Analysis of Grain Colonies in Type 430 Ferritic Stainless Steels by Electron Back Scattering Diffraction (EBSD)

Ridging is a serious problem which occurs in ferritic stainless steel after tensile deformation in the rolling direction, and steel makers are attempting to respond to the surface deterioration caused by this phenomenon. Many authors have suggested that a long distance order in the lattice orientation of a sheet could be responsible for ridging. In this study, the authors performed local orientation measurement on two samples of type 430 stainless steel using orientation imaging microscopy, and analyzed the grain orientations of the RD and ND planes. Data on areas covering more than 5 mm2 are presented here for the first time in the literature. The experimental results prove the existence of grain bands in the ND plane of samples with severe ridging. However, the texture maps for the RD planes are in disagreement with many previously proposed theories. Therefore, a new mathematical model is introduced. The simulated ridging profiles of the samples calculated with this new model agree with the experimental results. Finally, a method of amelioration that can significantly improve the theoretical model is proposed.