Thermal properties of cemented carbides used for metal cutting

Abstract

High temperatures, generated during machining, may have a detrimental effect on the cutting tool. Therefore, tool material's ability to effectively lead away the heat is an important property that needs to be understood and quantified. To accomplish that, thermal conductivity, diffusivity and specific heat of 20 cemented carbide grades were studied using light flash analysis at temperatures between 22 and 800 °C.The results demonstrate how thermal conductivity of cemented carbides increases with coarser WC grain size and lower Co content. Presence of cubic carbides in the material is shown to greatly reduce its thermal conductivity. Specific heat of investigated materials increases with higher Co and cubic carbides content, but it is not affected by WC grain size. Influences of temperature on thermal properties are illustrated and discussed.Most importantly, using regression analysis, an attempt is made to predict thermal conductivity based on reliable, readily available or easily measurable material characteristics. It is shown that thermal conductivity of cemented carbide grades could be estimated with good accuracy from the material's chemical composition and coercivity value.