• Proceedings of the KWS Conference
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• 2007.11a
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• pp.155-157
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• 2007

The Friction spot dissimilar welding of galvanized steel/Al6061-T6 was performed to investigate the mechanical characteristics of the joints. The presence of thin film of aluminum oxide on the surface and melting of zinc in the coating, made substandard joint characteristics for dissimilar Friction spot joining(FSJ) performed with out removing the coating. Where as, for dissimilar FSJ of galvanized steel/Al6061-T6 after removing the coating, superior agitation and welding quality has been obtained for a configuration of galvanized steel as the upper plate and Al6061-T6 as lower plate. The results from tensile tests and microscopic examination for various combinations of the welding parameters have been presented.

• Corrosion Science and Technology
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• v.14 no.5
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• pp.207-212
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• 2015

The purpose of this research was to synthesize fluorine modified waterborne polyurethane dispersion (F-WPU) by soap-free (internal emulsifier) emulsion polymerization techniques, to prepare coating solution based on fluorine modified waterborne polyurethane dispersion (F-WPU) and to compare the chemical and thermo-mechanical properties on the electrogalvanized steel sheet. Environmentally friendly F-WPU was prepared with a fluorinated polyol containing 60 wt% of fluorine. There are various ways of combining a wide variety of fluorinated polyols and diisocyanate to exhibit novel properties of waterborne polyurethane dispersion. Components of coating solution were largely divided into 4 kinds i.e., F-WPU, acrylic emulsion, silane coupling agent, and colloidal silicate. F-WPU coating solution on the electro-galvanized steel sheet showed excellent properties of corrosion resistance, alkali resistance and heat resistance, as compared to other coating solutions using a general waterborne resin. The F-WPU coating solution's reliable effects are possibly due to the fluorine atoms incorporated even in a small amount of F-WPU.

• Journal of the Korean institute of surface engineering
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• v.24 no.1
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• pp.18-24
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• 1991

In the present work the adhesion failure of a hot-dip galvanized coating has been studied as a function gas composition temperature of strip and of atmospheric gas in furnace. The adhesion failure of the hot-dip galvani-zed coating is classified as three mechanisms : carbon deposition, oxide film formation and alloy layer formation. The adhesion failure due to oxide film formation decreased markedly by increasing the gases temperature of direct fired furnace(DFF) in order to improve the reducing ability of steel strip. Optimum conditions of operating and manufacturing facilities for improving the coating adherence are suggested by analyzing the interface between steel substrate and coating layer.

• Journal of the Korean institute of surface engineering
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• v.32 no.1
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• pp.31-42
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• 1999

The effect was investigated that aluminium in the zinc bath has on the coating adhesion of Hot-rolled Galvanized Iron(HGI) manufactured without pickling process. It is thought that the coating adhesion of HGI manufactured without pickling process is good due to the fact that increasing aluminium content in the zinc bath makes zinc and aluminium diffuse to the cracks or pores in the scale formed through the reduction heat treatment, and Fe-Zn-Al compound with good ductility is formed in the scale layer and plays a role of anchor between zinc coating and substrate. It is possible that HGI with the good coating adhesion was produced without pickling treatment in the zinc bath with more that 3wt% of Al content even at the $550^{\circ}C$ of conventional reduction heating temperature. In creasing the temperature of heating section and aluminium content in the zinc bath prevents the Zn-Fe alloy. The corrosion resistance of HGI manufactured without pickling process is excellent because of the mixed reaction of zinc sacrifice and aluminium passivity film.

• Journal of the Korean institute of surface engineering
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• v.36 no.6
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• pp.466-474
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• 2003

To develop a method of detecting dross in coating layer on hot-dip galvanizing steel, chemical etching behavior of the artificial coating layers with top and bottom dross were investigated. After chemical etching with the mixture of picric acid and sodium thiosulfate, each of the top and bottom dross take its distinct color, and alloy layer in coating is also observed. Defects in the coating layers of HGI(hot rolled galvanized iron), CGI(continuous galvanized steel sheet) and GA(galvannealed steel) were analysed, and methods of dross detection which can be applied to inspection process in manufacture were suggested.

