Abstract
A nano/ultrafine-grained (NG/UFG) structure was obtained by heavy cold deformation (80%) and annealing in the range between 700 and 950°C for 60 s to explore the effects of temperature on the development of NG/UFG structures in austenitic stainless steel. Results showed that martensite was reversibly transformed to austenite, with the accumulation of twins, dislocations and subgrain boundaries. At 700°C, the microstructure exhibited low elongation and consisted of 65% austenite. Above 750°C, the amount of reversed austenite was nearly 100%. The tensile strength of the sample decreased slightly, whereas the elongation increased further, showing co-dependent strengthening and toughening. At 850°C, micrometre-sized grains were embedded in the nanocrystalline/ultrafine grains. In this case, both the microstructure and mechanical properties were optimal.
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