Role of nano second laser wavelength embedded recast layer and residual stress on electrochemical corrosion of titanium alloy

Abstract

Surface and electrochemical characteristics are analysed for Laser Peened Ti6Al4V in present study. X-ray diffraction studies disclose that peaks shifts and broadening of peaks took place after laser peening. The laser parameters will have effect in varying the material hardness and its gradual decrease in hardness is observed when measured from surface to depth profile. Microstructural changes are recognized during microscopic observation of cross-sectional laser peened samples. Mechanical and thermal surface damage with dimples and recast layer is observed for 1064 nm and 532 nm laser wavelengths respectively at same power density of 3 GW cm−2. These damages quantify the surface roughness variation between two laser wavelengths. SEM observation reveals the melted and distorted regions of the surface that would change the electrochemical properties after laser peening. Anodic potential shift has observed in both Open Circuit Potential (OCP) and Tafel Exploitation for samples with thermal damage which is not seen in samples with surface distortion. To analyse the effect of residual stress on electrochemical corrosion resistance, the samples are electro polished for 50 μm and electrochemical studies are analysed once again. A complete anodic shift compared to untreated sample is observed for all the peened samples.