INFLUENCE OF SUBSURFACE LAYERS ON TEXTURE AND MICROSTRUCTURE DEVELOPMENT IN RGO ELECTRICAL STEEL

RGO (regular grain oriented) electrical steel is produced by a two stage cold rolling process with intermediate annealing. In this study the influence of surface layers on the recrystallization behaviour is investigated. By controlled thinning of the sheets at different processing stages surface layers were removed single- and double-sidedly in successive steps of 1/10th of half thickness keeping the final thickness, as well as the 2nd cold reduction, constant. All specimens were processed to the final product relating to standard conditions and texture analysis as well as magnetic measurements being performed, indicating very sensitively any disturbance in Goss-texture development. A deterioration of Goss-texture sharpness only appears if a critical surface layer is removed from both sides of the sheet, no matter the processing stage at which the removal was performed. This result suggests a kind of ''texture inheritance'' due to a texture profile being present at hot strip with a strong Goss-texture at its surface layer. The observed detrimental effect on secondary recrystallization due to the surface removal can be explained by the texture and microstructure development during the processing of RGO electrical steel. Thus the complete texture and microstructure development was investigated first and explained relating to theoretical models of texture development during deformation and leading to a new understanding of what was called ''texture inheritance''.