Modelling Damage Initiation in WC–Co Cemented Carbides Using Microstructure–Based Finite Element Analysis

Sammanfattning

Tungsten carbide cobalt (WC-Co) cemented carbide dominates industrial applications, particularly for metal-cutting and mining tools, owing to its exceptional hardness, toughness, and abrasion resistance. These outstanding properties arise from its microstructure, in which the hard, brittle WC phase is embedded in a ductile Co matrix. The performance of WC-Co is highly sensitive to microstructural characteristics such as WC grain size and cobalt content. Finite element analysis (FEA) was employed to model WC-Co microstructures and predict their mechanical performance, enabling exploration of the relationships between microstructure and material properties. Although FEA has previously been applied to WC-Co, modelling assumptions and approaches in the literature vary widely. Traditionally, both WC and Co phases are modelled as elastic-plastic materials with idealized, perfectly bonded interfaces—a simplification of the true microstructure. In this study, a baseline model was established using these conventional assumptions. Subsequently, non-ideal interfaces were introduced using cohesive zone material (CZM) models to more accurately capture interfacial behaviour. This methodology enables assessment of how interface damage influences results and whether WC can be modelled as purely elastic when CZM models are present. The results reproduce a baseline model consistent with previous studies. Incorporation of CZM models alongside the elastic-plastic description of WC led to reductions in both overall strength and stress-strain curve amplitude. These findings suggest that part of the weakening previously attributed to WC plasticity actually arises from interface damage. To further test this hypothesis, the WC phase was modelled as purely elastic while systematically varying CZM properties. CZM parameters were unable to fully replicate the stress-strain behaviour of the baseline model when WC was treated as purely elastic. Nevertheless, the results indicate that interface damage plays a significant role in the overall weakening, a phenomenon previously attributed only to WC plasticity. Continued research into the relationship between WC plasticity and CZM properties in WC-Co composites under compression remains essential for developing more accurate predictive models.