Microstructure and properties of Mn–Si–Cr alloy steel modified by quenching and partitioning

Abstract

This study investigates the influence of modification on the microstructure and properties of Mn–Si–Cr alloy steel. The results indicate that the as-cast microstructure of Mn–Si–Cr alloy steel is composed of black acicular bainitic ferrite lath and white retained austenite. The microstructure of the alloy steel changes to martensite, austenite, and carbide after quenching and partitioning treatment. After rare-earth magnesium modification and compound modification, the as-cast microstructure of Mn–Si–Cr steel becomes more refined and displays a more regular arrangement. Furthermore, the martensite and austenite grains in the modified samples show refinement, and the arrangement of martensite is more systematic. Additionally, the amount of austenite decreases, and the amount of carbides increases after quenching and partitioning heat treatment. In comparison with the unmodified samples, the modified samples show negligible changes in hardness. However, the impact toughness of modified quenched and partitioned steel increases by 20 %. Moreover, the wear resistance of compound modified quenched and partitioned steel is 38 % higher than that of the unmodified sample. The compound modified sample steel exhibits excellent wear resistance and comprehensive mechanical properties.