Selective oxidation of 1.2379 tool steel surfaces : an approach for Dry Metal Forming

Subject of this work is the development of a simple and cost-efficient process for conditioning the surface of forming tools for deep drawing processes in order to minimize friction and wear to a level that dry forming processes without any lubricants will be possible in future. The approach chosen is an oxidative heat treatment of the tool surfaces at controlled oxygen partial pressures and temperatures. Thus, alloying elements of the tool shall constitute oxide layers with advantageous tribological properties suitable for the aimed application. In this paper results from parameter studies concerning the controlled surface oxidation of a hardened conventional tool steel (EU alloy grade 1.2379 X153CrMoV12) are presented. Beside the dependence of the oxide layer morphology from the chosen heat treatment parameters first results of their tribological behavior gained from measurements of the friction coefficients using an application-oriented strip drawing test are presented. From these investigations promising results and conclusions for future work have been obtained which are discussed in the paper