Grain refinement of austenitic stainless steels by cross rolling and annealing treatment: A review

The effects of cross rolling and annealing treatment, as an advanced thermomechanical processing route, on the microstructure and grain refinement of metastable austenitic stainless steels were overviewed. It was summarized that cross rolling promotes the formation of intersecting shear bands and leads to higher dislocation density, which are favorable for the formation of strain-induced α′-martensite. Moreover, contrary to unidirectional rolling, cross rolling retains the equiaxed morphology of grains. It was demonstrated and formulated that cross rolling and reversion/recrystallization annealing treatment leads to more intense grain refinement compared to the unidirectional rolling and annealing route, which is quite important for grain refinement of more stable grades. Future prospects include investigating the effects of special alloying elements, initial grain size, and deformation variables on the cross rolled microstructure, analyzing the kinetics parameters of the deformation-induced martensitic transformation during cross rolling, and characterizing the transformation-induced plasticity (TRIP) effect for the grain refined austenitic stainless steels and high-entropy alloys by cross rolling and annealing treatment.