Effects of Quenching Medium on Microstructure and Mechanical Properties of High Chromium Cast Iron

The cooling properties of different cooling mediums were studied and heat treatment of high chromium cast iron was carried out by different cooling mediums. The results showed that the maximum cooling rate, cooling rate at 300 °C and the quenching liquid cooling capacity of water at 20 °C was 193.6 °C/s, 88.6 °C/s and 2431.1, respectively. With the increase in PAG concentration, the maximum cooling rate and the cooling rate at 300 °C of the coolant decreased. The microstructure of high chromium cast iron treated by water cooling, 10% PAG coolant and 20% coolant was white carbide + tempered martensite + retained austenite, and its impact toughness and fracture toughness were gradually improved. The water-cooled high chromium cast iron had the highest Rockwell hardness of 66.2 HRC, good wear resistance of 0.6103 g and the greatest friction coefficient of 0.4233, the high chromium cast iron treated with 10% PAG had the best wear resistance of 0.5715 and the lowest friction coefficient 0.4182, the high chromium cast iron treated with 20% PAG had the lowest Rockwell hardness 58.1 HRC and the worst wear resistance 0.8213 g.