Abstract:The Low cycle fatigue properties of the commercially pure zirconium (CP-Zr) were investigated by a method under axial loading controlled by symmetric strain. The characteristics of cyclic stress-strain response and hysteresis loop of CP-Zr were discussed. Cycle softening and hardening characteristics and cumulative hysteresis of the CP-Zr were analyzed and then the fatigue life was predicted. The results indicate that the CP-Zr displays cyclic hardening when the total strain amplitude is more than 0.5%. The fatigue life of CP-Zr matches Basquin-Coffin-Manson"s empirical relationship, whose transitional life is 1548 cycles. And the plastic strain energy can be suitably utilized as an essential parameter in fatigue failure model to evaluate the fatigue damage. The hysteresis loop area (i.e. the plastic strain energy) decreases with the total strain amplitude decreasing and the number of fatigue cycles increasing. The fatigue striation can be obviously observed, as the total strain amplitude increases, the number of fatigue striation decreases and the width increases.