Investigation of structure and properties of cemented carbide inserts of rock cutting tools

The object of the paper is the structure and properties of cutter inserts made of VK8 cemented carbide alloy of various producers. Chemical composition of carbide particles and the binder between them was studied. Carbide particle size was estimated and compared to the State Standard requirements. Fracture types of inserts were statistically treated. Results of comparative industrial tests of cutters at the JSC “Uralkaliy” in potassium ore and rock salt layers are presented. It was established that durability of rock destroying tools is determined to a great extent by the mass fraction of carbide phase and the number of most coarse grains. Great number of coarse grains (at the upper limit permitted by State Standard 4411-79 or even more) deteriorates durability of tools.