Effect of Heat Treatments on the Fretting Wear Characteristics of Laser Metal-Deposited Inconel 718

In view of the potential fretting wear issues of Laser Metal Deposition (LMD) In718 in engineering applications, this paper investigates the fretting wear behavior of LMD In718 alloy subjected to two different heat treatment processes: homogenized Solution-Treated and Aged (STA) and direct-aged only. This was conducted utilizing a newly designed fretting wear apparatus to enable real-time dynamic monitoring of the contact interface and maintain uniform normal force distribution. Furthermore, to provide a more comprehensive understanding of how different heat treatments influence the fretting wear performance of LMD In718, this study systematically evaluates their distinct tribological responses and underlying wear mechanisms. The wear resistance of the material was predicted by analyzing the proportion of the main strengthening phase γ″ in samples with different heat treatments using microstructural characterization methods. Wear resistance tests were conducted under ambient conditions. The results show that the homogenized STA sample has a specific wear rate of 1.375 × 10−7 mm3/(N∙m), while the direct-aged sample has a wear rate of 1.550 × 10−7 mm3/(N∙m). The direct-aged sample exhibited severe fatigue spalling accompanied by adhesive and abrasive wear, with numerous subsurface cracks. The homogenized STA sample demonstrated a combined mechanism of oxidative wear and localized abrasive wear.