On adhesion and metal transfer in sliding contact between TiN and austenitic stainless steel

Austenitic stainless steels are known to be very difficult to machine and form. This is due to their tendency to adhere to the tool material, which then initiates galling. In this paper, austenitic stainless steel has been tested against TiN in un-lubricated sliding contact. The interface between TiN and adhered stainless steel was investigated by transmission electron microscopy. An oxide layer, emanating from the stainless steel, was revealed to be present between the tool surface and the adhered stainless steel. It is concluded that the stainless steel oxide plays a major role for the sticky behavior of this material. To further investigate this phenomenon, austenitic stainless steel samples were also pre-oxidised before testing to examine if the oxide thickness and composition are important for the adhesion tendency. The test showed that the sample oxidised at 800 °C had less tendency to adhere than those oxidised at lower temperatures. The explanation is either its higher thickness, or its high content of Cr-oxide in its surface. The surface of the oxides formed at lower temperatures consists mainly of iron oxide.