Comparison between Quench Tempering and Quasi Quench Partitioning Treatment on Structure and Mechanical Properties of Cr-Mo Steel

Abstract

Abstract In this study, the microstructure and mechanical properties of chromium-molybdenum steel, which is used in mining mills as a liner, were compared after quench and tempering (QT) and quenching and partitioning (QP). Quasi QP was performed by austenitizing and quenching to the exact martensite start temperature (Ms), with the partitioning procedure at an upper temperature Ms in a furnace (common QP is done in a salt bath, so this process is called quasi QP). The procedure was characterized by optical microscopy, scanning electron microscopy, and X-ray diffraction. During the QP procedure, the bainitic ferrite is shaped, and carbon diffuses from the martensite and ferrite to the remaining austenite, but the microstructure of QT is a mixture of martensite and lower bainite. The mechanical properties were measured by a tensile test and Charpy impact test. Samples treated by QP had much higher strength and ductility than those treated by QT. The hardness and wearing weight loss of the QP process was less than QT, but the difference was not great.