Relationship between rupture strength and fracture toughness of WC-Co alloys

Fracture toughness estimated by taking account of the yielding of the plastic zone at the tip of a defect agrees with the measured value by the Bridge Indentation (BI) method. On the relationship between rupture strength and fracture toughness, the rupture strength follows linear elastic fracture mechanics and increases with fracture toughness in the case of a large defect. In the case of a small defect, the rupture strength increases to the maximum strength which reaches the yield strength and decreases with an increase in fracture toughness. Rupture strength variation with fracture toughness depends on the defect size and plastic zone.