Experimental and theoretical research on creep-fatigue behaviors of 316L steel with and without 650°C thermal aging

In this paper, tensile test and creep-fatigue test at 650 degrees C were carried out for 316L steel with and without prior thermal aging. The effect of aging on creep-fatigue interaction of 316L steel is analyzed in detail. Microscopic observations are performed on fatigue and creep-fatigue specimens to study the microstructure characteristics affected by aging, creep, and fatigue. Actually, three strain amplitude loadings of +/- 0.3%, +/- 0.4%, and +/- 0.5% are adopted in creep-fatigue tests. The creep-fatigue behaviors of unaged and aged 316L steel are investigated in depth for varying strain amplitude. The creep-fatigue constitutive model is constructed by using Chaboche mixed softening and hardening model combined with strain hardening creep. Life prediction models are compared and used to do prediction. The applicability of different models is recommended. The accuracy of the models is analyzed by comparing with the test data. The agreement is achieved between theoretical and experimental predictions.

Automated summary

This paper investigates the effect of aging on the creep-fatigue behavior of 316L steel through creep-fatigue tests before and after thermal aging. Microscopic observations reveal that aging, creep, and fatigue affect the microstructure characteristics of the steel. A creep-fatigue constitutive model is constructed and used for life prediction, and the accuracy of the model is analyzed through comparing with test data.