Low cycle fatigue behavior and fatigue life prediction of 2195 Al-Li alloy at warm temperatures

Abstract

The strain-controlled low cycle fatigue (LCF) tests were firstly carried out to investigate the LCF behavior of the 2195 Al-Li alloy at warm temperatures (100 and 200 °C). All initial and mid-life hysteresis loops showed a centrosymmetric characteristic. The cyclic stress response curve at 100 °C and strain of 0.6% exhibited complete cyclic hardening, while response curves under other conditions showed cyclic hardening initially followed by cyclic softening. Then, various fatigue life prediction models were employed to evaluate LCF life. The prediction model based on the total strain energy density could present the best prediction accuracy. Finally, the fatigue fracture under different conditions was observed to reveal the fatigue fracture mechanism. The fatigue striations were visible at 100 °C and strain of 0.6%, but gradually diminished with increasing temperature and strain. Furthermore, the fatigue fracture zone at 200 °C and strain of 1.0% presented an evident intergranular fracture characteristic.