INVESTIGATION OF HARDNESS AND WEAR BEHAVIOUR OF THE DEEP CRYOGENIC TREATED 1.3255 TOOL STEEL

Cryogenic heat treatment, as a supplementary process after quenching and before tempering, has been conducted on the tool steels in order to improve their wear resistance. In this research, the effect of deep cryogenic treatment on microstructure, hardness, and wear resistance of 1.3255 tool steel was studied by optical microscopy (OM), scanning electron microscopy (SEM), hardness test, and the pin on-disk wear test. The deep cryogenic treatment was proceeded by austenitising treatment in oil media and holding on different times (1, 24, and 48 h) at -196 degrees C. The obtained results showed that deep cryogenic treatment causes an increase in hardness and wear resistance levels of 4.5 and 75%, respectively, in holding duration times of 24 to 48 h. The increase of hardness and wear resistance during deep cryogenic treatment was related to decrease of retained austenite value, very fine carbides precipitation, and high volume fraction of the carbides. The wear mechanism was determined by scanning electron microscopy in terms of adhesive wear.