Yield strength 500 MPa class High elongation rate Aluminum zinc hot-dip galvanized steel sheet and color plated steel sheet manufacturing method

摘要

An aluminium-zinc-hot-dipped and colour-coated steel plate having a 500 MPa yield strength grade and a high elongation and a manufacturing method thereof, with the chemical components in mass percentage of a substrate of the steel plate being: 0.07-0.15% of C, 0.02-0.5% of Si, 1.3-1.8% of Mn, N≤0.004%, S≤0.01%, Ti≤0.15%, Nb≤0.050%, and the balance being Fe and other inevitable impurities, and meanwhile satisfying the conditions of: (C+Mn/6)≥0.3%; Mn/S≥150; Nb satisfying 0.01%≤(Nb-0.22C-1.1N)≤0.05% where no Ti is contained; Ti satisfying 0.5≤Ti/C≤1.5 where no Nb is contained; and 0.04%≤(Ti+Nb)≤0.2% where Ti and Nb are added in combination. The steel plate has a yield strength of ≥500 MPa, a tensile strength of ≥550 MPa, an elongation after fracture of ≥15%, a good strength and toughness and an excellent corrosion resistance.