Deconvoluting the influences of heat and plastic deformation on internal strains generated by friction stir processing

Internal-strain profiles in friction-stir processed aluminum-alloy plates were investigated using neutron diffraction. Three different specimens were prepared with a purpose of separating the effects of frictional heating and severe plastic deformation on the internal-strain distribution: (Case 1) a plate processed with both stirring pin and tool shoulder, (Case 2) a plate processed only with the tool shoulder, and (Case 3) a plate processed only with the pin. The comparison between Cases 1 and 2 shows distinctly different strain profiles revealing deconvoluted effects of the different sources (i.e., heat, deformation, or the combination) on the internal strains generated during the friction-stir processing.