Improvement of fatigue properties of Ti-6Al-4V alloy under four-point bending by low temperature nitriding

• Published in: International journal of fatigue 2019-03, Vol.120, p.134-140
• Main Authors: Kikuchi, Shoichi, Yoshida, Sho, Ueno, Akira
• Format: Article
• Language: English
• Subjects: Bending fatigue; Coarsening; Fatigue; Fatigue limit; Fatigue tests; Fractography; Fracture mechanics; Heat treating; Low temperature; Materials fatigue; Nitriding; Nitrogen; Nitrogen compounds; Stress ratio; Titanium alloy; Titanium alloys; Titanium base alloys
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2018.11.005

•A nitrogen compound layer is formed on the surface of Ti-6Al-4V nitrided at 873 K.•Nitrogen diffusion is observed on the surface of Ti-6Al-4V nitrided at 823 K.•Low temperature nitriding suppresses the grain-coarsening of Ti-6Al-4V.•Low temperature nitriding at 823 K increases the fatigue limit of Ti-6Al-4V. Low temperature nitriding (LTN) was performed for titanium alloy (Ti-6Al-4V) to improve its fatigue properties. A nitrogen compound layer was formed on the surface nitrided at temperatures higher than 873 K, whereas nitrogen diffusion was observed on the surface nitrided at 823 K. Fatigue tests were performed by four-point bending in air under a stress ratio of 0.1. The fatigue limit for Ti-6Al-4V tended to increase with a decrease in the nitriding temperature. LTN at 823 K increased the fatigue limit of Ti-6Al-4V due to the formation of the surface with no nitrogen compound layer and suppression of grain-coarsening.