Quench and Partitioning Heat Treatment to Improve the Ductility of Ultra High Strength Steel

Abstract

Quench & Partitioning (Q&P) heat treatment was carried out on an ultra high strength steel with the Q&P temperatures below the Ms-Temperature. It was found that by increasing the single stage Q&P temperature resulted in decrease in yield strength, ultimate tensile strength and hardness with marginal increase in the total elongation of the steel where no retained austenite is found. With the double stage Q&P heat treatment a very marginal decrease in the ultimate tensile strength found with a significant increase in its total elongation due to presence of 3-5% retained austenite detected by XRD. Hence, double stage Q&P heat treatment can be an effective method to improve the ductility of ultra high strength steels by stabilizing the retained austenite which give the TRIP effect while deformation.