Corrosion behavior and resistance of hot-dip Al−Cr coated steel sheet under a salt corrosive environment

The corrosion behavior and resistance of hot-dip Al and Al-Cr coated steel sheets (SS) were investigated via scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), electron probe mirco analysis (EPMA), glow discharge light spectroscopy (GDLS), and X-ray diffraction patterns...

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Bibliographic Details
Published in:Metals and materials international 2005-04, Vol.11 (2), p.149-156
Main Authors: Chung, U C, Lim, B M, Park, I M, Park, Y H, Cho, K M, Kim, I B
Format: Article
Language:English
Subjects:
Alloys
Aluminum
Chromium
Corrosion
Corrosion currents
Corrosion resistance
Corrosion resistant steels
Cracks
Diffraction patterns
Electron probe microanalysis
Glow discharges
Hot dipping
Immersion coating
Intermetallic compounds
Iron
Metal sheets
Radioactive wastes
Scanning electron microscopy
Sheet metal
Silicon
Steel
Steels
Substrates
Surface layers
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Summary:The corrosion behavior and resistance of hot-dip Al and Al-Cr coated steel sheets (SS) were investigated via scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), electron probe mirco analysis (EPMA), glow discharge light spectroscopy (GDLS), and X-ray diffraction patterns (XRD). The AlCr coated layer was composed of the following three phases. Al phase comprised the surface layer, Al,3Cr2 the middle layer, and Al13Fe4 and Al5Fe2 phases the interfacial layer between the Fe substrate and the coated layer. The corrosion behavior of the Al-Cr coated layer showed different aspects compared with the Al coated layer. In the Al-Cr coated layer, Cr was observed at an intermediate layer having a band shape. From the analysis of the polarization curve, the initial corrosion current of the Al-Cr coated SS was 10 times lower than that of Al in the early stage, and the corrosion resistance was superior to that of Al. The Al coated SS formed an Al-Fe-Si IMC layer, and the coated layer was almost destroyed. Many cracks were produced, and the corroded parts were enlarged from the cracks. The upper part of the Al-Cr coated SS, an Al-Si coated layer, was corroded. In contrast, the Cr-rich intermediate layer was not destroyed. Consequently, the high corrosion resistance was attributed to the densely covered Al(OH)3 and the intermetallic compound layer of A1,3Cr2. These results significantly contribute toward attaining a detailed understanding of the corrosion behavior and resistance Al-Cr coated steel sheets.
ISSN:1598-9623
2005-4149
DOI:10.1007/BF03027459