Nitriding is a thermo-chemical process that diffuses nitrogen (N) into surface of metals to improve surface properties, wear and corrosion resistance as well as fatigue strength of metal components [1]. Two nitriding heat treatments have been applied to Ti64 (Grade 5) alloy in this study to improve wear properties without negative effect on fatigue and strength. Hardness, wear, fatigue and tensile tests were performed in laboratory air on both untreated and treated Ti64 at room temperature. The hardness and wear results have been published in [2]. The tensile tests were performed on round bar specimens at a constant loading rate and a clip-on strain gauge mounted on the samples for strain measurements. Axial fatigue tests were performed on round bar specimens under constant amplitude load-controlled mode at a frequency of 20 Hz. Subsequently, the fractures surfaces were analysed using SEM. The microstructures and nitrided surfaces were investigated by scanning electron microscopy (SEM), focused ion beam (FIB) and transmission electron microscopy (TEM).

References
[1] www.bodycote.com
[2] S. Stekovic, R. Ramirez-Romero and L. Selegård, ICAS Proceedings: 33th Congress of the International Council of Aeronautical Sciences, 2022, 33.