Enhancing the corrosion properties and microhardness of titanium alloy by laser surface remelting

Laser surface remelting (LSR) was performed on the Ti80 alloy, and the effects of different laser powers with 50 W, 100 W and 200 W on the microstructure, microhardness and corrosion properties were systematically investigated. The results showed that after LSR treatment, the microstructure of the Ti80 alloy was significantly refined because of the rapid cooling effect of laser processing, and the microhardness of the remelted zone gradually increased with the increase of laser power. The electrochemical test results reveal that the corrosion resistance of the Ti80 alloy can be significantly improved after LSR treatment and the corrosion resistance in 3.5 wt% NaCl solution was as follows from high to low: 100 W>50 W>200 W>As-received. It was concluded that the content of Ti2O3 decreased and TiO2 increased after LSR, and the stability of the passive film exhibited a corresponding improvement. The LSR can improve the surface hardness and corrosion resistance of the Ti80 alloy, which can be attributed to the homogenization of the composition of the remelting zone and the reduction of the point defect density of passive film. It is believed that results documented in this study can provide an important reference for deepening understanding of the surface modification mechanisms of LSRed Ti80 alloys.