Effect of MC-type Carbide on Belag Formation of High Speed Tool Steel

Abstract

The present study investigated the microstructure of cutting tool in order to clarify their wear mechanism of cutting tool made of high speed tool steel in the metal cutting process. A special protective oxide surface, which mainly consist of iron, vanadium and oxygen is formed on the surface of the tool during dry cutting wear test. Iron could be diffused from cutting tool and cutting material, and vanadium which alloyed to improve tool life as MC carbide in high speed steel is from cutting tool. During cutting wear test, an amorphous oxide surface seems to exist in a liquid state. At the cutting temperature on the contact point of tool, the surface as so-called "Belag" is melted as a result of eutectic reaction of iron oxide and vanadium oxide. The surface has a role of fluid lubrication between work material and tool. Therefore, the surface is effective in protecting against tool wear at this cutting speed.