Dynamic pulse sensitivity of WC/Co composite

Abstract

Cutting tools are manufactured among others from cermet (e.g. WC/Co) having excellent mechanical properties. Geometry of the internal microstructure is complex and mechanical response due to quasi-static or dynamic loading is difficult to be described. Particularly, the dynamic loading is not investigated enough precise up till now.Experimental evidences, e.g. Siegl and Fischmester (1988), Ravichandran (1994), indicate that the fracture energy of WC/Co is expended through ductile failure of the Co: (1) near the binder/tungsten carbide interface or by (2) dimple rupture across the interphase. Concentrations of stresses around grain boundaries lead to initiation of microcrack system, which is dispersed for dynamic loading.The aim of the paper is to extend the previously formulated models (Sadowski et al., 2005, 2006, 2007, Dębski and Sadowski, 2014, 2017) of the polycrystalline composite towards more advanced finite element formulation, applicable for description of the cermet behavior under dynamic pulses. The model takes into account: (1) spatial distribution of the cermet constituents, (2) system of grain boundaries/binder interfaces modeled by interface elements, (3) rotation of brittle grains.The obtained results show that stress distributions and gradual microcracking processes are quite different for quasi-static and dynamic loadings. It was revealed by damage parameter indicating concentration of microcracks.