above aspect of the present invention, a hot stamped molded product having excellent deformation characteristics and corrosion resistance at the time of a collision can be obtained, which contributes to weight reduction of an automobile body and improvement of collision safety. Embodiment for carrying out the invention [0016] Hereinafter, the steel plate for hot stamping and the hot stamp molded body according to the present embodiment will be described in detail. First, the reason for limiting the chemical composition of the hot stamping steel sheet according to the present embodiment will be described. [0017] In addition, the lower limit value and the upper limit value are included in the numerical limitation range described below with "~" in between. Numerical values ​​indicated as "less than" and "greater than" do not include the value in the numerical range. All% of the chemical composition indicate mass%. [0018] [Steel sheet for hot stamping] The steel plate for hot stamping according to the present embodiment has a chemical composition of% by mass, C: 0.035 to 0.100%, Si: 0.005 to 0.500%, Mn: 0.10 to 2.00. %, Al: 0.010 to 0.080%, Sn: 0.005 to 0.200%, P: 0.030% or less, S: 0.0100% or less, N: 0.0100% or less, Cr: It contains 0 to 1.00%, Mo: 0 to 1.00% and B: 0 to 0.0050%, and Ti: 0.005 to 0.100%, Nb: 0.015 to 0.100. %, V: 0.005 to 0.100% and Zr: 0.005 to 0.100%, containing one or more of the group, the balance of which consists of Fe and impurities. Hereinafter, each element will be described in detail. [0019] C: 0.035 to 0.100% C is an element that greatly affects the strength of the hot stamping steel sheet (hot stamp molded product) after hot stamping. When the C content is low, the strength of the hot stamped compact is low, and the amount of energy absorbed at the time of collision is low. Therefore, the C content is 0.035% or more. Preferably, it is 0.040% or more and 0.045% or more. On the other hand, if the C content is high, the strength of the hot stamped molded product becomes too high, and cracks may occur during deformation at the time of collision. Therefore, the C content is set to 0.100% or less. Preferably, it is 0.090% or less and 0.085% or less. [0020] Si: 0.005 to 0.500% Si is a solid solution reinforced alloy element, which is an element necessary for ensuring the strength of the hot stamped article. When the Si content is extremely low, this effect cannot be obtained, so the Si content is set to 0.005% or more. It is preferably 0.010% or more and 0.015% or more. On the other hand, if the Si content exceeds 0.500%, a problem of surface scale will occur. That is, after pickling the scale generated during hot rolling, a pattern caused by surface irregularities is generated, and the surface appearance becomes inferior. Further, when the surface of a steel sheet is plated, the plating property deteriorates if the Si content is high. Therefore, the Si content is set to 0.500% or less. Preferably, it is 0.480% or less, 0.450% or less, and 0.400% or less. [0021] Mn: 0.10 to 2.00% Mn is an element that improves the strength of hot stamped bodies and the hardenability of steel. When the Mn content is less than 0.10%, the strength is sufficient in the hot stamp molded product.Cannot be obtained. Therefore, the Mn content is set to 0.10% or more. Preferably, it is 0.20% or more, 0.40% or more, 0.70% or more, and 1.00% or more. On the other hand, even if Mn is contained in excess of 2.00%, the above effect is saturated, so the Mn content is set to 2.00% or less. It is preferably 1.80% or less and 1.60% or less. [0022] Al: 0.010 to 0.080% Al is an element used as a deoxidizing material for molten steel. In order to sufficiently deoxidize the molten steel, the Al content should be 0.010% or more. It is preferably 0.020% or more and 0.030% or more. On the other hand, when the Al content exceeds 0.080%, a large amount of non-metal inclusions are formed, and surface defects are likely to occur in the product. Therefore, the Al content is 0.080% or less. Preferably, it is 0.070% or less and 0.060% or less. [0023] Sn: 0.005 to 0.200% Sn is an element necessary to improve the corrosion resistance of the hot stamp molded product. In order to obtain this effect, the Sn content is 0.005% or more. Preferably, it is 0.015% or more, 0.030% or more, 0.045% or more, and 0.060% or more. On the other hand, even if Sn of more than 0.200% is contained, the above effect is saturated, so the Sn content is set to 0.200% or less. Preferably, it is 0.180% or less and 0.160% or less. [0024] P: 0.030% or less P is a solid solution reinforced alloy element, which is a useful element for improving the strength of a hot stamped article. However, if the P content exceeds 0.030%, the weld crackability and toughness are adversely affected. Therefore, the P content is limited to 0.030% or less. It is preferably 0.020% or