• Corrosion Science and Technology
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• v.13 no.4
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• pp.125-129
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• 2014

Shinning spot defects on galvanized steel sheets were studied by optical microscope, scanning electron microscope(SEM), Energy Dispersive Spectrometer (EDS) and Laser-Induced Breakdown Spectroscopy Original Position Statistic Distribution Analysis (LIBSOPA) in this study. The research shows that the coating thickness of shinning spot defects which caused by the substrate defect is much lower than normal area, and when skin passed, the shinning spot defect area can not touch with skin pass roll which result in the surface of shinning spot is flat while normal area is rough. The different coating morphologies have different effects on the reflection of light, which cause the shinning spot defects more brighter than normal area.

• Journal of the Korean institute of surface engineering
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• v.32 no.1
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• pp.21-30
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• 1999

Coating adherance behavior of low carbon steels, produced by POSCO, Korea, was studied in order to study the characteristics of hot rolled galvanized iron(HGI) manufactured without pickling line and the development of its process. Galvanizing experiments were carried out in zinc pot with 0.2wt% Al after hot rolled plates with scale were reduced at $550~750^{\circ}C$ in 10~30% hydrogen gas atmosphere during 60~400seconds. The reduced plates and coated products were examined by SST, XRD, SEM and EPMA on their surfaces and cross sections. Coating layer of HGI manufactured with pickling line was composed of retained scale, Fe-Zn-Al compound, Fe-Zn compound ($\delta_1\;and\;\zeta$ Phase) and pure zinc. It was superior to HGI in coating adhesion. It seems to be due to forming of Fe-Zn-Al compound in interface of matrix and retained porous scale.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1474-1486
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• 1990

The frictional characteristics of galvanized sheet steels(GA, EG, EGF, EGN) for automobiles were studied and compared with that of cold rolled sheet steel. A draw bead tester which simulates metal flow through a draw bead in stamping die face was used to measure coefficients of friction of galvanized sheet steels for four kinds of lubricants. Stamping formability of galvanized sheet steels for quarter outer panel was examined. The results show that stamping formability and friction characteristics were mainly influenced by the nature of zinc coating, surface roughness and micro hardness of coated layer, and proved to be very sensitive to the lubricant used.

• Journal of the Korean institute of surface engineering
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• v.34 no.4
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• pp.327-336
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• 2001

The skinpassing conditions such as roll type, roll force and roll roughness of the work roll were evaluated to give the surface properties of the galvanized steel sheets that were required for automotive and to get rid of the surface defects that caused with the bad control of galvanized coating process parameters. The surface defects of the galvanized steel sheets such as the ripple mark and the scratch were completely removed as the roll force of SPM work roll was increased and the amount of the transfer of roll surface texture to the strip was also gained a lot. The image clarity of electro discharge textured (EDT) coated steel sheets before and after painting was higher than that of the bright (BRT) and shot blasted (SBT) coated steel sheets because of higher PPI value, lower waviness and uniform surface pattern. Since micro-craters transferred on the surface of the galvanized steel sheets played a role of nucleation sites of chromate reaction, Increase of micro-craters was bring to better corrosion resistance with the increase of the roll force and the use of EDT roll at the skin pass mill.

• Corrosion Science and Technology
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• v.16 no.1
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• pp.38-47
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• 2017

Due to various types of Zn coatings for many decades for various applications, it is imperative to study and compare their corrosion resistance properties of some of these. Here, we introduce a systematic methodology for evaluation and validation of corrosion protection properties of metallic coatings. According to this methodology, samples are were exposed in an advanced cyclic corrosion test chamber according to ISO 14993, and removed at the end of each withdrawal for respective corrosion and electrochemical characterization to evaluate both barrier and galvanic protection properties. Corrosion protection properties of coatings were evaluated by visual examination according to ISO 10289, mass loss and subsequent corrosion rate measurements, electrochemical properties, and advanced electrochemical scanning techniques. In this study, corrosion protection properties of a commercial zinc rich coating (ZRC) on AISI 1020 mild steel substrates were evaluated and benchmarked against hot dip galvanized (HDG). Results were correlated, and corrosion protection capabilities of the two coatings were compared. The zinc rich coating performed better than hot dip galvanized coating in terms of overall corrosion protection properties, according to the exposure and experimental conditions used in this study. It proved to be a suitable candidate to replace hot dip galvanized coatings for desired applications.