Fatigue behavior of ultrafine-grained and coarse-grained Cr-Ni austenitic stainless steels

► Fatigue resistance of ultrafine-grained 301LN is highly increased by grain refinement. ► Fatigue mechanism differs distinctly from that of coarse-grained steel. ► Grain boundary cracking is intensive in ultrafine-grained steel. ► Cyclic hardening is minimal in ultrafine-grained steel compared to that in coarse-grained one