HOT-STAMPING FORMED BODY

Abstract

A hot-stamping formed body includes: a steel sheet having a predetermined chemical composition; and a plating layer provided on a surface of the steel sheet, the plating layer having an adhesion amount of 10 g/m.sup.2 to 90 g/m.sup.2 and a Ni content of 10 mass % to 25 mass %, and containing a remainder consisting of Zn and impurities. The hot-stamping formed body includes, in a surface layer region of the steel sheet, a metallographic structure has one or more of martensite, tempered martensite, and lower bainite as a primary phase, and with respect to the sum of the lengths of grain boundaries having a rotation angle of 57° to 63°, the lengths of grain boundaries having a rotation angle of 49° to 56°, the lengths of grain boundaries having a rotation angle of 4° to 12°, and the lengths of grain boundaries having a rotation angle of 64° to 72° with a <011> direction as a rotation axis among the grain boundaries of grains having a phase of a body-centered structure, the ratio of the lengths of the grain boundaries having a rotation angle of 64° to 72° is 35% or more.

Claims

1. A hot-stamping formed body comprising: a steel sheet containing, as a chemical composition, by mass %, C: 0.15% or more and less than 0.70%, Si: 0.005% to 0.250%, Mn: 0.30% to 3.00%, sol. Al: 0.0002% to 0.500%, P: 0.100% or less, S: 0.1000% or less, N: 0.0100% or less, Nb: 0% to 0.150%, Ti: 0% to 0.150%, Mo: 0% to 1.000%, Cr: 0% to 1.000%, B: 0% to 0.0100%, Ca: 0% to 0.010%, REM: 0% to 0.30%, and a remainder consisting of Fe and impurities; and a plating layer provided on a surface of the steel sheet, the plating layer having an adhesion amount of 10 g/m.sup.2 to 90 g/m.sup.2 and a Ni content of 10 mass % to 25 mass %, and containing a remainder consisting of Zn and impurities, wherein, in a surface layer region, which is a region from the surface of the steel sheet to a position at a depth of 50 μm from the surface, a metallographic structure has one or more of martensite, tempered martensite, and lower bainite as a primary phase, and with respect to the sum of the lengths of grain boundaries having a rotation angle of 57° to 63°, the lengths of grain boundaries having a rotation angle of 49° to 56°, the lengths of grain boundaries having a rotation angle of 4° to 12°, and the lengths of grain boundaries having a rotation angle of 64° to 72° with a <011> direction as a rotation axis among the grain boundaries of grains having a phase of a body-centered structure, the ratio of the lengths of the grain boundaries having a rotation angle of 64° to 72° is 35% or more.

2. The hot-stamping formed body according to claim 1, comprising, as the chemical composition, by mass %, one or more selected from the group of: Nb: 0.010% to 0.150%; Ti: 0.010% to 0.150%; Mo: 0.005% to 1.000%; Cr: 0.005% to 1.000%; B: 0.0005% to 0.0100%; Ca: 0.0005% to 0.010%; and REM: 0.0005% to 0.30%.

3. A hot-stamping formed body comprising: a steel sheet containing, as a chemical composition, by mass %, C: 0.15% or more and less than 0.70%, Si: 0.005% to 0.250%, Mn: 0.30% to 3.00%, sol. Al: 0.0002% to 0.500%, P: 0.100% or less, S: 0.1000% or less, N: 0.0100% or less, Nb: 0% to 0.150%, Ti: 0% to 0.150%, Mo: 0% to 1.000%, Cr: 0% to 1.000%, B: 0% to 0.0100%, Ca: 0% to 0.010%, REM: 0% to 0.30%, and a remainder comprising Fe and impurities; and a plating layer provided on a surface of the steel sheet, the plating layer having an adhesion amount of 10 g/m.sup.2 to 90 g/m.sup.2 and a Ni content of 10 mass % to 25 mass %, and containing a remainder comprising Zn and impurities, wherein, in a surface layer region, which is a region from the surface of the steel sheet to a position at a depth of 50 μm from the surface, a metallographic structure has one or more of martensite, tempered martensite, and lower bainite as a primary phase, and with respect to the sum of the lengths of grain boundaries having a rotation angle of 57° to 63°, the lengths of grain boundaries having a rotation angle of 49° to 56°, the lengths of grain boundaries having a rotation angle of 4° to 12°, and the lengths of grain boundaries having a rotation angle of 64° to 72° with a <011> direction as a rotation axis among the grain boundaries of grains having a phase of a body-centered structure, the ratio of the lengths of the grain boundaries having a rotation angle of 64° to 72° is 35% or more.

Description

EXAMPLES

[0126] Next, examples of the present invention will be described. The conditions in the examples are one example of conditions adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to this one example of conditions. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

[0127] Steel pieces manufactured by casting molten steels having the chemical compositions shown in Tables 1 to 4 were subjected to hot rolling, cold rolling, and plating under the conditions shown in Tables 5, 7, 9, and 11 to obtain steel sheets for hot stamping shown in Tables 6, 8, 10, and 12. The obtained steel sheets for hot stamping were subjected to hot-stamping forming by heat treatments shown in Tables 13, 15, 17, and 19 to obtain hot-stamping formed bodies. Furthermore, for some of the hot-stamping formed bodies, a portion of the hot-stamping formed body was irradiated with a laser to be tempered, thereby forming a partially softened region. The tempering temperature by laser irradiation was set to 200° C. to 500° C. Tables 14, 16, 18, and 20 show the microstructure and mechanical properties of the obtained hot-stamping formed bodies.

[0128] The underlines in the tables indicate those outside the range of the present invention, those deviating from preferable manufacturing conditions, and those having characteristic values that are not preferable.

