| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a high-strength hot-dip zinc-coated steel sheet having high strength satisfying tensile strength of 980 MPa or more and excellent workability, weldability and fatigue properties, and a process for producing the steel sheet. <P>SOLUTION: The steel sheet comprises, by mass, not less than 0.05% and less than 0.12% of C, not less than 0.35% and less than 0.80% of Si, 2.0 to 3.5% of Mn, 0.001 to 0.040% of P, 0.0001 to 0.0050% of S, 0.005 to 0.1% of Al, 0.0001 to 0.0060% of N, 0.01 to 0.5% of Cr, 0.010 to 0.080% of Ti, 0.010 to 0.080% of Nb and 0.0001 to 0.0030% of B, or further comprises one or more selected from 0.01 to 0.15% of Mo, 0.0001 to 0.0050% of Ca, 0.0001 to 0.1% of REM and 0.0001 to 0.1% of Sb, and the balance Fe with inevitable impurities. The steel sheet has a structure composed of a ferrite phase having a volume fraction of 20 to 70% and an average crystal particle diameter of 5μm or less, and also has a hot-dip zinc coating layer formed on the surface of the steel sheet in an amount of 20 to 150 g/m<SP>2</SP>(per one surface). <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
