Microstructure and Texture Evolution During the Accumulative Roll Bonding of Pure Ni

Abstract

Evolution of microstructure and texture was studied in severely plastically deformed (up to an equivalent strain of 6.4) high purity (99.99%) Ni sheets processed through Accumulative Roll Bonding (ARB). As received Ni plates (~ 10 mm in thickness) were cold rolled to ~ 80% reduction in thickness (~ 2 mm) and vacuum annealed at 600°C for one hour and these were used as the starting materials (average grain size ~ 25 μm) for the subsequent ARB processing. ND and TD plane normal sections of the ARB processed sheets were subjected to Electron Back Scatter Diffraction (EBSD) and Transmission Electron Microscope (TEM) studies. The ARB processed Ni sheets were found to be filled with ultrafine grains (average grain size ~ 400 nm) after 8 cycles of ARB. Extensive shear band formation was observed particularly in the high cycle ARBed materials. The deformation textures were found to be quite inhomogeneous at the low cycle regime of the ARB. However, the deformation texture achieved remarkable homogeneity after 6 and 8 cycles of ARB and S ({123} ) component of the deformation texture was found to be quite strong.