Inductive heat treatment as an alternative tempering method for the selective oxidation of 1.2379 tool steel surfaces

Selective surface oxidation of a hardened conventional tool steel (1.2379) was carried out with controlled oxygen partial pressures at elevated temperatures. In order to obtain a defined oxygen partial pressure, the experiments were carried out under pure nitrogen and silane doped nitrogen atmosphere. Depending on the actual heat treatment parameters, morphologically different iron based oxide systems could be generated. Some of the selectively oxidized surfaces featured advantageous tribological properties, which appear suitable for lubricant free forming applications. For selected oxide layer systems a batch process for the heat treatment was developed. This set-up is described including the sensitive process control with respect to gas composition. The oxide layer systems generated were characterized by analyzing their composition and surface morphology. In addition, an inductive heat treatment procedure was developed. With this hybrid approach mixed layer systems could be realized that combine different characteristics of conventionally oxidized specimen surfaces.