HOT-STAMP-MOLDED ARTICLE

Abstract

A hot-stamped article according to the present invention has a plating layer being attached to a single surface in an amount of 10 g/m.sup.2 or more and 90 g/m.sup.2 or less and having a Ni content of 10 mass % or more and 25 mass % or less with a remainder including Zn and impurities on a surface of a base steel sheet having a predetermined chemical composition, in a surface layer region, a metallographic structure includes 80.0% or more of martensite and 8.0% or more of residual austenite in terms of area percentage, and the concentration of Ni in the surface layer region is 8 mass % or more.

Claims

1. A hot-stamped article comprising: a base steel sheet containing, as chemical components, by mass %, C: 0.15% or more and less than 0.70%, Si: 0.005% or more and 0.250% or less, Mn: 0.30% or more and 3.00% or less, sol. Al: 0.0002% or more and 0.500% or less, P: 0.100% or less, S: 0.1000% or less, N: 0.0100% or less, Nb: 0% or more and 0.150% or less, Ti: 0% or more and 0.150% or less, Mo: 0% or more and 1.000% or less, Cr: 0% or more and 1.000% or less, B: 0% or more and 0.0100% or less, Ca: 0% or more and 0.0100% or less, and REM: 0% or more and 0.30% or less with a remainder including Fe and impurities; and a plating layer on a surface of the base steel sheet, the plating layer being attached to a single surface in an amount of 10 g/m.sup.2 or more and 90 g/m.sup.2 or less and having a Ni content of 10 mass % or more and 25 mass % or less with a remainder including Zn and impurities, wherein a metallographic structure of a surface layer region that is a region from the surface of the base steel sheet to a depth of 50 μm includes 80.0% or more of martensite and 8.0% or more of residual austenite in terms of area percentage, and a concentration of Ni in the surface layer region is 8 mass % or more.

2. The hot-stamped article according to claim 1, wherein the base steel sheet contains, as chemical components, by mass %, one or more selected from the group of Nb: 0.010% or more and 0.150% or less, Ti: 0.010% or more and 0.150% or less, Mo: 0.005% or more and 1.000% or less, Cr: 0.005% or more and 1.000% or less, B: 0.0005% or more and 0.0100% or less, Ca: 0.0005% or more and 0.0100% or less, and REM: 0.0005% or more and 0.30% or less.

Description

EXAMPLES

[0150] Next, examples of the present invention will be described. Conditions in the examples are examples of conditions adopted to confirm the feasibility and effect of the present invention, and the present invention is not limited to these examples of conditions. The present invention is capable of adopting a variety of conditions as long as the objective of the present invention is achieved without departing from the gist of the present invention.

[0151] Steel pieces manufactured by casting molten steel having a chemical composition shown in Tables 1 and 2 were hot-rolled, cold-rolled, and plated under conditions shown in Tables 3 and 4, thereby obtaining steel sheets for hot stamping shown in Tables 3 and 4. The obtained steel sheets for hot stamping were hot-stamped by carrying out a heat treatment shown in Tables 5 and 6, thereby obtaining hot-stamped articles shown in Tables 5 and 6. A partial softened region was formed by irradiating a part of the hot-stamped article with a laser, cooling the irradiated portion to lower than the Ms−15° C., and tempering the irradiated portion.

[0152] Underlined values in the tables indicate that the values are outside the scope of the present invention, the preferred manufacturing conditions are not satisfied, or property values are not preferable.

