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

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

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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 languageEnglish
Title of host publicationFusion Engineering (SOFE), 2015 IEEE 26th Symposium on
PublisherIEEE
Number of pages6
ISBN (Electronic)9781479982646
DOIs
Publication statusPublished - 2 Jun 2016
Event26th Symposium on Fusion Engineering (SOFE) - Hilton Austin, Austin, United States
Duration: 31 May 20154 Jun 2015
http://ece-events.unm.edu/ppcsofe2015/

Publication series

Name
ISSN (Electronic)2155-9953

Conference

Conference26th Symposium on Fusion Engineering (SOFE)
CountryUnited States
CityAustin
Period31/05/154/06/15
Internet address

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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