less. The lower limit of the P content is not particularly specified, but if the P content is excessively reduced, the refining cost increases, so the P content may be 0.001% or more. [0025] S: 0.0100% or less S affects the non-metal inclusions in the steel and deteriorates the ductility of the hot stamped body. Therefore, the S content is limited to 0.0100% or less. Preferably, it is 0.0080% or less and 0.0050% or less. The lower limit of the S content is not particularly specified, but the S content may be 0.0001% or more because the manufacturing cost of the desulfurization step increases if the S content is excessively reduced. [0026] N: 0.0100% or less N is an element contained in steel as an impurity, and if the N content exceeds 0.0100%, the ductility of the hot stamped product may deteriorate due to the coarsening of the nitride. Therefore, the N content is limited to 0.100% or less. Preferably, it is 0.0080% or less and 0.0060% or less. The lower limit of the N content is not particularly specified, but the N content may be 0.0010% or more because the manufacturing cost of the steelmaking process increases if the N content is excessively reduced. [0027] Ti: 0.005 to 0.100%, Nb: 0.015 to 0.100%, V: 0.005 to 0.100%, and Zr: 0.005 to 0.100%. Seeds or more than one Ti, Nb, V and Zr have the effect of forming carbonitride in steel and improving the strength of the hot stamped body by strengthening precipitation. In order to exert this effect, one or more kinds of Ti: 0.005% or more, Nb: 0.015% or more, V: 0.005% or more and Zr: 0.005% or more are contained. It is preferably one or more of Ti: 0.010% or more, Nb: 0.020% or more, V: 0.010% or more, and Zr: 0.010% or more. On the other hand, when the content of even one of these elements is more than 0.100%, a large amount of carbonitride is generated and the ductility of the hot stamped body is lowered. Therefore, the contents of Ti, Nb, V and Zr are set to 0.100% or less, respectively. Preferably, each is 0.080% or less. [0028] The balance of the chemical composition of the hot stamping steel sheet according to the present embodiment may be Fe and impurities. Examples of impurities include elements that are unavoidably mixed from steel raw materials or scrap and / or in the steelmaking process and are allowed as long as they do not impair the characteristics of the hot stamping steel sheet according to the present embodiment. [0029] The hot stamping steel sheet according to the present embodiment may contain the following elements as optional elements instead of a part of Fe. When the following optional elements are not contained, the content is 0%. [0030] Cr: 0.005 to 1.00% and Mo: 0.005 to 1.00% Cr and Mo are elements that improve the hardenability of steel and have the effect of improving the strength of the hot stamped body, so they may be contained as necessary. In order to surely exert this effect, it is preferable that the content of either Cr or Mn is 0.005% or more. However, if the content of either Cr or Mn exceeds 1.00%, the carbides present after hot rolling, cold rolling or annealing (including after plating) are stabilized and hot. Hardenability may be reduced by delaying the dissolution of carbides by heating during stamping. Therefore, the contents of Cr and Mo are set to 1.00% or less, respectively. [0031] B: 0.0002 to 0.0050% B has the effect of improving the hardenability during press molding (hot stamping) or cooling during press molding to improve the strength of the hot stamped body, and may be contained as necessary. In order to surely exert this effect, the B content is preferably 0.0002% or more. However, if B is contained in an excessive amount, cracks may occur during hot rolling and the above effects may be saturated. Therefore, the B content is set to 0.0050% or less. [0032] In addition to the above-mentioned elements, the steel sheet for hot stamping according to this embodiment may contain Ni, Cu, W, Sb, As, Ca, REM and Y. The contents of Ni, Cu and W are not particularly restricted, but if these elements are excessively contained, the castability may be deteriorated. Therefore, the content of each of these elements is preferably 1.00% or less. .. Elements that may be unavoidably contained, such as Sb and As, may deteriorate the ductility of the hot stamped product if they are contained in excess, so the total content of these elements is 0.100% or less. It is preferable to do so. Further, Ca, REM and Y may be contained for controlling the morphology of the sulfide. If these elements are excessively contained, the ductility of the hot stamping steel sheet may deteriorate. Therefore, the total content of these elements is preferably 0.01% or less. [0033] The chemical composition of the above-mentioned hot stamping steel sheet may be measured by a general analysis method. For example, ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrum) may