TABLE-US-00001 TABLE 1 Steel Chemical composition (mass %) with remainder of Fe and impurities A.sub.3 No. C Si Mn P S sol•Al N Nb Ti Mo Cr B Ca REM (° C.) Note 1 0.16 0.250 1.10 0.006  0.0020 0.030 0.0026 0.130 865 Invention steel 2 0.44 0.250 1.80 0.010  0.0090 0.400 0.0040 0.03 858 Invention steel 3 0.23 0.250 1.20 0.010  0.0100 0.030 0.0050 0.020 0.200 860 Invention steel 4 0.08 0.220 0.81 0.008  0.0009 0.044 0.0026 851 Comparative steel 5 0.16 0.150 0.71 0.011  0.0006 0.043 0.0037 851 Invention steel 6 0.31 0.250 0.80 0.015  0.0011 0.041 0.0039 853 Invention steel 7 0.36 0.180 0.81 0.005  0.0005 0.045 0.0037 853 Invention steel 8 0.44 0.250 0.71 0.015  0.0007 0.034 0.0042 853 Invention steel 9 0.67 0.190 0.71 0.014  0.0003 0.037 0.0035 855 Invention steel 10 0.78 0.250 0.90 0.014  0.0011 0.031 0.0026 857 Comparative steel 11 0.36 0.002 0.86 0.005  0.0003 0.041 0.0032 853 Comparative steel 12 0.38 0.007 0.83 0.005  0.0011 0.050 0.0030 853 Invention steel 13 0.37 0.210 0.72 0.011  0.0007 0.030 0.0041 853 Invention steel 14 0.37 0.240 0.90 0.015  0.0007 0.047 0.0037 853 Invention steel 15 0.37 0.150 0.15 0.005  0.0003 0.035 0.0030 851 Comparative + steel 16 0.44 0.170 0.44 0.007  0.0005 0.049 0.0029 852 Invention steel 17 0.36 0.240 0.82 0.010  0.0011 0.035 0.0038 853 Invention steel 18 0.37 0.180 1.29 0.007  0.0010 0.030 0.0028 855 Invention steel 19 0.37 0.150 1.99 0.009  0.0005 0.035 0.0042 857 Invention steel 20 0.38 0.170 2.89 0.007  0.0005 0.046 0.0037 861 Invention steel 21 0.38 0.150 3.15 0.012  0.0009 0.036 0.0042 862 Comparative steel 22 0.38 0.240 0.82 0.0004 0.0007 0.045 0.0026 853 Invention steel 23 0.36 0.160 0.90 0.009  0.0006 0.030 0.0038 853 Invention steel 24 0.36 0.150 0.77 0.094  0.0010 0.043 0.0033 853 Invention steel 25 0.37 0.190 0.84 0.123  0.0010 0.033 0.0032 853 Comparative steel 26 0.36 0.200 0.75 0.009  0.0002 0.047 0.0045 853 Invention steel 27 0.37 0.150 0.81 0.013  0.0003 0.031 0.0029 853 Invention steel 28 0.37 0.190 0.89 0.008  0.0022 0.044 0.0032 853 Invention steel 29 0.36 0.230 0.80 0.007  0.0900 0.049 0.0030 853 Invention steel 30 0.36 0.190 0.72 0.006  0.1334 0.045 0.0025 853 Comparative steel

