The duplex treatment consists of a coating deposition over steel
substrates that were previously thermochemically treated. The most
common thermochemical process applied in tool steels are nitriding
and borizing. The duplex treatment has been widely applied in die
casting, cutting and forming tools. A wide number of coatings systems
such as TiN, TiAlN, CrAlN and CrN have been applied on previously
nitrided tool steel such as AISI H13, AISI D2 and low to medium carbon
steels [1–4]. The most important function of the nitriding layer is to
improve the coating load bearing capacity through the formation of a
subsurface diffusion zone, while the coating serves to reduce
adhesive, abrasive and corrosion wear [5,6].