Evaluation of static and fatigue strength characteristics for thermal sprayed WC-Co materials by indentation method

Static and cyclic indentation tests were performed on the surface and the cross-section of thermal sprayed WC-Co materials. Micro indentation tests revealed that the mechanical properties on the surface are different from those on the cross-section. Also, the static strength on the surface is lower than that on the cross section. Under the static indentation tests, the cracks on the surface formed a ring crack around the impression. On the other hand, the crack on the cross-section grew in the direction perpendicular to the sprayed direction. The results of cyclic indentation tests showed that the cyclic number for the crack initiation decreased with increasing the maximum surface stress. The fatigue strength on the cross section was slightly higher than on the surface. These results mean that thermal-sprayed WC materials clearly have cyclic fatigue behavior and remarkable anisotropy.