• Corrosion Science and Technology
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• 제23권2호
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• pp.121-130
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• 2024

In recent years, Zn-Al-Mg alloy galvanized steel sheets have been widely used as coated steel sheets to support social capital in the infrastructure field. A feature of Zn-Al-Mg alloy-coated steel sheets is that they provide a better corrosion protection period than Zn-coated steel sheets. In this study, the corrosion resistance of a new Zn-Al-Mg alloy-coated steel sheet was investigated and compared to that of conventional commercially available coated steel sheets. The investigation confirmed that increasing the Mg concentration in the Zn-Al-Mg-coated steel sheet improved corrosion resistance, which was more than 10 times that of the galvanized steel sheet specified in JIS G 3302. The study findings also confirmed that the corrosion resistance reached more than twice that of the coated steel sheet specified in JIS G 3323. If such galvanized steel sheets are applied to social infrastructures that are exposed to severely corrosive environments, the service life of the infrastructure might be extended.

• 열처리공학회지
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• 제25권6호
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• pp.283-291
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• 2012

In order to increase the anti-oxidation property during the tailor welding blanked hot press forming process for a high strength boron steel sheet, we performed a different coating method on the boron-steel sheet such as 87% Al - 13% Si and Fe - 8.87 Zn dipping plating procedure. However, during laser welding process, the Al-Si coated steel sheet has showed a low tensile strength and about half value of elongation than the original boron-steel sheet. Aluminum and silicon, elements of coating layer were diffused into the boron-steel matrix and have shown a low strength result than non-coated specimen. On the other hand, Zinc-coated boron-steel has expectedly showed a excellent tensile strength and micro-harness value in the welded area like original boron-steel.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.25-30
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• 2010

The authors have studied on the corrosion resistance of the hot stamped steel sheets for the application to automotive parts. Recently automotive companies have focused on the hot stamped parts to meet the light weighting needs and the safe reason. Because of the cost reduction of the hot stamped parts, automotive companies increase the usage of the coated steel sheets, especially Al-Si coated steel sheets. The coated layer of Al-Si coated steel sheets contains up to 50% of Fe, which was diffused from the steel sheet, after hot stamping. The hot stamped steel sheet was not phosphated due to the oxidation layer of the coating, however, the result of the water resistance test is similar to that of the conventional GA steel sheets. The pitting depth and the weight reduction of the coated layer of hot stamped steel sheets are less than those of GA steel.

• Journal of Advanced Marine Engineering and Technology
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• 제31권6호
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• pp.736-743
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• 2007

Laser welding has the advantage of high welding speed and Provides low heat distortion Thus laser welding is a very attractive process for joining thin steel sheet and surface treated steel sheet. And the major item in market for surface treated steel sheet is zinc coated steel. However. the laser welding of zinc coated steel is very difficult because of its low boiling point. Compared with zinc, on the other hand, aluminum has a high boiling point. Thus, laser weldability of aluminized steel is better than that of zinc coated steel. Moreover aluminized steel sheet is a material with excellent heat resistance, thermal reflection and corrosion resistance. The results of laser weldability of the aluminized steel for the full penetration welding will be described in this paper We focused on the investigation of the phenomenons caused by coating condition and behavior of aluminum in weld.

• Journal of Welding and Joining
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• 제30권2호
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• pp.54-58
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• 2012

Al-coated steel sheets with excellent heat and corrosion resistance are widely used in various applications. In welding of thin plate, some defects such as unmelted zone and metal-through occur easily in the beginning and ending of welding line. In the study, the welding defects in Al-coated steel sheets were investigated with respect to plasma arc current, height between Cu block and base metals, and using a roller to align the height of the base metal. Full penetration and voids free welds were obtained with a plasma arc current 52A and weld speed 2.3m/min. An unmelted zone increased and Ericshen rate decreased as the height between Cu block and base metal increased from 0 to 0.6mm. Using a roller moving ahead of the plasma arc, the length of unmelted zone decreased from 1.7mm to 0.5mm.