TABLE-US-00001 TABLE 1 Chemical composition (mass %) of base steel sheet, Steel remainder consisting of Fe and impurities No. C Si Mn P S sol.A1 N Note 1 0.16 0.250 1.10 0.006 0.0020 0.030 0.0026 Invention Steel 2 0.44 0.250 1.80 0.010 0.0090 0.400 0.0040 Invention Steel 3 0.23 0.250 1.20 0.010 0.0100 0.030 0.0050 Invention Steel 4 0.08 0.220 0.81 0.008 0.0009 0.044 0.0026 Comparative Steel 5 0.16 0.150 0.71 0.011 0.0006 0.043 0.0037 Invention Steel 6 0.31 0.250 0.80 0.015 0.0011 0.041 0.0039 Invention Steel 7 0.36 0.180 0.81 0.005 0.0005 0.045 0.0037 Invention Steel 8 0.44 0.250 0.71 0.015 0.0007 0.034 0.0042 lnvention Steel 9 0.67 0.190 0.71 0.014 0.0003 0.037 0.0035 Invention Steel 10 0.78 0.250 0.90 0.014 0.0011 0.031 0.0026 Comparative Steel 11 0.36 0.002 0.86 0.005 0.0003 0.041 0.0032 Comparative Steel 12 0.38 0.007 0.83 0.005 0.0011 0.050 0.0030 Invention Steel 13 0.37 0.210 0.72 0.011 0.0007 0.030 0.0041 Invention Steel 14 0.37 0.240 0.90 0.015 0.0007 0.047 0.0037 Invention Steel 15 0.37 0.150 0.15 0.005 0.0003 0.035 0.0030 Comparative Steel 16 0.44 0.170 0.44 0.007 0.0005 0.049 0.0029 Invention Steel 17 0.36 0.240 0.82 0.010 0.0011 0.035 0.0038 invention Steel 18 0.37 0.180 1.29 0.007 0.0010 0.030 0.0028 invention Steel 19 0.37 0.150 1.99 0.009 0.0005 0.035 0.0042 Invention Steel 20 0.38 0.170 2.89 0.007 0.0005 0.046 0.0037 Invention Steel 21 0.38 0.150 3.15 0.012 0.0009 0.036 0.0042 Comparative Steel 22 0.38 0.240 0.82 0.0004 0.0007 0.045 0.0026 Invention Steel 23 0.36 0.160 0.90 0.009 0.0006 0.030 0.0038 Invention Steel 24 0.36 0.150 0.77 0.094 0.0010 0.043 0.0033 Invention Steel 25 0.37 0.190 0.84 0.123 0.0010 0.033 0.0032 Comparative Steel 26 0.36 0.200 0.75 0.009 0.00015 0.047 0.0045 Invention Steel 27 0.37 0.150 0.81 0.013 0.0003 0.031 0.0029 Invention Steel 28 0.37 0.190 0.89 0.008 0.0022 0.044 0.0032 Invention Steel 29 0.36 0.230 0.80 0.007 0.0900 0.049 0.0030 Invention Steel 30 0.36 0.190 0.72 0.006 0.1334 0.045 0.0025 Comparative Steel

TABLE-US-00002 TABLE 2 Chemical composition (mass %) of base steel sheet, remainder Steel consisting of Fe and impurities A.sub.3 No. Nb Ti Mo Cr B Ca REM (° C.) Note 1 0.130 865 Invention Steel 2 0.03 858 Invention Steel 3 0.020 0.200 860 Invention Steel 4 851 Comparative Steel 5 851 Invention Steel 6 853 Invention Steel 7 853 Invention Steel 8 853 Invention Steel 9 855 Invention Steel 10 857 Comparative Steel 11 853 Comparative Steel 12 853 Invention Steel 13 853 Invention Steel 14 853 Invention Steel 15 851 Comparative Steel 16 852 Invention Steel 17 853 Invention Steel 18 855 Invention Steel 19 857 Invention Steel 20 861 Invention Steel 21 862 Comparative Steel 22 853 Invention Steel 23 853 Invention Steel 24 853 Invention Steel 25 853 Comparative Steel 26 853 Invention Steel 27 853 Invention Steel 28 853 Invention Steel 29 853 Invention Steel 30 853 Comparative Steel

TABLE-US-00003 TABLE 3 Chemical composition (mass %) of base steel sheet, Steel remainder consisting of Fe and impurities No. C Si Mn P S sol.A1 N Note 31 0.38 0.230 0.79 0.013 0.0008 0.0001 0.0027 Comparative Steel 32 0.38 0.160 0.85 0.010 0.0009 0.0003 0.0033 Invention Steel 33 0.35 0.200 0.72 0.014 0.0007 0.003 0.0042 Invention Steel 34 0.37 0.160 0.73 0.006 0.0006 0.031 0.0026 Invention Steel 35 0.35 0.240 0.83 0.009 0.0008 0.494 0.0034 Invention Steel 36 0.37 0.240 0.84 0.011 0.0007 0.581 0.0040 Comparative Steel 37 0.37 0.220 0.89 0.007 0.0007 0.035 0.0001 Invention Steel 38 0.38 0.150 0.89 0.009 0.0008 0.038 0.0073 invention Steel 39 0.38 0.190 0.71 0.007 0.0007 0.039 0.0090 Invention Steel 40 0.36 0.210 0.73 0.008 0.0003 0.035 0.0160 Comparative Steel 41 0.37 0.230 0.87 0.009 0.0006 0.031 0.0025 Invention Steel 42 0.36 0.170 0.70 0.009 0.0009 0.046 0.0030 Invention Steel 43 0.37 0.220 0.73 0.008 0.0004 0.033 0.0038 Invention Steel 44 0.37 0.230 0.90 0.009 0.0011 0.044 0.0044 Invention Steel 45 0.35 0.170 0.89 0.011 0.0007 0.043 0.0028 Invention Steel 46 0.36 0.170 0.88 0.007 0.0004 0.031 0.0033 Invention Steel 47 0.36 0.210 0.80 0.005 0.0003 0.037 0.0035 invention Steel 48 0.37 0.200 0.78 0.009 0.0010 0.031 0.0026 Invention Steel 49 0.38 0.160 0.82 0.015 0.0009 0.031 0.0041 Invention Steel 50 0.36 0.230 0.77 0.011 0.0008 0.043 0.0038 Invention Steel 51 0.35 0.160 0.70 0.005 0.0006 0.047 0.0026 Invention Steel 52 0.37 0.250 0.83 0.006 0.0010 0.033 0.0039 Invention Steel 53 0.37 0.150 0.70 0.015 0.0008 0.031 0.0044 Invention Steel 54 0.36 0.230 0.86 0.005 0.0003 0.050 0.0044 Invention Steel 55 0.36 0.160 0.74 0.015 0.0006 0.034 0.0044 Invention Steel 56 0.36 0.160 0.78 0.015 0.0006 0.037 0.0039 Invention Steel 57 0.36 0.190 0.80 0.010 0.0006 0.034 0.0027 Invention Steel 58 0.18 0.210 1.29 0.006 0.0020 0.030 0.0026 Invention Steel 59 0.21 0.220 1.31 0.006 0.0020 0.030 0.0028 Invention Steel 60 0.23 0.200 1.30 0.006 0.0020 0.030 0.0030 Invention Steel 61 0.25 0.190 1.28 0.006 0.0020 0.030 0.0029 Invention Steel

