Study on Fatigue Properties of Hydrided CZ2 Alloy

CZ2 alloy is a new Zr-Nb zirconium alloy independently developed by China Nuclear Power Research and Technology Institute (CNPRI), which has independent intellectual property rights. Zirconium will react with coolant to absorb hydrogen in reactor service, which will degrade the performance of zirconium alloy and lead to failure. Therefore, in many studies of zirconium alloy performance, hydriding is often used to simulate burnup. In this paper, CZ2 alloy with hydrogen content of about 400 ppm was obtained by gaseous hydrogen charging method. The sample was heated to 500°C with the furnace in hydrogen environment and kept for 1.5 h. Then the fatigue tests of hydrided/un-hydrided CZ2 alloy and un-hydrided Zr-4 alloy under asymmetric axial pull-pull loading at 343°C were carried out to study the effect of hydride on the fatigue properties of CZ2 alloy. The results show that with the decrease of stress level, the difference between the fatigue life of CZ2 alloy un-hydrided and that of hydrided becomes larger, and the fatigue life of CZ2 alloy un-hydrided is higher than that of hydrided. The fatigue properties of un-hydrided CZ2 alloys are better than Zr-4 alloys. The two-parameter model and three-parameter model are used to fit the fatigue data of CZ2 alloy. It is found that the three-parameter model can better describe the fatigue life of CZ2 alloy.