Experimental investigation of plastic grain interaction

Aluminum polycrystals with columnar coarse grains are plastically compressed in a channel die. The spatial distribution of the accumulated plastic surface strains is determined by measuring the displacement fields using photogrametry. For this purpose digital stereological image pairs of the sample surface are taken at the beginning and after each deformation step. The displacement field is derived from them by applying an image analysis method based on pattern recognition to the data before and after straining. The three components of the plastic displacement vector field are used to derive the surface portion of the plastic strain tensor field. The microtexture of the specimens is determined by the analysis of electron backscattering patterns obtained in a scanning electron microscope. The experiments are interpreted by comparing them to the corresponding crystal plasticity finite element simulations.