Research on the Microscopic Mechanism of the Bond Breakage of Cemented Carbide Tools

摘要

The bond breakage on the rake face of cemented carbide tools has a significant impact on the life of the tool. Using the finite element method, a three-dimensional microstructure model is established for the bond breakage of cemented carbide tools and, based on the analysis of the force conditions in the bond zone, the crack propagation path is investigated at the microscopic scale by varying the cohesive strength of the cemented carbide and the angle between the crack and the rake face to determine the bond breakage process of the cemented carbide tool rake face. The results show that in the absence of the initial cracks, the cracks tend to propagate along the vertical load direction and are deflected due to the increase in the local bonding strength. The angle and location of the cracks and the rake face have a significant influence on the crack propagation path. The stronger the combined force of the cemented carbide, the greater the tensile strength of the material is when there are no cracks in the cemented carbide. In contrast when initial cracks are present, the crack propagation and crack pinning increase the tensile strength of the material to some extent; however, the increase in the intergranular cracks reduces the overall tensile strength of the material. It is observed from the experiment that intergranular fractures are mainly responsible for the bond breakage of the cemented carbide tools and this result is consistent with the simulation results.