TABLE-US-00002 TABLE 2 Steel Chemical composition (mass %) with remainder of Fe and impurities A.sub.3 No. C Si Mn P S sol•Al N Nb Ti Mo Cr B Ca REM (° C.) Note 31 0.38 0.230 0.79 0.013 0.0008 0.0001 0.0027 853 Comparative steel 32 0.38 0.160 0.85 0.010 0.0009 0.0003 0.0033 853 Invention steel 33 0.35 0.200 0.72 0.014 0.0007 0.0029 0.0042 853 Invention steel 34 0.37 0.160 0.73 0.006 0.0006 0.031  0.0026 853 Invention steel 35 0.35 0.240 0.83 0.009 0.0008 0.494  0.0034 853 Invention steel 36 0.37 0.240 0.84 0.011 0.0007 0.581  0.0040 853 Comparative steel 37 0.37 0.220 0.89 0.007 0.0007 0.035  0.0001 853 Invention steel 38 0.38 0.150 0.89 0.009 0.0008 0.038  0.0073 853 Invention steel 39 0.38 0.190 0.71 0.007 0.0007 0.039  0.0090 853 Invention steel 40 0.36 0.210 0.73 0.008 0.0003 0.035  0.0160 853 Comparative steel 41 0.37 0.230 0.87 0.009 0.0006 0.031  0.0025 0.012 857 Invention steel 42 0.36 0.170 0.70 0.009 0.0009 0.046  0.0030 0.032 864 Invention steel 43 0.37 0.220 0.73 0.008 0.0004 0.033  0.0038 0.120 895 Invention steel 44 0.37 0.230 0.90 0.009 0.0011 0.044  0.0044 0.013 857 Invention steel 45 0.35 0.170 0.89 0.011 0.0007 0.043  0.0028 0.036 862 Invention steel 46 0.36 0.170 0.88 0.007 0.0004 0.031  0.0033 0.140 888 Invention steel 47 0.36 0.210 0.80 0.005 0.0003 0.037  0.0035 0.006 854 Invention steel 48 0.37 0.200 0.78 0.009 0.0010 0.031  0.0026 0.012 854 Invention steel 49 0.38 0.160 0.82 0.015 0.0009 0.031  0.0041 0.980 951 Invention steel 50 0.36 0.230 0.77 0.011 0.0008 0.043  0.0038 0.006 853 Invention steel 51 0.35 0.160 0.70 0.005 0.0006 0.047  0.0026 0.009 853 Invention steel 52 0.37 0.250 0.83 0.006 0.0010 0.033  0.0039 0.960 863 Invention steel 53 0.37 0.150 0.70 0.015 0.0008 0.031  0.0044 0.0006 853 Invention steel 54 0.36 0.230 0.86 0.005 0.0003 0.050  0.0044 0.0011 853 Invention steel 55 0.36 0.160 0.74 0.015 0.0006 0.034  0.0044 0.0090 853 Invention steel 56 0.36 0.160 0.78 0.015 0.0006 0.037  0.0039 0.0080 853 Invention steel 57 0.36 0.190 0.80 0.010 0.0006 0.034  0.0027 0.28 853 Invention steel 58 0.14 0.110 0.84 0.011 0.0008 0.036  0.0031 851 Comparative steel 59 0.20 0.210 1.32 0.012 0.0007 0.028  0.0027 853 Invention steel

