Effects of annealing temperature on nano/ultrafine-grained structure in austenite stainless steel

摘要

A nano/ultrafine-grained (NG/UFG) structure was obtained by heavy cold deformation (80%) and annealing in the range between 700 and 950 degrees C for 60s 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 degrees C, the microstructure exhibited low elongation and consisted of 65% austenite. Above 750 degrees 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 degrees C, micrometre-sized grains were embedded in the nanocrystalline/ultrafine grains. In this case, both the microstructure and mechanical properties were optimal.