Equilibrium concentration of carbon in high-carbon high-alloy steel during carbon partitioning process

Abstract

Carbon partitioning was applied to treat high-carbon high-alloy steel. Equilibrium concentration of carbon was studied by constrained carbon equilibrium (CCE) criterion and modified model (CCEA) which took the effect of alloying elements on the carbon activity into account. The results of X-ray diffraction (XRD) analyses showed that the carbon concentration of retained austenite increased first and then decreased with the holding time, and the approximate equilibrium concentration of carbon was closer to the predicted results by CCEA. Simultaneously, the results of XRD analyses represented that the structure of martensite in quenched and partitioned steel was body-centred tetragonal. Carbide precipitation was observed in specimens during the partitioning step by scanning electron microscope and high-resolution transmission electron microscopy.