Effect of Annealing on Microhardness and Phase Composition of High-Manganese Austenitic Steels with Twinning-Associated Microstructures Produced by High-Pressure Torsion

摘要

For three high-manganese steels, Fe-13Mn-1.3C, Fe-13Mn-2.7Al-1.3C, Fe-28Mn-2.7Al-1.3C subjected to high-pressure torsion, the limit of thermal stability of microhardness during annealing coincides with a start of γ→ α(α') phase transformation (about 500 ~°C). The volume fraction of α(α')-phase is strongly dependent of steel composition and number of HPT-revolutions. Increase in manganese concentration, which is austenite stabilizer, reduces the tendency to γ-α(α') transformation during annealing at temperatures higher than 500°C, but addition of aluminum, contrarily, intensifies it. Increase in number of HPT revolutions provides higher volume fraction of α(α') phase during 1h-annealing.