be used for measurement. In addition, C and S may be measured by using the combustion-infrared absorption method, and N may be measured by using the inert gas melting-heat conductivity method. When the hot stamping steel sheet has a plating layer on the surface, the plating layer on the surface may be removed by mechanical grinding, and then the chemical composition may be analyzed. [0034] Sn concentration in the surface layer region: 0.90 to 1.10 times the Sn concentration at the 1/4 position of the plate thickness in the plate thickness direction from the surface. When Sn is concentrated in the surface layer region of the hot stamping steel sheet, the corrosion resistance of the surface layer region at the initial stage of corrosion is improved, but due to exposure to a corrosive environment for a long time, corrosion pits are formed more than in the surface layer region where Sn is concentrated. When it is generated in a deep region, it becomes difficult to obtain the effect of suppressing corrosion by Sn. Therefore, the Sn concentration in the surface layer region of the steel sheet for hot stamping is the Sn concentration at the position of 1/4 of the plate thickness in the plate thickness direction from the surface of the steel plate (hereinafter, may be referred to as the Sn concentration at the position of 1/4 of the plate thickness). 0.90 to 1.10 times. The surface layer region refers to a region 5 μm in the plate thickness direction from the surface of the hot stamping steel plate to 30 μm in the plate thickness direction from the surface. [0035] When the Sn concentration in the surface layer region is more than 1.10 times the Sn concentration at the plate thickness 1/4 position, Sn is concentrated in the surface layer region, and excellent corrosion resistance is obtained when exposed to a corrosive environment for a long time. I can't get it. Therefore, the Sn concentration in the surface layer region is 1.10 times or less the Sn concentration at the position where the plate thickness is 1/4. It is preferably 1.05 times or less. On the other hand, if the Sn concentration in the surface layer region is less than 0.90 times the Sn concentration at the plate thickness 1/4 position, the corrosion resistance at the initial stage of corrosion is lowered, and many starting points of corrosion pits are formed, resulting in swelling of the coating film. Is not preferable because it becomes large. Therefore, the Sn concentration in the surface layer region is 0.90 times or more the Sn concentration at the position where the plate thickness is 1/4. Preferably, it is 0.95 times or more. [0036] Measurement method of Sn concentration An electron probe microanalyzer (EPMA) is used to measure the Sn concentration. The Sn concentration in the surface layer region is 5 μm in the plate thickness direction from the surface to the plate from the surface at an arbitrary position 50 mm or more away from the end face of the hot stamping steel plate (a position avoiding the end if this position cannot be measured). The Sn concentration in the region at the position of 30 μm in the thickness direction is measured. The Sn concentration at the plate thickness 1/4 position is the Sn concentration in the region of 20 μm in the plate thickness direction (the region of 40 μm in the plate thickness direction with the front and back combined) centered on the position of 1/4 thickness from the surface. Measure. [0037] The measurement method uses mapping to perform the above-mentioned measurement with a width of 50 μm in the plate surface direction, and obtain the average value of the Sn concentration in the width direction in the surface layer region and the plate thickness 1/4 position. As a result, the Sn concentration in the surface layer region and the Sn concentration at the plate thickness 1/4 position are obtained. By dividing the Sn concentration of the obtained surface layer region by the Sn concentration at the plate thickness 1/4 position, it is obtained how many times the Sn concentration of the surface layer region is the Sn concentration at the plate thickness 1/4 position. [0038] Plating layer The hot stamping steel sheet according to the present embodiment may have a plating layer on the surface of the steel sheet for the purpose of further improving the corrosion resistance. The plating layer is, for example, an Al-based plating layer such as a hot-dip aluminum plating layer and an aluminum-zinc plating layer, a hot-dip zinc plating layer, an alloyed hot-dip zinc plating layer, an electric zinc plating layer, and a Zn-based plating layer such as a zinc nickel plating layer. Can be considered. [0039] The plating layer may be arranged on the surface of either one of the hot stamping steel plates or on both sides. The amount of adhesion is not particularly limited, but Al-based