Abstract
The kinetic energy (Ek) of flying fragments in three-point bending test of WC-10mass%Co cemented carbide was experimentally evaluated by our devised convenient method for a test piece with size of 4×3×36mm3 and a span of 30mm, and the ratio of Ek to the elastic strain energy (E ?? )which was stored in the test piece just before the fracture was calculated. It was found that Ek increased from 0.016J to 0.046J and the ratio of Ek/E ?? increased from 0.09 to 0.15 with increasing flexural strength (σm). It was suggested that the error due to Ek in the relative value of fracture toughness (KIc) estimated by using the equation of σm= ?? KIcSmf1/2 ( ?? is a factor including the shape of fracture source, the roughness of fracture surface and the correction parameter, etc., and Smf is the total macroscopic area of fracture surfaces of fragments of one test piece), in the derivation of which Ek is neglected, was +6.5%, if the effect of the other factors on the relative value of KIc are small.
