Microstructural evolution and mechanical properties of Fe-0.14C-5Mn-1Al-Ce steel during intercritical annealing

Abstract

The effects of intercritical annealing time on microstructure evolution and mechanical properties of a novel medium Mn steel (Fe-0.14C-5Mn-1Al-Ce) were investigated. The microstructure composed of lamellar ferrite and retained austenite (RA)/α’-martensite mixed phases after intercritical annealing. With the extension of intercritical annealing holding time, the volume fraction of RA first increases and then decreases, and RA is always formed at the high-angle grain boundaries of the ferrite. Both the product of Rm*A and the total elongation increase as the volume fraction of RA increases. The greater volume fraction of RA, the greater total elongation and Rm*A. The enrichment of carbon in RA was investigated by XRD and DICTRA. As intercritical annealing holding time increases, the carbon concentration in austenite decreases, while the change of the carbon concentration will affect the volume fraction of RA after intercritical annealing.