Diode laser assisted surface nitriding of Ti-6Al-4v: properties of the nitrided surface

Abstract

In the present study, a detailed investigation of mechanical and electrochemical properties of laser-surface-nitrided Ti-6Al-4V has been carried out. Laser treatment is carried out by melting the surface of Ti-6Al-4V substrate using a high power CW diode laser with nitrogen as shrouding environment. The effect of laser parameters (applied power and gas flow rate) on the properties of the nitrided surface was evaluated. The microhardness of the nitrided surface was improved to a maximum of 1175 VHN in the present set of laser processing conditions as compared to 280 VHN of as-received substrate. Surface nitriding increased the potential for pit formation (E _pit) significantly as compared to as-received Ti-6Al-4V. Immersion in Hank's solution showed calcium phosphate deposition from the solution. The optimum process parameters for laser surface nitriding were derived.