On the initiation and propagation of fatigue cracks in WC-Co

Erling, Ghita
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This research examines fatigue in WC-Co, both under compressive and tensile loading conditions. A new macro-mechanism for compression fatigue crack propagation is put forward, which contradicts existing data on compression fatigue cracks as being self-limiting. Evidence of this macro-mechanism is presented in the form of final crack length versus number of cycles data, and micrographs of the compression fatigue cracks. A finite element study of the stress distribution in the WC-Co microstructure during compression fatigue loading has been developed. This model verifies possible methods of compression fatigue crack initiation. Examination of tensile fatigue and fast: fracture surfaces is used to show that fatigue is a separate mechanism to fast fracture in WC-Co. Characteristic features of the fatigue fracture surface are presented. A possible fatigue crack propagation mechanism is also presented. Finally, fatigue crack growth rate data in the form of the Paris equation is presented for WC-Co grades T6 and G6.
A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering, Johannesburg, 1998
Erling, Ghita (1998) On the initiation and propagation of fatigue cracks in WC-Co, University of the Witwatersrand, Johannesburg,<http://hdl.handle.net/10539/22772>