Influence of prior creep-fatigue exposure on remnant tensile and creep properties of AISI 321 austenite stainless steel

AISI 321 steels used as heat exchange tube are generally subjected to creep-fatigue exposure during service. Assessing their remnant properties is therefore required to ensure components safety. In this work, cyclic responses during different prior creep-fatigue exposure, and remnant tensile and creep behaviors of AISI 321 were studied. Results revealed cyclic responses showed initial hardening and subsequent softening. Due to pinning effects of M23C6 and increased twining boundary fractions, remnant properties were improved when prior creepfatigue lifetime fraction is below 50%. However, degraded remnant properties with lifetime fraction further increasing to 80% were found, resulted from de-twinning and carbide coarsening.

Automated summary

This study investigated the cyclic responses and remnant tensile and creep behaviors of AISI 321 under different prior creep-fatigue exposures. The results showed that the cyclic responses exhibited initial hardening followed by softening. The remnant properties were improved when the prior creep-fatigue lifetime fraction was below 50% due to pinning effects and increased twining boundary fractions. However, degraded remnant properties were observed when the lifetime fraction further increased to 80% as a result of de-twinning and carbide coarsening.