Effects of hot rolled shear bands on formability and surface ridging of an ultra purified 21%Cr ferritic stainless steel

An ultra purified 21%Cr ferritic stainless steel (FSS) was hot rolled at a low finisher entry temperature (FET) of 750 °C to generate shear bands through large shear flow localizations in grain interiors. The effects of shear bands on the formability and surface ridging have been studied as compared to a conventional hot rolled band at the FET of 970 °C with few shear bands. The results showed that as compared to the final sheet produced with the FET of 970 °C, the average r-value for the final sheet with the FET of 750 °C was increased by 25%, and the surface roughness of the final sheet strained by 15% along the rolling direction was decreased by 40%. It has been observed that the existence of shear bands could enhance the nucleation for recrystallization during hot rolling and annealing for microstructure refinement, and modify the texture by intensifying the {1 1 1} textures in the final sheet. The influence of shear bands on sheet formability and resistance against surface ridging was discussed.