plating layer: one side 15 to 120 g / m 2, hot-dip galvanized layer: one side 30 to 120 g / m 2, alloyed hot-dip galvanized layer: one side 30 to 120 g / m 2, electricity. Zinc-plated layer and zinc-nickel-plated layer: preferably 5 to 100 g / m 2 on one side. [0040] When a hot stamping steel sheet having an Al-based plating layer is hot-stamped, Fe diffuses from the steel sheet to the Al-based plating layer when the hot stamp is heated, and an Fe—Al alloy layer is formed. Of this Fe—Al alloy layer, the surface side (opposite to the steel plate) of the Al-based plating layer is a Fe—Al compound layer (a Fe—Al alloy layer including a part of the Fe—Al—Si alloy layer). Is generated, and a layer called a diffusion layer is formed on the steel plate side of the Al-based plating layer. If the heating conditions at the time of hot stamping are optimized, Sn can be concentrated in the diffusion layer. This is because when Fe in the steel sheet and Al in the Al-based plating layer are alloyed, Fe in the steel sheet diffuses into the Al-based plating layer, and Sn in the steel sheet is also Fe at the same time as the Al-based plating layer. This is to spread inside. [0041] When Sn is concentrated in the diffusion layer in the Al plating layer, the corrosion resistance of the hot stamp molded product is further improved. Therefore, it is preferable that the hot stamping steel sheet according to the present embodiment has an Al-based plating layer on the surface of the steel sheet. The amount of the plating layer adhered may be 10 to 150 g / m 2 per side. [0042] In the present embodiment, the Al-based plating layer means a plating layer containing 50% by mass or more of Al. Elements other than Al include Si: 0.1 to 20% by mass, Fe: 0.1 to 10% by mass and Zn: 0.1 to 45% by mass, and the balance (Cu,Na, K, Co, Ni, Mg, etc.): It may be contained in an amount of less than 0.5% by mass. [0043] Further, when a hot stamping steel sheet having a Zn-based plating layer is hot-stamped, Fe diffuses from the steel sheet to the Zn-based plating layer to form an Fe—Zn alloy layer when the hot stamp is heated. As the Fe—Zn alloy layer, a Zn solid solution phase, a capital gamma (Γ) phase and the like are generated. [0044] In the present embodiment, the Zn-based plating layer means a plating layer containing 50% by mass or more of Zn. Elements other than Zn include Si: 0.01 to 20% by mass, Fe: 0.1 to 10% by mass, Al: 0.01 to 45% by mass, and the balance (Cu, Na, K, Co, Ni, Mg). Etc.): It may be contained in an amount of less than 0.5% by mass. [0045] The component analysis of the plating layer is performed by the following method. Cut out a sample so that a cross section perpendicular to the surface (thick cross section) can be observed from an arbitrary position 50 mm or more away from the end face of the hot stamping steel plate (a position avoiding the end if it cannot be collected from this position). The size of the sample depends on the measuring device, but is set to a size that can be observed by about 10 mm in the rolling direction. [0046] After embedding the above sample in a resin and polishing it, the layer structure of the plate thickness cross section is observed with a scanning electron microscope (SEM: Scanning Electron Microscope). Specifically, the observation is performed by SEM at a magnification at which the steel plate and the plating layer are included in the observation field of view. For example, by observing with a backscattered electron composition image (COMPO image), it is possible to infer how many layers the cross-sectional structure is composed of. [0047] Next, using an electron probe microanalyzer (EPMA), the range of 50 μm in the plate surface direction and the plating layer thickness + 30 μm in the plate thickness direction is analyzed by mapping. When the plating layer is an Al-based plating layer, the average values ​​of the Fe concentration and the Al concentration in the plate surface direction are obtained. Next, the relationship between the plate thickness position and the Al concentration and the relationship between the plate thickness position and the Fe concentration are obtained. The plate thickness position where the Al concentration and Fe concentration are the same as the Al concentration and Fe concentration of the steel sheet may be determined as the interface between the steel sheet and the Al-based plating layer. The Al concentration and Fe concentration of the steel sheet referred to here are obtained by measurement by EPMA. [0048] When the plating layer is a Zn-based plating layer, the average values ​​of the Fe concentration and the Zn concentration in the plate surface direction are obtained. Next, the relationship between the plate thickness position and the Zn concentration and the relationship between the plate thickness position and the Fe concentration are obtained. The