Comparative study of symmetric and asymmetric deformation of Al single crystal under microscale laser shock peening

Abstract

Laser shock peening by a micron sized laser beam is a process in which compressive residual stresses are induced in order to improve material fatigue life of micro scale components. The size of the laser target interaction zone is of the same order of magnitude as the target material grains and thus the effects of anisotropic material response must be taken into account. Single crystals are therefore chosen to study such anisotropy. It is also of interest to investigate the response of symmetric and asymmetric slip systems with respect to the yield surface. In presented work, analytic, numerical and experimental investigations of two different orientations, (110) and (1 1 4) of aluminum single crystals are studied. Anisotropic slip line theory is employed for the construction of slip line fields for both orientations and compared with numerical results. Theory is further used to explain the difference in plastic deformation for two different orientations. Lattice rotations on the top surface and cross section are also measured using Electron Backscatter Diffraction (EBSD), while residual stress is measured using X-ray microdiffraction. Both the analytical and numerical models are then validated via experimental results.