Manufacturing method for strip casting 550 mpa-grade high strength atmospheric corrosion-resistant steel strip

Abstract

A manufacturing method for strip casting 550 MPa-grade high strength atmospheric corrosion-resistant steel strip, comprising the following steps: 1) smelting, where the chemical composition of a molten steel is that: C is between 0.03-0.08%, Si≦0.4%, Mn is between 0.6-1.5%, P is between 0.07-0.22%, S≦0.01%, N≦0.012%, Cu is between 0.25-0.8%, Cr is between 0.3-0.8%, and Ni is between 0.12-0.4%, additionally, also comprised is at least one micro-alloying element among Nb, V, Ti, and Mo, where Nb is between 0.01-0.08%, V is between 0.01-0.08%, Ti is between 0.01-0.08%, and Mo is between 0.1-0.4%, and where the remainder is Fe and unavoidable impurities; 2) strip casting, where a 1-5 mm-thick cast strip is casted directly; 3) cooling the strip, where the cooling rate is greater than 20° C./s; 4) online hot rolling the cast strip, where the hot rolling temperature is between 1050-1250° C., where the reduction rate is between 20-50%, and where the deformation rate is >20 s; austenite online recrystallizing after hot rolling, where the thickness of the hot rolled strip is between 0.5-3.0 mm; and, 5) cooling and winding, where the cooling rate is between 10-80° C./s, and where the winding temperature is between 570-720° C. The microscopic structure of a steel strip acquired is primarily constituted by fine polygonal ferrite and pearlite.