Tensile and compressive asymmetry in creep and monotonic deformation of WC/Co hardmetals at high temperature. (January 2015)

• Record Type: Journal Article
• Authors: Roebuck, B.; Moseley, S.
• Is Part Of: International journal of refractory metals & hard materials. Volume 48(2015:Jan.)
• Page Start: 126
• Page End: 133
• Publication Date: 2015-01
• Subjects: Hardmetal -- High temperature tests -- Tension and compression asymmetry; Heat resistant alloys -- Periodicals; Refractory materials -- Periodicals; Metallography -- Periodicals; Alliages réfractaires -- Périodiques; Matériaux réfractaires -- Périodiques; Métallographie -- Périodiques; Heat resistant alloys; Metallography; Refractory materials; Periodicals; Electronic journals; 669.73
• DOI: 10.1016/j.ijrmhm.2014.08.007
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: Solid solution single phase metallic alloys generally have the same or very similar flow stresses when deformed at high temperatures, whether the applied stresses are compressive or tensile. Experiments at temperature have shown in the current research that this is not the case for WC/Co hardmetals, a composite material composed of a hard inorganic carbide and a metallic binder. A miniaturised test system capable of mechanical tests at temperatures up to the solidus, about 1300 to 1350 °C in this system, has been used to investigate and compare compressive and tensile flow stresses, including the effect of strain rate as well as creep behaviour over temperatures from 1000 °C upwards. It was found that all materials examined were significantly more deformation resistant in compression than tension. This is vital knowledge for the increasing requirements to model processes and performance of hardmetals in a variety of manufacturing routes and application areas. The acquired data was fitted to analytical expressions to assess the utility of generating data useful for computer modelling and comments are made on the effects of microstructural constituents. Highlights: The NPL ETMT (electrothermomechanical test system) was used to measure the mechanical properties in tension and compression at high temperatures of several WC/Co hardmetals. It was shown that representative WC/Co hardmetals are considerably stronger in compression than tension around 1000 °C. The compression/tension asymmetry was evident both for constant creep loads as well as for monotonically increasing stresses. Uniaxial tension and compression flow stress curves were fitted to power law functions allowing the temperature dependence of the stresses to be codified in an efficient manner for modelling.