Effect of Low energy laser shock peening on plastic deformation, wettability and corrosion resistance of aluminum alloy 7075 T651

AA 7075 T651 alloys are often used in a variety of applications such as gears, shafts, chassis in automobile industries, missiles and extension tubes of rifles in defense and marine components, where wear and corrosion resistance is indispensable. It entails the enhancement in surface characteristics such as hardness, wear resistance and resistance to the corrosion emanate from high concentration of chlorides. This article is devoted to analyze the corrosion behavior of AA 7075 T651 alloy in 3.5 % NaCl solution subjected to the surface modification by low energy (200 mJ, 300 mJ and 400 mJ) pulsed Laser Shock Peening (LSP). Among the unpeened and peened specimens the specimen peened with pulse energy of 400 mJ exhibited the highest E-corr value of -1200 V and lowest I-corr value of 0.0221 mA/cm(2) in the potentiodynamic polarization test. The electro chemical impedance spectroscopy revealed a superior resistance to the localized corrosion. Further, the investigations on the variations in microstructure, plastic strain, dislocation density and Wettability due to LSP are carried out using Transmission Electron Microscope, Scanning Electron Microscope, X-ray diffraction (XRD) and Goniometry instrument. Besides the reduction in the grain size and 31 % increment in the micro strain, a transformation from hydrophilic to hydrophobic nature is observed in the specimen peened with 400 mJ LSP.