The effect of deep cryogenic treatment on mechanical properties of 80CrMo12 5 tool steel

Cryogenic treatment can be used as a supplemental treatment that is performed on some tool steels between quenching and tempering as an effective method for decreasing retained austenite and increasing wear resistance. In this research, the effect of deep cryogenic treatment (DCT) on dimensional stability and mechanical properties of 80CrMo12 5 tool steel was investigated. The martensitic transformation start and finish temperatures were also studied using dilatometry tests. The results show that the start and finish temperatures of the martensitic transformation are 254°C and - 87°C, respectively. The hardness increases (untempered) by 3 HRC after DCT. Thus, to decrease or eliminate the amount of retained austenite, cryogenic treatment is necessary. In DCT, impact energy and hardness at all tempering temperatures decreases and increases, respectively. Tempering transformations investigation using dilatometry tests, verified that the DCT increases dimensional stability. This is attributed to the transformation of retained austenite to martensite.