Finite element analysis of thermal residual stresses at cemented carbide rock drill buttons with cobalt-gradient structure
(1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;2. School of Mathematical Sciences and Computing Technology, Central South University,Changsha 410083, China)
Abstract: The aim of this study is to apply the concept of functionally graded materials(FGMs) to cemented carbides and to develop high-performance rock drill buttons. Cobalt-gradient structure was introduced to the surface zone of the buttons by carburizing process. Finite element method and XRD measurement were used to decide the distribution of thermal residual stress. Constitutive parameters were determined by constraint factor. Numerical results show that residual stresses of gradient buttons mainly concentrate in cobalt-gradient zone. There is compressive stress in the surface zone and tensile stress in the cobalt-rich zone. The maximum value of surface compressive stress is 180 MPa for WC-6Co cemented carbides. And the numerical results agree with the results of XRD measurement.
Key words: cemented carbide; cobalt-gradient structure; finite element method; rock drill button; constraint factor