TABLE-US-00004 TABLE 4 Chemical composition (mass %) of base steel Steel sheet remainder consisting of Fe and impurities A.sub.3 No. Nb Ti Mo Cr B Ca REM (° C.) Note 31 853 Comparative Steel 32 853 Invention Steel 33 853 Invention Steel 34 853 Invention Steel 35 853 Invention Steel 36 853 Comparative Steel 37 853 Invention Steel 38 853 Invention Steel 39 853 Invention Steel 40 853 Comparative Steel 41 0.012 857 Invention Steel 42 0.032 864 Invention Steel 43 0.120 895 Invention Steel 44 0.013 857 Invention Steel 45 0.036 862 Invention Steel 46 0.140 888 Invention Steel 47 0.006 854 Invention Steel 48 0.012 854 Invention Steel 49 0.980 951 Invention Steel 50 0.006 853 Invention Steel 51 0.009 853 Invention Steel 52 0.960 863 Invention Steel 53 0.0006 853 Invention Steel 54 0.0011 853 Invention Steel 55 0.0090 853 Invention Steel 56 0.008 853 Invention Steel 57 0.28 853 Invention Steel 58 0.017 0.120 0.207 871 Invention Steel 59 0.130 866 Invention Steel 60 0.121 865 Invention Steel 61 0.020 0.119 0.200 872 Invention Steel

TABLE-US-00005 TABLE 5 Hot rollnig Cooling Heat Average Average Average treat- cooling cooling cooling Cold ment rate up to rate at rate in rolling before Rough rolling Finish rolling temperature 550° C. or temperature Cumu- plating Rolling Cumulative Rolling Final Cooling range higher and range of lative Heating Steel temper- rolling temper- rolling start of 650° C. lower than 550° C. rolling temper- Steel sheet ature reduction ature reduction time or lower 650° C. or lower reduction ature No. No (° C.) (%) (° C.) (%) (sec) (° C./s) (°C./s) (° C./s) (%) (° C.) Note 1 1 1080 40 889 8 0.4 40 33 28 40 Absent Comparative Steel 2 2 1100 40 970 30 0.3 40 11 30 40 Absent Comparative Steel 3 3 1143 46 886 12 0.4 47 6 59 49 770 Comparative Steel 4 4 1099 49 905 11 0.4 48 5 60 59 Absent Comparative Steel 5 5 1149 58 885 9 0.4 41 6 54 45 Absent Invention Steel 6 6 1123 46 915 8 0.4 51 6 59 51 Absent Invention Steel 7 7 1141 40 908 12 0.2 40 6 62 49 Absent Invention Steel 8 8 1090 48 896 12 0.4 49 6 62 12 Absent Invention Steel 9 9 1099 57 886 11 0.2 47 6 48 58 Absent Invention Steel 10 10 1143 46 884 10 0.2 53 5 46 60 Absent Comparative Steel 11 11 1128 51 890 10 0.3 40 6 60 49 Absent Comparative Steel 12 12 1142 42 902 9 0.3 52 7 60 56 Absent Invention Steel 13 13 1145 54 909 12 0.4 47 5 55 53 Absent Invention Steel 14 14 1137 40 894 9 0.2 54 6 58 40 Absent Invention Steel 15 15 1101 45 904 9 0.3 44 7 55 52 Absent Comparative Steel 16 16 1121 57 881 9 0.4 43 5 46 58 Absent Invention Steel 17 17 1103 46 915 11 0.4 44 5 50 44 Absent Invention Steel 18 18 1130 53 892 11 0.4 43 6 59 43 Absent Invention Steel 19 19 1095 55 908 10 0.2 52 7 65 59 Absent Invention Steel 20 20 1136 59 885 8 0.3 48 4 65 51 Absent Invention Steel 21 21 1107 41 881 10 0.3 50 6 49 42 Absent Comparative Steel 22 22 1123 44 888 12 0.4 43 4 63 58 Absent Invention Steel 23 23 1123 44 888 11 0.3 55 7 46 49 Absent Invention Steel 24 24 1080 51 884 10 0.2 48 5 57 50 Abseil Invention Steel 25 25 1120 43 918 10 0.3 43 6 48 60 Absent Comparative Steel 26 26 1124 48 888 8 0.4 50 4 58 60 Absent Invention Steel 27 27 1078 49 892 10 0.3 40 7 62 51 Absent Invention Steel 28 28 1127 47 892 12 0.2 51 5 62 46 Absent Invention Steel 29 29 1101 58 887 11 0.4 53 4 50 47 Absent Invention Steel 30 30 1112 56 909 10 0.2 47 5 56 46 Absent Comparative Steel

TABLE-US-00006 TABLE 6 Steel sheet for hot stamping Grains having average crystal Plating Ni content orientation Steel adhesion in plating difference of 0.4° Sheet Steel sheet amount layer to 3.0° thickness No. No. (g/m.sup.2) (mass %) (area %) (mm) Note  1 1 41 15 30 1.6 Comparative Steel  2 2 53 12 25 1.6 Comparative Steel  3 3 40 12  3 1.6 Comparative Steel  4 4 56 15 86 1.6 Comparative Steel  5 5 50 14 87 1.4 Invention Steel  6 6 41 15 90 1.6 Invention Steel  7 7 54 17 89 1.8 Invention Steel  8 8 57 15 88 1.6 Invention Steel  9 9 40 16 89 1.9 Invention Steel 10 10 53 17 89 1.5 Comparative Steel 11 11 48 12 46 1.8 Comparative Steel 12 12 58 16 82 1.4 Invention Steel 13 13 48 17 84 1.6 Invention Steel 14 14 46 14 89 1.6 Invention Steel 15 15 58 10 92 1.7 Comparative Steel 16 16 51 17 89 1.4 Invention Steel 17 17 43 11 85 1.8 Invention Steel 18 18 52 12 93 1.6 Invention Steel 19 19 50 13 89 1.6 Invention Steel 20 20 45 11 93 1.9 Invention Steel 21 21 45 14 91 1.5 Comparative Steel 22 22 60 14 86 2.0 Invention Steel 23 23 47 15 91 1.9 Invention Steel 24 24 60 15 87 1.7 Invention Steel 25 25 58 13 87 1.4 Comparative Steel 26 26 60 15 87 1.8 Invention Steel 27 27 52 12 86 2.0 Invention Steel 28 28 50 10 86 1.4 Invention Steel 29 29 53 15 88 1.5 Invention Steel 30 30 51 11 90 1.5 Comparative Steel

