Influence of mean stress and pressurized water reactor environment on the fatigue behavior of a 304L austenitic stainless steel

Uniaxial strain-controlled fatigue tests were carried out on a 304L austenitic stainless-steel specimens in air at 300 & DEG;C and in pressurized water reactor (PWR), without or with the application of a mean stress, at different total strain amplitudes. For strain amplitude no less than 0.2%, a deleterious effect of PWR water on fatigue life is observed, associated with the enhancement of both crack initiation and propagation. Besides, the fatigue life is reduced by the application of a mean stress for a fixed strain amplitude in a given environment. In particular, due to the acceleration of crack initiation stage by an enhancement of the plastic strain accumulation, the PWR water effect on fatigue life is re-activated for strain amplitude below 0.2% in the presence of a mean stress. The fatigue life reduction under mean stress application is mostly related to the maximum stress level and strain amplitude, rather than the generated ratcheting strain.

Automated summary

Uniaxial strain-controlled fatigue tests were performed on 304L austenitic stainless-steel specimens at 300°C in air and in a pressurized water reactor (PWR) with or without the application of a mean stress. The tests were conducted at different total strain amplitudes. Results showed that for strain amplitudes greater than or equal to 0.2%, the presence of PWR water had a detrimental effect on fatigue life, characterized by increased crack initiation and propagation. Additionally, the application of a mean stress reduced the fatigue life for a fixed strain amplitude in a given environment. Specifically, the PWR water effect on fatigue life was re-activated for strain amplitudes below 0.2% in the presence of a mean stress due to accelerated crack initiation caused by enhanced plastic strain accumulation. The reduction in fatigue life under mean stress application was primarily influenced by the maximum stress level and strain amplitude, rather than the generated ratcheting strain.