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

Mikado, Hiroko; Ishihara, Sotomi; Oguma, Noriyasu; Kawamura, Shingo

doi:10.3390/met7070254

Cited by 10 publications

(7 citation statements)

References 25 publications

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“…On the one hand, fractographic analysis has been used for invoking correlations between fatigue life and the size of microstructural defects on the basis of Murakami's geometrical parameter of maximum flaw area [17][18][19]. On the other hand, notched specimens have been used for assessing microstructural effects on fatigue response under service-like conditions, e.g., presence of stress concentrators in component geometry as crack starting points and exposure to high temperatures [17,[20][21][22][23]. Tarragó and coworkers [13,15,16] have implemented the above protocol in several microstructurally different cemented carbides in terms of the binder chemical nature (either Co or Ni or CoNi) and content (between 10 and 15 wt%), as well as carbide grain size (between 0.4 and 2.4 µm).…”

Section: Fatigue Mechanicsmentioning

confidence: 99%

In-Depth Understanding of Fatigue Micromechanisms in Cemented Carbides: Implications for Optimal Microstructural Tailoring

Llanes

2019

Metals

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The fatigue mechanics and mechanisms of cemented carbides (composites usually referred to as hardmetals) are reviewed. The influence of microstructure on strength lessening and subcritical crack growth for these ceramic-metal materials when subjected to cyclic loads are highlighted. The simultaneous role of the ductile metallic binder as a toughening and fatigue-susceptible agent for hardmetals results in a tradeoff between properties measured under monotonic and cyclic loading: fracture strength and toughness on one hand, as compared to fatigue strength and crack growth resistance on the other one. Toughness/fatigue–microstructure correlations are analyzed and rationalized on the basis of specific crack–microstructure interactions, documented by the effective implementation of advanced characterization techniques. As a result, it is concluded that the fatigue sensitivity of cemented carbides may be reduced if either toughening mechanisms beyond ductile ligament bridging, such as crack deflection, are operative, or strain localization within the binder is suppressed. In this regard, grades exhibiting metallic binders of a complex chemical nature and/or distinct microstructural assemblages are proposed as options for effective microstructural tailoring of these materials.

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Section: Fatigue Mechanicsmentioning

confidence: 99%

In-Depth Understanding of Fatigue Micromechanisms in Cemented Carbides: Implications for Optimal Microstructural Tailoring

Llanes

2019

Metals

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“…Therefore, as compared with the short-surface cracks, the long through cracks are highly susceptible to K max and ∆K [6], and shows FCG characteristics of brittle materials such as ceramics.…”

Section: Comparison With the Fcg Behaviour Of Long Through Cracksmentioning

confidence: 99%

“…Ishihara et al [5] reported the FCG characteristics of the short surface crack at various stress ratios using the cemented carbide with comparatively large WC grain size. Mikado et al [6] studied the FCG behavior of the short surface crack at stress ratio, R = −1 using the finegrained cemented carbide.…”

Section: Introductionmentioning

confidence: 99%

A two-parameter analysis of surface fatigue crack growth behavior of fine-grained WC-Co cemented carbide at different stress ratios

et al. 2018

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In this study, the fatigue crack growth (FCG) characteristics of the short surface crack was studied at various stress ratios, R, using the fine grained cemented carbide. The FCG law for the material was studied using two parameters, the maximum stress intensity factor Kmax and the stress intensity factor range ΔK. It was found that the relationship between the rate of FCG, da/dN and ΔK depends on the R value. In the da/dN vs. Kmax relation, at the region of high crack growth rate, the FCG rate was nearly constant by the value of Kmax without depending on R. However, in the low FCG rate region, the FCG rate tended to accelerate as R became lower. Therefore, it was difficult to specify da/dN as a single value at different R ratios using either ΔK or Kmax from the low speed region to the high-speed region. For that reason, the FCG behaviour of the material was studied based on the crack growth law, da/dN = AKmaxmΔKn. The values of m and n were obtained as 6.6 and 1.4, respectively. Therefore, it was found that the FCG rate of the cemented carbide was strongly dependent on Kmax rather than ΔK, like the FCG characteristics of ceramics.

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“…The reason for failure is that, under the simultaneous action of mechanical stress and thermal stress, microcracks are formed and then propagate until the failure of the cemented carbide tools occurs [4,5]. Mikado et al [6] investigated the fatigue crack growth (FCG) behavior of short surface cracks in a fine-grained cemented carbide with a length of less than 1 mm and found that the FCG was along the brittle WC/WC interface in a low maximum stress intensity factor. Wu et al [7] conducted experiment on direct micro milling of cemented carbide with a polycrystalline diamond (PCD) micro end mill, whose research suggested that the tool wear process presented microchipping on the cutting edge and exfoliating on the rake face in the early stage, and then presented severe abrasive and adhesive wear on the bottom face in the following stage.…”

Section: Introductionmentioning

confidence: 99%

Effect of Graphene and Carbon Nanotubes on the Thermal Conductivity of WC–Co Cemented Carbide

Chen¹,

Xiao

et al. 2019

Metals

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In recent years, it has been found that the service life of cemented carbide shield machine tools used in uneven soft and hard strata is substantially reduced in engineering practice. The study found that thermal stress is the main reason for the failure of cemented carbide shield tunneling tools when shield tunneling is carried out in uneven soft and hard soil. To maintain the hardness of cemented carbide, improving the thermal conductivity of the shield machine tool is of great importance for prolonging its service life and reducing engineering costs. In this study, graphene and carbon nanotubes were mixed with WC–Co powder and sintered by spark plasma sintering (SPS). The morphology was observed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The Rockwell hardness, bending strength, and thermal conductivity of the samples were tested. The results show that adding a small amount of graphene or carbon nanotubes could increase the bending strength of the cemented carbide by approximately 50%, while keeping the hardness of the cemented carbide constant. The thermal conductivity of the cemented carbide could be increased by 10% with the addition of 0.12 wt % graphene alone.

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

Cited by 10 publications

References 25 publications

In-Depth Understanding of Fatigue Micromechanisms in Cemented Carbides: Implications for Optimal Microstructural Tailoring

In-Depth Understanding of Fatigue Micromechanisms in Cemented Carbides: Implications for Optimal Microstructural Tailoring

A two-parameter analysis of surface fatigue crack growth behavior of fine-grained WC-Co cemented carbide at different stress ratios

Effect of Graphene and Carbon Nanotubes on the Thermal Conductivity of WC–Co Cemented Carbide

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