TABLE-US-00007 TABLE 7 Hot rolling Cooling Average Average Average Heat cooling cooling cooling Cold treatment rate up to rate at rate in rolling before Rough rolling Finish rolling Cool- temperature 550° C. or temperature Cumu- plating Rolling Cumulative Rolling Final ing range of higher and range of lative Heating Steel temper- rolling temper- rolling start 650° C. lower than 550° C. rolling temper- Steel sheet ature reduction ature reduction time or lower 650° C. or lower reduction ature No. No. (° C.) (%) (° C.) (%) (sec) (° C./s) (° C./s) (° C./s) (%) (° C.) Note 31 31 1108 46 902 10 0.4 40 6 45 49 Absent Comparative Steel 32 32 1136 60 918 8 0.2 54 5 45 48 Absent Invention Steel 33 33 1128 56 895 12 0.2 41 6 57 43 Absent Invention Steel 34 34 1127 54 914 10 0.3 51 4 48 48 Absent Invention Steel 35 35 1118 47 881 10 0.3 51 4 64 57 Absent Invention Steel 36 36 1081 40 904 9 0.3 42 6 49 44 Absent Comparative Steel 37 37 1103 52 881 11 0.2 53 6 52 57 Absent Invention Steel 38 38 1081 41 889 9 0.2 53 7 56 59 Absent Invention Steel 39 39 1085 50 891 12 0.2 42 6 45 57 Absent Invention Steel 40 40 1073 53 901 10 0.2 53 4 45 60 Absent Comparative Steel 41 41 1128 55 917 12 0.2 50 7 53 57 Absent Invention Steel 42 42 1142 41 893 9 0.4 48 7 62 57 Absent Invention Steel 43 43 1090 54 890 12 0.2 53 7 49 54 Absent Invention Steel 44 44 1080 58 891 9 0.4 40 7 46 56 Absent Invention Steel 45 45 1126 53 890 10 0.2 52 6 50 42 Absent Invention Steel 46 46 1093 60 913 11 0.2 44 6 65 53 Absent Invention Steel 47 47 1136 52 882 12 0.2 54 6 57 52 Absent Invention Steel 48 48 1079 49 917 11 0.4 42 5 53 45 Absent Invention Steel 49 49 1112 57 892 8 0.3 41 4 64 45 Absent Invention Steel 50 50 1094 45 886 10 0.4 41 6 48 56 Absent Invention Steel 51 51 1121 51 896 12 0.2 52 7 47 57 Absent Invention Steel 52 52 1070 52 913 11 0.2 46 6 61 55 Absent Invention Steel 53 53 1109 56 910 11 0.4 47 4 45 43 Absent Invention Steel 54 54 1080 58 901 11 0.4 49 6 60 45 Absent Invention Steel 55 55 1129 42 903 8 0.4 49 7 55 54 Absent Invention Steel 56 56 1098 40 919 9 0.3 43 5 58 52 Absent Invention Steel 57 57 1079 57 887 12 0.4 50 7 57 52 Absent Invention Steel

TABLE-US-00008 TABLE 8 Steel sheet for hot stamping Grains having average crystal Plating Ni content orientation Steel adhesion in plating difference of 0.4° Sheet Steel sheet amount layer to 3.0° thickness No. No. (g/m.sup.2) (mass %) (area %) (mm) Note 31 31 46 16 90 1.5 Comparative Steel 32 32 40 16 87 2.0 Invention Steel 33 33 43 13 92 1.8 Invention Steel 34 34 46 16 85 1.6 Invention Steel 35 35 51 14 92 1.4 Invention Steel 36 36 47 13 90 1.5 Comparative Steel 37 37 52 12 92 1.6 Invention Steel 38 38 46 17 86 1.5 Invention Steel 39 39 60 16 91 1.9 Invention Steel 40 40 60 17 88 1.8 Comparative Steel 41 41 45 15 91 1.7 Invention Steel 42 42 58 15 86 1.5 Invention Steel 43 43 59 12 85 1.7 Invention Steel 44 44 45 17 86 1.9 Invention Steel 45 45 42 17 86 1.5 Invention Steel 46 46 58 16 91 1.8 Invention Steel 47 47 42 14 88 1.8 Invention Steel 48 48 48 13 86 1.7 Invention Steel 49 49 58 12 87 2.0 Invention Steel 50 50 42 10 86 1.4 Invention Steel 51 51 51 15 88 1.4 Invention Steel 52 52 60 10 91 1.9 Invention Steel 53 53 49 11 88 1.7 Invention Steel 54 54 40 16 87 1.6 Invention Steel 55 55 54 10 85 1.9 Invention Steel 56 56 44 14 90 2.0 Invention Steel 57 57 46 17 87 1.8 Invention Steel

