Investigation of the effect of shallow and deep cryogenic process on wear and impact performance of CPOH tool steel

CPOH cold work tool steel; It is used in places where high wear and impact resistance is required such as plastic and sheet metal molds, scouring rollers and chip blades. It is seen that limited research has been done in the literature about CPOH cold work tool steel, which has a wide usage area in the industry. In this study, the changes in the microstructure and mechanical properties of CPOH cold work tool steel, which were subjected to deep and shallow cryogenic treatment, were investigated. The test specimens were only tested with conventional heat treated "CHT" 18 hours holding time and -80 °C shallow cryogenic treatment "SCT-18" 18 and 36 hours deep cryogenic treatment at -196 °C temperature. It is classified in 4 different groups as DCT-18'' and ''DCT-36''. The cryogenically treated samples were tempered at 200 °C for 2 hours. Microhardness, macro hardness, abrasion resistance, impact energy and microstructure of the samples were investigated. As a result of the cryogenic treatment applied to CPOH tool steel, the highest proportional increase in macro hardness value of 1.1% and microhardness value of 2.17% was measured in the SCT-18 test sample. The friction coefficient values of the experimental samples named SCT-18, DCT-18 and DCT-36, which were subjected to cryogenic treatment, were improved by 13.47%, 11.77% and 3.71%, respectively.