Regularities in scratch formation on tungsten monocrystals

An attempt is made to clarify peculiar features of interaction between a solitary abrasive (indentor) and a bcc metal through the investigation of crystallographic orientation effect on the processes of scratch formation. The investigations were carried out on electron beam melted tungsten monocrystals. Scratches were produced by a three-surfaced pyramid edge under 20...50 g loads using a PMT-3 hardness meter. The analysis of geometric features of scratches on main surfaces of tungsten monocrystals permits to make a conclusion on the existence of a preferred direction of surface layer flow under loading conditions mentioned. It is found that on tungsten crystal scratching the anisotropy is connected both with orientation of active slip planes (112) and arrangement of twinning directions in these planes. Slip asymmetry on (112) plane of tungsten monocrystals reaches 11-15% under loading by scratching