Role of hot rolling procedure and solution treatment process on microstructure, strength and cryogenic toughness of high manganese austenitic steel

In this study, the relationship between mechanical properties and microstructure of high manganese steels processed by different rolling practice and solution temperatures were systematically studied in terms of strength and toughness using optical microscopy (OM), scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD), transmission electron microscopy (TEM) techniques. The experimental results suggested that the solution treatment is an effective method to improve Charpy impact toughness at −196 °C from ~68 J to ~120 J, while the strength decreases. The grain size coarsened with the increase of solution temperature. However, the change in strength and toughness was small. The role of grain coarsening on strength and toughness was weak. The stability of austenite at low temperature was high as the microstructure only consisted of austenite. The fracture mode during low-temperature impact process was ductile and the main deformation mechanism was mechanical twinning