Calorimetric study of carbon partitioning from martensite into austenite

Quenching and partitioning (Q) has been developed as a novel steel heat treatment to produce advanced high-strength microstructures consisting of a martensitic matrix containing significant amounts of retained austenite. Austenite stabilization is hypothesized to result from decarburization of the martensite and transport into the austenite. Differential scanning calorimetry was employed to study Q microstructures. Two exothermic events were observed when heating a Q sample from room temperature to 600 ^∘C. An activation energy suggesting a mechanism controlled by carbon diffusion in bcc iron is obtained for the first peak which is believed to be associated with carbon partitioning. The second peak is believed to be associated with austenite decomposition.