Abstract
Effect of additional carbides on the fracture toughness, and the relationship between the fracture tough-ness and the crack resistance of cemented carbides were investigated.
Results obtained are as follows. (1) The fracture toughness in relation to the hardness of cemented carbides is not changed by addition of TiC and NbC up to 20 to 30 vol%, while it decreases with addition of TaC and large amount of TiC. The fracture toughness of WC-TiC-Co alloys decreases with addition of TaC. (2) The crack resistance of cemented carbides has a correlation to the fracture toughness. And the crack resistance shows a linear relation to the critical strain energy release rate when Vickers hardness of these alloys is above 1200.