TABLE-US-00003 TABLE 3 Finishing rolling Cold Heat Steel sheet for hot stamping Final Cooling Coiling roll- treatment Ni Aver- Unauto- rolling Finish- Time Coiling ing before con- age mar- reduc- ing until Cool- initi- Roll- plating tent in dis- tensite tion of rolling initi- ing ation ing Heating Amount plating location and Sheet Steel finishing temper- ation rate temper- reduc- temper- of plate layer density lower thick- Steel sheet rolling ature of cool- (° C./ ature tion ature attached (mass (10.sup.14 m/ bainite ness No. No. (%) (° C.) ing (s) s) (°C) (%) (°C.) (g/m.sup.2) %) m.sup.3) (area %) (mm) Note 1 1 6 910 3 38 571 41 N/A 39 15 1 4.9 1.6 Com- parative steel 2 2 5 921 2 32 596 40 N/A 55 12 29 2.1 1.6 Com- parative steel 3 3 5 934 3 51 397 50 773 41 12 21 6.3 1.6 Com- parative steel 4 4 9 954 1 126 372 53 N/A 56 15 3 9.8 1.6 Com- parative steel 5 5 6 884 4 115 369 58 N/A 50 17 41 18.4 2.0 Invention steel 6 6 8 917 2 133 345 45 N/A 41 17 96 21.2 1.9 Invention steel 7 7 10 901 1 123 330 44 N/A 54 25 187 21.9 1.5 Invention steel 8 8 10 897 4 103 266 49 N/A 57 16 345 18.5 1.7 Invention steel 9 9 6 924 1 115 261 53 N/A 40 17 948 21.3 1.6 Invention steel 10 10 10 898 1 115 316 43 N/A 53 18 1120 24.7 1.3 Com- parative steel 11 11 8 905 1 142 292 55 N/A 48 18 155 18.1 1.3 Com- parative steel 12 12 5 887 4 118 353 60 N/A 58 15 230 19.9 1.6 Invention steel 13 13 5 926 3 146 390 47 N/A 48 15 223 22.3 1.6 Invention steel 14 14 9 890 3 134 283 55 N/A 46 15 219 17.6 1.8 Invention steel 15 15 8 933 1 123 329 53 N/A 58 18 11 3.7 1.6 Com- parative steel 16 16 6 885 4 115 329 52 N/A 51 17 372 22.0 1.3 Invention steel 17 17 9 900 3 133 379 45 N/A 43 18 157 22.7 1.2 Invention steel 18 18 7 876 4 134 250 42 N/A 52 17 184 16.6 1.7 Invention steel 19 19 10 942 1 105 315 59 N/A 50 17 229 20.3 1.9 Invention steel 20 20 10 960 3 125 273 49 N/A 45 17 217 22.4 2.0 Invention steel 21 21 5 895 2 147 343 41 N/A 45 17 192 24.4 1.6 Com- parative steel 22 22 8 931 3 123 354 43 N/A 60 17 178 20.3 1.8 Invention steel 23 23 10 961 1 138 272 48 N/A 47 15 159 18.4 2.0 Invention steel 24 24 10 955 2 124 330 45 N/A 60 15 189 18.9 1.2 Invention steel 25 25 5 901 1 104 310 50 N/A 58 15 237 20.9 1.6 Com- parative steel 26 26 5 892 4 134 329 52 N/A 60 16 206 21.2 1.2 Invention steel 27 27 10 938 3 104 251 41 N/A 52 17 164 19.2 1.5 Invention steel 28 28 7 953 1 149 372 60 N/A 50 18 172 23.4 1.8 Invention steel 29 29 10 943 1 126 382 41 N/A 53 17 201 21.5 1.6 Invention steel 30 30 7 948 1 148 260 44 N/A 51 16 237 16.9 1.2 Com- parative steel 31 31 5 895 1 115 328 52 N/A 46 16 152 18.5 1.8 Com- parative steel 32 32 6 918 1 126 341 52 N/A 40 15 214 22.4 1.2 Invention steel 33 33 6 885 4 106 314 47 N/A 43 18 181 18.0 1.5 Invention steel 34 34 5 883 3 149 266 45 N/A 46 15 156 19.9 1.8 Invention steel 35 35 6 947 1 131 387 57 N/A 51 15 151 22.3 1.9 Invention steel 36 36 8 877 3 109 291 47 N/A 47 15 206 16.1 1.6 Com- parative steel 37 37 9 947 2 118 365 45 N/A 52 16 171 21.4 1.7 Invention steel 38 38 6 924 4 145 393 45 N/A 46 15 212 23.1 1.8 Invention steel 39 39 9 938 3 143 354 51 N/A 60 16 173 22.2 1.2 Invention steel 40 40 5 943 1 144 395 40 N/A 60 16 220 23.7 1.8 Com- parative steel

