Interactive Effect of Dynamic Strain Ageing with High Temperature Water on the Crack Initiation Behaviour of Reactor Pressure Vessel Steels

Abstract

The effect of dynamic strain ageing (DSA) on stress corrosion cracking (SCC) of reactor pressure vessel (RPV) steels has been investigated. The experimental investigation was conducted on an A533B Class 1 steel subjected to slow strain rate test (SSRT) at a nominal strain rate of 2 {times} 10{sup {minus}6}/s in stagnant primary water at 250 C. Various DSA responses of the steel were achieved by appropriate heat-treatment processes. The evaluation was made under identical environment conditions. The results demonstrated that DSA enhanced the SCC which was consistently observed only in the steel that was heat-treated to give the most significant DSA hardening effect. The SSRT and fractographic evidence supports the previous observations based on the data analysis, i.e. there was a coincidence of temperature and strain rate between the DSA hardening and the susceptibility to environment-assisted cracking (EAC) of RPV steels. The mechanistic role of DSA and its interaction with other influential variables in the enhancement of SCC are discussed.