Effect of hot working on dynamic recrystallisation study of as-cast austenitic stainless steel

Abstract

Dynamic recrystallisation (DRX) behaviour of as-cast austenitic stainless steel strip is investigated in order to study the extent of DRX that could heavily refine the as-cast austenite prior to phase transformation. The specimens were very quickly heated to the deformation temperatures to ensure that there was little or no change to the as-cast structure in order to simulate accurately the microstructure evolution and recrystallisation behaviour of the cast strip on reheating in the thermo-mechanical testing system. This investigation will assist the generation of the fundamental knowledge required to develop advanced high strength and formable steels using thin strip/slab casting processes. The results reveal that DRX of the coarse austenite grains is a relatively slow process and austenite will be refined completely by DRX under high deformation temperature (1100–1200 1 C) and slow strain rate (0.5–5 s 1) conditions. It is observed that new grains nucleate predominantly at the parent austenite grain boundaries and tend to form in clusters.