Strength Properties and Microstructure of High Mn-Cr Austenitic Steels as Potential High Temperature Materials

The present authors have investigated the high temperature strength, toughness and microstructural phase instability of 12%Cr-15%Mn steels, for the development of high Mn-Cr austenitic steels as heat resisting materials. While high content of carbon and nitrogen (0.1 to 0.2 nass% C and N) and combined addition of vanadium and titanium were effective to increase the creep-rupture strength considerably compared with that of the regular type 316 steel or Tenelon, such addition of the elements deteriorated the toughness of the materials because of the large amounts of coarse precipitates of type M23C6 carbide and also fine precipitates of TiN. It was clarified that the reducing of carbon content to 0.02 mass%C improved much the toughness of the 12%Cr-15%Mn steel and also produced the creep-rupture strength which is comparable with that of the 316 steel.