• Corrosion Science and Technology
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• 제22권2호
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• pp.123-130
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• 2023

This study aimed to evaluate corrosion resistance of steel coated with GI and Zn-Al-Mg alloy using cyclic corrosion test (CCT) with electrochemical polarization and impedance measurements. Results showed that the Zn-Al-Mg alloy coated steel had a much higher corrosion rate than GI coated steel in early stages of corrosion. With prolonged immersion, however, the corrosion rate of the Zn-Al-Mg alloy coated steel greatly decreased, mainly owing to a significant decrease in the cathodic reduction reaction and an increase in polarization resistance at the surface. This was closely associated with the formation of protective corrosion products including Zn₅(OH)₈Cl₂·H₂O and Zn₆Al₂(OH)₁₆CO₃. Moreover, when the steel substrate was locally exposed due to mechanical damage, the kinetics of anodic dissolution from the coating layer and the formation of protective corrosion products on the surface of the Zn-Al-Mg alloy coated steel became much faster compared to the case of GI coated steel. This could provide a longer-lasting corrosion inhibition function for Zn-Al-Mg alloy coated steel used in plant farms.

• 한국표면공학회지
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• 제56권1호
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• pp.69-76
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• 2023

The effects of hairline treatment on surface blackening and thermal diffusion behaviors of Zn-Al-Mg alloy coated steel sheet were evaluated by the three-dimensional surface profiler and laser-flash technique. The metallographic observation of coating damages by hairline treatments showed that several cracks were initiated and propagated along the interface between primary Zn/eutectic phases. As the hairline processing became more severe, the crack occurrence frequency in eutectic phase of coating layer and the surface roughness increased, which had a proportional relationship with the level of blackening on the coating surface. In addition, the higher interfacial areas of the blackened coating surface, caused by the hairline process, led to an increase in thermal diffusivity and conductivity of the coated steel sheet. On the other hand, when the coating damage by hairline treatment was excessive and the steel substrate was exposed, there was little difference between the thermal diffusivity/conductivity of the untreated sample though the blackening degree was higher than that of untreated sample. This work suggests that the increase in the surface areas of the coating layer without exposure to steel substrate through hairline treatment can be one of the effective technical strategies for the development of Zn-Al-Mg alloy coated steel sheets with higher blackening level and thermal diffusivity.

• Corrosion Science and Technology
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• 제9권2호
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• pp.74-80
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• 2010

For the purpose of applying a hot-dip Zn-6mass%Al-3mass%Mg alloy coated steel sheet (ZAM) to automotive body materials, a laboratory study of the general properties required for inner and outer panels of automotive bodies was performed. Even with only light coating weight, ZAM showed an excellent corrosion resistance in terms of both cosmetic and perforation corrosion compared to the currently used materials for automotive bodies, GI70 and GA45. In our study, it was confirmed that ZAM exhibits as good as or better properties than GI70 in terms of spot weldability and press formability. Furthermore, since the same corrosion resistance can be achieved with less coating weight by applying ZAM, laser weldability is better than GI and GA.

• 한국기계가공학회지
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• 제1권1호
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• pp.71-78
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• 2002

Since the early 1980's the use of zinc-aluminum alloy-coated steel sheet(Galvalume) for vehicular corrosion protection has increased drastically. It is consisting of 55%Al-43.4% Zn-1.6%Si. Galvalume has a good corrosion resistance, heat reflectivity and shiny appearance, which has a dendritic structure of alloy layer. It has a good corrosion resistance due to dendritic structure. But, this also has a weak point against moisture during long period of transportation as sheeted and or coiled without any relation of chromating on the surface of steel sheet or not because of high humidity and temperature. Here, We studied the corrosion mechanism by the moisture.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1994년도 특별강연 및 춘계학술발표 개요집
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• pp.72-74
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• 1994