TABLE-US-00009 TABLE 9 Hot rolling Cooling Average Average Average Heat cooling cooling cooling Cold treatment rate up to rate at rate in rolling before Rough rolling Finish rolling Cool- temperature 550° C. or temperature Cumu- plating Rolling Cumulative Rolling Final ing range of higher and range of lative Heating Steel temper- rolling temper- rolling start 650° C. lower than 550° C. rolling temper- Steel sheet ature reduction ature reduction time or lower 650° C. or lower reduction ature No. No. (° C.) (%) (° C.) (%) (sec) (° C./s) (° C./s) (° C./s) (%) (° C.) Note 7 58  990 57 894 11 0.3 52 4 48 60 Absent Comparative Steel 7 59 1065 52 891 10 0.2 43 7 60 46 Absent Invention Steel 7 60 1133 36 911 11 0.3 47 7 52 55 Absent Comparative Steel 7 61 1084 42 896 12 0.3 42 4 54 49 Absent Invention Steel 7 62 1113 45 790 10 0.2 48 4 48 48 Absent Comparative Steel 7 63 1126 53 839 12 0.2 41 6 47 53 Absent Invention Steel 7 64 1074 51 914  3 0.2 40 5 53 47 Absent Comparative Steel 7 65 1086 45 917  6 0.4 45 5 49 45 Absent Invention Steel 7 66 1074 58 915  9 0.3 46 6 63 50 Absent Invention Steel 7 67 1149 49 892 17 0.2 54 6 65 57 Absent Invention Steel 7 68 1100 57 890 26 0.4 51 5 56 59 Absent Comparative Steel 7 69 1090 52 908  8 0.3 49 5 48 49 Absent Invention Steel 7 70 1119 46 914  9 0.4 55 7 57 43 Absent Invention Steel 7 71 1096 58 909 10 0.7 51 5 51 57 Absent Comparative Steel 7 72 1075 48 883 10 0.4 26 4 56 55 Absent Comparative Steel 7 73 1081 55 905 12 0.4 33 4 55 43 Absent Invention Steel 7 74 1118 47 895  8 0.4 49 6 62 47 Absent Invention Steel 7 75 1130 49 912 11 0.2 44   0.6 54 52 Absent Comparative Steel 7 76 1093 49 885 11 0.2 42 2 64 44 Absent Invention Steel 7 77 1141 51 906 11 0.2 52 5 57 44 Absent Invention Steel 7 78 1147 58 882 10 0.4 47 9 55 57 Absent Invention Steel 7 79 1144 51 916  8 0.4 41 13  45 55 Absent Comparative Steel 7 80 1096 51 896  9 0.3 41 7 34 41 Absent Comparative Steel 7 81 1094 50 886 12 0.3 50 7 41 47 Absent Invention Steel 7 82 1107 51 919 10 0.4 41 5 59 49 Absent Invention Steel 7 83 1087 54 910  9 0.4 43 5 50  0 Absent Invention Steel 7 84 1078 55 913 12 0.2 46 4 64 40 711 Invention Steel 7 85 1089 43 904 12 0.3 44 6 62 58 Absent Invention Steel 7 86 1109 49 896  9 0.2 51 5 61 48 Absent Invention Steel 7 87 1149 52 898  8 0.4 53 6 46 45 Absent Invention Steel 7 88 1141 47 895  8 0.2 51 6 65 57 Absent Invention Steel 7 89 1096 49 906 10 0.4 52 5 56 43 Absent Invention Steel 7 90 1107 51 916  9 0.4 41 4 55 47 Absent Invention Steel 7 91 1087 51 886 12 0.2 41 5 64 44 Absent Invention Steel 7 92 1078 50 913 10 0.2 46 4 62 41 Absent Invention Steel

TABLE-US-00010 TABLE 10 Steel sheet for hot stamping Grains having average crystal Plating Ni content orientation Steel adhesion in plating difference of 0.4° Sheet Steel sheet amount layer to 3.0° thickness No. No. (g/m.sup.2) (mass %) (area %) (mm) Note 7 58 58 17 66 1.8 Comparative Steel 7 59 54 17 82 1.8 Invention Steel 7 60 59 11 56 1.4 Comparative Steel 7 61 41 16 82 1.9 Invention Steel 7 62 54 14 61 1.4 Comparative Steel 7 63 51 13 84 1.9 Invention Steel 7 64 42 13 57 1.6 Comparative Steel 7 65 43 17 83 1.4 Invention Steel 7 66 44 11 85 1.4 Invention Steel 7 67 49 10 82 1.5 Invention Steel 7 68 44 17 68 1.5 Comparative Steel 7 69 43 11 86 1.7 Invention Steel 7 70 60 10 82 1.4 Invention Steel 7 71 52 11 58 1.5 Comparative Steel 7 72 55 11 59 1.9 Comparative Steel 7 73 42 17 82 1.8 Invention Steel 7 74 45 15 84 1.7 Invention Steel 7 75 51 10 74 2.0 Comparative Steel 7 76 42 17 82 1.9 Invention Steel 7 77 50 14 81 1.4 Invention Steel 7 78 45 17 83 1.7 Invention Steel 7 79 54 15 28 1.6 Comparative Steel 7 80 45 10 76 1.4 Comparative Steel 7 81 40 10 81 2.0 Invention Steel 7 82 52 10 83 2.0 Invention Steel 7 83 49 12 86 1.4 Invention Steel 7 84 40 12 90 1.6 Invention Steel 7 85 50 13 85 1.9 Invention Steel 7 86 40 17 82 1.7 Invention Steel 7 87 52 10 83 1.5 Invention Steel 7 88 49 11 85 1.7 Invention Steel 7 89 55 11 82 1.4 Invention Steel 7 90 45 15 84 1.8 Invention Steel 7 91 45 17 83 1.9 Invention Steel 7 92 45 10 90 1.7 Invention Steel

TABLE-US-00011 TABLE 11 Hot rolling Cooling Average Average Average Heat cooling cooling cooling Cold treatment rate up to rate at rate in rolling before Rough rolling Finish rolling Cool- temperature 550° C. or temperature Cumu- plating Rolling Cumulative Rolling Final ing range of higher and range of lative Heating Steel temper- rolling temper- rolling start 650° C. lower than 550° C. rolling temper- Steel sheet ature reduction ature reduction time or lower 650° C. or lower reduction ature No. No. (° C.) (%) (° C.) (%) (sec) (° C./s) (° C./s) (° C./s) (%) (° C.) Note 58 93 1150 57 917 11 0.3 47 6 47 45 Absent Invention Steel 59 94 1131 46 890 10 0.2 48 5 49 45 Absent Invention Steel 60 95 1110 48 908 10 0.2 40 6 56 45 Absent Invention Steel 61 96 1108 55 883 12 0.2 54 5 57 45 Absent Invention Steel 7 97 1099 47 906 8 0.3 49 3 55 45 Absent Invention Steel 7 98 1088 47 919 10 0.4 55 2 62 45 Absent Invention Steel 7 99 1103 51 913 12 0.2 51 2 54 45 Absent Invention Steel 7 100 1098 50 895 9 0.2 43 3 51 45 Absent Invention Steel

