Microstructure and cutting performance of carbonitride coated tools in high speed machining of 40Cr steel

TiN, TiCN and TiAlN coatings were deposited on K20 cemented carbide tools by arc ion plating method. The microstructure and mechanical properties of the coatings were investigated using an X-ray diffractometer, a scanning electron microscope and micromechanic probes. The cutting performances of the coated mills and drillers were accessed by milling and drilling the quenched and tempered 40Cr steels under dry and high speed cutting conditions. The performance of K20 cemented carbide tools was evaluated with respect to the tool wear and the torque generated during the cutting. The results revealed that the cutting tools coated with TiCN and TiAlN films obviously outperformed those with TiN film, especially at high cutting speeds.