E. Lee, H. Sanders, R. Taylor, C. Lei, NAVAIR-Naval Air Systems Command, Patuxent River, MD; C. Yu, AMETEK, Inc., Wallingford, CT

Summary:

Tubing and solid rod of Ti-3Al-2.5V alloy were subjected to low cycle fatigue straining at frequency 5 Hz and strain ratio –1 in laboratory air, and their fatigue behaviors were compared. As the representative fatigue behaviors, the changes in stress and shape of hysteresis loop under controlled strain were examined to define the fatigue crack initiation life Ni, fatigue fracture life Nf was determined, and the strain-life relations were established for the fatigue crack initiation and fracture. Furthermore, the related fractographic features were studied. Under a given strain range or strain amplitude, the LCF life was found to be longer for the tubing than for the rod.