Oxidation-induced strength degradation of WC–Co hardmetals

Casas, B.; Ramis, Xavier; Anglada, M.; Salla, Josep María; Llanes, L.

doi:10.1016/s0263-4368(01)00033-6

Cited by 96 publications

(40 citation statements)

References 8 publications

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“…In presumed order of importance, these are oxidative wear of WC ( Figures 4 and 6), and the increased brittleness due to the transformation of the WC binder. Lofaj et al [35] and Casas et al [36] reported that when WC reacts with oxygen, its volume expands by about 300% via an oxidation process that generates CO gas in the solid. The pressure of this gas is greater than the fracture strength of the WC and therefore leads to crack formation.…”

Section: Effect Of Wear On Microstructuresmentioning

confidence: 99%

Tool Wear Characteristics and Effect on Microstructure in Ti-6Al-4V Friction Stir Welded Joints

Fall

Fesharaki

Khodabandeh

et al. 2016

Metals

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Abstract:In the present paper, tool wear and the rate of wear during friction stir welding (FSW) of Ti-6Al-4V alloy are investigated. A conical tungsten carbide tool was used to produce butt-type friction stir welded joints in two-millimeter thick Ti-6Al-4V sheets. An original design of a movable pin allowed for the examination of the tool damage for each process condition. The influence of tool degradation on the quality of the welded joints and the damage brought to the microstructure are examined and discussed. For this purpose, optical and scanning electron microscopies as well as EDX analyses were used to examine the tool wear and the resulting macrostructures and microstructures. The type and nature of the defects are also analyzed as a function of FSW processing parameters. Important geometry and weight variations were observed on the pin and shoulder for all welding conditions, in particular when low tool rotation and travel speeds were used. Experimental results also show that the radial wear of the pin is not uniform, indicating the presence of important frictional temperature gradients through the thickness of the joint. The maximum wear was measured at a location of about one millimeter from the pin root center. Finally, tool rotation was determined as the most significant process parameter influencing both tool wear and microstructure of the joints.

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Section: Effect Of Wear On Microstructuresmentioning

confidence: 99%

Tool Wear Characteristics and Effect on Microstructure in Ti-6Al-4V Friction Stir Welded Joints

Fall

Fesharaki

Khodabandeh

et al. 2016

Metals

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“…Refs. [7][8][9]). Similar to other brittle materials, tensile strength of cemented carbides depends on the size of the major flaw and exhibits wide scatter due to the variability associated with defect distribution.…”

Section: Introductionmentioning

confidence: 99%

Strength and reliability of WC-Co cemented carbides: Understanding microstructural effects on the basis of R-curve behavior and fractography

Tarragó

Coureaux

Torres

et al. 2018

International Journal of Refractory Metals and Hard Materials

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Strength and reliability of WC-Co cemented carbides (hardmetals) are dependent on effective fracture toughness as well as on nature, size and distribution of processing flaws. Regarding toughness, they exhibit a crack growth resistance (R-curve) behavior, derived from the development of a multiligament bridging zone at the crack wake. Accordingly, successful implementation of fracture mechanics requires consideration of tangency criterion, between applied stress intensity factor and R-curve, in addition to fractographic inspection. It is the aim of this study to evaluate the strength behavior of a series of experimental WC-Co grades on the basis of R-curve failure criteria. Results indicate that microstructural effects on the strength of hardmetals may be satisfactorily rationalized following the referred criterion.The analysis includes consideration of nature and distribution of fracture origins, found to be more diverse and wider respectively for the harder fine-grained grades. This experimental evidence, together with the fact that these hardmetals exhibit steeper rising R-curves than tougher coarse-grained ones, leads to lower reliability for the former. This investigation documents and validates the great relevance of R-curve behavior for optimizing the mechanical performance of WC-Co cemented carbides on the basis of microstructural design.

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“…Refs. [2,8,[20][21][22][23][24]). Therefore, corrosion damage may also induce a detrimental effect on the strength and fatigue resistance of hardmetals due to the formation of corrosion pits with pronounced stress rising effects [8,9,[25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Microstructural influence on tolerance to corrosion-induced damage in hardmetals

et al. 2016

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The influence of the microstructure on the tolerance of WC-Co cemented carbides to corrosion damage was studied by using residual strength as the critical design parameter. In doing so, samples were immersed in synthetic mine water solution for different times, and changes induced by corrosion exposure were assessed. A detailed 3D FIB/FESEM tomography characterization of corrosion damage-microstructure interactions is included. Results reveal that corrosion damage may result in relevant strength degradation on the basis of stress rising effects associated with the formation of surface corrosion pits. Thus, as immersion time increases strength gradually decreases. Fractographic examination reveals the formation of semi-elliptical and sharp corrosion pits for studied medium-and ultrafine-sized cemented carbides, respectively. The latter has a much more pronounced stress rising effect, and consequently higher strength losses were determined for ultrafine grades. Corrosion process consists of a selective attack of the binder that is dissolved in the corrosive media. Initially, it is located at centres of binder pools and as exposure time in the media increases, corrosion evolves consuming the rest of the pools which finally leaves an unsupported WC grain skeleton at the surface.

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Oxidation-induced strength degradation of WC–Co hardmetals

Cited by 96 publications

References 8 publications

Tool Wear Characteristics and Effect on Microstructure in Ti-6Al-4V Friction Stir Welded Joints

Tool Wear Characteristics and Effect on Microstructure in Ti-6Al-4V Friction Stir Welded Joints

Strength and reliability of WC-Co cemented carbides: Understanding microstructural effects on the basis of R-curve behavior and fractography

Microstructural influence on tolerance to corrosion-induced damage in hardmetals

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