The effect of environment on fatigue life is currentlyassessed using methods (e.g. NUREG/CR-6909), whichmay be excessively conservative when applied to plantcomponents and loading transients. To reduce thisconservatism, the ASME WG-EFEM has proposed thedevelopment of an improved assessment methodology forenvironmental fatigue based on a Total Life Predictionapproach that would be adequately, but not excessively,conservative. Such an approach necessitates thedevelopment of analytical methods for the various stagesof crack nucleation, short crack growth and long crackgrowth. Hence, there is a requirement to undertake testingwithin the short crack growth regime that would bridge thegap between fatigue nucleation and long crack growth(Paris Law), to better enable prediction of total lifemeasured by fatigue endurance.A test methodology has been developed to enableshort crack growth testing with in-situ monitoring usingDirect Current Potential Drop (DCPD). Testing has beenundertaken in both high temperature air (300 ºC) andsimulated end-of-cycle primary water chemistry at 300 ºCon cold-worked stainless steel specimens, which weresubject to a load ratio of R = 0.05. Finite Element Analysis(FEA) modelling has been undertaken to both correlateDCPD response with crack growth measurements, and todetermine the effective stress intensity factors appliedunder the loading conditions based on the specific materialproperties.This paper presents this methodology for short crackgrowth measurements, and the preliminary resultsobtained from initial testing of 304L stainless steel. Crackgrowth rates have been compared to those predicted inASME Section XI for air rates, Code Case N-809 for waterrates, as well as in-house test results for longer cracks fromthis specific heat of material.
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