The flow stress of PcBN cutting tool materials at high temperatures

The onset of plastic deformation has serious implications when predicting the useable life of a cutting tool material. Through simulation of the tool/workpiece interface it is possible to determine the combination of mean pressure and temperature that would produce plastic deformation in these materials. This paper describes the effects of temperature and mean pressure on the plastic deformation characteristics of a range of polycrystalline cubic boron nitride cutting tool materials. Using a novel soft impressor technique, the brittle–ductile transition temperatures for a range of polycrystalline cubic boron nitride materials has been identified. It will also be shown that the minimum mean pressure to cause plastic deformation is greatest in the polycrystalline cubic boron nitride aggregate materials but decreases with the addition of the volume fraction of titanium and with an increase in temperature.