Microstructural Characterization of Pure Titanium Treated by Laser Surface Treatment Under Different Processing Parameters

Advanced characterization techniques are utilized to investigate the effect of laser surface treatment on microstructural evolution of pure titanium (Ti). The results show that there are three distinctly different types of microstructure from surface to substrate in Ti samples, including phase transformation and solidification microstructure in zone I (melting zone); insufficient recrystallization grains with residual alpha martensitic plates in zone II (heat-affected zone, HAZ); fully recrystallization microstructure in zone III (basemetal, BM). The hardness evolution profiles under different laser treatment parameters are similar. The highest hardness in MZis ascribed to alpha plate, while the lowest hardness value inHAZ is due to the insufficiently recrystallized grains. The metallurgical process on the laser-modified Ti samples is systematically discussed in this work.