Fatigue Lifetime and Crack Growth Behavior of WC-Co Cemented Carbide

Abstract

It is well known that WC-Co cemented carbides have excellent wear resistance. However, information about their fatigue crack growth behavior and fatigue properties is limited. In the present study, rotating bending fatigue tests were carried out on a fine grained WC-Co cemented carbide to evaluate its fatigue lifetime and crack growth behavior. From observations of the micro-notched specimen surface during the fatigue process, it was revealed that most of the fatigue lifetime of the tested WC-Co cemented carbide is comprised of crack growth cycles. Using the basic equation of fracture mechanics, the relation between the rate of fatigue crack growth da/dN and the maximum stress intensity factor Kmax of the WC-Co cemented carbide was derived. From this relation, both the threshold intensity factor Kth and the fatigue fracture toughness Kfc of the material were determined. Fatigue lifetime of the WC-Co cemented carbide was estimated based on the fatigue crack growth law.

On the Short Surface Fatigue Crack Growth Behavior in a Fine-Grained WC-Co Cemented Carbide

“…Therefore, a value of 0.73 was used for Y, as used in Equation (1). From the fracture surface observations, it was confirmed that the fatigue crack initiation site for the present material was an aggregate of several WC grains or a coarse WC grain slightly beneath the specimen surface [21].…”

“…In the present study, the maximum stress intensity factor, Kmax, was utilized, as in previous studies [4,21]. To calculate the Kmax, the following expression was used:…”

“…Mikado et al [21] conducted a rotating bending fatigue test on a cemented carbide to evaluate its fatigue strength and the FCG behavior of short surface cracks in the material. It was found that reducing the rate of FCG at the initial stage of the fatigue fracture process is important for prolonging the fatigue lifetime.…”