Journal ArticleDOI
Precracking of fracture-toughness specimens of hardmetals by wedge indentation
E. A. Almond,B. Roebuck +1 more
TLDR
In this paper, a sharp crack is introduced into bend-test specimens using a wedge indenter and residual stresses are relieved by removing the surface layer containing the indentation, and it is found that annealing is not a satisfactory way of removing residual stresses from specimens precracked by indentation since it produces effects that give too high a value for fracture toughness.Abstract:
A technique has been devised for precracking fracture-toughness specimens of hardmetals whereby a sharp crack is introduced into bend-test specimens using a wedge indenter and residual stresses are relieved by removing the surface layer containing the indentation. The technique is reproducible, simple to use, and does not suffer from the inaccuracies and difficulties of interpretation inherent in using the spark-machining and pyramid-indentation techniques. It is found that annealing is not a satisfactory way of removing residual stresses from specimens precracked by indentation since it produces effects that give too high a value for fracture toughness. Spark-machined specimens do not give reliable fracture-toughness data because there are practical problems in introducing a notch sufficiently narrow to simulate the effect of a thin crack and because thermal damage caused by the spark discharge probably alters the properties of the material at the notch root.read more
Citations
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Journal ArticleDOI
Physical and chemical nature of cemented carbides
TL;DR: In this article, the physical and chemical aspects of transition metal carbides and iron-group metals are reviewed with emphasis on the materials science point of view focusing on those compositions which have gained technical interest.
Journal ArticleDOI
Deformation and fracture processes and the physical metallurgy of WC–Co hardmetals
Bryan Roebuck,E. A. Almond +1 more
TL;DR: In this paper, a detailed assessment of microstructural parameters is made of their effects on strength and fracture tests at ambient temperature, for the constituent phases separately and in combination, and the results of properties more relevant to service behaviour, such as fatigue and creep, are summarized.
Journal ArticleDOI
On the fracture toughness of cemented carbides
Lorenz Sigl,H.F. Fischmeister +1 more
TL;DR: In this article, a model for the fracture toughness of cobalt reinforced tungsten carbide hardmetals is presented, where the fracture energy of the composite is obtained from the sum of the energies dissipated during fracture along the four crack paths that are available in this composite.
Journal ArticleDOI
The Brittle-Ductile Transition in Silicon. I. Experiments
J. Samuels,Steve G. Roberts +1 more
TL;DR: In this article, the authors investigate the fundamental processes involved in the brittle-ductile transition in silicon, and form the basis of a new theoretical model, which is used to derive activation energies which are found to be equal to those for dislocation glide.
Journal ArticleDOI
Identification of optimum binder phase compositions for improved WC hard metals
E. A. Almond,Bryan Roebuck +1 more
TL;DR: In this article, the possibility of using measurements of the mechanical properties of alloys with binder phase compositions to identify binder phases that will provide high hardness and toughness in WC hard metals was investigated.
References
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Book
Theory of elasticity
TL;DR: The theory of the slipline field is used in this article to solve the problem of stable and non-stressed problems in plane strains in a plane-strain scenario.
Book ChapterDOI
Plane strain crack toughness testing of high strength metallic materials.
William F. Brown,John E. Srawley +1 more
Journal ArticleDOI
Fracture toughness and fracture of WC-Co composites
J. L. Chermant,F. Osterstock +1 more
TL;DR: In this paper, the critical stress intensity factor and related parameters have been measured in three-point bending for 18 different combinations of different volume fractions of cobalt and grain size of tungsten carbide.
Journal ArticleDOI
Stress Intensity Factors for Semicircular Cracks: Part 2—Semi-Infinite Solid
Journal ArticleDOI
The fracture toughness of cemented tungsten carbides
N Ingelstrom,H Nordberg +1 more
TL;DR: In this paper, the fracture toughness of a number of cemented carbide alloys have been determined using a wedge-impact method for precracking; the materials were of WC-Co type with cobalt content ranging from 6 to 25 wt-% and mean carbide grain size between 1.0 and 3.3 μ m.
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The fracture toughness of WCCo alloys measured on single-edge notched beam specimens precracked by electron discharge machining
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