Phase transformations of low-alloy steel at temperatures inside the eutectoid gap

Abstract

The width of the eutectoid gap in the quasi-binary metastable phase diagram of the steel with 2 wt.%Mn, 2wt.%Si, 1wt.%Cr and 0.8wt.%C was determined to be about 50°C. By heating this steel at temperatures inside this eutectoid gap and by subsequently quenching the structures, a ferrite-martensite two-phase matrix containing cementite particles was formed. Various morphologies of this structure were obtained when the initial states of the material were homogeneous austenite, homogeneous martensite and soft-annealed structure. In the structure prepared from the initial soft-annealed state, the chromium is concentrated mainly in cementite; the manganese is also present in cementite but most of it is contained in matrix phases, mainly in martensite; the silicon is dissolved entirely in the matrix, showing a preference for ferrite.