Investigation of shot peening combined with plasma-sprayed CuNiIn coating on the fretting fatigue behavior of Ti-6Al-4V dovetail joint specimens

Abstract

Dovetail joint specimens manufactured from the Ti-6Al-4V alloy were designed and used to investigate the fretting fatigue behavior of the blade/disk interface in gas turbine engines. Shot peening was combined with plasma-sprayed CuNiIn coating to improve the fretting fatigue resistance of the specimens. The finite element models were used to analyze the contact stress distribution in the fretting area. A plastic layer was added to simulate the CuNiIn coating that was sprayed on the surface of the dovetail blade. The fretting cracks tended to initiate at the contact edge, where the high stress concentration existed, and severe fretting wear damage occurred. The CuNiIn coating modified the local stress distribution under the fretting condition and mitigated the stress concentration degree of the contact edge. The surface strain hardening layer and the compressive residual stress were induced by the shot peening treatment, which promoted the wear and the fatigue resistance of the Ti-6Al-4V substrate under the fretting condition. The fretting fatigue property of specimens improved after the combined surface treatment.