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Surface chemistry and diffusion of trace and alloying elements during in vacuum thermal deoxidation of stainless steel

Zhu, Lin LU orcid ; Al-Sakeeri, Ali LU ; Lenrick, Filip LU orcid ; Darselius Berg, Oskar LU ; Sjödin, Per ; Zakharov, Alexei LU ; Knutsson, Axel and Mikkelsen, Anders LU (2021) In Surface and Interface Analysis
Abstract
Removal of the native surface oxide from steel is an important initial step during vacuum brazing. Trace and alloying elements in steel, such as Mn, Si, and Ni, can diffuse to the surface and influence the deoxidation process. The detailed surface chemical composition and grain morphology of the common stainless-steel grade 316L is imaged and spectroscopically analyzed at several stages of in-vacuum annealing from room temperature up to 850°C. Measurements are performed using synchrotron-based X-ray photoemission and low-energy electron microscopy (XPEEM/LEEM). The initial native Cr surface oxide is amorphous and unaffected by the underlying Fe grain morphology. After annealing to ~700°C, the grain morphology is seen at the surface,... (More)
Removal of the native surface oxide from steel is an important initial step during vacuum brazing. Trace and alloying elements in steel, such as Mn, Si, and Ni, can diffuse to the surface and influence the deoxidation process. The detailed surface chemical composition and grain morphology of the common stainless-steel grade 316L is imaged and spectroscopically analyzed at several stages of in-vacuum annealing from room temperature up to 850°C. Measurements are performed using synchrotron-based X-ray photoemission and low-energy electron microscopy (XPEEM/LEEM). The initial native Cr surface oxide is amorphous and unaffected by the underlying Fe grain morphology. After annealing to ~700°C, the grain morphology is seen at the surface, persisting also after the complete oxygen removal at 850°C. The surface concentration of first Mn and then Si increases significantly when annealing to 500°C and 700°C, respectively, while Ni and Cr concentrations do not change. Mn and Si are not located only in grain boundaries or clusters but are distributed across over the surface. Both Mn and Si appear as oxides, while Cr oxide becomes metallic Cr. Annealing from 500°C up to 850°C leads to the removal of first the Mn and then Si oxides from the surface, while Cr and Fe are completely reduced to metals. Deoxidation of Cr occurs faster at the grain boundaries, and the final Cr metal surface content varies between the grains. The findings are summarized in a general qualitative model, relevant for austenite steels. (Less)
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author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
annealing, deoxidation, diffusion, LEEM, microscopy, PEEM, steel alloys, surface, vacuum, XAS, XPS
in
Surface and Interface Analysis
pages
10 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:85117716349
ISSN
0142-2421
DOI
10.1002/sia.7024
language
English
LU publication?
yes
id
162df810-10e9-4b2d-8743-7986c754c55b
date added to LUP
2021-11-14 10:52:35
date last changed
2024-03-08 21:39:01
@article{162df810-10e9-4b2d-8743-7986c754c55b,
  abstract     = {{Removal of the native surface oxide from steel is an important initial step during vacuum brazing. Trace and alloying elements in steel, such as Mn, Si, and Ni, can diffuse to the surface and influence the deoxidation process. The detailed surface chemical composition and grain morphology of the common stainless-steel grade 316L is imaged and spectroscopically analyzed at several stages of in-vacuum annealing from room temperature up to 850°C. Measurements are performed using synchrotron-based X-ray photoemission and low-energy electron microscopy (XPEEM/LEEM). The initial native Cr surface oxide is amorphous and unaffected by the underlying Fe grain morphology. After annealing to ~700°C, the grain morphology is seen at the surface, persisting also after the complete oxygen removal at 850°C. The surface concentration of first Mn and then Si increases significantly when annealing to 500°C and 700°C, respectively, while Ni and Cr concentrations do not change. Mn and Si are not located only in grain boundaries or clusters but are distributed across over the surface. Both Mn and Si appear as oxides, while Cr oxide becomes metallic Cr. Annealing from 500°C up to 850°C leads to the removal of first the Mn and then Si oxides from the surface, while Cr and Fe are completely reduced to metals. Deoxidation of Cr occurs faster at the grain boundaries, and the final Cr metal surface content varies between the grains. The findings are summarized in a general qualitative model, relevant for austenite steels.}},
  author       = {{Zhu, Lin and Al-Sakeeri, Ali and Lenrick, Filip and Darselius Berg, Oskar and Sjödin, Per and Zakharov, Alexei and Knutsson, Axel and Mikkelsen, Anders}},
  issn         = {{0142-2421}},
  keywords     = {{annealing; deoxidation; diffusion; LEEM; microscopy; PEEM; steel alloys; surface; vacuum; XAS; XPS}},
  language     = {{eng}},
  month        = {{10}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Surface and Interface Analysis}},
  title        = {{Surface chemistry and diffusion of trace and alloying elements during in vacuum thermal deoxidation of stainless steel}},
  url          = {{http://dx.doi.org/10.1002/sia.7024}},
  doi          = {{10.1002/sia.7024}},
  year         = {{2021}},
}