Effects of test temperature on the ball-on-slab wear behavior of nickel-titanium shape memory alloys fabricated by laser powder bed fusion

Abstract

This work investigated the effects of test temperature on the ball-on-slab wear behavior of nickel-titanium (NiTi) alloy fabricated by laser powder bed fusion. The average steady-state coefficients of friction (COFs) at 16 °C, 36 °C, and 56 °C are similar, with an average of 0.61 (standard deviation 0.03), rising to 0.75 at 76 °C. The larger COFs at 76 °C can be ascribed to the large strain fluctuations around the estimated contact stress and more bulging debris. However, after 60 min of wear, the specific wear rate at 76 °C is the smallest (1.36 ± 0.4 × 10-4 mg/N·m) due to the largest elastic deformation energy of austenite and more adhesive debris. In addition, the dominant wear mechanisms of adhesive, abrasive, oxidative and delamination were discussed in depth.