Some aspects of the time dependent strength behaviour of a range of tungsten carbide - cobalt materials

Abstract

Delayed fracture, slow crack growth and, corrosion in sintered WC-Co alloys containing 6, 13 and 16% cobalt by weight, have been observed and evaluated at room temperature in a variety of environments including laboratory air, distilled water and dilute nitric acid. Data from strength tests and double torsion tests have been analysed using theories of stress corrosion and brittle fracture, to obtain estimates of the stress corrosion parameter, n, which best describe the behaviour. A statistical method has been developed for analysing strength data. Observation of specimens in soak tests has shown corrosion to occur in some environments. Inspection of bend strength specimen fracture faces has indicated the source of fracture initiation. A simple, and reliable method of precracking WC-Co double torsion specimens has been developed.