TABLE-US-00012 TABLE 12 Steel sheet for hot stamping Grains having average crystal Plating Ni content orientation Steel adhesion in plating difference of 0.4° Sheet Steel sheet amount layer to 3.0° thickness No. No. (g/m.sup.2) (mass %) (area %) (mm) Note 58 93 49 11 90 1.4 Invention Steel 59 94 40 13 82 1.4 Invention Steel 60 95 49 10 85 1.4 Invention Steel 61 96 45 10 84 1.6 Invention Steel 7 97 45 11 95 1.4 Invention Steel 7 98 51 17 94 1.6 Invention Steel 7 99 50 14 96 1.6 Invention Steel 7 100 52 15 95 1.4 Invention Steel

TABLE-US-00013 TABLE 13 Heat treatment step during hot stamping Elapsed time Average from start of Steel heating Holding heating to Tempering Partially Steel sheet Manufacturing rate temperature forming temperature softened No. No. No. (° C./s) (° C.) (s) (° C.) region Note  1  1 A1  43 911 287 Absent Absent Comparative Steel  2  2 A2  48 908 272 Absent Absent Comparative Steel  3  3 A3  43 913 244 Absent Absent Comparative Steel  4  4 A4  39 893 288 Absent Absent Comparative Steel  5  5 A5  53 920 285 Absent Absent Invention Steel  6  6 A6  41 890 240 Absent Absent Invention Steel  7  7 A7  39 913 280 Absent Absent Invention Steel  8  8 A8  46 893 347 Absent Absent Invention Steel  9  9 A9  39 894 320 480 Absent Invention Steel 10 10 A10 52 919 283 Absent Absent Comparative Steel 11 11 A11 56 903 322 Absent Absent Comparative Steel 12 12 A12 46 890 346 Absent Absent Invention Steel 13 13 A13 55 903 321 Absent Absent Invention Steel 14 14 A14 47 910 357 Absent Absent Invention Steel 15 15 A15 45 899 304 Absent Absent Comparative Steel 16 16 A16 47 907 289 Absent Absent Invention Steel 17 17 A17 43 915 243 Absent Absent Invention Steel 18 18 A18 54 906 287 Absent Absent Invention Steel 19 19 A19 54 917 358 Absent Absent Invention Steel 20 20 A20 51 909 305 Absent Absent Invention Steel 21 21 A21 33 894 277 Absent Absent Comparative Steel 22 22 A22 45 919 268 Absent Absent Invention Steel 23 23 A23 34 902 317 Absent Absent Invention Steel 24 24 A24 50 891 323 Absent Absent Invention Steel 25 25 A25 31 900 276 Absent Absent Comparative Steel 26 26 A26 60 917 273 Absent Absent Invention Steel 27 27 A27 49 908 317 Absent Absent Invention Steel 28 28 A28 54 892 332 Absent Absent Invention Steel 29 29 A29 42 891 249 Absent Absent Invention Steel 30 30 A30 40 899 255 Absent Absent Comparative Steel

TABLE-US-00014 TABLE 14 Microstructure of hot-stamping formed body Martensite, Ratio of lengths of grain Mechanical properties Plating tempered boundaries having rotation Impact Steel adhesion Ni content in martensite, and angle of 64° to 72° with <011> Tensile value at Steel sheet Manufacturing amount plating layer lower bainite direction as rotation axis strength −60° C. No. No. No. (g/m.sup.2) (mass %) (area %) (%) (MPa) (J/cm.sup.2) Note  1  1 A1  41 15 92 25 2052  8 Comparative Steel  2  2 A2  53 12 97 21 2006  6 Comparative Steel  3  3 A3  40 12 93  4 2124  3 Comparative Steel  4  4 A4  56 15 47 42  972 46 Comparative Steel  5  5 A5  50 14 95 45 1620 38 Invention Steel  6  6 A6  41 15 94 44 1929 31 Invention Steel  7  7 A7  54 17 90 42 2011 28 Invention Steel  8  8 A8  57 15 94 43 2520 21 Invention Steel  9  9 A9  40 16 95 41 2580 23 Invention Steel 10 10 A10 53 17 96 42 2791  3 Comparative Steel 11 11 A11 48 12 90 29 2100 15 Invention Steel 12 12 A12 58 16 89 37 2144 26 Invention Steel 13 13 A13 48 17 88 41 2106 28 Invention Steel 14 14 A14 46 14 96 51 2017 30 Invention Steel 15 15 A15 58 10 44 42 1420 38 Comparative Steel 16 16 A16 51 17 87 45 2519 22 Invention Steel 17 17 A17 43 11 89 36 1890 27 Invention Steel 18 18 A18 52 12 89 39 1899 26 Invention Steel 19 19 A19 50 13 87 37 1910 28 hivention Steel 20 20 A20 45 11 92 41 1530 21 Invention Steel 21 21 A21 45 14 91 44 1540  3 Comparative Steel 22 22 A22 60 14 97 45 2087 31 Invention Steel 23 23 A23 47 15 91 44 2016 28 Invention Steel 24 24 A24 60 15 97 38 2070 22 Invention Steel 25 25 A25 58 13 92 42 2070 14 Comparative Steel 26 26 A26 60 15 94 44 2106 33 Invention Steel 27 27 A27 52 12 92 38 2119 31 Invention Steel 28 28 A28 50 10 91 39 2104 25 Invention Steel 29 29 A29 53 15 95 37 2049 22 Invention Steel 30 30 A30 51 11 87 45 2068 16 Comparative Steel

