Abstract: Effect of cryogenic treatment temperature on high temperature wear resistance of the M2Al high speed steel was investigated. The results show that the microstructure of the M2Al high speed steel specimen after cryogenic treatment is changed, the retained austenite is transformed into martensite, the carbide is reduced in size and dispersed on the martensite matrix. With the decrease of cryogenic temperature, the size of carbides decreases and the distribution is uniform. The high temperature friction coefficient of the steel after cryogenic treatment is lower than that without cryogenic treatment. The high temperature friction coefficient of -160 ℃ cryogenic treatment specimen is lower than that without cryogenic treatment by 55.7%. The wear loss of the steel after cryogenic treatment is lower than that without cryogenic treatment, and the wear loss after -160 ℃ cryogenic treatment is the smallest. The wear morphology of the steel specimen without cryogenic treatment is rough, and serious adhesive wear occurs. The specimen cryogenic treated at -160 ℃ has shallow wear marks, and the wear form is mainly abrasive wear. The M2Al high speed steel has the best effect of improving the high temperature wear resistance when the cryogenic treatment temperature is -160 ℃.

Key words: M2Al high speed steel, cryogenic treatment, high temperature wear resistance