Residual stress and constraint effects on cleavage fracture in the transition temperature regime

Lee, K. S.; Goldthorpe, M. R.; Birkett, R. P.; Sherry, Andrew H.

doi:10.1111/j.1460-2695.2009.01383.x

Cited by 10 publications

(11 citation statements)

References 22 publications

(54 reference statements)

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“…The effect of constraint on cleavage fracture toughness was discussed by Beardsmore 10 , who suggested that the presence of a residual stress field of the magnitude and distribution produced in these samples should result in a higher level of constraint, such that the failure condition is actually reached at a lower value of J than in an unstrained sample. This is in agreement with the constraint calculations of Lee et al 15 . who calculated a higher (positive) T ‐ and Q ‐stress for PCT specimens when compared with CT specimens.…”

Section: Discussionsupporting

confidence: 92%

“…The K Jc values at failure were calculated (i) according to the ASTM procedure, based on the area under the primary load versus crack mouth opening displacement record from each test 8 and (ii) using the JEDI procedure to determine J inclusive of any residual stress fields 15 . In each case the value of J at cleavage was converted to an equivalent K Jc using the standard plane strain formulation: where E is Young's modulus, ν is Poisson's ratio and J c is the derived value of J at cleavage.…”

Section: Methodsmentioning

confidence: 99%

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The effect of a residual stress field on fracture initiation in RPV steel

Ortner

Lee

Sherry

2011

Fatigue &Amp; Fracture of Engineering Materials &Amp; Structures

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A B S T R A C T Whether flaws in structures containing residual (secondary) stresses will extend under particular operational (primary) loads depends on the extent to which the residual stress field affects: (a) the nature and distribution of initiators; (b) the combined (primary + secondary) stresses and strains experienced by potential initiators. This paper compares fractographic data from specimens loaded by only a primary stress with data from specimens also containing a tensile residual stress field. Three-dimensional elastic-plastic finite element calculations are used to characterize the stress-strain conditions at the initiation sites at the onset of brittle fracture. The introduction of a residual stress changes the dominant stage in fracture nucleation from microcrack extension to particle cracking. This offsets some of the decrease in fracture toughness expected when the residual stress field increases specimen constraint.CT = compact tension specimen E = Young's modulus EDX = energy-dispersive X-ray analysis of composition FE = finite element HT = heat treatment J = contour integral J c = value of J at cleavage K = stress intensity K Jc = stress intensity at specimen failure MVC = ductile microvoid coalescence PCT = pre-loaded compact tension specimen SEM = scanning electron microscope X c = separation of initiation site from pre-crack front (in direction of macroscopic crack growth) Z c = separation from initiation site from mid-line of specimen, in plane normal to loading direction ε 22elastic = elastic portion of ε 22,total ε 22,total = total (elastic+plastic) strain in loading direction, acting on plane normal to loading direction ν = Poisson's σ 22 = principal tensile stress, in loading direction, acting on plane normal to loading direction

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Section: Discussionsupporting

confidence: 92%

Section: Methodsmentioning

confidence: 99%

The effect of a residual stress field on fracture initiation in RPV steel

Ortner

Lee

Sherry

2011

Fatigue &Amp; Fracture of Engineering Materials &Amp; Structures

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“…8, can be used to calculate the residual stress triaxiality (ratio of hydrostatic to von Mises stresses) at any location along the measurement line. This parameter can have a significant effect on crack initiation and opening behaviour in ductile materials [34] and on fracture [35][36][37]. The measurements show that exceptionally high stress triaxiality is present (approaching unity) in the region between 17 and 22 mm from the CT blank front face.…”

