The Influence of Deep Cryogenic Treatment on Transformation during Tempering of Quenched D2 Steel. Studies oF XRD, Structures, DSC, Dilatometry, Hardness and Impact Energy

The study analyses of influence of cryogenic treatment on the resultant structures, the development of changes during tempering and the charcteristic obtained. It was observed that cryo treatment affects the changes through: a significant reduction in retained austenite content, gradual reduction in value of martensite tetragonality and an increase in the number of carbon atoms in transformations during tempering. The consequence of the transformations taking place during cryogenic treatment is precipitation of η – carbide during low tempering instead of ε – carbide. The number of η – carbides precipitated is higher than that of ε – carbide. This affects the functional properties of steel products. Key words: cryogenic processing, supersaturation, dilatometry, DSC, ageing.