Failure assessment curve for austenitic stainless steel pipes of nuclear power plants

摘要

This paper presents a failure assessment curve (FAC), which predicts a conservative failure load of austenitic stainless steel pipes with a circumferential surface crack. Changes in material deformation properties due to cold working, neutron irradiation and thermal aging were taken into account. First, stress-strain curves for stainless steels were assumed for welded, irradiated, cold worked, thermal aged materials as well as undamaged materials using the Swift-type constitutive equation, whose material constants were estimated from the yield and ultimate strengths. Second, the FACs were analyzed for various material properties and crack and pipe geometries. It was shown that the FAC depended on the crack and pipe geometries, and the lower bound FAC were obtained. Finally, the universal FAC, applicable to stainless steel pipes regardless of crack geometries and material properties, was proposed.