High temperature wear and frictional properties of duplex-treated tool steel sliding against a two phase brass

Improvement of die life in the hot forging of brass alloys is considered vital from both technical and economical points of view. In this research, pin-on- disc tests were carried out at a range of temperatures to evaluate the influence of plasma nitriding and duplex nitriding-physical vapour deposition (PVD), including TiN–TiAlN and TiN–TiAlN–CrAlN coatings, on the tribological properties of AISI H13 steel. PVD coatings were deposited by a cathodic arc technique on the surface of the steel pins. The mechanical properties, surface roughness and composition of the coatings were determined by microhardness, nanoindentaion, Scanning Electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Performance tests were conducted under real working conditions by hot forging of a two phase brass alloy. The results of pin-on-disc tests at 250 °C revealed the minor adhesion of brass alloy on the surface of duplex TiN–TiAlN coating. At 700 °C, this coating was relatively more resistant to oxidation and thus, it performed better than other coatings. The performance tests indicated improvement of 200% in die life compared to H13 hot work tool steel dies.