EBSD-based FEM simulation of residual stresses in a WC6wt.-%Co hardmetal

Abstract

Tungsten carbide hardmetals are widely used in cutting, tooling, and wear based applications. During the cooling stage of liquid phase sintering, severe internal micro stresses form between carbide and binder. A detailed microstructural FEM model, capable of predicting these residual stresses accurately, has been developed on the basis of EBSD images of a WC6wt.-%Co hardmetal. This approach yields an extruded 2.5D model that is generated using 2D geometry information on the grains of each phase and the corresponding 3D grain-orientation data. The orientations of the carbides and the binder were detected using samples prepared by ion beam etching. The simulation approach presented, utilizes a temperature-dependent, isotropic elasto-viscoplastic constitutive description of the binder and a temperature-dependent, orthotropic elastic description of the carbides. Using these constitutive models, the type-II residual-stress response is calculated for the hardmetal microstructure. The temperature-dependent phase-averaged hydrostatic stresses, which are predicted by the model, are in good agreement with experimental neutron-diffraction data.