Relation between KIc and microscopic strength for low alloy steels

Alkin, J.M.; Tetelman, A. S.

doi:10.1016/0013-7944(71)90006-3

Cited by 77 publications

(18 citation statements)

References 5 publications

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“…Notice that the assumption of constant strains over a certain area in the plastic zone near stress concentrators was mentioned in several studies, e.g., [8]. The crack propagates if e max equals the strain limit e c .…”

Section: Deformation and Fracture In The Plastic Zonementioning

confidence: 98%

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Material strengthening by crack and cavity healing

Sylovanyuk

Yukhim

2011

Strength Mater

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The d c -model of a crack-containing elastoplastic body was used to specify parameters that influence the healing of crack-type defects by filling them with the other material. The relationships are derived, which can predict the extent of crack-containing body strength recovery with various fillings. The "characteristic distance" of crack (filled or free) growth is established, when the intensity of external loads reaches its limit. It is shown that this distance is the constant of the material for unfilled macrocracks and constitutes a certain portion of the plastic zone formed near the defect.

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Section: Deformation and Fracture In The Plastic Zonementioning

confidence: 98%

“…The other point of view lies in the fact that near the macrocrack the characteristic distance is the constant of the material and determines the point of microcrack origination ahead of the macrocrack tip [8,11,13].…”

Section: Deformation and Fracture In The Plastic Zonementioning

confidence: 99%

Material strengthening by crack and cavity healing

Sylovanyuk

Yukhim

2011

Strength Mater

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“…A further increase in radius beyond the limiting crack tip radius increases the value of fracture toughness. Using the slip line field analysis and elastic-plastic stress distribution in the notched bars, a criterion for cleavage fracture was given [3,10] which is based on the fact that the unstable fracture occurs when the plastic zone spreads to a critical distance such that the maximum tensile stress level in the plastic zone is raised from the yield strength to the cleavage fracture strength over a small volume in front of the notch. The toughness, Kic is expressed in terms of the microscopic cleavage strength, a~ and the tensile yield strength oy s as [10],…”

Section: Evaluation Of Limiting Crack Tip Radiusmentioning

confidence: 99%

Significance of limiting (equivalent) tip radius and crack tip deformation for cleavage induced fracture in structural steels

Pandey

1984

J Mater Sci

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In two structural steels, the limiting crack tip radius (LTR) and the crack tip blunting radius have been evaluated at the instant of fracture initiation by cleavage. The effect of yield strength on LTR and the blunting radius has been investigated. The relationship between the limiting and the blunting tip radius has been studied. The limiting tip radius has been found to be of the order of the plastic zone radius in the structural steels investigated.

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“…Schematic of the notch root of a Charpy V standardised specimen subject to three-point bending and stress and strain fields ahead of the notch for various applied loads (afterMalkin and Tetelman, 1971 and Griffith and Owen, 1971).…”

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confidence: 99%

Microscopic aspect of fracture: Cleavage and ductile rupture

Miannay

1998

Mechanical Engineering Series

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In Chapter I, the theoretical cohesive stress of the material on the scale of the crystalline lattice, i.e., on the scale of nm, has been estimated from the theoretical surface energy. This energy for some metals is given in Table 5.1. The value is ofthe order of 10-5 da J . cm-2 . In Chapters 2 and 3, it was emphasised that the fracture theories based only on this theoretical stress and on purely elastic behaviour were insufficient and in fault, because for microcracks and cracks, a plastic deformation that appears around the crack normally for physical reasons is to be taken into account. This plastic behaviour will have to particularly explain why energies of the order of G tC = O.5daJ . cm-2 (with Ktc = 100M Pa.,;m for a steel) are associated with fracture.In fact, as it is experimentally observed, plasticity is necessary to trigger a fracture nucleation, which will lead to the whole fracture of the cracked or uncracked body. This aspect is illustrated in Figure 5.1, first with a tensile test of a plain specimen, i.e., without flaw, with a dimension of the order of cm, of an ideal totally homogeneous material, which breaks in an ideal manner after a total plastic deformation when the stress reduced to the current section and the area of this section go simultaneously to zero. But more in agreement with experience, some inhomogeneity appears during the plastic deformation and at the scale ofthe specimen, fracture occurs at various levels of deformation, (Fig. 5.1): for low values of deformation, fracture is said to be brittle; it requires low strain deformation energy and the preceding deformation does not allow the detection of its occurrence. For high values of deformation and generally beyond the necking, fracture is said to be ductile: it needs high energy and its occurrence can be predicted a long time before. As for necking, this corresponds to a geometrical instability and not to a fracture mechanism. (Exercise 5.1).When the preceding fractures are observed and analysed on their fracture surfaces and on axial metallographic sections, at a midway scale between the inter-atomic spacing, the nm, and the dimension of the specimen, the cm, i.e., at the scale of the inclusion, the /J-m, or at the scale of the grain, 10 /J-m, these fractures can be classified in a decreasing order of brittleness ( Figures 5.2 and 5.3) as • brittle or semi-brittle intergranular fracture, D. P. Miannay, Fracture Mechanics

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Relation between KIc and microscopic strength for low alloy steels

Cited by 77 publications

References 5 publications

Material strengthening by crack and cavity healing

Material strengthening by crack and cavity healing

Significance of limiting (equivalent) tip radius and crack tip deformation for cleavage induced fracture in structural steels

Microscopic aspect of fracture: Cleavage and ductile rupture

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