Influence of electrical discharge machining on the sliding contact response of cemented carbides

The correlation between electrical-discharge machining (EDM) and surface integrity and its influence on the sliding contact response of a fine-grained WC-10%Co-wt hardmetal have been studied. Different surface finish conditions were evaluated corresponding to sequential EDM as well as grinding and polishing employing diamond as abrasive. Surface integrity was characterized in detail for all conditions through scanning electron microscopy (SEM). Sliding contact response was determined through microscratch measurements using a nanoindentation system. Contrary to the results obtained from conventional hardness evaluation, the above testing technique allows discrimination of EDM effects on the contact behavior of the studied cemented carbide. The experimental results, given in terms of scratch penetration-load curves and friction coefficient, indicate that microscratch resistance increases with finer-executed EDM, up to values similar to those exhibited by the reference ground and polished condition. The findings are discussed in terms of contact damage features as related to surface integrity and intrinsic microstructural features. (C) 2001 Elsevier Science Ltd. All rights reserved.