TABLE-US-00015 TABLE 15 Heat treatment step during hot stamping Elapsed time Average from start of Steel heating Holding heating to Tempering Partially Steel sheet Manufacturing rate temperature forming temperature softened No. No. No. (° C./s) (° C.) (s) (° C.) region Note 31 31 A31 52 896 349 Absent Absent Comparative Steel 32 32 A32 42 917 329 Absent Absent Invention Steel 33 33 A33 47 909 256 Absent Absent Invention Steel 34 34 A34 36 896 356 Absent Absent Invention Steel 35 35 A35 35 908 269 Absent Absent Invention Steel 36 36 A36 46 915 286 Absent Absent Comparative Steel 37 37 A37 42 914 263 Absent Absent Invention Steel 38 38 A38 45 917 256 Absent Absent Invention Steel 39 39 A39 57 897 295 Absent Absent Invention Steel 40 40 A40 52 903 329 Absent Absent Comparative Steel 41 41 A41 38 906 260 Absent Absent Invention Steel 42 42 A42 47 899 337 Absent Absent Invention Steel 43 43 A43 43 905 350 Absent Absent Invention Steel 44 44 A44 36 896 341 Absent Absent Invention Steel 45 45 A45 47 917 259 Absent Absent Invention Steel 46 46 A46 42 920 343 Absent Absent Invention Steel 47 47 A47 53 892 317 Absent Absent Invention Steel 48 48 A48 41 897 256 Absent Absent Invention Steel 49 49 A49 31 895 320 Absent Absent Invention Steel 50 50 A50 38 916 331 Absent Absent Invention Steel 51 51 A51 51 908 315 Absent Absent Invention Steel 52 52 A52 52 891 254 Absent Absent Invention Steel 53 53 A53 33 920 265 Absent Absent Invention Steel 54 54 A54 36 905 322 Absent Absent Invention Steel 55 55 A55 41 918 307 Absent Absent Invention Steel 56 56 A56 33 894 254 Absent Absent Invention Steel 57 57 A57 60 898 317 Absent Absent Invention Steel

TABLE-US-00016 TABLE 16 Microstructure of hot-stamping formed body Martensite, Ratio of lengths of grain Mechanical properties Plating tempered boundaries having rotation Impact Steel adhesion Ni content in martensite, and angle of 64° to 72° with <011> Tensile value at Steel sheet Manufacturing amount plating layer lower bainite direction as rotation axis strength −60° C. No. No. No. (g/m.sup.2) (mass %) (area %) (%) (MPa) (J/cm.sup.2) Note 31 31 A31 46 16 91 44 2147 13 Comparative Steel 32 32 A32 40 16 88 37 2067 23 Invention Steel 33 33 A33 43 13 96 36 2064 26 Invention Steel 34 34 A34 46 16 90 38 2139 29 Invention Steel 35 35 A35 51 14 95 45 2125 21 Invention Steel 36 36 A36 47 13 91 43 2025 17 Comparative Steel 37 37 A37 52 12 95 39 2025 29 Invention Steel 38 38 A38 46 17 96 39 2090 25 Invention Steel 39 39 A39 60 16 88 40 2015 23 Invention Steel 40 40 A40 60 17 94 42 2048 12 Comparative Steel 41 41 A41 45 15 96 36 2218 30 Invention Steel 42 42 A42 58 15 89 41 2185 25 Invention Steel 43 43 A43 59 12 97 45 2193 22 Invention Steel 44 44 A44 45 17 87 43 2213 27 Invention Steel 45 45 A45 42 17 95 36 2250 20 Invention Steel 46 46 A46 58 16 94 44 2129 22 Invention Steel 47 47 A47 42 14 88 43 2206 27 Invention Steel 48 48 A48 48 13 87 45 2152 30 Invention Steel 49 49 A49 58 12 87 45 2181 26 Invention Steel 50 50 A50 42 10 88 36 2199 26 Invention Steel 51 51 A51 51 15 88 39 2143 28 Invention Steel 52 52 A52 60 10 88 41 2182 28 Invention Steel 53 53 A53 49 11 88 37 2008 26 Invention Steel 54 54 A54 40 16 95 43 2068 31 Invention Steel 55 55 A55 54 10 93 43 2082 31 Invention Steel 56 56 A56 44 14 97 43 2066 33 Invention Steel 57 57 A57 46 17 94 39 2070 32 Invention Steel

TABLE-US-00017 TABLE 17 Heat treatment step during hot stamping Elapsed time Average from start of Steel heating Holding heating to Tempering Partially Steel sheet Manufacturing rate temperature forming temperature softened No. No. No. (° C./s) (° C.) (s) (° C.) region Note 7 58 A58 57 912 304 Absent Absent Comparative Steel 7 59 A59 47 910 296 Absent Absent Invention Steel 7 60 A60 43 894 256 Absent Absent Comparative Steel 7 61 A61 45 907 322 Absent Absent Invention Steel 7 62 A62 38 900 269 Absent Absent Comparative Steel 7 63 A63 57 912 336 Absent Absent Invention Steel 7 64 A64 59 890 339 Absent Absent Comparative Steel 7 65 A65 46 913 246 Absent Absent Invention Steel 7 66 A66 57 894 267 Absent Absent Invention Steel 7 67 A67 46 893 312 Absent Absent Invention Steel 7 68 A68 42 900 326 Absent Absent Comparative Steel 7 69 A69 60 913 286 Absent Absent Invention Steel 7 70 A70 42 903 343 Absent Absent Invention Steel 7 71 A71 52 903 241 Absent Absent Comparative Steel 7 72 A72 49 920 290 Absent Absent Comparative Steel 7 73 A73 38 903 253 Absent Absent Invention Steel 7 74 A74 60 912 342 Absent Absent Invention Steel 7 75 A75 54 896 250 Absent Absent Comparative Steel 7 76 A76 38 894 278 Absent Absent Invention Steel 7 77 A77 55 909 318 Absent Absent Invention Steel 7 78 A78 46 896 336 Absent Absent Invention Steel 7 79 A79 43 898 297 Absent Absent Comparative Steel 7 80 A80 49 918 360 Absent Absent Comparative Steel 7 81 A81 48 920 321 Absent Absent Invention Steel 7 82 A82 36 901 342 Absent Absent Invention Steel 7 83 A83 40 911 260 Absent Absent Invention Steel 7 84 A84 55 915 303 Absent Absent Invention Steel 7 85 A85  2 892 302 Absent Absent Invention Steel 7 86 A86 11 914 354 Absent Absent Invention Steel 7 87 A87 52 901 326 Absent Absent Invention Steel 7 88 A88 91 912 343 Absent Absent Invention Steel 7 89 A89 41 790 264 Absent Absent Comparative Steel 7 90 A90 58 1009  305 Absent Absent Comparative Steel 7 91 A91 36 918 336 180 Absent Invention Steel 7 92 A92 47 904 251 Absent Present Invention Steel

