Evolution of solidification structure for Si–Mn bearing AHSS under typical cooling rates

In this paper, two near-net-shape continuous casting technologies (strip casting and compact strip production) were used to produce a typical Si–Mn bearing Advanced High Strength Steel (AHSS) slab/strip, aiming to provide a clear understanding on the cooling rate on the solidification structure and corresponding properties. The results showed that strip casting (SC) technology under sub-rapid cooling conditions owns a higher heat transfer efficiency, and the solidified grains have been obviously uniformed and refined. Meanwhile, a substituted quenching process has been completed under high cooling strength of SC, leading the structural transformation from the initial ferrite/pearlite to the composite structure of martensite and bainite, which provides a very good structural basis for the excellent comprehensive mechanical performance of Si–Mn AHSS.