Influence of application of GN+Cr/CrN hybrid layer on durability improvement of die inserts used in hot forging process of wheel forging

Abstract This work presents the results of tests of forging tools in a hot forging process of wheel forgings. The upper die inserts with GN+Cr/CrN hybrid layer, applied to improve their durability, were tested in comparison the a gas-nitrided tool. The hybrid layer was produced on a plasma-nitrided substrate, onto which a PVD Cr/CrN coating was deposited. All tools were checked and analyzed for changes in the surface layer under a complex research including: analysis of process conditions, macroscopic and geometrical analysis (by scanning), as well SEM research microscopy. The tests confirmed the effect of an improved forging tool durability in case of application of the GN+Cr/CrN hybrid layer in relation to the hitherto used -gas nitriding.