Brittleness of ?, ?, and ? solid solutions of Fe-Mn alloys

Abstract

1. Iron-manganese alloys with ferritic and martensitic structures have high ductile-brittle transition temperatures and transcrystalline brittle fractures. 2. Alloys with e martensite (α+e+γ and e+γ) are characterized by a lower ductile-brittle temperature (−20 to −80°) and higher fracture toughness than α alloys; the ductile fractures are dimpled and the brittle fractures are intercrystalline. 3. A clear ductile-brittle transition is observed in γ alloys; the ductile dimpled fracture changes to brittle intergranular fracture in a relatively narrow temperature range. 4. Manganese raises the ductile-brittle temperature of γ alloys in contrast to α and e alloys, for which the transition temperature drops with increasing manganese concentrations. 5. Brittleness of austenitic Fe-Mn alloys is not associated with structural transformations: The transition to the brittle condition may be due to changes in electron structure.