Combined effect of gas blow induction heating nitriding and post-treatment with fine particle peening on surface properties and wear resistance of titanium alloy

In order to fabricate a titanium alloy with superior wear resistance and fatigue strength, fine particle peening (FPP) was introduced as a post-treatment after gas blow induction heating (GBIH) nitriding. The surface characteristics of the treated alloy were examined using X-ray diffraction, scanning electron microscopy, laser microscopy and a micro-Vickers hardness tester. GBIH nitriding and post-treatment with FPP formed nitrided layers with high hardness and compressive residual stress at the surface of the alloy within a short period of time. This is due to the diffusion of nitrogen atoms during GBIH nitriding and plastic deformation of the surface layer during FPP. Reciprocating ball-on-disk wear tests were performed to investigate the wear resistance of the surface-treated alloy. The wear resistance of the titanium alloy was improved by the proposed surface treatment compared with samples that were only polished or FPP-treated. This is due to the presence of a nitrogen compound layer with high hardness at the surface. The abrasiveness toward the wear test counter material was also decreased by the combined surface treatment.