Calibration of the local IGSCC engineering model for Alloy 600

Abstract : Many Stress Corrosion Cracking (SCC) models have been developed so far. Quantitative empirical models, trying to predict initiation and crack growth rate of nickel alloys exposed to pressurized water reactor primary water do not describe physical mechanism and suffer a lack of accuracy. By contrast, models describing the possible involved physical mechanisms responsible for degradation (selective oxidation of grain boundaries in the case of Alloy 600 exposed to PWR primary water) are usually qualitative. In the current paper, a ‘local’ model is proposed to better predict SCC. In order to succeed, behaviors assumed to be involved in the SCC process were calibrated and coupled: intergranular oxidation rate, intergranular stresses, resistance to cracking of oxidized grain boundaries. The output of the model is the time to reach a given crack depth. This paper introduces the first calibration of parameters for Alloy 600 exposed to primary water.