Manganese dependence of microstructure and mechanical properties in Fe–Mn alloy

Two Fe–Mn alloys with relatively low Mn content were designed. The microstructure characteristics and resultant mechanical properties were investigated in detail by means of electron back-scattered diffraction, transmission electron microscopy and X-ray diffraction. The results show that the formation of α′-martensite is effectively suppressed and the yield strength and total elongation are significantly enhanced by increasing Mn content from 12 to 13 mass%. A great amount of α′-martensite can effectively enhance strain hardening rate, but they deteriorate ductility. The austenite grain is always divided by multiple-variant ?-martensite plate. In addition, the prior austenite grain boundaries and austenite/?-martensite interfaces can act as obstacle to suppress the growth of ?-martensite plates.