Laser Scanning Speed Influences on Assessment of Laser Remelted Commercially Pure Titanium Grade 2

In this research, the influences of laser surface remelting using different scanning speeds on the microstructure, roughness, and hardness of Commercial pure Titanium (Grade 2) were investigated. High power Nd: YAG pulsed laser was used. The laser scanning speeds used in this study were 4, 6, 8, and 10 mm/s and the other laser parameters (power, pulse frequency, beam diameter) were constant. The corrosion performance of the laser surface remelted and Cp titanium was then evaluated by potential dynamic measurements in a 3.5% NaCl solution. The results revealed that due to the diffusionless transformation after laser surface treatment and the formation of the martensite phase, the surface post-laser treatment was significantly different from those before the treatment. The results were indicated using an optical microscope, FE-SEM, XRD, AFM, and microhardness analysis. It was found the lowest scanning speed, 4 mm/s, had the slightest roughness and the smallest average grain size (26.06 nm) due to the high input energy and slow cooling rate, while the highest scanning speed (10 mm/s) had the greatest microhardness (291.5 Hv) due to the short interaction time between the substrate surface and laser beam and the higher cooling rate. The results also demonstrated the obvious improvement in the pitting resistance of Cp Ti in harsh environments as a result of the influence of laser remelting.