Mechanistic study on the cut-edge corrosion behaviors of Zn-Al-Mg alloy coated steel sheets in chloride containing environments

Lee, Jae Won; Park, Bo Ra; Oh, Se‐Young; Yun, Dae Won; Hwang, Joong‐Ki; Oh, Min‐Suk; Kim, Sung Jin

doi:10.1016/j.corsci.2019.108170

Cited by 56 publications

(24 citation statements)

References 22 publications

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“…According to the maps, the cathodic reaction mostly occurred in the middle of the cut-edge on the entire exposed steel substrate. Same results with regards to anodic and cathodic activtity has been reported in other studies as well [2,53,54]. It was due to the galvanic coupling of Fe and Zn, resulting in the reduction of O2 as shown in Equation 2 on the surface of exposed steel, and releasing OH − species [2].…”

Section: Resultssupporting

confidence: 78%

Cut-edge corrosion behavior assessment of newly developed environmental-friendly coating systems using the Scanning Vibrating Electrode Technique (SVET)

et al. 2021

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Section: Resultssupporting

confidence: 78%

Cut-edge corrosion behavior assessment of newly developed environmental-friendly coating systems using the Scanning Vibrating Electrode Technique (SVET)

et al. 2021

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“…On the other hand, the preferential dissolution of Mg from the active phases can provide sacrificial protection. Previous studies [ 16 , 35 ] have shown that Mg and Zn cations, which are supplied by the selective dissolution of MgZn 2 (reaction (2)), can also lead to rapid coverage of the coating surface by the precipitation of corrosion products with a protective nature, such as simonkolleite (Zn 5 (OH) 8 Cl 2 ·H 2 O), which can prevent further corrosion. MgZn 2 (s)→Mg 2+ (aq) + 2Zn 2+ (aq) + 6e − …”

Section: Resultsmentioning

confidence: 99%

Effects of the Combined Addition of Zn and Mg on Corrosion Behaviors of Electropainted AlSi-Based Metallic Coatings Used for Hot-Stamping Steel Sheets

2020

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The effects of the combined addition of Zn and Mg on the corrosion resistance of AlSi-based coating for automotive steel sheets were investigated using a variety of analytical and electrochemical techniques. The preferential dissolution of Mg and Zn from MgZn2/Mg2Si phases occurred on the AlSi-based coating that had been alloyed with a smaller portion of Zn and Mg, which contributed to the rapid surface coverage by corrosion products with a protective nature, reducing the corrosion current density. On the other hand, localized corrosion attacks caused by the selective dissolution of Mg were also observed in the AlSi-based coating with a smaller portion of Zn and Mg. Such alloying can also worsen its corrosion resistance when coated additionally with electrodeposited paint. The mechanistic reasons for these conflicting results are also discussed.

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“…It facilitates the formation of a protective and insoluble simonkolleite (Zn 5 Cl 2 (OH) 8 .H 2 O) layer on the exposed surface of the coating, which reduces the corrosion rate. It has been reported that the corrosion process of Zn-Al-Mg coatings takes place according to the following electrochemical reactions (1) to (6) (Lee et al, 2019):…”

Section: Introductionmentioning

confidence: 99%

Corrosion behaviour of hot-dip Zn-Al-Mg coatings with different Al content

Kumar

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Kumar

et al. 2021

ACMM

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Purpose The purpose of the present study is to simulate the industrial hot-dip process of Zn-2.5Wt.%Mg-3 Wt.%Al and Zn-2.5 Wt.%Mg-9 Wt.%Al-0.15 Wt.%Si coatings and to study the effect of low and high Al variation on their microstructure, microhardness, adhesion and corrosion behaviour. Design/methodology/approach The hot-dip Zn-2.5 Mg-xAl coating simulation on steel substrate was carried out using a hot-dip process simulator. The microstructure of the coatings was characterized using a scanning electron microscope, energy dispersive spectroscopy and X-ray diffraction. The corrosion behaviour of the coatings was studied using a salt spray test in 5% NaCl solution as well as dynamic polarization in 3.5% NaCl solution. Findings Microhardness of the developed Zn-2.5 Mg-xAl coatings has been found to be approximately two times higher than that of the conventional galvanized coating. Zn-2.5 Mg-3Al coating has exhibited two times higher corrosion resistance as compared to that of Zn-2.5 Mg-9Al-0.15Si coating because of formation of more homogeneous and defect-free microstructure of the former. The MgZn2 phase has undergone preferential dissolution and provided Mg2+ ions to form a protective film. Originality/value The relative corrosion resistance of the two Zn–Al–Mg coatings with different Al content has been studied. The defect formed because of higher Al addition in the coating has been detected, and its effect on corrosion behaviour has been analysed.

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Mechanistic study on the cut-edge corrosion behaviors of Zn-Al-Mg alloy coated steel sheets in chloride containing environments

Cited by 56 publications

References 22 publications

Cut-edge corrosion behavior assessment of newly developed environmental-friendly coating systems using the Scanning Vibrating Electrode Technique (SVET)

Cut-edge corrosion behavior assessment of newly developed environmental-friendly coating systems using the Scanning Vibrating Electrode Technique (SVET)

Effects of the Combined Addition of Zn and Mg on Corrosion Behaviors of Electropainted AlSi-Based Metallic Coatings Used for Hot-Stamping Steel Sheets

Corrosion behaviour of hot-dip Zn-Al-Mg coatings with different Al content

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