Fatigue mechanics of carbide composites

The present article is an overview of mechanical degradation during monotonic and cyclic loading of powder composite materials based on the tungsten- and titanium carbides, also known as hardmetals and cermets. Heterogeneous structure of powder metallurgy (PM) hardmetals and cermets make its difficult to predict their mechanical properties. The TiC-based cermets (with Fe/Ni binder) were tested and results are compared with that of conventional WC-Co hardmetal grades. The three-point bending cyclic and surface fatigue tests are performed in order to define fatigue properties of studied materials. Fatigue crack developments during testing are analysed by scanning electron microscopy (SEM). On the bases of received experimental results and fracture analysis, fatigue failure mechanisms are developed. New numerical model for prediction of fatigue properties is proposed. Tungsten-free composites (cermets) are prospective candidates to replace the hardmetals in metalforming operations (especially blanking of sheet metals). Comparative studies are shown the superiority of the cermets over ordinary hardmetals.