A New Methodology for Optimizing Quench Temperature in Q&P Steel

Quenched and partitioned (Q&P) steels are designed to maintain strength and improve formability while utilizing leaner alloyed steels through the development of martensitic microstructures with retained austenite. Literature regarding Q&P steels primarily focus on maximizing retained austenite volume fractions rather than considering the influence of chemical and morphological characteristics of the retained austenite. In this work, consideration of retained austenite characteristics and the influence of prior processing on the heat treating response and resulting microstructures of Q&P steels are investigated in a 0.17C-2.8Mn-1.5Si steel through dilation simulations. A new methodology for optimizing quench temperature for a set of fixed partitioning and austenitizing parameters, involving careful monitoring of secondary martensite formation during final quenching, was introduced. Findings suggest that a general Q&P heat treatment could be applied to a material of the same composition but with variations in the prior processing and result in similar microstructures and amounts of retained austenite.