An insight into the microstructure effects on removal mechanisms of cemented carbide WC-Co via molecular dynamics simulations

The optical industry has raised the roughness requirements for molds made from cemented carbide to the sub-nanometer level. An in-depth understanding of the factors related to the mechanical removal of cemented carbide is imperative. In this study, molecular dynamic simulations are used to explore the behaviors of the microstructure and their effects on the removal mechanisms of cemented carbide. Two models of cemented carbide WC-Co and binderless WC are constructed, and a taper cutting simulation is designed with a diamond tool. Firstly, it is found that the WC grain amorphization is a temporary metastable phenomenon that is related to exterior stresses. Dislocations and stacking faults inside WC grains are primarily caused by the shear stress and grain rotation. Additionally, the size effect is interpreted through the transition between the elastic and plastic deformation. Then, the cutting force at the grain scale is found to be determined by the evolution and behaviors of microstructure. Finally, the impact of Co phases on stress accommodation and WC grain displacement are analyzed. The details revealed in this study can contribute to the understanding of the mechanical removal of cemented carbide and inspire more work on the improvement of machinability.