TABLE-US-00004 TABLE 4 Finishing rolling Cold Heat Steel sheet for hot stamping Final Cooling Coiling roll- treatment Ni Aver- Unauto- rolling Finish- Time Coiling ing before con- age mar- reduc- ing until Cool- initi- Roll- plating Amount tent in dis- tensite tion of rolling initi- ing ation ing Heating of plating location and Sheet Steel finishing temper- ation rate temper- reduc- temper- plate layer density lower thick- Steel sheet rolling ature of cool- (° C./ ature tion ature attached (mass (10.sup.14 m/ bainite ness No. No. (%) (° C.) ing (s) s) (° C.) (%) (° C.) (g/m.sup.2) %) m.sup.3) (area %) (mm) Note 41 41 9 921 2 114 394 58 N/A 45 16 169 23.1 2.0 Invention steel 42 42 9 898 1 106 330 48 N/A 58 15 229 18.9 1.8 Invention steel 43 43 10 952 4 131 376 55 N/A 59 15 233 23.2 1.6 Invention steel 44 44 5 902 4 119 291 52 N/A 45 16 219 19.7 1.2 Invention steel 45 45 6 929 4 131 342 42 N/A 42 18 223 22.4 1.5 Invention steel 46 46 10 929 3 117 316 54 N/A 58 17 219 21.5 2.0 Invention steel 47 47 9 896 4 149 269 55 N/A 42 17 226 17.5 1.5 Invention steel 48 48 10 928 2 110 331 46 N/A 48 17 223 20.5 1.8 Invention steel 49 49 9 987 2 102 386 58 N/A 58 17 176 23.4 1.3 Invention steel 50 50 5 953 2 109 343 43 N/A 42 17 198 19.7 1.6 Invention steel 51 51 9 928 4 101 316 46 N/A 51 15 216 19.2 1.6 Invention steel 52 52 10 939 4 106 338 56 N/A 60 16 197 21.5 1.6 Invention steel 53 53 5 936 4 144 276 57 N/A 49 17 239 19.9 1.9 Invention steel 54 54 10 876 1 104 315 51 N/A 40 18 211 18.3 1.4 Invention steel 55 55 9 944 2 108 338 40 N/A 54 16 209 21.6 1.7 Invention steel 56 56 9 883 3 138 344 50 N/A 44 15 181 22.6 1.7 Invention steel 57 57 9 916 4 127 263 47 N/A 46 16 166 18.9 1.5 Invention steel 7 58 7 887 7 137 255 40 N/A 54 25 21 8.9 1.9 Com- parative steel 7 59 10 890 4 72 260 47 N/A 54 25 34 3.9 1.3 Com- parative steel 7 60 9 900 2 88 379 54 N/A 54 25 213 19.7 1.8 Invention steel 7 61 6 946 2 176 325 47 N/A 54 25 216 21.3 1.4 Invention steel 7 62 8 963 2 113 536 56 N/A 54 25 28 1.8 1.8 Com- parative steel 7 63 9 905 3 134 308 51 N/A 54 25 238 25.1 1.3 Invention steel 7 64 6 911 3 118 220 59 N/A 54 25 174 28.6 1.9 Invention steel 7 65 5 908 3 139 94 45 N/A 54 25 204 39.4 1.4 Invention steel 7 66 8 881 4 137 42 56 N/A 54 25 206 46.8 1.6 Invention steel 7 67 10 874 2 108 365 43 320 54 25 94 15.3 1.5 Invention steel 7 68 6 898 2 119 386 0 N/A 54 25 203 21.5 2.8 Invention steel 7 69 10 901 1 123 330 44 N/A 54 8 187 21.9 1.5 Com- parative steel 7 70 10 901 1 123 330 44 N/A 54 11 187 21.9 1.5 Invention steel 2 71 40 901 5 82 418 51 N/A 47 15 2 3.1 1.4 Com- parative steel 9 72 9 932 2 58 403 53 N/A 41 16 721 12.6 1.4 Com- parative steel 58 73 8 946 3 87 486 49 N/A 55 14 29 44.4 1.6 Com- parative steel 59 74 9 957 3 102 283 50 N/A 45 17 71 19.7 1.6 Invention steel

