Corrosion fatigue behaviour of A508 Class III steel in a simulated PWR water environment at 3250C

Fatigue crack growth data in a simulated PWR environment for A508 Class III steel at 3250C generally exhibited good agreement with crack growth data recorded for A533B steel at 2880C. All data were positioned below the ASME XI high R 'wet' line. It has been shown through sulphur printing and fractography that the morphology and distribution of non-metallic sulphide inclusions play an important part in initiating environmentally assisted crack (EAC) growth which is identifiable by its fan-shaped fracture mode. In regions of EAC crack growth a significant area of the fatigue fracture surface can still exhibit ductile striated growth. Indeed it has been shown that significant EAC growth occurs when the amount of fan-shaped growth prevalent on the fatigue surface exceeds approx. 20%. Also, fan-shaped growth tended to occur at the centre of the test specimen. (author)