Crystal-plasticity analysis of ridging in ferritic stainless steel sheets

The occurrence of ridging in ferritic stainless steel (FSS) sheets is caused by the collective deformation of bandlike clusters of grains with a similar crystallographic orientation. In this article, largescale (1.8×3.6 mm) orientation maps obtained by electron backscattered diffraction (EBSD) are input into a viscoplastic self-consistent polycrystal plasticity model to analyze the strain anisotropy caused by the topographic arrangement of the recrystallization-texture orientations. Two versions of the ridging model were devised: (1) the local dispersion in strain-rate components is analyzed for the full EBSD map, and (2) narrow bands in the EBSD maps aligned parallel to the ridges on the sheet surface are considered, and the variation in macroscopic strain response from band to band is derived. The effects caused by spatial variations in through-thickness strains and in out-of-plane shears are compared and related to ridging. The model is applied to two sheets distinguished by different levels of ridging.