Rotating wheel abrasion of WC/Co hardmetals

The abrasion resistance of a range of hardmetals has been examined in two different types of rotating wheel wear test. These were an ASTM B611 steel wheel test, and a modified ASTM G65 test system. The aim of the work was to examine the effects of changing the conditions of the test on the results that were obtained. The parameters that were examined were the test load, the abradant material, the relative speed of the wheel and sample, the counterface material, and environment, and to compare the results for the two different test systems. Thus, tests were carried out with both the normal rubber rimmed wheel and a steel wheel in both wet and dry environments. Tests were performed using silica and alumina abrasives. It was found that in all cases the highest wear was obtained with a steel wheel in dry conditions using the silica abrasive in the G65 format or in wet conditions using the alumina abrasive in the B611 format, and the lowest wear with a rubber wheel in wet conditions in the G65 configuration. These changes in test condition gave a variation in wear of nearly three orders of magnitude. A marked increase in wear was seen as the load was increased. There was little effect on wear from relative speed. The observed mechanisms of wear are discussed with respect to the magnitude of wear that was found. For the ASTM B611 test format, some experimental materials were also manufactured with a grain size distribution that was much wider than that in the conventional materials. It was found that, for equivalent HV30 hardness values, the materials with wide grain size distributions were significantly more wear resistant than standard materials when tested using the ASTM B611 method. The observed mechanisms of wear are discussed with respect to the magnitude of wear that was found.