High strength hot-dip galvanized steel sheet and production method therefor
Abstract:
A high-strength hot-dip galvanized steel sheet contains predetermined amounts of C, Si, Mn, P, S, N, O, sol. Al, Ti, and B, 0.1 to 1.5 mass % of Cr+2×Mo, and a balance in a form of Fe and inevitable impurities. A steel structure includes, in area %, ferrite: 1 to 50%, martensite: 20 to 70%, residual austenite: 0 to 5%, pearlite: 0 to 5%, MA and cementite having 0.2 μm or more grain size: 0 to 5% in total, and a balance in a form of bainite. A number density of MA or cementite having 0.2 μm or more grain size and isolated in ferrite or bainite grains is 100 pcs/1000 μm2 or less, and an average hardness of martensite is in a range from 330 to 500 Hv.
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