plate thickness position where the Zn concentration and the Fe concentration are the same as the Zn concentration and the Fe concentration of the steel sheet may be determined as the interface between the steel sheet and the Zn-based plating layer. The Zn concentration and Fe concentration of the steel sheet referred to here are obtained by measurement by EPMA. [0049] In the present embodiment, even when the hot stamping steel sheet has a plating layer, the Sn distribution state in the hot stamping steel sheet is the same as when it does not have a plating layer. That is, even when the steel sheet for hot stamping has a plating layer, the Sn concentration in the surface layer region of the steel sheet is 0.90 to 1. It is 10 times. [0050] In the measurement of Sn concentration when the steel sheet for hot stamping has an Al-based plating layer, the position where the Fe concentration and the Al concentration are the same as those of the steel sheet is the position where the Fe concentration and the Al concentration are the same as those of the steel sheet and the Al-based plating layer, as in the case of component analysis of the plating layer. The Sn concentration may be measured by judging that it is an interface with. Further, in the measurement of Sn concentration when the steel sheet for hot stamping has a Zn-based plating layer, the position where the Fe concentration and the Zn concentration are the same as those of the steel sheet is determined to be the interface between the steel sheet and the Zn-based plating layer. The Sn concentration may be measured. [0051] [Hot stamp molded body] Next, a hot stamp molded body manufactured by using the above-mentioned steel plate for hot stamping will be described. The hot stamped body according to the present embodiment has the same chemical composition as the above-mentioned chemical composition of the steel sheet for hot stamping. The chemical composition of the hot stamped product may be measured by the same method as for the hot stamped steel sheet. [0052] The Sn concentration in the surface layer region of the hot stamped product is 0.90 to 1.10 times the Sn concentration at the position of 1/4 of the plate thickness in the plate thickness direction from the surface of the steel plate. This is the same as the Sn concentration in the surface layer region of the hot stamping steel sheet. The surface layer region of the hot stamped product refers to a region 5 μm in the plate thickness direction from the surface of the hot stamped product to 30 μm in the plate thickness direction from the surface. [0053] When the Sn concentration in the surface layer region is more than 1.10 times the Sn concentration at the plate thickness 1/4 position, Sn is concentrated in the surface layer region, and excellent corrosion resistance is obtained when exposed to a corrosive environment for a long time. I can't get it. Therefore, the Sn concentration in the surface layer region is 1.10 times or less the Sn concentration at the position where the plate thickness is 1/4. It is preferably 1.05 times or less. [0054] On the other hand, when the Sn concentration in the surface layer region is less than 0.90 times the Sn concentration at the plate thickness 1/4 position, the corrosion resistance at the initial stage of corrosion is lowered, and many starting points of corrosion pits are formed, resulting in a coating film. It is not preferable because the swelling becomes large. Therefore, the Sn concentration in the surface layer region is 0.90 times or more the Sn concentration at the position where the plate thickness is 1/4. Preferably, it is 0.95 times or more. [0055] Similar to the hot stamping steel plate, the hot stamp molded body may have a plating layer on the surface for the purpose of further improving the corrosion resistance. The plating layer is, for example, an Al-based plating layer such as a hot-dip aluminum plating layer and an aluminum-zinc plating layer, a hot-dip zinc plating layer, an alloyed hot-dip zinc plating layer, an electric zinc plating layer, and a Zn-based plating layer such as a zinc nickel plating layer. Can be considered. [0056] The plating layer may be arranged on the surface of either one of the hot stamped bodies, or may be arranged on both sides. Since Fe in the steel sheet diffuses into the plating layer at the time of heating the hot stamp, these plating layers become an alloy of the plating metal and Fe. [0057] The chemical composition of the hot stamped product, the measurement of the Sn concentration, and the analysis of the plating layer may be performed by the same method as that of the hot stamping steel plate. [0058] When a hot stamping steel sheet having an Al-based plating layer on the surface is hot-stamped, the Al-based plating layer becomes a Fe-Al alloy layer, and a part of the hot-stamping steel sheet becomes a Fe-Al-Si