Surface modification of AA7075 T651 by laser shock peening to improve the wear characteristics

Abstract

The Enhancement of surface properties of various materials by laser shock peening (LSP) to prolong the service life of the industrial components gained significant importance for the past decade. Though several investigations are made on the different aluminum alloys through LSP route, very limited studies are reported on AA 7075 T651 aluminum alloy, which is extensively used in upper wing cover and fuselages of aerospace industries. In the present investigation, a Q-switched Nd:YAG laser having different pulse energies of 200, 300 and 400 mJ with black paint and water as the ablative layer and confinement medium respectively are used to study the variations in the mechanical properties. A deformed layer thickness of about 500 μm with a peak hardness of 236 Hv at the surface is obtained with pulse energy of 400 mJ. Further, the maximum compressive residual stress induced in the said specimen is 317 MPa and a wear rate of 1.18 × 10−6 g m−1 is measured. The microstructural studies performed using HR-TEM, revealed the enhancement in the properties are attributed to the grain refinement and dislocation strengthening effected by the LSP process.