FRACTURE-TOUGHNESS MEASUREMENT WITH FATIGUE-PRECRACKED SINGLE EDGE-NOTCHED BEAM SPECIMENS OF WC-CO HARD METAL

The plain-strain fracture toughness of WC-8%Co hard metal, K(IC), was measured using single edge-notched beam (SENB) specimens with fatigue precrack. The fatigue precrack was introduced with compressive fatigue cycling in four-point bending at room temperature. Since stable fatigue-crack propagation was obtained from the notch tip, it was easy to control the fatigue-precrack length. A reasonable K(IC) value of 13.3 MPa m1/2 was obtained with the fatigue-precracked SENB specimens in four-point bending. The compressive fatigue-precracking technique in four-point bending was simple and convenient, and is therefore applicable to precracking in a variety of brittle materials prior to fracture-toughness measurements.