Effect of Residual Stresses on the Surface Fatigue of TiC-based Carbide Composites

Abstract

The degradation of the carbide composites during cyclic loading is usually associated with binder phase extrusion or its plastic deformation. XRD studies have shown that “plasticity” of carbide grains is very much the case for fatigue mechanisms description of the carbide composites. The TiC carbide grains better absorb plastic deformation during cyclic loading (fatigue) or have lower fatigue sensitivity if compared to conventional WC-based hardmetal. This is why the wear resistance and fatigue performance of some TiC-Fe/Ni cermets is better than that of conventional hardmetals (WC-Co) with same microstructural parameters (carbide phase volumetric content, average grain size, carbide phase contiguity).The aim of the current study is to investigate the effect of residual stresses, appearing in the core-rim structures of the carbide grains of TiC-based cermets during production process (powder metallurgy route). The surface fatigue is studied using dynamic indentation with the ball indenter (dynamic Hertz theory) made from WC-based hardmetal (WC-6 wt% Co). The Wohler like curves are plotted allowing make prediction of the surface fatigue properties of studied carbide composites. The study is supplemented by SEM and XRD investigations.