Process and corrosion property of laser-chemical hybrid polishing of TC4 alloy

In order to reduce the adverse effects of recast layer and heat-affected zone during laser polishing of titanium alloys, a novel laser-chemical hybrid polishing method was proposed. The surface of TC4 alloy in phosphoric acid solution was irradiated by nanosecond laser for polishing experiments. White light interferometer was used to measure the surface roughness at different number of laser scanning times. The surface composition was analyzed by XPS. The results showed that the surface roughness of the substrate was reduced from 304 nm to 59 nm, and the corrosion resistance of the polished substrate were significantly improved compared with the original substrate. Local electrochemical effects occur on the substrate surface due to thermal difference caused by uneven energy distribution of the laser beam on the substrate. Under the continuous irradiation of the laser, further corrosion under the electrochemical effect gradually reduced the surface roughness of the substrate. After laser-chemical hybrid polishing, the surface roughness of the titanium alloy substrate was reduced, and no recast layer and heat-affected zone were found on the surface of the substrate.