Measurement of Residual Stresses in Different Thicknesses of Laser Shock Peened Aluminium Alloy Samples

This study focused on depth-resolved residual stress results determined with a number of complementary techniques on Laser Shock Peening (LSP) treated aluminium alloy 7075-T651 samples with different thicknesses (6 mm and 1.6 mm). Samples were prepared from a single commercially produced rolled plate that was then treated with LSP. Residual stresses were measured using Laboratory X-Ray Diffraction (LXRD), Incremental Hole Drilling (IHD), Neutron Diffraction (ND) and Synchrotron XRD (SXRD). The LSP treatment resulted in the establishment of compressive residual stresses that varied rapidly in the near surface region. The compressive stresses extended up to 1.5 mm in depth in the 6 mm thick sample. Some surface stress relaxation was observed in the first 25 mu m, but substantially large stresses existed at 50 mu m. This investigation strongly motivated why residual stress profiles should be obtained using a variety of techniques.