Low Cycle Fatigue Crack Damage Behavior of TC21 Titanium Alloy with Basketweave Microstructure

Low cycle fatigue (LCF) crack initiation, propagation and damage behaviors of TC21 alloy with basketweave microstructure were investigated. The process of LCF damage was observed by a long-focus optical microscopic imaging system, and fatigue crack propagation was analyzed through in-situ SEM fatigue. The results indicated that LCF crack damage displayed different sensitivity to cyclic stress. LCF microcracks initiated from slip bands and propagated through the microcrack coalescences at high stress, while LCF cracks tended to initiate at the alpha(L)/beta interface and connect with these interface microcracks. Furthermore, the LCF damage model was established on the basis of Lemaitre damage theory. When the maximum stress exceeded yield stress, LCF damage increased sharply and fatigue life decreased significantly, which agreed with experiment data.

Automated summary

The crack initiation, propagation, and damage behaviors of TC21 alloy with basketweave microstructure under low cycle fatigue (LCF) were investigated. The process of LCF damage was observed, and in-situ SEM fatigue analysis was conducted. The study found that LCF crack damage showed different sensitivity to cyclic stress, with different initiation and propagation patterns.