Crack Initiation Mechanism and Life Prediction of Ti60 Titanium Alloy Considering Stress Ratios Effect in Very High Cycle Fatigue Regime

• Published in: Materials Vol. 15; no. 8; p. 2800
• Main Authors: He, Ruixiang, Peng, Haotian, Liu, Fulin, Khan, Muhammad Kashif, Chen, Yao, He, Chao, Wang, Chong, Wang, Qingyuan, Liu, Yongjie
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 11.04.2022; MDPI
• Subjects: Crack initiation; Crack propagation; Fatigue cracks; Fatigue failure; fatigue failure mechanism; Fatigue life; fatigue life prediction; fatigue strength prediction; Fatigue tests; Fracture mechanics; High cycle fatigue; Life prediction; Metal fatigue; Morphology; Prediction models; Propagation; S N diagrams; stress ratio; Ti60 titanium alloy; Titanium alloys; Titanium base alloys; very high cycle fatigue; China; stress ratio; Ti60 titanium alloy; fatigue life prediction; fatigue failure mechanism; fatigue strength prediction; very high cycle fatigue
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma15082800

Ultrasonic fatigue tests were performed on Ti60 titanium alloy up to a very high cycle fatigue (VHCF) regime at various stress ratios to investigate the characteristics. The S-N curves showed continuous declining trends with fatigue limits of 400, 144 and 130 MPa at 10 cycles corresponding to stress ratios of R = -1, 0.1 and 0.3, respectively. Fatigue cracks found to be initiated from the subsurface of the specimens in the VHCF regime, especially at high stress ratios. Two modified fatigue life prediction models based on fatigue crack initiation mechanisms for Ti60 titanium alloy in the VHCF regime were developed which showed good agreement with the experimental data.