Impact of laser shock peening on microstructure hardness and corrosion properties of AA6061 alloy

In recent times, laser shock peening (LSP) has emerged as a pioneering technique to modify the surface properties of various aluminium-based alloys. In this study, AA6061 was treated by single and multi-pass LSP, and its microstructure, hardness, and corrosion behaviour were investigated. Microstructural studies were performed using X-ray diffraction, electron back-scattered diffraction, and transmission electron microscopy methods. Texture studies were conducted using the neutron diffraction method, while hardness measurements were carried out using a Vickers hardness tester. Corrosion studies were conducted using the potentiodynamic method, and surface examination was performed using scanning electron microscopy. The results indicate that laser peening led to the dissolution of strengthening precipitates, resulting in a microstructure characterized by a greater volume of low-angle grain boundaries and dense dislocations. The texture index of laser-peened specimens decreased drastically to 1.1952 and 1.0970, with a significant rise in the volume fraction of Goss, S, and brass components. Specimens subjected to a single LSP pass exhibited a maximum hardness of 132.4 HV and better resistance to pitting, with Ecorr and Icorr values of -0.6721 V and 0.0043 A/cm2, respectively, while multiple LSP passes resulted in reduced hardness and pitting resistance due to excess heat.