Abstract
To study the mechanical properties of Zircaloy-4 in hydrogen gas, notched Zircaloy-4 plate specimens were tested in a hydrogen gas environment of various pressures up to 2020 kPa at 25, 100 and 200°C. The results showed that, for all test temperatures, the notch tensile strength of Zircaloy-4 was slightly increased with hydrogen pressure until 101 kPa and then decreased with increasing hydrogen pressure. A ductile-brittle transition of reduction of area at 25°C was found when the alloy was tested at hydrogen pressure between 101 and 1010 kPa. From the fractographic finding, the ductile-brittle transition was closely related to the precipitation of brittle hydrides. The ductile-brittle transition became less distinct at 100°C and above. This was attributed to the improved ductility of zirconium matrix with increasing temperature. © 1994.