A newly-designed hot stamping plus non-isothermal Q&P process to improve mechanical properties of commercial QP980 steel

Abstract

A brand-new process with the combination of hot stamping and non-isothermal quenching and partitioning (Q&P) on a controlled servo press has been applied on a commercial QP980 steel to generate a microstructure of martensite and retained austenite. The results indicate that non-isothermal partitioning can be successfully carried out in this newly proposed novel hot stamping process. Compared to the conventional hot stamped steel, the total elongation can be increased from 12.5% to 14.6%, the uniform elongation can be increased by 19% (from 5.28% to 6.27%) and the product of strength and elongation can be enhanced by 9% (from 19.3 GPa% to 21.0 GPa%) for the steels treated by the new hot stamping plus non-isothermal Q&P process. These improved mechanical properties can be attributed to the increased fraction of retained austenite, as a result of the non-isothermal partitioning.