Milling of hardox steel with crygenic processed cutting tools

In this study, the performance of cryogenically treated and untreated cutting tools was experimentally investigated during the dry milling process of Hardox 450 steel under different cutting parameters. Cutting tools were cryogenically treated at -196 °C for 24 hours and then tempered at 200 °C for 2 hours. Milling experiments were conducted using four different feed rates (0.03, 0.06, 0.09, and 0.12 mm/tooth), four different cutting speeds (30, 50, 70, and 90 m/min), and constant depth of cut (1.2 mm). Cutting tool wear tests were performed under the parameters of a 0.12 mm/tooth feed rate, 90 m/min cutting speed, and 1.2 mm depth of cut. During the experiments, the effects of cryogenic treatment and various cutting parameters on the milling of Hardox 450 steel were evaluated by analyzing surface roughness, cutting forces, chip morphology, cutting tool wear and microhardness values in detail. The results revealed that an increase in feed rate led to higher main cutting forces and surface roughness, while an increase in cutting speed resulted in lower main cutting forces but higher surface roughness. Examination of chip formation indicated that discontinuous chips (C-type) were produced at lower cutting parameters, whereas semi-continuous chips were observed at higher cutting parameters. The overall findings demonstrated that cryogenically treated cutting tools exhibited lower cutting tool wear, main cutting forces, and surface roughness compared to untreated tools. Additionally, the cryogenic treatment was found to enhance the microhardness of the cutting tool by 9%.