SEM Investigation of High-Alloyed Austenitic Stainless Cast Steels With Varying Austenite Stability at Room Temperature and 100°C

The deformation mechanisms of high-alloyed cast austenitic steels with 16% of chromium, 6% of manganese, and a nickel content of 39% were investigated by in situ and ex situ scanning electron microscopy. The austenite stability and the stacking fault energy were influenced by variation of the chemical composition as well as by changing deformation temperature (room temperature; RT and 100 degrees C). The study shows that both an increase in austenite stability and stacking fault energy yield a significant change in the deformation mechanisms. Both increase of nickel content and increase in deformation temperature reduce the intensity of the martensitic phase transformation. Thus, the steel with low nickel content shows at RT pronounced formation of a'-martensite. The steel with the highest nickel content, however, shows pronounced twinning.