TABLE-US-00005 TABLE 5 Heat treatment process during hot stamping Ni Elapsed content Surface layer region Heat- Hold- time from Tem- in Concen- Resi- Mechanical ing ing initiation of pering Amount plating tration Mar- dual properties Steel Manu- rate temper- heating to temper- Partial of plate layer of Ni tensite γ Tensile Bending Steel sheet facture (°C./ ature initiation of ature softened attached (mass (mass (area (area strength angle No. No. No. s) (°C.) forming (s) (°C.) region (g/m.sup.2) %) %) %) %) (MPa) (°) Note 1 1 A1  6 901 296 N/A No 39 15 3 96.7 2.1 1503 48 Com- parative steel 2 2 A2  48 889 303 N/A No 55 12 1 96.4 1.1 2403 33 Com- parative steel 3 3 A3  23 906 305 N/A No 41 12 3 93.4 2.0 1618 45 Com- parative steel 4 4 A4  4 903 319 N/A No 56 15 2 87.4 2.3 1001 — Com- parative steel 5 5 A5  1 877 306 N/A No 50 17 13 85.5 12.4 1555 71 Invention steel 6 6 A6  4 909 284 N/A No 41 17 13 82.9 12.8 1867 68 Invention steel 7 7 A7  2 873 287 N/A No 54 25 18 86.5 13.2 2025 59 Invention steel 8 8 A8  13 867 297 N/A No 57 16 10 89.9 9.9 2520 51 Invention steel 9 9 A9  8 896 295 247 No 40 17 10 89.4 10.1 1716 65 Invention steel 10 10 A10 2 935 302 N/A No 53 18 11 85.3 10.8 1298 — Com- parative steel 11 11 A11 15 894 318 N/A No 48 18 14 86.5 8.3 2208 41 Com- parative steel 12 12 A12 10 946 292 N/A No 58 15 11 90.1 8.9 2022 52 Invention steel 13 13 A13 2 886 284 N/A No 48 15 11 84.9 10.3 1936 61 Invention steel 14 14 A14 12 904 313 N/A No 46 15 11 86.8 10.9 2134 66 Invention steel 15 15 A15 53 862 301 N/A No 58 18 3 60.9 4.5 1361 — Com- parative steel 16 16 A16 68 902 306 N/A No 51 17 10 87.7 9.9 2544 50 Invention steel 17 17 A17 19 949 306 N/A No 43 18 8 87.5 8.6 2008 63 Invention steel 18 18 A18 9 881 307 N/A No 52 17 9 88.3 8.6 2163 57 Invention steel 19 19 A19 74 939 315 N/A No 50 17 14 82.9 13.0 2018 52 Invention steel 20 20 A20 23 911 316 N/A No 45 17 9 90.3 8.9 2101 51 Invention steel 21 21 A21 37 911 306 N/A No 45 17 15 81.7 14.9 2208 46 Com- parative steel 22 22 A22 51 917 313 N/A No 60 17 15 81.5 15.3 1935 65 Invention steel 23 23 A23 33 898 285 N/A No 47 15 13 84.7 13.3 2111 61 Invention steel 24 24 A24 39 888 292 N/A No 60 15 12 85.4 11.6 1967 55 Invention steel 25 25 A25 34 870 305 N/A No 58 15 9 90.6 9.1 2043 42 Com- parative steel 26 26 A26 31 932 310 N/A No 60 16 13 84.3 13.3 2204 64 Invention steel 27 27 A27 72 918 286 N/A No 52 17 14 85.8 13.1 2062 65 Invention steel 28 28 A28 19 940 296 N/A No 50 18 10 87.3 10.6 2069 64 Invention steel 29 29 A29 15 864 284 N/A No 53 17 15 80.6 15.3 2068 58 Invention steel 30 30 A30 30 942 312 N/A No 51 16 16 82.2 15.1 2083 48 Com- parative steel 31 31 A31 33 941 302 N/A No 46 16 9 86.6 9.1 2170 38 Com- parative steel 32 32 A32 42 893 314 N/A No 40 15 13. 84.4 13.7 1981 57 Invention steel 33 33 A33 27 915 288 N/A No 43 18 14 84.0 14.3 2053 60 Invention steel 34 34 A34 17 889 287 N/A No 46 15 14 81.8 13.4 2040 62 Invention steel 35 35 A35 49 881 304 N/A No 51 15 14 83.3 13.6 1985 56 Invention steel 36 36 A36 23 888 282 N/A No 47 15 16 81.9 16.4 2045 46 Com- parative steel 37 37 A37 28 946 305 N/A No 52 16 9 86.6 9.2 2027 61 Invention steel 38 38 A38 13 921 295 N/A No 46 15 14 82.8 13.2 2096 55 Invention steel 39 39 A39 60 915 302 N/A No 60 16 12 83.7 11.9 2007 51 Invention steel 40 40 A40 65 925 305 N/A No 60 16 13 85.0 12.7 1988 45 Com- parative steel

