The Effect of Cryogenic Treatment on Microstructure and Properties of WC–Co Cemented Carbides

Abstract

ISO coded K06 cemented carbides are gradually becoming a commonly used tool materials for machining difficult-to-machine materials such as superalloy due to their excellent cutting performance. Researchers are exploring advanced manufacturing processes that can further enhance the performance of this material. Therefore, the cryogenic treatment of ISO coded K06 WC–Co cemented carbide was studied by uniform design experiment. The equation of the effect of cryogenic treatment on the properties of cemented carbide was fitted by multivariate quadratic nonlinear regression. The phase composition, grain size, and residual stress of the material were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicate that cryogenic treatment significantly changes the residual stress of WC grains, accompanied by a phase transition of the bonding phase (Co phase). However, cryogenic treatment has no significant effect on the grain size of the material. The wear resistance and impact toughness of cemented carbide have been significantly improved. At the same time, the wear scar and impact fracture of the material were observed, and the mechanism of impact fracture was analyzed. The residual compressive stress of the WC phase increased by about 120% and the rockwell hardness of the material increased by about 2.61% after cryogenic treatment, but the increase was insignificant. However, the wear resistance increased by about 88.89% and the impact toughness increased by about 19.30%.