Grinding of WC-Co hardmetals

This paper concentrates on the morphology of the ground surface of cobalt t ungsten carbide (WC) composite materials that belong to the category of so- called hardmetals. A deformed and detached surface layer was found on top o f the specimens after surface grinding with a diamond wheel. In order to de termine aspects of material removal, various routes were followed. Etching the surface layer revealed WC grains in the subsurface of the machined samp les. Most of these grains were plastically deformed by prismatic slip in th e hexagonal lattice of WC. Also cracks were found in these grains. Further, the increase in residual stress due to the grinding process was examined b y X-ray diffraction (XRD). The stress increases to a maximum stress in the carbide grains before the relaxation occurs by slip and cracking. The surfa ce roughness after grinding was measured by scanning confocal microscopy. R oughness exponents were calculated from the 3D profiles and the values of t his process were in good comparison with values for grinding ceramics. (C) 2001 Elsevier Science B.V. All rights reserved.