Effect of microstructure on cleavage fracture toughness of quenched and tempered steels

Curry, David; Knott, J. F.

doi:10.1179/msc.1979.13.6.341

Cited by 279 publications

(89 citation statements)

References 4 publications

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“…The current mode 1 a 1 so imp 1 i es, contrary to ear 1 i er ana 1 yses (14,(17)(18)(19)(20)(21), that the fracture stress for cleavage cracking is not identical for failure ahead of sharp cracks and rounded notches.…”

Section: Methodsmentioning

confidence: 99%

“…In stochastic terms, these models can be re-formulated using weakest link statistics (11,(18)(19)(20)(21)(22). Accordingly, the cleavage fracture toughness is estimated in terms of the volume of material within the p 1 as tic zone needed to assure the presence of an "eligible" cracked particle, at which the fracture criterion is…”

Section: Statistical Relation For Transgranular Cleavagementioning

confidence: 99%

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Statistical analysis of cleavage fracture ahead of sharp cracks and rounded notches

1986

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Section: Methodsmentioning

confidence: 99%

Section: Statistical Relation For Transgranular Cleavagementioning

confidence: 99%

Statistical analysis of cleavage fracture ahead of sharp cracks and rounded notches

1986

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“…It is observed that inclusions also serve as the sites for microcrack nuclei in fracture toughness (K 1c ) tests and it appears therefore that the combination of fracture criterion, stress analysis and fractographic observation should be sufficient to calculate values of 'critical distance'. When such calculations are made, agreement with RKR/Curry, Knott theory [12,15] is not good at the lower temperatures and it appears that the 'pre-strain' or 'warm-pre-stressing' (WPS) effect on σ F induced by the (room-temperature) fatigue pre-cracking process employed for K 1c tests is affecting low-temperature behaviour. Better agreement is obtained with theory at higher temperatures, when the process zone associated with fracture is significantly larger than the fatigue 'pre-strained' zone [33].…”

Section: Microstructural Features Of Transgranular Cleavagementioning

confidence: 99%

“…The critical tensile stress criterion has been used to explain the values of fracture toughness, Curry & Knott [13][14][15] …”

Section: Slow Notched-bend Tests and Fracture Toughness Valuesmentioning

confidence: 99%

Brittle fracture in structural steels: perspectives at different size-scales

Knott

2015

Phil. Trans. R. Soc. A.

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This paper describes characteristics of transgranular cleavage fracture in structural steel, viewed at different size-scales. Initially, consideration is given to structures and the service duty to which they are exposed at the macroscale, highlighting failure by plastic collapse and failure by brittle fracture. This is followed by sections describing the use of fracture mechanics and materials testing in carryingout assessments of structural integrity. Attention then focuses on the microscale, explaining how values of the local fracture stress in notched bars or of fracture toughness in pre-cracked test-pieces are related to features of the microstructure: carbide thicknesses in wrought material; the sizes of oxide/silicate inclusions in weld metals. Effects of a microstructure that is 'heterogeneous' at the mesoscale are treated briefly, with respect to the extraction of test-pieces from thick sections and to extrapolations of data to low failure probabilities. The values of local fracture stress may be used to infer a local 'work-of-fracture' that is found experimentally to be a few times greater than that of two free surfaces. Reasons for this are discussed in the conclusion section on nano-scale events. It is suggested that, ahead of a sharp crack, it is necessary to increase the compliance by a cooperative movement of atoms (involving extra work) to allow the crack-tip bond to displace sufficiently for the energy of attraction between the atoms to reduce to zero.

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“…Statistical model have been developed [14] in which the cleavage fracture characteristics are related to the distribution of brittle particles, involving a statistical competition between different sized crack nuclei in the rapidly changing stress gradient ahead of the crack tip. Some of the microstructural features and events preceding the fracture initiation have statistical nature.…”

Section: Introductionmentioning

confidence: 99%

The Susceptibility of Local Parameters to Steel Microstructure Evaluated Using Charpy Type Specimen

et al. 1996

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Abstract. Accepting the Beremin approach to the analysis of cleavage failure criteria the local fracture parameters have been calculated using FEM for Charpy type specimen. Two types, of model fenitic microstructures have been selected for presentation differing by carbide thickness and scatter of fracture toughness data. For the microstructures investigated the Weibull stresses (location parameters) were related to cleavage fracture stresses determined supposing deterministic nature of cleavage fracture events at initiation. The results of static three point bending and low blow impact testing were used for these purposes. Microstructural and rnicrohctographic reasons for scatter of data were determined. Relation of microstructural and microfractographic features to local fracture criteria was analysed.

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Effect of microstructure on cleavage fracture toughness of quenched and tempered steels

Cited by 279 publications

References 4 publications

Statistical analysis of cleavage fracture ahead of sharp cracks and rounded notches

Statistical analysis of cleavage fracture ahead of sharp cracks and rounded notches

Brittle fracture in structural steels: perspectives at different size-scales

The Susceptibility of Local Parameters to Steel Microstructure Evaluated Using Charpy Type Specimen

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