Low-cycle fatigue behavior of small slice specimens of zircaloy-4 at elevated temperature

A series of strain fatigue tests were carried out on small bugle-like slice-specimens of Zr-4 alloy at 20 degrees C and 400 degrees C. According to Elastic and Plastic Finite Element Analysis (EPFEA) and assumption of local damage equivalence, a strain formula was given to transform transverse strain of the specimen to uniaxial strain. Based on the test results of the alloy and the strain transform formula, M-C (Manson-Coffin) models to be used for estimating uniaxial fatigue life of Zr-4 alloy were obtained. The results show that, the alloy mainly behaves as cyclic softening at 20 degrees C and as cyclic hardening at 400 degrees C, and the elevated temperature can lead serious additional fatigue damage of the alloy and the effect of the elevated temperature impairs gradually with increasing of amplitude strain. A conclusion is helpful that prediction life by using M-C model based on traditional strain transform equation is quite conservative when uniaxial strain amplitude is less than 0.5%.