The influence of the prior austenite grain size (PAGS), varying between 6 and 185 μm, on the microstructural development of a low carbon steel during quenching and partitioning (Q&P) processing is investigated. The effect on the size and morphological aspects of the microconstituents is discussed based on the kinetics of carbon redistribution between martensite and austenite upon partitioning conditions of 400 °C and 50 s. Under fixed quenching and partitioning conditions, decreasing the PAGS leads to a more efficient carbon partitioning process through the smaller and more homogeneously distributed phases developed during the first quench. In contrast, the microstructural heterogeneity obtained with larger PAGSs makes it more difficult to control the degree of carbon enrichment in austenite during partitioning and thus the austenite stability. Additionally, large volumes of fresh martensite are more likely to form in the interior of large-scale austenite grains due to the incomplete carbon homogenisation process. To consider the PAGS in the design of Q&P microstructures the selection of an optimum fraction of primary martensite is proposed, which ensures the minimisation of fresh martensite in the final microstructure and the sufficient stabilisation of the austenite phase. This new methodology facilitates the applicability of the Q&P process providing a controlled and reproducible development of optimised Q&P microstructures.

Original languageEnglish
Article number107847
Number of pages12
JournalMaterials and Design
Publication statusPublished - 2019

    Research areas

  • Carbon partitioning, Martensite, Microstructural design, Prior austenite grain size, Quenching & Partitioning, Retained austenite

ID: 54217635