HOT-ROLLED STEEL SHEET HAVING HIGH TENSILE STRENGTH AND METHOD FOR PRODUCTION THEREOF

摘要

A hot-rolled steel sheet having a high tensile strength which comprises a steel containing, in mass %, 0.04 to 0.09 % of C, 0.1 % or less of Si, 0.5 to 1.5 % of Mn, 0.02 % or less of P, 0.01 % or less of S, 0.1 % or less of Al, 0.001 to 0.008 % of N, and 0.01 to 0.15 % of Ti, contents of respective components satisfying the following formula (1): [C] + 7 x [Si] + 0.1 x [Mn] + [P] + 14 x [S] + 1.75 x [Al] + 23 x [N] + [Ti] + 18 x [O] + 7 x [Cu] + 18 x [Sn] + 7 x [Mo] + 1.7 x [Cr] + 70 x [B] + 7 x [Ca] + 14 x [Zr] + 14 x [V] + 7 x [Nb]