The effect of deep cryogenic treatment on the hardness and wear behavior of Din 1.2344 tool steel

Deep cryogenic heat treatment is a conventional supplementary treatment are used on tool steels, carburized steel and high speed steel to improve their wear resistance and hardness. In this research, the effect of deep cryogenic treatment on the hardness, structure and wear resistance of 1.2344 hot work tool steel has been investigated. To perform heat treatment, the samples were preheated at 650°C for 20 minutes. The samples were then austenized at 1050 ºC for 50 min followed by oil quenching. To investigate the effect of deep cryogenic treatment, some specimens were placed under cryogenic treatment at -196 ºC for 24 hours. It can be conducted that deep cryogenic heat treatment eliminates the retained austenite from 15% in the quench samples to a percentage lower than the detection limit of the XRD technique in the deep cryogenic samples. The results of this research showed that cryogenic treatment leads to an increase in hardness and wear resistance levels by 25 % and 49 %, respectively, in comparison with the quenching tempering treatments. The deep cryogenic heat treatment eliminated retained austenite and increased the carbide percentage. Moreover, the deep cryogenic heat treatment made a more homogeneous carbide distribution with a more uniform particle size and some newly formed nano-sized carbides. These improvements increased the hardness and microhardness of the deep cryogenically treated samples. It was also clarified that the predominant wear mechanism is a combination of adhesive and tribo-chemical wear and the collected wear derbies of the cryogenically treated samples were more brittle and smaller.