Dynamic hardness of cemented tungsten carbides. (September 2018)

• Record Type: Journal Article
• Authors: Hanner, Luke A.; Pittari, John J.; Swab, Jeffrey J.
• Is Part Of: International journal of refractory metals & hard materials. Volume 75(2018)
• Page Start: 294
• Page End: 298
• Publication Date: 2018-09
• Subjects: Tungsten carbide-cobalt -- Tungsten carbide-chromium-nickel alloy -- "Binderless" tungsten carbide -- Knoop hardness -- Dynamic hardness testing -- Strain rate dependence; 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.2018.05.007
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: Cemented tungsten carbides are composed of a hard tungsten carbide (WC) phase held together by a soft, ductile binder phase, typically cobalt (Co). This study examines the role of the binder composition and content on the Knoop hardness at quasi-static and dynamic strain rates. Seven different tungsten carbide materials were tested: four WC-Co systems containing 10%, 15%, 20% and 25% cobalt, two with a chromium‑nickel alloy binder phase, and one "binderless" tungsten carbide. Quasi-static Knoop hardness testing was performed at strain rates of 10 −3 s −1 and at indentation loads between 300 and 30, 000 g using a Wilson Tukon 2100 unit. Dynamic Knoop hardness testing was conducted at strain rates of 10 3 s −1 using a Dynamic Indentation Hardness Tester over a range of indentation loads. All of the materials exhibited a rate-dependent Knoop hardness, with the hardness increasing by up to 60% with increasing strain rate. Highlights: Seven cemented carbide materials were evaluated for indentation hardness under quasi-static and dynamic testing conditions. Dynamic hardness was measured at strain rates of ~ 10 3 s −1 with an apparatus based on Kolsky pressure bar principles. All of the tungsten carbide materials exhibited a rate-dependent Knoop hardness value. The change in Knoop hardness from quasi-static to dynamic was observed to grow with an increasing amount of binder phase.