TABLE-US-00018 TABLE 18 Microstructure of hot-stamping formed body Martensite, Ratio of lengths of grain Mechanical properties Plating tempered boundaries having rotation Impact Steel adhesion Ni content in martensite, and angle of 64° to 72° with <011> Tensile value at Steel sheet Manufacturing amount plating layer lower bainite direction as rotation axis strength −60° C. No. No. No. (g/m.sup.2) (mass %) (area %) (%) (MPa) (J/cm.sup.2) Note 7 58 A58 58 17 97 16 2086 16 Comparative Steel 7 59 A59 54 17 93 36 2014 23 Invention Steel 7 60 A60 59 11 92 15 2133 17 Comparative Steel 7 61 A61 41 16 95 44 2015 24 Invention Steel 7 62 A62 54 14 91 12 2119 13 Comparative Steel 7 63 A63 51 13 91 40 2035 27 Invention Steel 7 64 A64 42 13 87 17 2123 18 Invention Steel 7 65 A65 43 17 87 42 2061 22 Invention Steel 7 66 A66 44 11 96 39 2092 28 Invention Steel 7 67 A67 49 10 91 39 2022 20 Invention Steel 7 68 A68 44 17 88 21 2057 15 Invention Steel 7 69 A69 43 11 96 36 2119 23 Invention Steel 7 70 A70 60 10 90 43 2044 22 Invention Steel 7 71 A71 52 11 94 19 2086 17 Comparative Steel 7 72 A72 55 11 96 22 2129 18 Comparative Steel 7 73 A73 42 17 93 44 2114 28 Invention Steel 7 74 A74 45 15 87 44 2112 26 Invention Steel 7 75 A75 51 10 90 12 2111 17 Comparative steel 7 76 A76 42 17 88 38 2040 23 Invention Steel 7 77 A77 50 14 90 41 2056 29 Invention Steel 7 78 A78 45 17 92 42 2124 27 Invention Steel 7 79 A79 54 15 97 14 2075 11 Comparative Steel 7 80 A80 45 10 87 31 2138 16 Comparative Steel 7 81 A81 40 10 89 43 2074 25 Invention Steel 7 82 A82 52 10 90 49 2025 32 Invention Steel 7 83 A83 49 12 89 45 2094 21 Invention Steel 7 84 A84 40 12 94 36 2068 22 Invention Steel 7 85 A85 50 13 87 55 2108 35 Invention Steel 7 86 A86 40 17 90 51 2118 33 Invention Steel 7 87 A87 52 10 90 41 2007 30 Invention Steel 7 88 A88 49 11 89 36 2143 26 Invention Steel 7 89 A89 55 11 91  6 2094  8 Comparative Steel 7 90 A90 45 15 95  7 2066 14 Comparative Steel 7 91 A91 45 17 88 43 2125 22 Invention Steel 7 92 A92 45 10 88 42 2025 26 Invention Steel

TABLE-US-00019 TABLE 19 Heat treatment step during hot stamping Elapsed time Average from start of Steel heating Holding heating to Tempering Partially Steel sheet Manufacturing rate temperature forming temperature softened No. No. No. (° C./s) (° C.) (s) (° C.) region Note 58 93 A93 38 912 312 Absent Absent Invention Steel 59 94 A94 46 900 286 Absent Absent Invention Steel 60 95 A95 42 912 290 Absent Absent Invention Steel 61 96 A96 38 920 250 Absent Absent Invention Steel  7 97 A97 55 912 278 Absent Absent Invention Steel  7 98 A98 43 913 336 Absent Absent Invention Steel  7 99 A99 40 915 321 Absent Absent Invention Steel  7 100   A100 39 912 281 Absent Absent Invention Steel

TABLE-US-00020 TABLE 20 Microstructure of hot-stamping formed body Martensite, Ratio of lengths of grain Mechanical properties Plating tempered boundaries having rotation Impact Steel adhesion Ni content in martensite, and angle of 64° to 72° with <011> Tensile value at Steel sheet Manufacturing amount plating layer lower bainite direction as rotation axis strength −60° C. No. No. No. (g/m.sup.2) (mass %) (area %) (%) (MPa) (J/cm.sup.2) Note 58 93 A93 42 14 96 45 1620 38 Invention Steel 59 94 A94 54 11 95 44 1591 35 Invention Steel 60 95 A95 40 11 94 41 1578 38 Invention Steel 61 96 A96 49 10 91 43 1599 32 Invention Steel  7 97 A97 40 11 90 59 2091 31 Invention Steel  7 98 A98 49 17 93 62 2101 29 Invention Steel  7 99 A99 55 12 91 66 2077 28 Invention Steel  7 100   A100 45 10 92 63 2061 34 Invention Steel

[0129] The microstructure of the steel sheets for hot stamping and the hot-stamping formed bodies was measured by the above-mentioned measurement methods. The mechanical properties of the hot-stamping formed bodies were evaluated by the following methods.

“Tensile Strength”

[0130] The tensile strength of the hot-stamping formed body was obtained in accordance with the test method described in JIS Z 2241:2011 by producing a No. 5 test piece described in JIS Z 2201:2011 from any position in the hot-stamping formed body.

“Toughness”

[0131] The toughness was evaluated by a Charpy impact test at −60° C. The toughness was evaluated by collecting a sub-size Charpy impact test piece from any position of the hot-stamping formed body and obtaining an impact value at −60° C. according to the test method described in JIS Z 2242:2005.

[0132] In a case where the tensile strength was 1,500 MPa or more and the impact value at −60° C. was 20 J/cm.sup.2 or more was determined to be an invention example as being excellent in strength and toughness. In a case where any one of the above two performances was not satisfied, the case was determined to be a comparative example.

[0133] In the invention examples of Tables 14, 16, 18, and 20, the remainder in the microstructure contained one or more of residual austenite, ferrite, pearlite, granular bainite, and upper bainite.

[0134] Referring to Tables 14, 16, 18, and 20, it can be seen that a hot-stamping formed body in which the chemical composition, the plating composition, and the microstructure are within the ranges of the present invention has excellent strength and toughness.

[0135] On the other hand, it can be seen that a hot-stamping formed body in which any one or more of the chemical composition and the microstructure deviates from the present invention is inferior in one or more of strength and toughness.

INDUSTRIAL APPLICABILITY

[0136] According to the present invention, it is possible to provide a hot-stamping formed body having high strength and having better toughness than in the related art is obtained.