Microstructure Evolution and Cooling Characteristics at C−Si−Mn−Cr Steel during Different Quenching Processes

The industrial importance of steel is reflected in the wear resistance, which is related to its changes of microstructure and temperature changes during heat treatment. Herein, C−Si−Mn−Cr steels are produced to understand the microstructure evolution and cooling characteristics during quenching in water and air. The samples of several feature points are selected along the radial direction from the treated steel, and the temperature distribution of steel is obtained via numerical simulations. The microstructures at different temperature feature points and the corresponding hardness are studied. The results show that the quenching processes with the water−air alternating cycle regulate the temperature distribution. Martensite and pearlite phases are primarily formed during water and air cooling, respectively. In the water−air alternating cycle quenching process, the microstructure includes bainite, martensite, and retained austenite. The obtained microstructure is more ideal and the value of hardness is 525.2 HV. The maximum hardness value is 695.3 HV for water quenching, while that for air cooling is 248.2 HV. The microstructure evolution of steel at different positions is closely related to the temperature change in varied quenching processes.