Oxidation Behavior of Reheating Hot Work Die Steels

Abstract

At hot working condition, forming tools must be durable at operating temperatures during continuous forming process and especially dimensional stability and corrosion resistant property are required. In this paper, oxidation behavior of several hot work die steels was studied at elevated temperature forming condition. It is shown that test specimens begin to form oxides at the surface during the initial heating period. Transient oxidation is observed during the initial stage of oxidation, in which the initial fast reaction rates may be related to local thermal instabilities such as fast nucleation of oxide grains due to microstructural variation or chemical potential differences through the thin initial oxide layer. When initial mass gain does not contribute to steady state parabolic law, the Pieraggi model is successfully applied to the high temperature oxidation of tool steels. Based on this information, suitable forming die material was selected for reheating application above 850°C.