Importance

Loading Importance Indicators...

Abstract

A hot-rolled flat steel product having a product of Rm and A80 of ≧18,000 MPa*%, a composition including (in wt.) C:0.10-0.60%, Si:0.4-2.0%, Al:≦2.0%, Mn:0.4-2.5%, Ni:≦1%, Cu:≦2.0%, Mo:≦0.4%, Cr≦2%, Ii:≦0.2%, Nb:≦0.2%, V:≦0.5%, remainder Fe and unavoidable impurities, and a microstructure of bainite and residual austenite, wherein the microstructure includes ≧60 vol.% bainite, and wherein at least some of the residual austenite is in block form and ≧98% of the residual austenite blocks have a size of ≦5 μm. Also, a method where a slab, thin slab or a cast strip having the aforementioned composition is hot-rolled at a hot-rolling end temperature of ≧880° C., cooled with a cooling rate of ≧5° C./s to a coiling temperature between the martensite start temperature and 600° C., coiled, and cooled in the coil while being held between the bainite start temperature and the martensite start temperature until ≧60 vol.% of the hot strip microstructure is bainite.

Loading the Abstract Image...

First Claim