Fatigue Crack Growth Curve in Air Environment at 300°C for Stainless Steels

The need exists to define a fatigue crack growth design curve in an air environment for austenitic stainless steels in the temperature range of 300°C, which is the operating temperature range of pressurized water reactors. In the present study, elements to determine such a curve in a deterministic way are developed. In particular, effects of R ratio (Kmin/Kmax) are reviewed, and high R ratio tests, which were lacking, have been performed. To take into account R ratio effects, a relationship giving realistic predictions in accordance with high R ratio experiments is determined. A design curve, defined from a large compilation of results from several laboratories, allows a conservative calculation of all known fatigue crack growth tests on austenitic stainless steels in the temperature range of 300°C.