Numerical Modelling of the Tribology of a Selective Oxidised 1.2379 Tool Steel Surface Developed for Dry Metal Forming

Abstract

An oxidative heat treatment of a hardened conventional tool steel surface (EU alloy grade 1.2379 X153CrMoV12) at controlled oxygen partial pressures and temperatures was carried out to condition the surface of a forming tool for deep drawing processes in order to minimise the wear on this tool without adding lubricants. By means of this method an oxide layer of à ±-Fe2O3 with advantageous tribological properties suitable for the aimed application was generated. The subject of this paper is to numerically investigate the tribological behaviour of the created surface and to parameter-ise and validate a numerical model in order to predict the wear development on this surface in practice. To realise the intended investigation the approach of Sarkar, which is based on the wear model of Archard, was used in a finite-element-model of a strip-drawing experiment of a DP600 Z sheet metal strip on a wear-specimen of 1.2379 steel coat-ed with à ±-Fe2O3. This model was validated with experimental continuous strip-drawing tests and shows good results. The mathematical approach was parameterised through experimental tests to determine the coating hardness using a Nanoindenter and the friction coefficient determined by strip-drawing tests with a strip of DP600 Z formed around a steel cylinder coated with the same à ±-Fe2O3 layer as generated on the wear-specimen.