Effects of residual stress on dislocations and microcracks evolution in WC-Co cemented carbides – A simulation study

In this paper, the effects of residual stress (RS) on the microstructure, crystal defects evolution, and mechanical behavior of WC-Co cemented carbides were investigated by molecular dynamics (MD) simulations. The microscopic behaviors, such as dislocation generation, proliferation and interaction, microcrack initiation and propagation, were studied for the WC-Co cemented carbides under different predefined stress states. The results showed that the cemented carbide with RS had a lower compressive strength. The dislocation densities in both WC and Co increased significantly compared with those in the cemented carbide without RS, and the dislocations in WC with RS initiated at a smaller strain. Due to the presence of RS, the critical stress required for microcrack nucleation at WC/WC grain boundaries and WC/Co phase boundaries decreased, and the proportion of crack propagation along WC/WC grain boundaries increased. The RS increased the probability of fracture in Co and decreased the probability of WC transgranular fracture. It was proposed that tailoring microstructure to decrease the WC contiguity would be beneficial to improve the compressive strength of WC-Co cemented carbides with inevitable RS.