| 摘要 |
PROBLEM TO BE SOLVED: To provide a high strength automobile member having excellent uniformity of the strength in the member and particularly suitable for an automobile, and to provide its production method. SOLUTION: The high strength automobile member having excellent uniformity of the hardness in the member is composed of the tailored blank of steel sheets having a composition comprising, by mass, 0.001 to 0.40% C, 0.01 to 2.0% Si, 0.01 to 3% Mn, 0.0010 to 0.1% P, 0.0010 to 0.05% S, 0.0001 to 0.0050% B and 0.0010 to 0.01% N, and comprising one or more kinds selected from 0.001 to 0.5% Ti and 0.005 to 2.0% Al in the ranges simultaneously satisfying the inequalities (a) and (b), and, regarding the distribution of the hardness in the member, the minimum value of the Hv hardness in the weld zone including the heat-affected zone is the average hardness on the lower side in the two kinds of steel sheets×0.8 or above, and the maximum value is the average hardness on the higher side in the two kinds of steel sheets×1.2 or below. (a): (Al/27+Ti/48)/(N/14)≥2, (b): B/11-äN/14-(Al/27+Ti/48)}≥1.5×10<SP>-5</SP>. COPYRIGHT: (C)2006,JPO&NCIPI
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