In-beam fatigue behavior of 20% cold-worked 316 stainless steel at 300 °C

Load-controlled fatigue tests in tension–tension mode were performed for the side-notched 20% cold-worked 316 stainless steel in the in-beam and post-irradiation conditions with 17 MeV protons at 300 °C. Fatigue life in the in-beam tests was almost double as much as that of unirradiated tests, while the extension of fatigue life was 2.5 times for post-irradiation tests. The SEM measurements of fatigue striations on fracture surface indicated substantial delay in the process of crack initiation and growth until 100 μm in length in the post-irradiation specimens. Pre-existence of larger faulted loops in the post-irradiation specimens would play an important role in delaying the fatigue fracture processes and subsequently lead to more substantial extension of fatigue lifetime in the post-irradiation condition than that in the in-beam condition at 300 °C.