Crack initiation mechanism of titanium alloy in very high cycle fatigue regime at 400℃ considering stress ratio effect

• Published in: International journal of fatigue Vol. 163; p. 107012
• Main Authors: Liu, Fulin, Peng, Haotian, Liu, Yongjie, Wang, Chong, Wang, Qingyuan, Chen, Yao
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2022
• Subjects: Crack initiation, Stress ratio; High temperature; Titanium alloy; Very high cycle fatigue; Titanium alloy; Very high cycle fatigue; RT; BOES; SSD; G; HCF; High temperature; HT; Crack initiation, Stress ratio; EBSD; BHKV; RA; IFM; R; UTS; KAM; YS; SEM; GB; GND; VHCF; IPF
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2022.107012

[Display omitted] •Very high cycle fatigue behavior of TC17 with stress ratios was investigated at 400℃.•Crack initiation depends on facets formation and is related to maximum shear stress.•Formation of facets is induced by basal or prismatic slips with high Schmid factor.•GNDs density is accumulated along with basal or prismatic slips, forming sub-GBs. Fatigue behavior of titanium alloy with various stress ratios was investigated at 400℃ in VHCF regime. Cracks initiation depends on the formation of facets and is related to the maximum shear stress. The formation of facets is induced by basal or prismatic slips with the high Schmid factor inside αp grains. The morphology of αp grains will affect the crack initiation. The high-density GNDs are found to be accumulated along with the basal or prismatic slips, then form subgrain boundaries (sub-GBs) inside αp grains. With the cyclic loading, the created sub-GBs will further form facets, thus initiating the microcracks.