| 摘要 |
<p>Disclosed are: a high-strength hot-dip zinc-coated steel sheet having tensile strength of 980 MPa or more and excellent workability, weldability and fatigue properties; and a process for producing the steel sheet. The steel sheet comprises not less than 0.05 mass% and less than 0.12 mass% of C, not less than 0.35 mass% and less than 0.80 mass% of Si, 2.0 to 3.5 mass% of Mn, 0.001 to 0.040 mass% of P, 0.0001 to 0.0050 mass% of S, 0.005 to 0.1 mass% of Al, 0.0001 to 0.0060 mass% of N, 0.01 to 0.5 mass% of Cr, 0.010 to 0.080 mass% of Ti, 0.010 to 0.080 mass% of Nb and 0.0001 to 0.0030 mass% of B, and optionally comprises at least one component selected from 0.01 to 0.15 mass% of Mo, 0.0001 to 0.0050 mass% of Ca, 0.0001 to 0.1 mass% of REM and 0.0001 to 0.1 mass% of Sb, with the remainder being Fe and unavoidable 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 5 µm 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/m2 (per one surface).</p> |