alloy layer. In the Al-based plating layer, a layer called a diffusion layer in which Al is solid-dissolved in Fe having a crystal structure of bcc is formed in the vicinity of the interface between the Al-based plating layer and the steel sheet. That is, the Al-based plating layer is specifically composed of a Fe—Al alloy layer (partly a Fe—Al—Si alloy layer) and a diffusion layer. The layer structure of the hot stamped body having an Al-based plating layer on the surface is, in order from the surface, a Fe—Al alloy layer including a Fe—Al—Si alloy layer, a diffusion layer, and a base iron (steel plate). [0059] If the Sn concentration in the diffusion layer existing in the Al-based plating layer is made higher than the Sn concentration in the surface layer region of the steel sheet, the corrosion resistance of the hot stamped body can be further improved. Specifically, by setting the Sn concentration in the diffusion layer existing in the Al-based plating layer to 1.05 times or more the Sn concentration in the surface layer region of the steel sheet, the corrosion resistance of the hot stamped body is further improved. be able to. The Sn concentration in the diffusion layer is preferably 1.10 times or more and 1.20 times or more the Sn concentration in the surface layer region of the steel sheet. The upper limit of the Sn concentration in the diffusion layer is not particularly limited, but it may be 1.70 times or less and 1.50 times or less the Sn concentration in the surface layer region of the steel sheet. [0060] The Sn concentration in the diffusion layer and the Sn concentration in the surface layer region of the steel sheet are obtained by measuring from the outermost surface of the plating to a depth of plating thickness (μm) + 30 μm using EPMA. Other conditions are the same as the above-mentioned method for measuring the Sn concentration. The diffusion layer means a region of the Al-based plating layer from the plate thickness position where the Al concentration is 30% by mass or less to the interface between the Al-based plating layer and the steel plate. [0061] Plate thickness, tensile strength and total elongation The plate thickness of the hot stamping steel plate and the hot stamp molded body according to the present embodiment is not particularly specified, but may be 0.5 to 3.5 mm from the viewpoint of reducing the weight of the vehicle body. [0062] Further, it is preferable that the hot stamped compact according to the present embodiment has the tensile (maximum) strength desired as a low-strength material for a tailored blank to be hot-stamped. Specifically, the tensile strength of the hot stamp molded product is preferably 450 to 1200 MPa. [0063] The total elongation is 10% or more when the tensile strength is 450 to 700 MPa, 7% or more when the tensile strength is 700 MPa or more and 800 MPa or less, 6% or more when the tensile strength is 800 MPa or more and 1000 MPa or less, 1000 MPa or more, 1200 MPa or more. In the following cases, it is preferably 5% or more. [0064] Tensile strength and total elongation may be obtained by conducting a tensile test in accordance with JIS Z 2241: 2011. [0065] [Production method] Next, a method for manufacturing a steel sheet for hot stamping according to this embodiment will be described. In the present embodiment, it is important to control the Sn concentration in the surface layer region of the steel sheet by suppressing the oxidation of Sn, which is a factor that causes Sn to be concentrated in the surface layer region of the steel sheet. [0066] The steel piece (steel material) to be used for hot rolling may be a steel piece manufactured by a conventional method, and may be, for example, a steel piece manufactured by a general method such as a continuously cast slab or a thin slab caster. Steel pieces having the above-mentioned chemical composition are subjected to hot rolling. In order to uniformly disperse Sn in the steel sheet, during hot rolling, the oxidation time in the temperature range of 1050 to 1150 ° C., which corresponds to the temperature range of rough rolling, is suppressed. [0067] Sn is incorporated into the scale at the time of oxidation at a high temperature of 1200 ° C. or higher, so that the concentration on the surface of the steel sheet is unlikely to occur. On the other hand, in the temperature range of 1050 to 1150 ° C., Sn is concentrated on the ground iron side at the interface between the scale and the base iron during oxidation, so it is necessary to prevent oxidation for a long time in this temperature range. By suppressing the concentration of Sn, which is an easily oxidizable element, in the surface layer region due to oxidation, it is possible to maintain a uniform dispersion state of Sn. [0068] The steel pieces (steel materials) to be subjected to hot rolling may be heated to a temperature range of 1200 to 