CARBON ENRICHMENT OF AUSTENITE AND CARBIDE PRECIPITATION DURING THE QUENCHING AND PARTITIONING (QP) PROCESS

摘要

A novel heat treatment process for obtaining superior properties in a variety of steel compositions has been recently proposed. The process, designated Quenching and Partitioning (Q&P), is based on the partial transformation of austenite into martensite, followed by partitioning of carbon under conditions preventing tempering reactions. During partitioning, escape of carbon from supersaturated martensite results in carbon enrichment of austenite, promoting stabilization of this phase during subsequent quenching to room temperature. The final microstructure can consist of ferrite, carbon enriched martensite and retained austenite, exhibiting interesting combinations of mechanical properties. Carbon enrichment of the austenite is dependent on the ability to prevent formation of carbides. In the present work, the kinetics of carbon escape from martensite is investigated for a high Si steel subjected to Q&P processing and the results discussed with regard to carbide precipitation and austenite stabilization.