Effects of Cryogenic Treatment on the Microstructure and Hardening Behaviour of High Chromium White Cast Iron with Mo-V

Effects of cryogenic treatment on the microstructure and the hardening behavior of high chromium white cast iron were investigated by X-ray diffraction,magnetic method and hardness test.The results show that the microstructures of the cast iron under air cooling and cryogenic treating respectively after destabilized treatment consist of austenite,martensite and eutectic carbides.In the course of destabilized and air cooling treatment,with the heating temperature(from 900℃ to 1150℃) increasing,the hardness of the cast iron increase until the temperature reaches 1000℃,and then decreases.In destabilized cryogenic treatment,there is similar characteristic,but the hardness is higher than that under the treatment without cryogenic.Under cryogenic treatment,the content of retained austenite decreases greatly,so the hardness increases obviously,but there are still a little retained austenite in the microstructure when the hardness reaches the max.