Effects of Cryogenic Treatment on Microstructure and Hardening Behaviour of 13Cr-2Mn-2V High Chromium Cast Iron

The effects of deep cryogenic treatment on the microstructure and the hardening behavior for the 13Cr 2Mn 2V high chromium cast iron were investigated by X ray diffraction, magnetic method and hardness test. The results show that in the course of destabilized treatment without cryogenic, with increasing the heating temperature (from 900℃to 1150℃), the hardness of high chromium cast iron increase until the temperature reaches 1 000℃, and then the hardness begin to fall. In deep cryogenic treatment, there is similar disciplinarian, but the hardness are higher than that of the treatment without cryogenic. After deep cryogenic treatment, the content of retained austenite decreases greatly, and many tiny secondary carbide precipitate from matrix. Although the content of the martensite increases, the content of carbide decreases. The secondary carbide plays a greater role than the martensite for increasing bulk hardness. But there are still retained austenites in microstructures when the hardness reaches the maximum.