Corrosion Fatigue Crack Growth in Reactor Pressure Vessel Steels in PWR Primary Water

Abstract

Experimental results for corrosion fatigue crack growth in several different ferritic pressure vessel steels including A533-B and A508-III exposed to simulated PWR primary water at 288°C are described. Since relatively little influence of environment was detected in low-frequency tests on these materials, in contrast with data reported from another laboratory, specimens have been exchanged and tested in each laboratory. These results are described, and possible reasons for the observed differences when each tested the same material are discussed. The environmental influence on corrosion fatigue crack growth is analyzed on the basis of a model of a sequence of protective oxide rupture/repassivation events during fatigue cycling. The repassivation kinetics and the controlling electrochemical factors are judged to be of crucial significance in determining the extent of environmental enhancement of fatigue crack growth.