A three-dimensional characterization of creep void formation in hydrogen reformer tubes

Wahab, Azmi Abdul; Hutchinson, Christopher; Kral, Milo V.

doi:10.1016/j.scriptamat.2006.02.045

Cited by 17 publications

(11 citation statements)

References 11 publications

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“…The previous observations of Wahab et al . 30 that the relative frequency of creep void formation in gas reformer tubes is highest at boundaries decorated with carbides and inclined at 40° – 70° away from the direction of the principal stress, and that of Burnett et al . 21 that heavily creep cavitated boundaries are decorated with carbides and other precipitates and lie at approximately 45° to the apparent direction of the principal tensile stress, both suggest that shear at boundaries containing precipitates is conducive to the development of creep voids and that grain boundary sliding may play a significant role in void formation, as expounded in theoretical models of creep cavitation 21 , 22 , 24 .…”

Section: Discussionmentioning

confidence: 81%

“…Previous studies have indicated that cavitation at grain boundaries is primarily governed by the orientation of the boundary to the residual stress field 21 , 30 . For this reason, the angle between each grain boundary plane and the direction of principal stress was measured here.…”

Section: Resultsmentioning

confidence: 99%

“… 21 that heavily creep cavitated boundaries are decorated with carbides and other precipitates and lie at approximately 45° to the apparent direction of the principal tensile stress, both suggest that shear at boundaries containing precipitates is conducive to the development of creep voids and that grain boundary sliding may play a significant role in void formation, as expounded in theoretical models of creep cavitation 21 , 22 , 24 . The present observation that boundaries at angles of 63° and 62° to the principal stress axis were cavitated but that one at an angle of 31° to the stress axis is consistent with Wahab et al .’s observation 30 that at the mid-wall-thickness of a tube (i.e. where there is the highest constraint) most creep voids formed at boundaries themselves lying at 50° – 70° to the stress axis.…”

Section: Discussionmentioning

confidence: 98%

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Multiscale correlative tomography: an investigation of creep cavitation in 316 stainless steel

Slater

Bradley

Bertali

et al. 2017

Sci Rep

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Creep cavitation in an ex-service nuclear steam header Type 316 stainless steel sample is investigated through a multiscale tomography workflow spanning eight orders of magnitude, combining X-ray computed tomography (CT), plasma focused ion beam (FIB) scanning electron microscope (SEM) imaging and scanning transmission electron microscope (STEM) tomography. Guided by microscale X-ray CT, nanoscale X-ray CT is used to investigate the size and morphology of cavities at a triple point of grain boundaries. In order to understand the factors affecting the extent of cavitation, the orientation and crystallographic misorientation of each boundary is characterised using electron backscatter diffraction (EBSD). Additionally, in order to better understand boundary phase growth, the chemistry of a single boundary and its associated secondary phase precipitates is probed through STEM energy dispersive X-ray (EDX) tomography. The difference in cavitation of the three grain boundaries investigated suggests that the orientation of grain boundaries with respect to the direction of principal stress is important in the promotion of cavity formation.

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Section: Discussionmentioning

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 98%

See 1 more Smart Citation

Multiscale correlative tomography: an investigation of creep cavitation in 316 stainless steel

Slater

Bradley

Bertali

et al. 2017

Sci Rep

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“…These features, when incorporated in a dataset containing tomographic information on damage, provides multi-modality which can contain provide new mechanistic insights on the failure process in materials. In this regard Kral and co-workers 50,51 characterised the creep voids in an ex-service hydrogen reformer tube of austenitic stainless steel using serial sectioning over a small volume of 400µm x 300µm x 30-50µm. From a cross-section of the reformer tube exposed to varying temperature -stress condition from the inner to outer wall, serial sectioning carried out at four locations revealed significant difference in the creep void characteristics such as void count, volume and size distribution.…”

Section: Multi-modal and Multi-scale Characterisation Of Cavitation Imentioning

confidence: 99%

3D creep cavitation characteristics and residual life assessment in high temperature steels: A critical review

Gupta

Toda

Mayr

et al. 2015

Materials Science and Technology

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The paper seeks to assess critically the need for a new paradigm in creep life estimation of service exposed steels and provide possible new directions of residual life assessment, in the light of a decade of explosive application of micro-tomography on structural materials to characterise the 3D nature of cavitation damage. The phenomenon of creep failure using synchrotron micro-tomography (SR-µCT) has been studied at large synchrotron sources where imaging on conventional structural materials such as steels with high absorption to X-rays has been realized. The unique feature of the SR-µCT studies is the direct imaging in 3D of cavitation present in the bulk (hundreds of micrometers in size), revealing the spatial characteristics and morphology of the creep voids. Further the quantitative analyses of cavitation characteristics contained in the 3D datasets, which when scaled with time, stress and temperature provides functional information amenable for developing constitutive equations for creep fracture. These being based on SR-µCT, which due to its non-destructive feature provides high fidelity data that significantly reduces the ambiguity in the development of the functional relationships related to creep failure. Thus the use of such constitutive equations in an explicit manner to estimate the residual life of the components affected by creep and the consequent assessment of structural integrity would prove invaluable. This paper summarizes the studies related to creep in materials using micro-tomography with special emphasis on a 10.86%Cr heat resistant steel to show the type of data available which could be relevant for life assessment and design against creep failure. A brief discussion of the existing methods of residual life estimations in the light of the availability of the 3D micro-tomography data available in recent literature follows. Finally the possible new directions of using the microtomography data to formulate advanced residual life estimation methods are briefly touched.

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“…Measurement of the inner diameter of a tube and its outer circumference are most commonly used. In advanced stages of tube wear, the assessment of degradation consists in measuring the depth of creep cracks of the tubes with methods taking the advantage of eddy currents or ultrasounds [6,7,8].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Long Term Service at Elevated Temperatures on Microstructure Degradation of Austenitic Reformer Tubes

Łabanowski

Jurkowski

Landowski

2018

Advances in Materials Science

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The paper analyses the relationship between an increase of the inner diameter of tubes made of Manaurite XM cast steel and transformations occurring in their microstructure due to long-lasting operation in methane reformer. Examinations included metallographic analysis with light microscope (LM), scanning electron microscope (SEM) and microanalysis of the chemical composition of precipitates (EDX). It was indicated that there is a relationship between the microstructure degradation ratio, morphology of the precipitates and an increase of the inner diameter of the tubes.

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A three-dimensional characterization of creep void formation in hydrogen reformer tubes

Cited by 17 publications

References 11 publications

Multiscale correlative tomography: an investigation of creep cavitation in 316 stainless steel

Multiscale correlative tomography: an investigation of creep cavitation in 316 stainless steel

3D creep cavitation characteristics and residual life assessment in high temperature steels: A critical review

The Effect of Long Term Service at Elevated Temperatures on Microstructure Degradation of Austenitic Reformer Tubes

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