Wear and corrosion behaviors of Ti-6Al-4 V alloy gradient-hardened by vacuum rapid oxynitriding

Abstract

Aircraft parts, particularly engine fan blades, require composite improvements in wear and corrosion owing to continuous particle impact and repeated exposure to low and ambient temperatures. Titanium alloys, which are known for their inherent TiO₂, provide excellent corrosion resistance and superior strength. Thus, they are effectively utilized to enhance fuel efficiency, making them a preferred material for many fan-blade applications. However, the low wear resistance of titanium alloys shortens the lifespan of materials because erosion and wear occurs due to particle impact. Therefore, this study aims to form a hardened surface layer on a Ti-6Al-4 V alloy using a highly efficient and economical vacuum rapid oxynitriding process by mixing N and O gases. Most previous studies have focused solely on the wear characteristics resulting from the surface hardening of the Ti-6Al-4 V alloy due to the addition of nitrogen alone; limited research has been conducted on the surface-hardening mechanism with a mixture of N and O gases. Furthermore, the wear and corrosion properties have been evaluated independently in separate environments, which has resulted in a lack of research on the combined effects of corrosion and wear. Therefore, this study systematically elucidates the corrosion, wear, and combined corrosion–wear behavior mechanisms of Ti alloys in a 3.5 wt% NaCl environment.