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In-situ synchrotron X-ray diffraction study of microstructure and strain evolution in brazed stainless steel joints under tensile loading

Jafarzadeh, Ata LU ; Rajashekar, Praneeth LU ; Hektor, Johan LU ; Knutsson, Axel ; Mikkelsen, Anders LU ; Wallentin, Jesper LU and Lenrick, Filip LU orcid (2026) In Materials and Design 266.
Abstract

Brazed stainless steel joints are critical in heat exchanger applications but often suffer from residual stresses and brittle intermetallics. Using in-situ synchrotron X-ray diffraction and fluorescence at the DanMAX beamline, we investigated Fe-based filler joints in SS316 under tensile loading. Elemental mapping and phase analysis revealed distinct interfacial solidification zones (ISZ), athermal solidification zones (ASZ), and diffusion-affected zones (DAZ). Relative to the base composition, the ISZ showed an average Ni enrichment of ∼35%, while the ASZ exhibited localized Mo and Cr enrichment of up to ∼40% and ∼10%, respectively. The diffusion affected zone was strongly asymmetric, spanning approximately 400μm on one side of the... (More)

Brazed stainless steel joints are critical in heat exchanger applications but often suffer from residual stresses and brittle intermetallics. Using in-situ synchrotron X-ray diffraction and fluorescence at the DanMAX beamline, we investigated Fe-based filler joints in SS316 under tensile loading. Elemental mapping and phase analysis revealed distinct interfacial solidification zones (ISZ), athermal solidification zones (ASZ), and diffusion-affected zones (DAZ). Relative to the base composition, the ISZ showed an average Ni enrichment of ∼35%, while the ASZ exhibited localized Mo and Cr enrichment of up to ∼40% and ∼10%, respectively. The diffusion affected zone was strongly asymmetric, spanning approximately 400μm on one side of the ∼250μm wide joint and approximately 200μm on the other. Strain tensor mapping showed strong elastic anisotropy and stress localization at boride-rich zones, correlating with the observed fracture path. The results demonstrate the capability of synchrotron-based analysis to provide comprehensive insight into the interplay between chemical composition, microstructure, and stress in governing joint integrity, thereby informing strategies for improving toughness through process optimization.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Brazed stainless steel, In-situ mechanical testing, Joint integrity, Microstructure–property relationship, Phase identification, Strain distribution, Synchrotron XRD and XRF characterization
in
Materials and Design
volume
266
article number
116053
publisher
Elsevier
external identifiers
  • scopus:105037056144
ISSN
0264-1275
DOI
10.1016/j.matdes.2026.116053
language
English
LU publication?
yes
id
592287de-3ce0-4a24-9d5c-33daa8c2324c
date added to LUP
2026-05-29 14:56:39
date last changed
2026-05-29 14:57:09
@article{592287de-3ce0-4a24-9d5c-33daa8c2324c,
  abstract     = {{<p>Brazed stainless steel joints are critical in heat exchanger applications but often suffer from residual stresses and brittle intermetallics. Using in-situ synchrotron X-ray diffraction and fluorescence at the DanMAX beamline, we investigated Fe-based filler joints in SS316 under tensile loading. Elemental mapping and phase analysis revealed distinct interfacial solidification zones (ISZ), athermal solidification zones (ASZ), and diffusion-affected zones (DAZ). Relative to the base composition, the ISZ showed an average Ni enrichment of ∼35%, while the ASZ exhibited localized Mo and Cr enrichment of up to ∼40% and ∼10%, respectively. The diffusion affected zone was strongly asymmetric, spanning approximately 400μm on one side of the ∼250μm wide joint and approximately 200μm on the other. Strain tensor mapping showed strong elastic anisotropy and stress localization at boride-rich zones, correlating with the observed fracture path. The results demonstrate the capability of synchrotron-based analysis to provide comprehensive insight into the interplay between chemical composition, microstructure, and stress in governing joint integrity, thereby informing strategies for improving toughness through process optimization.</p>}},
  author       = {{Jafarzadeh, Ata and Rajashekar, Praneeth and Hektor, Johan and Knutsson, Axel and Mikkelsen, Anders and Wallentin, Jesper and Lenrick, Filip}},
  issn         = {{0264-1275}},
  keywords     = {{Brazed stainless steel; In-situ mechanical testing; Joint integrity; Microstructure–property relationship; Phase identification; Strain distribution; Synchrotron XRD and XRF characterization}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Materials and Design}},
  title        = {{In-situ synchrotron X-ray diffraction study of microstructure and strain evolution in brazed stainless steel joints under tensile loading}},
  url          = {{http://dx.doi.org/10.1016/j.matdes.2026.116053}},
  doi          = {{10.1016/j.matdes.2026.116053}},
  volume       = {{266}},
  year         = {{2026}},
}