Strain ageing of quenched zircaloy-2

The stain ageing behaviour of quenched Zircaloy-2 has been studied in the temperature range 150 to 475°C. Quenching from 750°C enhanced the strain ageing response at 300° C and suppressed it at ~450°C compared with the behaviour of annealed and slow cooled Zircaloy-2. Increasing the quenching temperature in the range 750 to 850°C increased the strain ageing response at all test temperatures. The yield stress and tensile strength increased with quenching temperature whereas the ductility was decreased.The enhanced strain ageing at 300°C is thought to be due to the presence of interstitial-interstitial atom pairs. The suppression of strain ageing at ~450°C is considered to be due to trapping of Fe atoms by quenched-in defects.