Residual stress generation in tungsten-copper brazed joint using brazing alloy

D. Easton; J. Wood; S. Rahimi; A. Galloway; Y. Zhang; C. Hardie

doi:10.1109/SOFE.2015.7482328

Residual stress generation in tungsten-copper brazed joint using brazing alloy

D. Easton, J. Wood, S. Rahimi, A. Galloway, Y. Zhang, C. Hardie

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution book

51 Downloads (Pure)

Abstract

Understanding the residual stress state in brazed joints is crucial for operational design and life time performance of the part in service. High magnitudes residual stresses are expected in the joined materials following cooling from brazing temperatures (≈950°C) due to large mismatches in material properties such as coefficient of thermal expansion and Young’s modulus. This study aims at further understanding of the generation and distribution of residual stresses when brazing tungsten to copper using a eutectic gold-copper brazing alloy. This configuration is potentially useful for future divertor designs. Finite Element Analysis (FEM) has been used to predict the brazing induced stresses and residual stress measurements were carried out on the brazed joint by X-ray diffraction (XRD) to validate the prediction model. Large residual stresses are predicted and measured in the tungsten; however there is disagreement in the sign of the stress. Predicted stresses are highly tensile in nature close to the brazing interface, whereas the measured stresses are highly compressive. The disagreement is believed to be caused by the model not accurately simulating the complex brazing process. Residual stress measurements on the copper were not possible due to texturing during brazing, grain growth and significant inelastic strains and deformations. Misalignment of parent materials was also observed to significantly affect residual stresses.

Original language	English
Title of host publication	Fusion Engineering (SOFE), 2015 IEEE 26th Symposium on
Publisher	IEEE
Number of pages	6
ISBN (Electronic)	9781479982646
DOIs	https://doi.org/10.1109/SOFE.2015.7482328
Publication status	Published - 2 Jun 2016
Event	26th Symposium on Fusion Engineering (SOFE) - Hilton Austin, Austin, United States Duration: 31 May 2015 → 4 Jun 2015 http://ece-events.unm.edu/ppcsofe2015/

Publication series

Name
ISSN (Electronic)	2155-9953

Conference

Conference	26th Symposium on Fusion Engineering (SOFE)
Country	United States
City	Austin
Period	31/05/15 → 4/06/15
Internet address	http://ece-events.unm.edu/ppcsofe2015/

Fingerprint

Brazing

Tungsten

Residual stresses

Copper

Stress measurement

Texturing

Grain growth

Eutectics

Thermal expansion

Materials properties

Gold

Elastic moduli

Cooling

Finite element method

X ray diffraction

Keywords

residual Stress
brazed joints
XRD
fusion reactor design
tungsten
copper
x-ray scattering
x-ray diffraction

Cite this

Easton, D., Wood, J., Rahimi, S., Galloway, A., Zhang, Y., & Hardie, C. (2016). Residual stress generation in tungsten-copper brazed joint using brazing alloy. In Fusion Engineering (SOFE), 2015 IEEE 26th Symposium on IEEE. https://doi.org/10.1109/SOFE.2015.7482328

Easton, D. ; Wood, J. ; Rahimi, S. ; Galloway, A. ; Zhang, Y. ; Hardie, C. / Residual stress generation in tungsten-copper brazed joint using brazing alloy. Fusion Engineering (SOFE), 2015 IEEE 26th Symposium on. IEEE, 2016.

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Easton, D, Wood, J, Rahimi, S , Galloway, A, Zhang, Y & Hardie, C 2016, Residual stress generation in tungsten-copper brazed joint using brazing alloy. in Fusion Engineering (SOFE), 2015 IEEE 26th Symposium on. IEEE, 26th Symposium on Fusion Engineering (SOFE), Austin, United States, 31/05/15. https://doi.org/10.1109/SOFE.2015.7482328

Residual stress generation in tungsten-copper brazed joint using brazing alloy. / Easton, D.; Wood, J.; Rahimi, S.; Galloway, A.; Zhang, Y.; Hardie, C.

Fusion Engineering (SOFE), 2015 IEEE 26th Symposium on. IEEE, 2016.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution book

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AU - Wood, J.

AU - Rahimi, S.

AU - Galloway, A.

AU - Zhang, Y.

AU - Hardie, C.

N1 - © 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

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N2 - Understanding the residual stress state in brazed joints is crucial for operational design and life time performance of the part in service. High magnitudes residual stresses are expected in the joined materials following cooling from brazing temperatures (≈950°C) due to large mismatches in material properties such as coefficient of thermal expansion and Young’s modulus. This study aims at further understanding of the generation and distribution of residual stresses when brazing tungsten to copper using a eutectic gold-copper brazing alloy. This configuration is potentially useful for future divertor designs. Finite Element Analysis (FEM) has been used to predict the brazing induced stresses and residual stress measurements were carried out on the brazed joint by X-ray diffraction (XRD) to validate the prediction model. Large residual stresses are predicted and measured in the tungsten; however there is disagreement in the sign of the stress. Predicted stresses are highly tensile in nature close to the brazing interface, whereas the measured stresses are highly compressive. The disagreement is believed to be caused by the model not accurately simulating the complex brazing process. Residual stress measurements on the copper were not possible due to texturing during brazing, grain growth and significant inelastic strains and deformations. Misalignment of parent materials was also observed to significantly affect residual stresses.

AB - Understanding the residual stress state in brazed joints is crucial for operational design and life time performance of the part in service. High magnitudes residual stresses are expected in the joined materials following cooling from brazing temperatures (≈950°C) due to large mismatches in material properties such as coefficient of thermal expansion and Young’s modulus. This study aims at further understanding of the generation and distribution of residual stresses when brazing tungsten to copper using a eutectic gold-copper brazing alloy. This configuration is potentially useful for future divertor designs. Finite Element Analysis (FEM) has been used to predict the brazing induced stresses and residual stress measurements were carried out on the brazed joint by X-ray diffraction (XRD) to validate the prediction model. Large residual stresses are predicted and measured in the tungsten; however there is disagreement in the sign of the stress. Predicted stresses are highly tensile in nature close to the brazing interface, whereas the measured stresses are highly compressive. The disagreement is believed to be caused by the model not accurately simulating the complex brazing process. Residual stress measurements on the copper were not possible due to texturing during brazing, grain growth and significant inelastic strains and deformations. Misalignment of parent materials was also observed to significantly affect residual stresses.

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KW - fusion reactor design

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KW - copper

KW - x-ray scattering

KW - x-ray diffraction

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