Effects of hydride precipitation on the mechanical property of cold worked zirconium alloys in fully recrystallized condition

The effects of hydrogen precipitation on the mechanical properties of Zircaloy–4 and Zirlo alloys were examined with uniaxial tensile tests at room temperature and at 400 °C and accompanying microstructural changes in the Zircaloy–4 and Zirlo alloy specimens were discussed. The elastic moduli of Zircaloy–4 and Zirlo alloys decreased with increasing hydrogen concentrations. Yield strengths of both materials tended to decrease gradually. The reductions of yield stress seems to be caused by the dissipation of yield point phenomena shown in stress-strain curves. Ultimate tensile strengths (UTS) of Zircaloy–4 and Zirlo slightly increased at low hydrogen contents, and then decreased when the concentrations exceeded 500 and 700 wppm, respectively. Uniform elongations were stable until 600 wppm and drops to 0% around 1400 wppm at room temperature.