Plain fatigue and fretting fatigue behaviour of plasma nitrided Ti-6Al-4V

Effect of Plasma Nitriding Environment and Time on Plain Fatigue and Fretting Fatigue Behavior of Ti–6Al–4V

“…Grill et al [14] reported that the fatigue resistance of a plasma-nitrided titanium alloy depends on the relative concentration of the different phases [e, d and a(N)] and their crystallographic orientations, which can be varied by changing the processing parameters. This may be the reason for the observed difference between the results obtained in the previous study [18] and those of this study. This result also implies that an improvement in fatigue lives can be achieved through proper selection of the plasma nitriding process parameters.…”

“…Grill et al [14] reported that fatigue resistance of a plasma-nitrided titanium alloy depends on the relative concentration of different phases and their crystallographic orientations, which could be varied by changing the processing parameters. Improvement in plain fatigue lives by plasma nitriding (performed at 500°C for 6 h in nitrogen-hydrogen mixture, 3:1) was also reported by Rajasekaran and Ganesh Sundara Raman [18].…”

“…Liu and He [16] found that the fretting fatigue resistance of this alloy was decreased due to a decrease in the toughness of the plasma-nitrided layer. In contrast, Rajasekaran and Ganesh Sundara Raman [18] reported that plasma nitriding marginally improved the fretting fatigue lives of Ti-6Al-4V samples. Vadiraj and Kamaraj [17] have also reported the beneficial effect of plasma nitriding (performed at 450-500°C for 4 h in a nitrogen-hydrogen mixture, 3:1).…”

“…For samples nitrided in the nitrogen-hydrogen mixture, those nitrided for 18 h exhibited superior fatigue lives than those nitrided for 4 h. This trend was observed for samples nitrided in nitrogen gas at lower stress levels only, and the converse was true at higher stress levels of 550 and 700 MPa. In an earlier study on the same material, Rajasekaran and Ganesh Sundara Raman observed the beneficial influence of plasma nitriding in improving plain fatigue lives [18]. In that study, plasma nitriding was performed at 500°C for 6 h in a nitrogen-hydrogen mixture (ratio 3:1).…”

“…One proposal for overcoming this problem is to perform the nitriding process at relatively lower temperatures (less than 600°C) [11,13]. To date, however, only a limited amount of work has been performed on low-temperature plasma-nitrided Ti-6Al-4V [14][15][16][17][18].…”