Dynamic improvement of fatigue strength via local phase transformation in a circumferentially-notched austenitic stainless steel under fully-reversed loading condition

摘要

The fatigue limit of a circumferentially-notched austenitic stainless steel exhibited peculiar improvement under fully-reversed loading (R = -1), as compared with that under tension-tension loading (R=0.1), behavior considered to be unconventional in smooth specimens of similar materials. This was attributed to the different cyclic stress-strain responses at the notch-root, where it was almost elastic at R=0.1, whereas an elasto-plastic response continued up to later stage of the fatigue process at R = -1. Such cyclic plasticity enhanced martensitic transformation locally and resulted in hardening, thereby restricting fatigue crack initiation from the notch-root. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.