Ferrite structure in plastically deformed stainless steel

Abstract

Optical and electron metallography have been used to examine the substructures developed in supersaturated ferrite in a high-alloy steel after rolling at room temperature up to 4·35 strain. At low true strains, deformation twins are formed and characteristic noises accompany their formation. The dislocation distribution is generally heterogeneous with bands of increased dislocation density parallel to {110} planes. At strains higher than 0·16, microbands of 0·1–0·2 μm thickness are developed which are parallel to {110} planes and orientated at ∼30° to the rolling direction. Strains above 0·52 induce the formation of clusters of microbands as well as shear bands, the latter occurring in regions of high microband density and orientated at ∼35° to the rolling direction. In shear bands, heavy shear strain is developed and their structure is similar to that of kink bands. In the entire strain range, independent of the inhomogeneities developed, deformation takes place also in the adjacent matrix. This results in a rapid increase of dislocation density in regions without inhomogeneities, the development of the latter being strongly dependent on matrix orientation. A high density of microbands and shear bands occurs only in grains with orientation 〈111〉 ‖ transverse direction.