Cyclic loading of WC-Ni by FEM with a realistic 3D morphology

A Finite Element Model produced from a real WC-10wt.%Co sample is used to study the mechanical behavior of cemented carbides in compression tests. The model is obtained by slicing the sample by Focused Ion Beam and reconstructing it. This model is used to represent a WC-Ni sample with the same binder fraction, due to the proximity of the two materials in term of microstructure. The WC is defined as elastic, and the Ni phase includes plasticity. The post sintering cooling is simulated, followed by loading-unloading cycles. The results are compared with experimental data obtained by Neutron Diffraction. The residual thermal stresses are in good agreement with the experimental data, showing high tensile stress in the Ni phase and high anisotropy in the spatial distribution of the stress in the WC phase. The observation of the strain in transverse direction in the Ni phase during the first loading-unloading cycle reveals that the Ni phase in the highly constrained WC-Ni structure cannot be represented by a simple elasto-plastic behavior. An alternative solution is proposed to improve the accuracy of the representation of this material. • A realistic 3D model of the WC-Co structure is obtained by Focused Ion Beam, and used to represent a WC-Ni sample with the same binder volume fraction. • This model is used to simulate the stress partition between Ni and WC during cooling after sintering and during compression cycles. • The model returns coherent results for the residual thermal stresses when compared with neutron diffraction measurements • The compression cycles reveal that a simple elasto-plastic behavior cannot represent accurately the Ni phase. • A change of the yield stress with the load is envisaged to improve the accuracy of the simulation.