Comparative study of very high cycle tensile and torsional fatigue in TC17 titanium alloy

• Published in: International journal of fatigue Vol. 139; pp. 105720 - 10
• Main Authors: Liu, Hanqing, Wang, Haomin, Huang, Zhiyong, Wang, Qingyuan, Chen, Qiang
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2020; Elsevier BV
• Subjects: Comparative studies; Crack initiation; Crack initiation driven force; Crack propagation; Fatigue cracks; Fatigue failure; Fatigue life; FIB; Ion beams; Materials fatigue; Metal fatigue; Morphology; Shear stress; Short crack propagation; Short cracks; Stress ratio; Tensile and torsional fatigue; Titanium alloys; Titanium base alloys; Torsional fatigue; Very high cycle fatigue; Short crack propagation; Crack initiation driven force; Very high cycle fatigue; Tensile and torsional fatigue; FIB
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2020.105720

•Ultrasonic torsional fatigue tester with the capacity to modify the mean stress is developed.•VVery high cycle tensile and torsional fatigue behavior of turbine blade titanium alloy is comparatively studied.•The short crack nucleation and propagation character of interior initiated fatal crack induced by tensile and torsional loadings are analyzed using FIB milling method. Very high cycle tensile and torsional fatigue of TC17 titanium alloy with bimodal microstructure have been firstly and comparatively studied at the stress ratio of 0.1. Like the tensile cracks, torsional cracks were substantiated to nucleate from specimen surface or interior sites and presented in a fatigue life-dependent mode. Internal tensile and torsional fatigue cracks with faceted morphology were analyzed using focus ion beam and unraveled to initiate in modes II + III that driven by maximum shear stress. Particularly, short crack branching and deflection beneath the crack initiation rough area can be observed for torsional loading condition.