Fatigue of Cemented Carbides

Llanes, L.; Anglada, M.; Torres, Yadir

doi:10.1016/b978-0-08-096527-7.00011-8

Cited by 14 publications

(29 citation statements)

References 90 publications

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“…Fatigue is a relevant service degradation phenomenon in hardmetals and is associated with premature and unexpected failure [8]. Although the earliest information on fatigue of cemented carbides dates from 1941 [9], the more relevant scientific and technical advances on this field are concentrated in the last two decades.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

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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“…They exhibit exceptional combinations of hardness, toughness, strength and wear resistance, which are the result of the different properties of their two interpenetrating constituents: hard and brittle tungsten carbide, and soft and ductile cobalt-base binder [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Mechanical strength of ground WC-Co cemented carbides after coating deposition

Yang

Odén

Johansson-Jöesaar

et al. 2017

Materials Science and Engineering: A

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Manufacturing of hardmetal tools often involves surface grinding, ion etching and final coating.Each stage throughout the manufacturing chain introduces surface integrity changes which may be critical for defining the final mechanical behavior of the coated tools. Within this context, an experimental test program has been developed to assess the influence of a coating (TiN) deposition on surface integrity and transverse rupture strength of a previously ground finegrained WC-Co grade substrate. Four different substrate surface finish conditions (prior to ion etching and coating) were evaluated: as sintered (AS), ground (G), polished (P), and ground plus high temperature annealing (GTT). Surface integrity and fracture resistance characterization, complemented with a detailed fractographic analysis, were performed on both uncoated and coated samples. Results show that the surface integrity after grinding has been partly modified during the ion etching and film deposition processes, particularly in terms of a reduced compressive residual stress state at the substrate surface level. Consequently, the grinding induced strength enhancement in hardmetals is reduced for coated specimens. Main reason behind it is the change of nature, location and stress state acting on critical flaw: from processing defects existing at the subsurface (uncoated G specimens) to grinding-induced microcracks located close to the interface between coating and substrate, but within the subsurface of the 1 Current address: AMES-Sintered Metal Components, Camí de Can Ubach, 8, Pol. Ind. ¨Les Fallulles¨, 08620 -Sant Vicenç dels Horts, Barcelona -Spain latter (coated G specimens). This is not the case for AS and P conditions, where flexural strength does not change as a result of ion etching and coating. Finally, fracture resistance increases slightly for GTT specimens after coating process, possibly caused by a beneficial effect of the deposited film on the residual stress state at the surface.

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“…For example, many papers have reported that the fatigue strength of cemented carbide is decreased by applying a cyclic load [5]. In addition, the reduction of fatigue strength becomes marked with increasing Co content in the material [6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

On the Short Surface Fatigue Crack Growth Behavior in a Fine-Grained WC-Co Cemented Carbide

Mikado

Ishihara

Oguma

et al. 2017

Metals

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Abstract:In the present study, the fatigue crack growth (FCG) behavior of short surface cracks in a fine-grained cemented carbide with a length of less than 1 mm was investigated. The rotating bending and the four-point bending fatigue tests were carried out at stress ratios of R = −1 and R = 0.1 (R = maximum stress/minimum stress). It was found that a short surface crack had a longer stable fatigue crack growth area than a long through-thickness crack; the FCG behaviors of the two types of crack are clearly different. Furthermore, the FCG path of short surface cracks was investigated in detail to study the interaction between fatigue cracks and microstructures of the cemented carbide such as WC grains and the Co phase. At a low K max (K max = the maximum stress intensity factor), it was found that fatigue crack growth within WC grains is difficult because of a small driving force; instead, crack growth is along the brittle WC/WC interface. On the other hand, at a high K max , WC grain breakage often occurs, since the driving force of FCG is large, and the fatigue crack grows linearly.

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Fatigue of Cemented Carbides

Cited by 14 publications

References 90 publications

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

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

Mechanical strength of ground WC-Co cemented carbides after coating deposition

On the Short Surface Fatigue Crack Growth Behavior in a Fine-Grained WC-Co Cemented Carbide

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