TABLE-US-00006 TABLE 6 Heat treatment process during hot stamping Ni Elapsed content Surface layer region Heat- Hold- time from Tem- in Concen- Resi- Mechanical ing ing initiation of pering Amount plating tration Mar- dual properties Steel Manu- rate temper- heating to temper- Partial of plate layer of Ni tensite γ Tensile Bending Steel sheet facture (°C./ ature initiation of ature softened attached (mass (mass (area (area strength angle No. No. No. s) (°C.) forming (s) (°C.) region (g/m.sup.2) %) %) %) %) (MPa) (°) Note 41 41 A41 40 912 319 N/A No 45 16 13 84.3 12.8 2207 65 Invention steel 42 42 A42 65 877 299 N/A No 58 15 10 86.9 10.7 2171 65 Invention steel 43 43 A43 70 984 302 N/A No 59 15 10 86.8 10.1 2124 63 Invention steel 44 44 A44 76 898 289 N/A No 45 16 9 89.0 8.6 2250 58 Invention steel 45 45 A45 55 944 319 N/A No 42 18 13 87.3 12.4 2044 62 Invention steel 46 46 A46 39 918 307 N/A No 58 17 15 81.6 16.0 2272 61 Invention steel 47 47 A47 57 885 320 N/A No 42 17 9 91.2 8.8 2217 61 Invention steel 48 48 A48 33 867 307 N/A No 48 17 9 90.5 8.8 2225 58 Invention steel 49 49 A49 49 1005 302 247 No 58 17 13 85.7 12.7 2265 61 Invention steel 50 50 A50 52 879 285 N/A No 42 17 13 82.2 13.1 2143 64 Invention steel 51 51 A51 47 871 305 N/A No 51 15 16 81.6 15.0 2247 64 Invention steel 52 52 A52 70 903 311 N/A No 60 16 12 84.1 11.5 2088 61 Invention steel 53 53 A53 69 925 299 N/A No 49 17 9 88.8 9.4 2109 60 Invention steel 54 54 A54 59 923 305 N/A No 40 18 14 83.6 13.7 1999 61 Invention steel 55 55 A55 63 898 304 N/A No 54 16 16 83.4 14.7 2045 63 Invention steel 56 56 A56 57 953 307 N/A No 44 15 9 90.4 8.5 2029 64 Invention steel 57 57 A57 61 939 294 N/A No 46 16 10 88.3 10.3 2102 60 Invention steel 7 58 A58 52 933 307 N/A No 54 25 4 84.3 2.9 2132 41 Com- parative steel 7 59 A59 6 878 302 N/A No 54 25 5 85.5 4.1 2112 43 Com- parative steel 7 60 A60 67 890 280 N/A No 54 25 8 86.4 8.9 1989 51 Invention steel 7 61 A61 44 942 320 N/A No 54 25 18 88.0 10.1 2132 71 Invention steel 7 62 A62 75 878 301 N/A No 54 25 2 84.5 3.8 2112 47 Com- parative steel 7 63 A63 7 865 318 N/A No 54 25 18 84.8 15.1 1968 58 Invention steel 7 64 A64 38 887 309 N/A No 54 25 20 82.1 15.8 1989 61 Invention steel 7 65 A65 31 882 299 N/A No 54 25 22 82.9 16.1 2009 69 Invention steel 7 66 A66 5 909 308 N/A No 54 25 23 84.7 15.1 2030 72 Invention steel 7 67 A67 21 917 284 N/A No 54 25 8 90.3 8.1 2132 56 Invention steel 7 68 A68 42 950 290 N/A No 54 25 13 86.7 12.1 2009 58 Invention steel 7 69 A69 75 914 319 N/A No 54 8 7 90.0 7.5 1948 46 Com- parative steel 7 70 A70 70 943 313 N/A No 54 11 8 88.1 8.2 2037 52 Invention steel 7 7 A71 92 937 294 N/A No 54 25 12 89.3 10.1 2018 53 Invention steel 7 7 A72 105 935 306 N/A No 54 25 4 94.7 2.8 2079 48 Com- parative steel 7 7 A73 30 779 314 N/A No 54 25 5 76.4 0.8 1323 — Com- parative steel 7 7 A74 40 1040 303 N/A No 54 25 14 82.9 14.1 2110 34 Com- parative steel 7 7 A75 87 891 227 N/A No 54 25 6 90.3 6.2 2171 37 Com- parative steel 7 7 A76 26 947 523 N/A No 54 25 14 66.6 1.1 1599 38 Com- parative steel 7 7 A77 10 891 304 N/A Yes 54 25 13 83.8 13.1 2129 61 Invention steel 2 71 A78 16 902 300 N/A No 47 15 1 71.1 3.3 2289 48 Com- parative steel 9 72 A79 77 907 289 N/A No 41 16 6 94.1 3.8 2601 29 Com- parative steel 58 73 A80 6 918 280 N/A No 55 14 8 91.7 8.1 1458 — Com- parative steel 59 74 A81 3 922 291 N/A No 45 17 9 88.2 9.9 1521 69 Invention steel

