Duplex treatments (plasma nitriding – PVD coating) are a new generation of surface engineering methods with two practical approaches; increase the die life and replacement of lubricant by coating in the forging process. The aim of this study was to evaluate the performance of the new generation of duplex coatings on improvement of forging die life for two phase brass alloy and fundamental study of lubricating properties of PVD coatings. In this research, pin-on- disc tests were carried out at a range of temperatures to evaluate the influence of plasma nitriding and duplex treatment (plasma nitriding-physical vapour deposition), including TiN-TiAlN and TiN-TiAlN-CrAlN coatings, on the tribological properties of AISI H13 steel. Also, the influence of temperature on the tribological behavior of duplex-coated die steel rubbing against forging brass was investigated. Performance tests were conducted under real working conditions by hot forging of a two phase brass alloy. In order to evaluate the possibility of using PVD coatingfor lubrication, non-isothermal compression tests were designed. PVD coatings were deposited by a cathodic arc technique on the surface of 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). The results of pin-on-disc tests at 250 o C revealed minor adhesion of brass alloy on the surface of duplex TiN-TiAlN coating. At 700 o 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. Applied duplex treatment on the surface of dies decreased heat transfer coefficient between die and sample in non-isothermal compression tests. Friction factor of contact surface decreased about 36% in PN+TiN-TiAlN coating and 30% in PN+TiN-TiAlN-CrAlN coating at strain rate of 0.01 s -1 .
