Nickel-free iron-manganese alloys

Abstract

1. Melt purity has a marked effect on the level of mechanical properties for Fe−Mn alloys and the nature of their change with an increase in manganese concentration. 2. For high-purity alloys strength properties increase markedly in the two-phase (e+γ)-region. Alloy with 21–24% Mn has the maximum strength (σf = MPa; σ0.2 = 4.50 MPa). 3. At the boundary of the (e+γ)-and γ-regions for high-purity alloys "boundary" or concentration superplasticity is observed; a reduction in test temperature to −196°C is accompanied by an increase in relative elongation. 4. For industrial purity alloys strength properties decrease gradually with a changeover from α- to e- and γ-solid solutions. Strength and ductility properties of these alloys are insensitive to the position of the (e+γ)- and γ-region boundary. 5. With an increase in melt purity reserve ductility for Fe−Mn alloys increases, and this has been established by fractographic study of the nature of their failure.