An experimental investigation of the effect of positivemean stress and of PWR primary environment on thefatigue life of 304L austenitic stainless steel (SS) ispresented in this work. Uniaxial strain amplitudecontrolledfatigue tests in a regime near the fatigue limitwere performed in the air (300°C) and in PWR primarywater environment (300°C), with or without positive meanstress. Strain and stress fatigue life curves, cyclic stressstrainof the material were studied. It is shown that theapplication of mean stress under constant strain amplitudeenhances and extends the hardening stage, and generatesa ratcheting effect. Fatigue life is reduced with mean stressfor a given strain amplitude in two environments, and thisnegative effect is less pronounced in PWR water. Themodel of Smith-Watson-Topper is applied, and showssatisfactory agreement with test data in PWR water with orwithout mean stress, at a strain amplitude of 0.2%.
展开▼
