Vliv mikrostruktury na vznik a šíření tepelných trhlin u slinutých karbidů

Abstract

During metal cutting process the cemented carbide tools have to resist extreme thermal and mechanical shocks. Under conditions of cyclic rapid temperature variations the nucleation and propagation of thermal fatigue cracks were observed. These cracks are caused due to the great difference in thermal expansion coefficients between the WC grains in hard phase and the cobalt in softer binder phase. The influence of the microstructural indicators such as the the WC grain size and cobalt content on the propagation rate of thermal cracks was evaluated. The informations about evolution of microcracks morphology were obtained by scanning electron microscope (SEM).