Dislocation shielding model of fracture toughness
A recently developed dislocation model of fracture has shown that fracture toughness of a material depends directly on the number of dislocations in the plastic zone. The model is based on TEM observations that there is a dislocation-free zone between the crack tip and the plastic zone and the crack tip is shielded from the applied stress by the dislocations in the plastic zone. Elasticity is restored in the region immediately ahead of the crack tip and hence it is possible to define a crack tip stress intensity factor. In the present paper, a review is given of the dislocation-free zone model of fracture and the concept of dislocation shielding of a crack tip. An expression for the fracture toughness of a material is derived from the model in terms of the parameters describing the crack tip geometry. A criterion for ductile vs brittle fracture is proposed in terms of the condition for crack tip deformation.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5219456
- Report Number(s):
- CONF-840218-5; ON: DE84007539
- Country of Publication:
- United States
- Language:
- English
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