Section: Discussionmentioning

confidence: 86%

Measurement of the Residual Stress Tensor in a Compact Tension Weld Specimen

et al. 2012

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Neutron diffraction measurements have been performed to determine the full residual stress tensor along the expected crack path in an austenitic stainless steel (Esshete 1250) compact tension weld specimen. A destructive slitting method was then implemented on the same specimen to measure the stress intensity factor profile associated with the residual stress field as a function of crack length. Finally deformations of the cut surfaces were measured to determine a contour map of the residual stresses in the specimen prior to the cut. The distributions of transverse residual stress measured by the three techniques are in close agreement. A peak tensile stress in excess of 600 MPa was found to be associated with an electron beam weld used to attach an extension piece to the test sample, which had been extracted from a pipe manual metal arc butt weld. The neutron diffraction measurements show that exceptionally high residual stress triaxiality is present at crack depths likely to be used for creep crack growth testing and where a peak stress intensity factor of 35 MPa√m was measured (crack depth of 21 mm). The neutron diffraction measurements identified maximum values of shear stress in the order of 50 MPa and showed that the principal stress directions were aligned to within~20°of the specimen orthogonal axes. Furthermore it was confirmed that measurement of strains by neutron diffraction in just the three specimen orthogonal directions would have been sufficient to provide a reasonably accurate characterisation of the stress state in welded CT specimens.

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“…Because the heat treatments used for these samples will not necessarily be the same as those used in other published tests on JRQ and JFL, these particular materials are identified as JRQ (BSL) and JFL (BSL). An A533B Class 1 plate heat treated such that the mean fracture toughness at room temperature would be ∼100 MPa√m (UM). Fracture toughness measurements and fractography were carried out on both standard and previously compressed compact tension samples., 19 This present report uses data from the standard samples only.…”

Section: Investigation Of Modelsmentioning

confidence: 99%

“…An A533B Class 1 plate heat treated such that the mean fracture toughness at room temperature would be ∼100 MPa√m (UM). Fracture toughness measurements and fractography were carried out on both standard and previously compressed compact tension samples., 19 This present report uses data from the standard samples only.…”

Section: Investigation Of Modelsmentioning

confidence: 99%

Comparison between particle cracking criteria in models for the fracture of steels

Ortner

2011

Fatigue &Amp; Fracture of Engineering Materials &Amp; Structures

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A B S T R A C T Several models of fracture in ferritic steel consider matrix strain to be an indicator of the condition required for second-phase particle cracking (i.e. microcrack nucleation). Recent simulations predict that stress × strain (W ) is a better supported indicator. This paper examines the effect of replacing strain by W within the EOH fracture model. There is no improvement in the descriptions of fracture toughness and initiation site properties for eight different steels over a range of temperatures. The use of W , however, leads to the convergence of data from different steels, and permits estimates of the particle cracking criterion to be made from metallographic data, when suitable fractographic data are unavailable. Overall, experiment agrees with simulation in finding W a more appropriate parameter to use than strain alone. B = specimen thickness c = diameter of fracture-initiating particle parallel to crack growth direction X = distance increment in calculation step E m = Young's modulus of matrix E = E in plane stress and E (1−ν 2 ) in plane strain E p = Young's modulus of particle F = fraction of particles taking part in failure L = diameter of fracture-initiating particle normal to crack growth direction N a = number of particles per unit area P fx = cumulative probability of failure out to distance, X , from the pre-crack tip r = particle radius r 0 = minimum size of microcrack which will extend r ## = ##th percentile particle radius r max = maximum size of second-phase particle left uncracked after quenching from final heat treatment V actual = volume of particle nucleating fracture V ## = volume of particle with ##th percentile particle radius W = σ 11,matrix x ε total,matrix W min = minimum W required for particle cracking W Xc = W measured at X c X c = distance from pre-crack tip to fracture initiation site X p = distance from pre-crack tip to location of peak in tensile stress field ε min = minimum total matrix strain required for particle cracking

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Residual stress and constraint effects on cleavage fracture in the transition temperature regime

Cited by 10 publications

References 22 publications

The effect of a residual stress field on fracture initiation in RPV steel

The effect of a residual stress field on fracture initiation in RPV steel

Measurement of the Residual Stress Tensor in a Compact Tension Weld Specimen

Comparison between particle cracking criteria in models for the fracture of steels

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