Under-film Corrosion Behavior of Zinc and Zinc Alloy Coated Steel Sheets for Automobiles

Hayashi, Kimitaka; Ito, Yoichi M.; Kato, Chuichi; Miyoshi, Yasuhiko

doi:10.2355/tetsutohagane1955.76.8_1317

Cited by 12 publications

(5 citation statements)

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“…For this purpose, the corroded sample is usually angle-polished, and a cross-sectional image of the sample is analyzed by micro-analysis methods such as SEM-EDS. Several models of underfilm corrosion have been proposed on the basis of these destructive analyses (Shastry and Townsend, 1989;Hayashi, et al, 1990).…”

Section: All Copyrights For the Document Are Retained By Icddmentioning

confidence: 99%

“…For this purpose, the corroded sample is usually angle polished, and a cross-sectional image of the sample is analyzed by micro-analysis methods such as scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDS). Several models of underfilm corrosion have been proposed on the basis of these destructive analyses (Shastry and Townsend, 1989; Hayashi et al , 1990). The proposed mechanism of underfilm corrosion depended on the corrosion condition.…”

Section: Introductionmentioning

confidence: 99%

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Underfilm corrosion of steel sheets observed by confocal 3D-XRF technique

et al. 2014

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A confocal micro-X-ray fluorescence (XRF) method with a vacuum chamber was used for investigation of underfilm corrosion that occurs on a painted steel sheet used for automotive applications. A painted steel sheet was prepared by applying electrodeposition coating onto an electro-galvanized steel sheet with a zinc phosphate conversion coating. The spatial resolution of the confocal micro-XRF was about 10.9 ?m at an energy of 17.4 keV. The phosphorus signal from the zinc phosphate layer was able to be observed nondestructively by measuring under the vacuum condition. Each layer of the painted steel sheet was observed from the depth profile analysis of the characteristic elements of each layer. The painted steel sheet was scratched to expose the substrate surface, and then the sheet was then immersed in a NaCl solution for 10 days. The in-depth elemental map of Ti of the corroded steel sheet revealed blister-type corrosion around the scratch. The in-depth elemental maps of Zn and P suggested that the zinc phosphate layer dissolved from the scratched part into the NaCl solution.

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Section: All Copyrights For the Document Are Retained By Icddmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Underfilm corrosion of steel sheets observed by confocal 3D-XRF technique

et al. 2014

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“…Cosmetic corrosion has also been studied in many reports. 6,7) However, the specimens observed in these previous studies were usually examined after corrosion tests or exposure tests consisting of a few dozen cycles including both wet and dry conditions. Therefore, the results obtained by these conventional methods are not able to show the difference between the corrosion behaviors under wet and dry conditions because the specimens are taken out and analyzed after exposure to both conditions.…”

Section: Introductionmentioning

confidence: 99%

<i>In-situ</i> Observation of Cosmetic Corrosion Behavior under Atmospheric Environment

Yamamoto,

Ando

2023

Mater. Trans.

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It is well known that the types of automotive corrosion can be divided into perforation and cosmetic corrosion. Although many studies concerning the mechanism of perforation corrosion have been conducted so far, very few have investigated the mechanism of cosmetic corrosion. In our previous work, the authors found that the initial corrosion behavior in cosmetic corrosion consists of three steps by conducting in-situ observation during a cyclic corrosion test. In the present work, in-situ observation of painted samples with a scratch was performed during an exposure test in Okinawa to examine the cosmetic corrosion behavior under an actual environment. It was found that corrosion started at the moment of salt deposition around the scribed part from air containing salts, and the initial corrosion behavior in the exposure test consisted of three steps, which were the same as in the cyclic corrosion test. In the 1st step, black rust of Fe 3 O 4 formed at the scribed part, and in the 2nd step, under-film corrosion progressed from the scribed part where the black rust had formed. In the 3rd step, the tip of the under-film corrosion displayed swelling behavior. The behavior of each step was also discussed by combining the in-situ observation results with an analysis of environmental factors such as relative humidity and an EPMA analysis.

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“…To analyze surface phenomena, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS), and similar methods have generally been used. [1][2][3] However, these methods require cutting the sample to observe its cross section. Non-destructive analysis is usually impossible.…”

Section: Introductionmentioning

confidence: 99%

Depth Elemental Imaging during Corrosion of Hot-Dip Galvanized Steel Sheet by Confocal Micro XRF Analysis

et al. 2019

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The elucidation of the mechanism for steel corrosion under a coating layer has been attracting research attention. Herein, we utilized a confocal micro-X-ray fluorescence (XRF) analytical instrument to conduct non-destructive elemental analysis near the surface of a steel sheet. Using this method, elemental map images of steel sheet cross sections were obtained without sample destruction. To confirm corrosion suppression in the presence of Mg ions, we observed the corrosion behavior of hot-dip galvanized steel sheets immersed in an aqueous NaCl solution to which Mg ions were added. By using the confocal micro XRF system, the elution of the coating components and the precipitation process of the corrosion products were confirmed.

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Under-film Corrosion Behavior of Zinc and Zinc Alloy Coated Steel Sheets for Automobiles

Cited by 12 publications

References 1 publication

Underfilm corrosion of steel sheets observed by confocal 3D-XRF technique

Underfilm corrosion of steel sheets observed by confocal 3D-XRF technique

<i>In-situ</i> Observation of Cosmetic Corrosion Behavior under Atmospheric Environment

Depth Elemental Imaging during Corrosion of Hot-Dip Galvanized Steel Sheet by Confocal Micro XRF Analysis

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