Abstract
As micrograin carbide alloys with average WC grain size below 1μm have been widely used for cutting tools and wear resistant tools, it is very important to acquire knowledge on bending fatigue characteristics of the alloys in order to estimate and improve a tool life. Therefore, in this study, the characteristics of three points bending fatigue in micrograin WC-6-15 mass%Co-0.4-1.2mass%Cr3C2 alloys with grain size of 0.8μm which were treated by HIP or Sinter-HIP process was mainly investigated in relation to a fracture origin.
The results obtained were as follows: (1) As regarding the effects of Co content on bending fatigue of the HIP-treated alloys, the fatigue life was almost same in 6-12mass%Co alloys, but it decreased in 15 mass% Co alloy. (2) The fracture origin observed on the fractured surface after bending fatigue test in the HIP-treated alloys was Co pool with the step-shaped form in all cases. (3) There was some correlation between the size of Co pool origin and the fatigue life under same applied stress. In the Sinter-HIP treated alloys, the fatigue life was considerably improved
due to the decrease of the size of Co pool defect in the microstructure.
