Cryogenic Properties of Iron-Manganese and Iron-Manganese-Chromium Alloys
SourceA wide range of microstructures were obtained in iron-manganese alloys by varying the manganese and chromium contents. When a body centered cubic α structure was produced, increasing amounts of manganese were found to be detrimental to low temperature toughness. At manganese levels greater than 12 percent where appreciable amounts of ε and γ phases formed, the ductile-brittle transition temperature dropped rapidly. In terms of the ϵ + γ phases present, the ductile-brittle transition temperature decreased at a rate of 1.3°C/volume percent ε + γ. Increasing the ε + γ content to achieve good low temperature toughness, however, also caused a decrease in the yield strength. Increases in the yield strength were achieved without appreciable increase in the ductile-brittle transition temperature by greater manganese and chromium additions.