Abstract

Novel advanced steel developments in recent years have resulted in many steels with complex multiphase microstructures. Foremost currently are steels that contain significant fractions of untransformed parent austenite phase. “Quenched and partitioned” steels, commonly referred to as Q&P steels, important as potential advanced high-strength (AHS) automotive steels, are an example in which the austenite is chemically stabilized by carbon partitioning from martensite following an interrupted quench above the martensite finish temperature, Mf. It is evident that the progress of microstructural change during this novel quenching and partitioning treatment, the volume of untransformed austenite stabilized during partitioning and the behavior of this austenite according to its carbon content should be understood. In relation to these requirements, recent analysis of X-ray powder diffraction (XRD) and neutron diffraction experiments will be considered. Initially, the effect of sample preparation between the two measurement techniques is considered, followed by observation of the partitioning process in real time allowed by specially prepared Mn-containing experimental alloys, with and without a crucial silicon addition required to enable austenite retention during Q&P treatment.

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