Binder deformation in WC-(Co, Ni) cemented carbide composites

Vasel, C. H.; Krawitz, A.D.; Drake, E.F.; Kenik, E.A.

doi:10.1007/bf02670431

Cited by 86 publications

(41 citation statements)

References 7 publications

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“…In this regard, it should be pointed out that the already complex point-to-point residual stress state in both phases may be relaxed or enhanced by local tensile stresses related to the Poisson effect under the nominally compressive applied one [12,14]. Such deformation may take place through mechanical twinning, planar slip and/or phase transformation (fcc to hcp) [24][25][26][27]. Identification of the specific irreversible deformation mechanisms would require an additional transmission electron microscopy analysis, and it is beyond the scope of this study.…”

Section: Resultsmentioning

confidence: 99%

Mechanical deformation of WC–Co composite micropillars under uniaxial compression

Tarragó

Roa

Jiménez‐Piqué

et al. 2016

International Journal of Refractory Metals and Hard Materials

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Section: Resultsmentioning

confidence: 99%

Mechanical deformation of WC–Co composite micropillars under uniaxial compression

Tarragó

Roa

Jiménez‐Piqué

et al. 2016

International Journal of Refractory Metals and Hard Materials

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“…Very interesting is that it seems to apply, even though the nature of the binder plastic deformation mechanisms shift from fcc-hcp transformation to slip plus twinning, as the Ni content in the binder increases [29]. In this regard, it is interesting to highlight that plastic deformation mechanisms in the Ni binder include slip and twinning [29,30], also discerned in the Co-base binders, but not stress-induced phase transformation, as it is the case in WC-Co grades.…”

Section: Fatigue Sensitivitymentioning

confidence: 99%

Fracture and fatigue behavior of WC–Co and WC–CoNi cemented carbides

Tarragó

Roa

Valle

et al. 2015

International Journal of Refractory Metals and Hard Materials

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The fracture and fatigue characteristics of several cemented carbide grades are investigated as a function of their microstructure. In doing so, the influence of binder chemical nature and content (Co and 76 wt% Co-24 wt% Ni), as well as carbide grain size on hardness, flexural strength, fracture toughness and fatigue crack growth (FCG) behavior is evaluated. Mechanical testing is combined with a detailed inspection of crack-microstructure interaction, by means of scanning electron microscopy, in order to evaluate crack-path tortuosity and to discern fracture and fatigue micromechanisms within the metallic binder. Results show that CoNi-base hardmetals exhibit slightly lower hardness but higher toughness values than Co-base grades. Meanwhile, flexural strength is found to be rather independent of the binder chemical nature. Regarding FCG behavior, experimental results indicate that: (1) FCG threshold (K th ) values for coarse-grained grades are higher than those measured for the medium-grained ones; and (2) fatigue sensitivity levels exhibited by CoNi-and Co-base cemented carbides, for a given binder mean free path, are similar. These findings are rationalized on the basis of the increasing relevance of crack deflection mechanisms as microstructure gets coarser and the evidence of similar fatigue degradation phenomena within the binder independent of its chemical nature, respectively.

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“…In order to characterize the structural changes induced by grinding in the Co-phase, two complementary characterization techniques: transmission electron microscopy (TEM) and electron back-scatter diffraction (EBSD), are employed in this study. They have previously been proven to be well-suited to characterize structural changes in cemented carbides [26][27][28][29][30][36][37][38][39]. Specifically, we report nearsurface cross-sectional analyses of ground specimens, showing metallurgical alterations of the binder phase and correlate the results to grinding-induced changes (e.g., microcracking and residual stresses).…”

Section: Accepted Manuscriptmentioning

confidence: 94%

“…The main deformation mechanism for fcc stabilized Co is reported to be martensitic phase transformation to the room temperature stable hcp phase [26][27][28][29][30]. In order to characterize the structural changes induced by grinding in the Co-phase, two complementary characterization techniques: transmission electron microscopy (TEM) and electron back-scatter diffraction (EBSD), are employed in this study.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…Within this context, fracture mechanics and mechanisms related to crackmicrostructure interactions in hardmetals, under both monotonic and cyclic loading, are now wellestablished and understood [20][21][22][23][24][25]. On the other hand, the plastic deformation mechanisms within the metallic binder, when hardmetals are subjected to external loads, have been given less attention [26][27][28][29][30]. This is particularly true in the case of alterations induced by grinding and scratching, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Grinding-induced metallurgical alterations in the binder phase of WC-Co cemented carbides

Yang

Roa

Schwind³

et al. 2017

Materials Characterization

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The metallic binder phase dictates the toughening behavior of WC-Co cemented carbides (hardmetals), even though it occupies a relative small fraction of the composite. Studies on deformation and phase transformation of the binder constituent are scarce. Grinding represents a key manufacturing step in machining of hardmetal tools, and is well-recognized to induce surface integrity alterations. In this work, metallurgical alterations of the binder phase in ground WC-Co cemented carbides have been assessed by a combination of electron back scattered diffraction and transmission electron microscopy techniques. The Co-base binder experiences a martensitic phase transformation from fcc to hcp crystal structure, predominantly in the first 5 μm below the surface.The hcp fraction decreases gradually along a depth of 10 μm. Surface Co displays severe plastic deformation under the highest strain, resulting in formation of nanocrystalline grains in the first micrometer below the surface. Microstructural refinement within the binder phase is observed even at greater depth. Stacking faults were detected in most of the refined grains. The metallurgical alterations of the binder phase modify the local stress distribution during grinding, which affects the discerned subsurface microcracking. The resulting residual stress profile is the sum of multiple subsurface changes, such as phase transformation, severe plastic deformation and grain refinement, where it is discerned that the depth profile of the transformed hcp-Co fraction coincides with the grinding-induced residual stress profile. The hcp fraction decreases gradually along a depth of 10 μm. Surface Co displays severe plastic deformation under the highest strain, resulting in formation of nanocrystalline grains in the first micrometer below the surface. Microstructural refinement within the binder phase is observed even at greater depth. Stacking faults were detected in most of the refined grains. The metallurgical alterations of the binder phase modify the local stress distribution during grinding, which affects the discerned subsurface microcracking. The resulting residual stress profile is the sum of multiple subsurface changes, such as phase transformation, severe plastic deformation and grain refinement, where it is discerned that the depth profile of the transformed hcp-Co fraction coincides with the grinding-induced residual stress profile.

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Binder deformation in WC-(Co, Ni) cemented carbide composites

Cited by 86 publications

References 7 publications

Mechanical deformation of WC–Co composite micropillars under uniaxial compression

Mechanical deformation of WC–Co composite micropillars under uniaxial compression

Fracture and fatigue behavior of WC–Co and WC–CoNi cemented carbides

Grinding-induced metallurgical alterations in the binder phase of WC-Co cemented carbides

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