Study on as-cast microstructure of Fe-15Mn-10Al-5Ni-0.8C low density duplex steel

Abstract

The microstructure of Fe-15Mn-10Al-5Ni-0.8C low density duplex steel ingots was studied by laser confocal scanning calorimetry, metallographic microscopy and scanning electron microscopy. The results indicated that: the microstructure of Fe-15Mn-10Al-5Ni-0.8C low density steel was mainly composed of coarse austenite dendrites and δ-ferrite phase in dendrite. The δ-ferrite could be completely eliminated by solution treatment. A dynamic model of austenite grain growth was established. Through analysis, it was concluded that the critical temperature for rapid austenite growth was 1250 °C. The activation energy for austenite grain growth was 365 KJ/mol as calculated by Sellars' model.