Wear of tungsten carbide–cobalt hardmetals and hot isostatically pressed high speed steels under dry abrasive conditions

Abstract

Tungsten carbide–cobalt (WC–Co) hardmetals and tool steels are materials that are widely used in applications where abrasion resistance is required. This paper describes the results of tests that were performed using a modified ASTM dry sand rubber wheel test system. It was found that although there was only a small increase in wear as the relative speed increased, a sudden increase in wear of two orders of magnitude was observed as the load was increased for both the WC–Co hardmetals and the tool steels. It was also interesting that under most test conditions the tool steel materials wore at the same rate as the WC–Co hardmetal of equivalent hardness. For all the materials the most noticeable difference was that under high applied load there was significant macroscopic grooving of the worn surfaces. By contrast the worn surfaces were dull but smooth under all other test conditions. When examined at high magnification, there was little difference in the appearance of the wear surface from one test condition to another. In the WC–Co hardmetals, the binder phase had been removed from the surface layers, and there was evidence for intragranular fracture to the WC grains. In the tool steel, decohesion fracture frequently occurred at the trailing edge of carbide particles. These results are complemented by examination of subsurface damage through cross-sectioning.