Microstructural aspects determining the adhesive wear of tool steels

In many machining applications, adhesion of the workpiece to the tool is a major problem. Adhesion may be reduced by changing the microstructure of the tool steel, e.g. by increasing the carbide content. The present work deals with the influence of some microstructural parameters in the adhesive wear of tool steels. The investigations were conducted using six model alloys based on the powder metallurgy high speed steel AISI M4, all of which had the same martensitic matrix composition after heat treatment. The alloys had MC carbide contents which varied between 0 and 25 mol% in 5 mol% increments. Ball-on-disc experiments were carried out in ambient air at room temperature using austenitic stainless steel and aluminum balls as counterfaces. Wear tracks on the disks were characterized using both a scanning electron microscope and an optical profiler. The results show that two main parameters determine the adhesive wear behavior: the carbide content and the distance between carbides.