Abstract
In this study, we developed a new coating by applying radical nitriding treatment to TRD-treated VC coating, and succeeded in improving the endurance of dies in the press working of ultra-high strength steel. The radical nitriding treatment on the TRD-VC coating extended the die life more than five times, and improved the endurance of the die. A metallic nitride layer is formed on the extreme surface (30 nm) of the TD-VC+RN coating. Cr and Fe diffuse in pole surface layer of the coating. The improvement in die endurance is attributed to the following two facts: (1) the nitride layer on the pole surface lowers the coefficient of kinetic friction and reduces adhesion, and (2) impurities inside the coating diffuse to the surface, improving toughness.
