Enhancement of yield strength by chromium/nitrogen alloying in high-manganese cryogenic steel

Chromium (Cr)/nitrogen (N) alloying can enhance the yield strength of high-manganese (Mn) steels. This work investigated the mechanical properties of a high-Mn twin-induced plastic (TWIP) steel with 6.3% Cr and 0.2% N by tensile testing in an ambient atmosphere and impact testing at -196 degrees C. The yield strength of the high-Mn steel was improved significantly with Cr/N alloying and an excellent low-temperature toughness was maintained. Solid solution strengthening resulting from dissolved nitrogen was the most effective strength mechanism to increase the yield strength of the steel compared with grain-boundary and precipitation strengthening, which result from the precipitation of aluminum nitride. Grain-boundary and precipitation strengthening result from the precipitation of aluminum nitride. Because of its excellent mechanical properties, high-Mn steel that is produced by Cr/N alloying can be used to manufacture storage tanks for liquefied natural gas.