Effect of Thermal Cycling on Tensile Properties and Impact Toughness of Hydrided Zr-2.5Nb PT Material

The effect of repeated thermal cycling between room temperature and 360 °C on the tensile properties and impact toughness of hydrided Zr-2.5%Nb pressure tube alloy was studied for soaking times of 10 and 30 min at peak temperature. The length of hydride platelet and interplatelet spacing of hydrides were observed to be decreasing with the increase in the number of thermal cycling. It was found that the change in hydride platelet length and its interplatelet spacing caused by thermal cycling affected the mechanical properties to a different extent. The mechanical properties, i.e., yield strength, ultimate tensile strength, elongation and impact toughness, were observed to decrease with the increase in the number of thermal cycles for 10 min soaking time, whereas no significant change was observed for the samples soaked for 30 min. The observed behavior could be attributed to the competition between the damage accumulation due to thermal cycling and stress relaxation due to soaking at peak temperature.