high-strength steel sheet for more than the tensile strength of 980MPa spot welding

摘要

PROBLEM TO BE SOLVED: To form a welded joint having a high cross tension strength and small unevenness of strength between respective joints by spot welding of a high strength steel plate having a tensile strength of 980 MPa or more.;SOLUTION: The high strength steel plate for spot welding having a tensile strength of 980 MPa or more includes, by mass, 0.10-0.30% of C, 0.01-2.50% of Si, 0.30-3.00% of Mn, ≤1.50% of Al, ≤0.015% of P, ≤0.010% of S, ≤0.010% of N, and the balance of Fe and inevitable impurities, and has a brittleness Br of ≤0.0055 which is defined by formula (1): Br=Ceqh×([P]+2×[S]+4×[N]), wherein Ceqh=[C]+[Si]/40+[Cr]/20, and [C], [Si], [Cr], [P], [S], and [N] represent, respectively, contents (mass%) of C, Si, Cr, P, S and N.;COPYRIGHT: (C)2012,JPO&INPIT