Wear behavior of selectively oxidized α-Fe2O3 oxide low-friction layer systems on PM tool steel surfaces

Abstract

Selective oxidization of tool steel surfaces was studied, as this is a promising approach to realize lubricant free forming processes. Powder metallurgically manufactured 1.2379 tool steel was employed as substrate. Heat treatment was realized inductively under controlled process atmosphere generating α-Fe2O3 oxide layer systems, which can act as friction reducing separation layers. In this context, it is important to note that hardened 1.2379 tool steel features precipitations of chromium carbides, which also occur in the near surface areas. As coarse carbides will not be covered by the α-Fe2O3 oxide layer, powder metallurgically manufactured tool steel with smaller, finely distributed chromium carbides was used, and better performance was obtained in this respect. Inductive heat treatment with varying frequency and strength of the coil current was employed. The effects on the characteristics of the oxide layer formed were determined by both experiments and simulations.