STRESS CORROSION CRACKING BEHAVIOR OF ZIRCALOY-2 IN IODINE ENVIRONMENT.

Abstract

The effects of strain rate, iodine partial pressure and testing temperature were studied by the slow strain rate technique (SSRT). SCC behavior of recrystallized specimens was influenced by test temperatures, and susceptibility of specimens tested at 623 K was higher than that at 573 K. Susceptibility increased with increasing iodine partial pressure at lower strain rates of 4. 2 multiplied by 10** minus **6 s** minus **1 and 8. 3 multiplied by 10** minus **7 s** minus **1. Cold worked specimens indicate no SCC failure in iodine environment regardless of strain rate at 573 K. Fractographic observations revealed two groups; one group tested at 573 K is characterized by cracks initiated from corrosion pits. The other group is characterized by transgranular SCC in the absence of pitting. This type of crack is found on specimens tested in environments containing more than 570 Pa iodine and is produced by iodine embrittlement.