1400 ° C. and then subjected to hot rolling. [0069] The suppression of oxidation time can be controlled by the maximum interpass time and descaling in the temperature range of 1050 to 1150 ° C. In the method for manufacturing a steel sheet for hot stamping according to the present embodiment, descaling is performed before each pass in hot rolling. In order to control the oxidation time, the maximum value of the time between rolling and rolling (maximum pass-to-pass time) is controlled in the temperature range of 1050 to 1150 ° C. of hot rolling, and descaling is performed before each pass. It is effective to do it. In hot rolling, by setting the maximum pass-to-pass time in the temperature range of 1050 to 1150 ° C. to 120 seconds or less, the surface layer concentration of Sn can be suppressed. If there is even one pass between passes with a time between passes of more than 120 seconds, Sn will be concentrated in the surface layer region. [0070] As the descaling conditions, for example, it is preferable that the amount of spray water per nozzle is 10 to 100 L / min, the discharge pressure is 6 MPa or more, and the nozzle spacing in the width direction is 150 to 350 mm. The discharge pressure is more preferably 12 MPa or more. [0071] In the temperature range of 1050 to 1150 ° C., descaling is performed before each pass and the time between passes is controlled, so that the scale that is the oxygen supply source to Sn can be removed. As a result, the Sn concentration in the surface layer region of the steel sheet can be reduced. Descaling also has the significance of controlling the temperature of the steel sheet. Descaling may be performed not only before the rolling pass but also after the rolling pass so that the time of staying in the temperature range of 1050 to 1150 ° C. is not unnecessarily prolonged due to the temperature rise due to the processing heat generation. [0072] When the temperature of the steel sheet is less than 1050 ° C, the surface layer of Sn is less likely to be concentrated due to the oxidation reaction. The temperature of the steel sheet drops, causing the diffusion of Sn.It is presumed that it will be difficult. Therefore, it is not necessary to control the maximum inter-pass time and descaling in the temperature range below 1050 ° C. [0073] The finish rolling completion temperature may be in a temperature range that does not impair productivity, and may be 800 to 1000 ° C. From the same viewpoint, the winding temperature may be 400 to 800 ° C. As a result, a hot-rolled steel sheet is obtained. In the present embodiment, from the viewpoint of suppressing the production cost, it is desirable not to slowly cool the coil in the state of the coil by using a heat insulating cover, a heat insulating chamber, or the like after winding. [0074] Cold-roll the obtained hot-rolled steel sheet. The cumulative rolling reduction rate during cold rolling may be within a range that does not impair productivity, and may be 30 to 80%. As a result, a cold-rolled steel sheet is obtained. [0075] The obtained cold-rolled steel sheet may be annealed to soften it. After annealing, it is preferable to perform temper rolling. The rolling reduction of the steel sheet in temper rolling may be 2% or less as long as it does not hinder the productivity. A tension leveler may be used for shape correction. [0076] If necessary, the cold-rolled steel sheet may be subjected to Al-based plating such as aluminum plating and aluminum-zinc plating, or Zn-based plating. Although the plating composition is mainly composed of aluminum and zinc, elements such as Ni may be added in order to improve corrosion resistance. Further, the plating may contain an element such as iron as an impurity. [0077] There is no problem with the conventional method of applying plating. For aluminum plating, the Si concentration in the bath is 5 to 12% by mass, and the balance is suitable for aluminum and impurities of less than 0.5%. For aluminum-zinc plating, a Zn concentration in the bath is 40 to 50% by mass, and the balance is suitable for aluminum and impurities of less than 0.5%. Further, there is no particular problem whether Mg or Zn is mixed in the aluminum plating or Mg is mixed in the aluminum-zinc plating. The atmosphere at the time of applying plating may be the normal plating conditions regardless of whether it is a continuous plating facility having a non-oxidizing furnace or a continuous plating facility not having a non-oxidizing furnace. For zinc plating, methods such as hot-dip galvanizing, electrozinc plating, and alloyed hot-dip galvanizing may be adopted. [0078] Metal pre-plating may be applied to the surface of the steel sheet before plating. Examples of the metal pre-plating include Ni pre-plating, Fe pre-plating, and other metal pre-plating for improving the plating property. Further, there is no particular problem