Study of Iodine-Induced Stress Corrosion Cracking of CZ2 Alloy

Abstract

This paper is dealing with the iodine-induced stress corrosion cracking behavior of CZ2 zirconium alloy which is developed by China General Nuclear Power Group. The alloy in this study was fabricated with four different final annealing temperature in the range of 450 °C to 600 °C. In order to investigate the iodine-induced stress corrosion cracking behavior of CZ2 alloy, the slow strain rate tensile tests of four different CZ2 were conducted with three different iodine partial pressure of 0Pa, 10Pa and 10000Pa. The temperature of the tests was 350 °C and the strain rate was 1.4 × 10−6s−1. Also, the sensitivity index of iodine-induced stress corrosion cracking was calculated. The iodine-induced stress corrosion cracking sensitivity index of recrystallized CZ2 alloy is lower than that of stress-relieved CZ2 alloy, and with the increase of final annealing temperature, the sensitivity index decreases gradually. Finally, the fracture surface of CZ2 alloy was observed by scanning electron microscopy. The fracture feature of all four different CZ2 alloy changes from ductile fracture morphology to brittle fracture morphology with the increase of iodine partial pressure. Under the condition of 10000 Pa iodine partial, the fracture feature of stress-relieved CZ2 shows obvious brittle cleavage fracture, the fracture feature of partially recrystallized CZ2 is partly ductile fracture and partly cleavage fracture morphology. For recrystallized CZ2, there are many dimples in the fracture morphology, and shows obvious ductile fracture.