Effect of Preliminary Heat Treatment on the Formation of Structure and Residual Stresses in the AMg6 Alloy at Laser Shock Peening Without Coating

We consider the effect of laser shock peening without coating (LSPwC) on the structure and stress state of the AMg6 Aluminum alloy with a thickness from 4 to 14 mm before and after preliminary thermal annealing. The roughness parameters R_a and R_z after LSPwC are determined. The magnitude, depth, and profile of compressive residual stresses (CRS) are found to depend on the thickness of the material and preliminary heat treatment. The layer-by-layer X-ray diffraction analysis shows a correlation between the parameters of the crystal structure and the profile of residual stresses for the processed samples. We find homological distortions of the crystal lattice in the CRS zone and observe the formation of significant (up to - 100 MPa) residual stresses on the unprocessed side of the samples. Also, we determine the surface CRS magnitudes for double unilateral and bilateral processing.