| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength hot dip galvanized steel sheet excellent in formability, which has a TS (Tensile Strength) of≥780 MPa and also has excellent elongation El, and has a TS×EL of≥18,000. SOLUTION: A hot dip galvanized layer is provided on a steel sheet which has a component composition containing, by mass%, C: 0.03-0.15%, Si: 0.8-2.5%, Mn: 1.0-3.0%, P: 0.001-0.05%, S: 0.0001-0.01%, Al: 0.001-0.1%, N: 0.0005-0.01% and Cr: 0.1-2.0%, with the balance comprising Fe and inevitable impurities, and has a microstructure containing, by an area ratio, 50% or more of a ferritic phase and 10% or more of a martensitic phase. Further, on the surface of the hot dip galvanized layer, 3Zn(OH)2*ZnSO4*3-5H2O is formed in an average thickness of 10 nm or more. COPYRIGHT: (C)2011,JPO&INPIT |
