Experimental Study of Wear Performance of Tool Steel Undergone DUPLEX Surface Treatments for Hot Forging Applications

Abstract

In recent years, the DUPLEX surface treatment, consisting of vacuum gas nitride followed by physical vapor deposition (PVD) coating, has earn a lot of interest for enhance the wear performance of high temperature forming application, especially hot forging. In this work the wear performance of hot forging tool steel grade AISI H13 undergone DUPLEX treatments with different top coating have been investigated. Three types of PVD coatings, e.g. TiAlN, AlCrN and AlCrTiN, were studied. The microstructure, physical and mechanical properties and surface roughness were also investigated. The wear tests were performed using a high temperature pin-on-disc arrangement at the working temperature of the hot forging tool, i.e. 300°C. The experimental results indicate that the wear behavior is strongly influenced by the level of contact stress developed at the surface. At low contact stress, harder coating shows the better wear performance while, at high contact stress, the tougher coating serves better. Examination of worn surface suggests that this might be caused by change in failure mechanism from ductile fracture to a more brittle manner at high contact stress for hard material. The understanding of the influence of working conditions and coating properties on the wear resistance of tool steels obtained from this work can be very useful in the improvement of wear performance in hot-forging tools and also other high temperature applications.