Deformation mechanisms in a WC–Co based cemented carbide during creep

Yousfi, Mohamed Amine; Weidow, Jonathan; Nordgren, A.; Falk, L.K.L.; Andrén, Hans-Olof

doi:10.1016/j.ijrmhm.2014.07.016

Cited by 37 publications

(25 citation statements)

References 12 publications

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“…Indeed the penetration of Co between WC grains must clearly be by diffusion, with an additional driving force of the applied stress since penetration was only observed on boundaries closer to perpendicular to the tensile axis and thus more likely to be 'opened' by the applied stress. Uniform thickness lamellae of Co have been seen in both SEM and TEM samples from compression [2,3] and machining samples [4,5]. However, the predominant observation in the current case is of separate pockets or precipitates of Co along the length of a boundary, with a tendency to bulge into one grain only while leaving a flat facet on the other, which matches with the TEM observation of [5].…”

Section: Discussionsupporting

confidence: 81%

Microstructural observations of high temperature creep processes in hardmetals

et al. 2021

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High-temperature properties of hardmetals are critical to their use in many applications but a challenge to measure accurately. Creep behaviour is not well understood so this work has studied uniaxial tensile testing of small simple geometry samples to look at how modifications to the microstructure can affect creep behaviour at temperatures between 800 and 900°C. In particular, a carbon-ladder series with high, medium and low carbon contents in the 10wt-%Co binder has been investigated. Significant differences between the stress-strain curves of the different carbon contents have been observed, but the underlying microstructural mechanisms appear to be similar in detailed large area examination of samples after failure. Penetration of Co along WC-WC boundaries with 'precipitation' of discrete islands is seen as well as the formation of continuous thin lamellae while void formation tends to occur at WC-Co boundaries. EBSD mapping suggests Co penetration varies as a function of WC-WC misorientation.

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Section: Discussionsupporting

confidence: 81%

Microstructural observations of high temperature creep processes in hardmetals

et al. 2021

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“…Some studies on the changes in the properties of ultra-fine grained cemented carbides with temperature have been reported in the literature (Konyashin et al, 2005;Milman et al, 2002;Yousfi et al, 2015;Useldinger & Schleinkofer, 2017). It is commonly acknowledged that grain boundary sliding is the dominant mechanism for the plastic deformation of ultra-fine cemented carbides at high temperatures, which is accompanied by rotation of hard-phase grains and diffusion or redistribution of the Co binder (Milman et al, 2002;Yousfi et al, 2015;Petisme et al, 2015;Fang et al, 2019). Compared with ultra-fine cemented carbides, however, the high-temperature deformation behavior of coarse-grained cemented carbides can be distinguished because of the largely increased grain size of WC and reduced volume fraction of WC/WC grain boundaries and WC/Co phase boundaries (Useldinger & Schleinkofer, 2017;Song et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

How hard metal becomes soft: crystallographic analysis on the mechanical behavior of ultra-coarse cemented carbide

Hu¹,

Liu²,

Hou³

et al. 2019

Acta Crystallogr B Struct Sci Cryst Eng Mater

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Investigation into the temperature dependence of the mechanical behavior of ultra‐coarse grained cemented carbide materials is highly demanded due to its service conditions of concurrent applied stress and high temperature. In the present study, based on the designed experiments and microstructural characterization combined with crystallographic analysis, the evolution of slip systems, motion and interaction of dislocations with temperature are quantified for the WC hard phase. Mechanisms are proposed for the formation of the sessile dislocations in the main slip systems at the room temperature and the glissile dislocations in the new slip systems activated at high temperatures. Furthermore, the correlation of the plastic strain and fracture toughness with the temperature‐dependent slip activation, dislocation reaction and transformation is explained quantitatively. Enlightened by the present findings, potential approach to enhance the high‐temperature strength of ultra‐coarse cemented carbides based on WC strengthening was suggested.

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“…Mari [15], this change occurs from 527°C and is explained by an increase in toughness induced by the softening of cobalt under limited plastic deformation. The sliding of WC grain boundaries is one of the mechanisms involving this softening as reported by several authors [15,54]. Above 827 °C, the behaviour of the composite is entirely plastic.…”

Section: Simulation Of the Composite At Different Temperaturesmentioning

confidence: 64%