2016 Volume 61 Issue 11 Pages 775-783
WC-Co alloys are widely used as cutting and mold tools due to their high hardness, but their performance is difficult to evaluate with conventional tests. We have applied the micro slurry-jet erosion (MSE) test, which we have developed, to evaluate the surface strength of WC-Co alloys. The objective of this study is to understand the erosion mechanism of the WC-Co alloy in order to demonstrate the usefulness of the MSE test. Four specimens (Co content: 6 ~ 19 wt.%, WC grain size: 0.6 ~ 0.8 µm) were tested with angular alumina particle with an equivalent sphere diameter of 41 µm as erodent. The erosion debris was collected from the impacted slurry and analyzed with SEM and EDS, together with the observation of the eroded surfaces and cross-section. The erosion rate of the MSE increased with increasing Co content. The erosion debris was categorized into two types according to size, shape and composition of the particles. The erosion mechanism of the WC-Co alloy was determined to be removal of WC or WC and Co due to intergranular fracture. It was concluded that the MSE test has the possibility of evaluation for strength against intergranular fracture caused by impact force.
