Hydrogen effects in anodic grinding of Ti alloy

Intensification of wear and environmental degradation processes is a goal i n the case of anodic grinding of hardly machined materials. To achieve the goal, the mechanical and electrochemical processes occurring at anodic grin ding have been studied to select the optimum treatment parameters. The effe cts of cathodic prepolarization and application of different anodic polariz ation on the properties and quality of the surface layer of commercial Ti-A I-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 dislocati on density in ix-Ti phase, as well as the formation of the surface microcra cks were observed after cathodic polarization due to the hydrogen absorptio n. Hydrogen induced deterioration was affected by kind of electrolyte, appl ied 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 grin ding of non-prepolarized material. The optimum values of above parameters w ere achieved at application of anodic polarization at which the hydrogen in gress into the ground metal, affecting the microhardness and stress distrib ution within the subsurface layer was stated. The assistance of hydrogen in duced 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. 2001 Elsevier Science B.V. All rights reserved.