| 摘要 |
PROBLEM TO BE SOLVED: To provide a galvanized high strength steel sheet which has a tensile strength of≥800 MPa, and excellent weldability, hole expansibility and corrosion resistance, and to provide a production method therefor. SOLUTION: The steel sheet has a composition containing, by mass, 0.01 to 0.20% C,≤1.5% Si, 0.01 to 3% Mn, 0.0010 to 0.1% P, 0.0010 to 0.05% S, and 0.005 to 4% Al, and further containing one or two kinds selected from 0.01 to 5.0% Mo and 0.001 to 1.0% Nb in the ranges so as to simultaneously satisfy the following inequalities (A) and (B), and the balance Fe with inevitable impurities, and has a microstructure containing bainite or bainitic ferrite by≥70% in an area ratio, and has a tensile strength of≥800 MPa: 3.0Nb+2.5Mo+Mn-5C<SP>0.5</SP>>0 (A), and Al+15.0Si<SP>2</SP>+1.5Si-1.8<0 (B). COPYRIGHT: (C)2003,JPO
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