Improving the impact wear properties of medium carbon steel by adjusting microstructure under alternating quenching in water and air

The microstructure and mechanical properties of steel play important roles in its wear resistance. In this study, low alloy medium carbon steel was prepared by alternating quenching in water and air for up to 3 cycles, followed by air cooling (AC) to room temperature (RQ), to obtain different microstructures. The mechanical and impact abrasive wear properties of the steel were tested under different alternating cycles, and the influence of the microstructure on the wear properties and mechanism was analyzed. The microstructure of the steel gradually changed from pearlite and ferrite to fine bainite, martensite, and retained austenite during the quenching process with an increase in the water-air alternation cycles. Compared with no alternation quenching cycle, the steel after alternating 3 cycles had the best combination of hardness, toughness, and wear resistance; that is, the hardness and impact toughness increased from 245 to 464 HV, and 28–50 J/cm2, respectively, and the impact wear resistance increased from 4.99 g-1 to 12.31 g-1. This was mainly owing to the multiphase microstructure, such as bainite/martensite, increasing the dislocation density of the sample and improving the mechanical properties of the steel, and the work-hardening of the retained austenite in the wear surface under the impact deformation, which improved the wear resistance of the steel.