Deformation Mechanism and Mechanical Properties of Nano/Ultrafine Grained and Heterogeneous Fe–17Cr–6Ni Austenitic Steel

Deformation behavior and mechanical propertiesMechanical properties of Fe–17Cr–6Ni austenitic steelSteel with nanoNano/ultrafine grained structure/ultrafine grained microstructureMicrostructure and heterogeneous microstructureMicrostructure were studied in this investigation. With decreasing grain size, stacking fault and deformation twining gradually became the unique deformation mechanism in nanoNano/ultrafine grained structure/ultrafine grained austenitic steelSteel while in the coarse grained counterpart, deformation induced martensiteMartensite transformation was always the dominant deformation mechanism. This is due to that with decreasing grain size, the critical stress for nucleating partial dislocationsDislocations became smaller than that for nucleating perfect dislocationsDislocations. Besides, the heterogeneous nanoNano/ultrafine grained structure/ultrafine grained austenitic steelSteel was found to possess better mechanical propertiesMechanical properties compared with homogeneous nanoNano/ultrafine grained structure/ultrafine grained steelSteel, which can be attributed to high back stress hardeningBack stress hardening and multi-stage strain hardening.