Deformation Mechanism And Mechanical Properties Of Nano/Ultrafine Grained And Heterogeneous Fe-17cr-6ni Austenitic Steel

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