Cryogenic Treatment for Cr5 Steel and Its Retained Austenite Content

SLX-80 cryogenic treatment system was used in cryogenic treatment for Cr5 steel at different temperatures, and magnetization of samples was investigated in vibrating sample magnetometer option of physics property measurement system. The contents of retained austenite in Cr5 steel in different states were calculated. And hardnesses of Cr5 steel in different states were tested. The results show that the volume fractions of retained austenite in the samples quenched at 940 ℃, cryogenic treated at －60 ℃ and －100 ℃ were 14.1%, 12.1% and 10.5%, respectively. When cryogenic treatment temperature increased, the content of retained austenite in the steel reduced obviously. The maximum value of 65.1 HRC in hardness of steel in quenched state could be obtained at 940 ℃, but the cryogenic treatment at －100 ℃ after quenching can make the hardness of steel to further increase to 66.1 HRC.