Strain rate susceptibility of stress corrosion cracking for commercial Zr702 used in spent nuclear fuel reprocessing

Slow strain rate tensile (SSRT) experiments were applied to comprehensively examine the strain rate susceptibility of the stress corrosion cracking behaviour of commercial Zr702 used in the spent nuclear fuel reprocessing environment. Results revealed that layers formed on Zr702 in boiling HNO3 solutions was composed of monoclinic ZrO2 (m-ZrO2) and tetragonal ZrO2 (t-ZrO2). With strain rates above 10(-4) s(-1), oxide layers ruptured rapidly, evidenced by the drop down of opened circuit potential (OCP). However, the OCP curve displayed fluctuation with 10(-5) s(-1) during straining, indicating that oxide layer alternately ruptured and repaired, resulting in the thickening of the oxide layer and increasement of stress corrosion cracking susceptibility.