Carbide Grade Development
for Drilling and Milling Applications
Cobalt Content and WC Grain Size determine Material Properties
In general material properties of cemented carbides are determined by Cobalt content and tungsten carbide grain size. Hardness, the most important mechanical property, increases with decreasing grain size and binder content. In conventional coarse grain cemented carbides strength and toughness are reduced. For submicron cemented carbides such as a behavior is no longer valid.
Below a WC grain size of 1 µm increasing hardness is connected with increasing strength, while toughness is only slightly reduced or almost maintained. Simply speaking, Cobalt content adjusts hardness, small grain size preserves toughness.
Daily technical life situation is much more complex, since additional doping components prevent grain growth during sintering process and also act on material properties like hardness and toughness. Thus cemented carbide grade development is always based on a tailor-made carbide composition, i. e. Cobalt content, grain size and additive composition, for reaching an optimum application performance in machining.
In figure 1 an overview of our actual grade development with respect to grain size and cobalt content is displayed. Of course it is important to note, that for an excellent performance in each application area, e. g. hardness range of work piece, the correct carbide grade has to be employed.