[0153] The metallographic structures, the average dislocation densities, and the concentrations (amounts) of Ni of the steel sheets for hot stamping and the hot-stamped articles were measured by the above-described measurement methods. In addition, the mechanical properties of the hot-stamped articles were evaluated by the following methods.

[0154] “Tensile Strength”

[0155] Regarding the tensile strength of the hot-stamped article, a No. 5 test piece described in JIS Z 2201: 2011 was produced from an arbitrary position in the hot-stamped article, and the tensile strength was obtained according to the testing method described in JIS Z 2241: 2011. In a case where the tensile strength was lower than 1500 MPa, the tensile strength was evaluated as failure, and a test described below was not carried out.

[0156] “Bendability”

[0157] The bendability of the hot-stamped article was evaluated by the following method based on the VDA standard (VDA238-100) specified by Verband der Automobilindustrie. In the present examples, displacement under the maximum load that was obtained in a bending test was converted to an angle based on VDA, thereby obtaining the maximum bending angle (°).

[0158] Test piece dimensions: 60 mm (rolling direction)×60 mm (direction parallel to sheet width direction) or 30 mm (rolling direction)×60 mm (direction parallel to sheet width direction)

[0159] Test piece sheet thickness: 1.0 mm (the front and rear surfaces were polished the same amount, respectively)

[0160] Bending ridge: Direction parallel to sheet width direction

[0161] Testing method: Supported by rolls and pressed by a punch

[0162] Roll diameter: ϕ30 mm

[0163] Punch shape: Tip R=0.4 mm

[0164] Distance between rolls: 2.0×sheet thickness (mm)+0.5 mm

[0165] Pressing rate: 20 mm/min

[0166] Tester: SHIMADZU AUTOGRAPH 20 kN

[0167] In a case where the maximum bending angle obtained by the above-described method was 50° or more, the bendability was considered to be excellent and determined to be a pass. However, in a case where the maximum bending angle was less than 50°, the bendability was determined to be a failure.

[0168] In Tables 5 and 6, in cases where the tensile strength was 1500 MPa or higher and the bendability was pass (50° or more), the strength and the bendability were considered to be excellent, and the steels were determined to be invention steel. In cases where any one of the two performances described above was not satisfied, the steels were determined to be a comparative steel.

[0169] From Tables 5 and 6, it is found that hot-stamped articles having a chemical composition, a plate composition, and a metallographic structure within the scope of the present invention have excellent strength and excellent bendability.

[0170] On the other hand, it is found that hot-stamped articles having any one or more of a chemical composition and a metallographic structure outside the scope of the present invention are poor in terms of one or more of strength and bendability.

INDUSTRIAL APPLICABILITY

[0171] According to the present invention, it is possible to provide a hot-stamped article having excellent strength and excellent bendability.