Hydrogen effects in anodic grinding of Ti alloy

Intensification of wear and environmental degradation processes is a goal in the case of anodic grinding of hardly machined materials. To achieve the goal, the mechanical and electrochemical processes occurring at anodic grinding have been studied to select the optimum treatment parameters. The effects of cathodic prepolarization and application of different anodic polarization on the properties and quality of the surface layer of commercial Ti–Al–V–Cr–Mo alloy and on the efficiency of treatment were studied. The formation of crystallographically oriented needle precipitates of TiH1.924 hydride, the change of the lattice parameters and increase in dislocation density in α-Ti phase, as well as the formation of the surface microcracks were observed after cathodic polarization due to the hydrogen absorption. Hydrogen induced deterioration was affected by kind of electrolyte, applied cathodic polarization and metal cold work. Cathodic prepolarization of Ti alloy affected the yield of subsequent anodic grinding. The nonmonotonical effect of increasing anodic polarization was observed on the surface roughness, the energy consumption and the wear of tool at grinding of non-prepolarized material. The optimum values of above parameters were achieved at application of anodic polarization at which the hydrogen ingress into the ground metal, affecting the microhardness and stress distribution within the subsurface layer was stated. The assistance of hydrogen induced deterioration of subsurface layer in the anodic grinding of Ti alloy has been discussed. In wear–corrosion degradation of Ti alloy exposed to different environments, the hydrogen effects should be considered.