Strain Ageing in Zircaloy-4

The strain ageing behaviour of Zircaloy-4 has been studied in the temperature range 175 to 575 for both quenched and annealed specimens. The strain ageing in quenched Zircaloy-4 was found in the temperature range 175 to 50 and its Peak occured at 3 while the strain ageing in annealed specimens occured in the temperature range 175-575, showing two peaks, one at 323 and a higher one at 45. The peak at 3 in both quenched and annealed specimens is considered to be due to the segregation of interstitial oxygen atoms to cell walls during ageing. The peak at 45 in annealed specimens is considered to he due to the interaction of dislocations with Fe atoms. It has been found that strain ageing stress at ~30 in zirconium alloys is proportional to the square root of oxygen content.