Improvement of hot forging tools with duplex treatment

Duplex treatment was applied to impove wear resistance of hot forging tools. Performance tests of these tools were carried out under laboratory conditions. Plates of construction steel, which were preheated at the temperature of approximately 1050 °C, were used as workpieces. A scanning electron microscope (SEM) was used to determine the coating damage on the cross-section of a worn tool. Microhardness depth profile on the polished cross-section, roughness of the tool working surface and roughness of the workpiece were measured after each 100 forgings. No visible wear of duplex treated tool was observed after 300 forgings. After 1100 forgings the TiN/TiAlN (Balzers, Futura) multilayer coating remained practically undamaged on the front side, while it was partially worn at the roundings of the tool, in the area of the largest sliding lengths.