Microstructure and mechanical properties of advanced austenitic steel

Microstructure and mechanical properties of new austenitic stainless steel are studied. The solution treatment and subsequent hot bar rolling at 1100°C form equiaxed austenite grains with an average size of 15 µm. Subsequent bar rolling at 1000 or 950°C leads to a decrease in the grains size to 11 or 8 µm, respectively. A decrease in the rolling temperature results in a significant increase in yield strength, which comprises 870 MPa at room temperature and 1000 MPa at –100°C in specimens finally hot rolled at 950°C. On the other hand, the impact toughness at room and cryogenic (–196°C) temperatures decreases from 420 and 173 J/cm2, respectively, in the initial (hot rolled at 1100°C) state to 237 and 61 J/cm2 in specimens finally rolled at 1000°C or to 68 and 28 J/cm2 in specimens finally rolled at 950°C.