even if a different kind of metal plating or a film of an inorganic or organic compound is applied to the surface of the plating layer. By the above method, a steel plate for hot stamping according to this embodiment is obtained. [0079] Next, a method for manufacturing the hot stamped molded product according to the present embodiment will be described. The hot stamped compact according to the present embodiment can be obtained by applying, for example, the following hot stamping conditions to the hot stamping steel sheet obtained by the above method. [0080] First, the steel sheet for hot stamping is heated to a temperature range of Ac 3 transformation point to 1000 ° C., held in the temperature range for 0.1 to 30.0 minutes, and then immediately conveyed onto a die for press molding. Perform (hot stamping). After that, the steel sheet is pressurized, and the steel sheet after press forming is cooled in the mold to a temperature range of 250 ° C. or lower by heat transfer between the steel sheet and the mold. [0081] The average heating rate from the Ac 3 transformation point to the temperature range of 1000 ° C. may be 0.1 to 200 ° C./s. The average cooling rate in the mold should be equal to or higher than the critical cooling rate at which martensitic transformation occurs when a metal structure containing martensite as the main phase (the area ratio of martensite is 80% or more) is obtained after hot stamping. is required. Since the critical cooling rate changes depending on the chemical composition of the steel sheet, the average cooling rate in the mold may be, for example, 1.0 to 200 ° C./s. If the metal structure containing martensite as the main phase is not required after hot stamping, it is not necessary to limit the cooling rate in the mold. However, when a tailored blank bonded to a high-strength material containing martensite as the main phase is used after hot stamping, it may be necessary to cool the bonded high-strength material at a cooling rate higher than the critical cooling rate at which martensitic transformation occurs. Conceivable. Alternatively, the surface pressure may be increased by adjusting the mold only for the portion of the high-strength material to improve the cooling rate. [0082] Further, in the temperature range from the Ac 3 transformation point to 1000 ° C., the temperature of the steel sheet may be changed or kept constant. The Ac 3 transformation point can be calculated by the following formula. [0083] Ac 3 transformation point (° C) = exp (X) + 31.5 x Mo-28 X = 6.8165-0.47132 x C-0.057321 x Mn + 0.0660261 x Si-0.050211 x Cr + 0.10593 x Ti + 2.0272 x N + 1.0536 x S-0.12024 x Si x C + 0.11629 x Cr x C + 0.29225 x C 2 + 0.01566 x Mn 2 + 0.017315 x Cr 2 The element symbol in the above formula is the content of the element in mass%, and if it is not contained, 0 is substituted. [0084] Regarding the transport time from the heating furnace to the mold, ferrite-pearlite transformation and bainite transformation start when a metal structure containing martensite as the main phase (the area ratio of martensite is 80% or more) is obtained after hot stamping. It is necessary to carry it onto the mold and perform press molding faster than this. For ferrite-pearlite transformation and bainite transformation, the time at which the transformation occurs can be investigated by attaching a thermocouple to a blank (steel plate for hot stamping) and measuring the temperature, and observing the transformation heat generation. However, when the metal structure containing martensite as the main phase is not required after hot stamping, it is not necessary to perform press molding earlier than the ferrite-pearlite transformation and the bainite transformation start. When the temperature at the time of press molding becomes low, the moldability deteriorates and molding defects such as cracks and wrinkles occur. Therefore, it is desirable to start the press molding at 600 ° C. or higher, preferably 700 ° C. or higher. [0085] When the hot stamping steel sheet has a Zn-based plating layer on the surface, blisters and the like may occur if the heating temperature is high and the heating time is long, so it is necessary to make appropriate adjustments within the above hot stamping conditions. .. [0086] When the hot stamping steel sheet has an Al-based plating layer, the heating temperature is such that the following formula (1) is satisfied in order to concentrate Sn in the diffusion layer in the Al-based plating layer during heating during hot stamping. And it is preferable to control the holding time. When the heating conditions at the time of hot stamping satisfy the following formula (1), the Sn concentration in the diffusion layer existing in the Al-based plating layer can be set to 1.05 times or more the Sn concentration in the surface layer region of the steel sheet. can. [0087] T