1 Key Laboratory for Ferrous Metallurgy and Resources Utilization(Ministry of Education), Wuhan University of Science and Technology, Wuhan 430081, China 2 The State Key Laboratory of Refractories and Metallurgy, Wuhan 430081, China 3 Hubei Collaborative Innovation Center for Advanced Steels, Wuhan 430081, China
The concept of phase reversion involving cold deformation of metastable austenite to generate strain-induced martensite, followed by temperature-time annealing sequence, was used to obtain grain size of nanograined/ultrafine-grained and coarse-grained austenitic stainless steels. The mechanical properties of austenitic stainless steels with different grain sizes were obtained by tensile testing, the deformation microstructure and fracture surface were analyzed by TEM and SEM observations, respectively. The results indicate that deformation twins contribute to excellent ductility in high yield strength nanograined/ultrafine-grained steel, while in the low yield strength coarse-grained steel, the high ductility is due to strain-induced martensite transformation. Interestingly, the tensile fracture of the two austensite stainless steels with different deformation mechanism is ductile fracture. The deformation mechanism from deformation twins to strain-induced martensite in the coarse-grained structure in nanograined/ultrafine-grained structures is owing to the increased stability of austenite with grain refining.
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2016, Vol. 44 
), 周博文2, 马江华1
