Influence of plasma molybdenizing and shot-peening on fretting damage behavior of titanium alloy

摘要

Effect of plasma molybdenizing and shot-peening on fretting wear and fretting fatigue behaviors of Ti6A14V alloy was investigated. The plasma molybdenized layer composed of a dense molybdenum deposition layer and a Mo-Ti solid-solution layer can increase surface hardness by 2.8 times and cause its volume loss by fretting wear to decrease to 1/14 compared with that of the substrate. Plasma molybdenized treatment results in a significant decrease in resistance of the substrate to fretting fatigue. It is ascribed that the molybdenized layer with high hardness yields a low toughness, and its high surface roughness leads to a micro-notched effect. However, proper combination plasma molybdenizing and subsequent shot-peening may enhance the simultaneous fretting fatigue and fretting wear resistance of Ti6A14V significantly, which can decrease the fretting wear volume loss to 1127, and may increase the fretting fatigue life by more than 69 times. A synergistic improvement in fretting fatigue of the titanium alloy by combining surface alloying with shot-peening can be achieved. The results indicate that a beneficial residual compressive stress distribution, high surface hardness with suitable hardness gradient distribution, good apparent toughness, relatively low surface roughness, and excellent surface integrity are achieved. (C) 2016 Elsevier B.V. All rights reserved.