• Title/Summary/Keyword: Galvannealed Coating

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Effect of Organic Lubricant Film on Various Properties of Galvannealed Steel Sheets (합금화용융아연도금강판의 품질특성에 미치는 유기윤활피막의 영향)

  • 김영근
    • Journal of the Korean institute of surface engineering
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    • v.36 no.2
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    • pp.176-184
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    • 2003
  • New lubricant film of organic and inorganic composite resin was developed to improve the press formability of galvannealed steel sheets (GA) for automotive body panels. The frictional coefficient of lubricant GA steel sheets is about 20% superior to that of uncoated GA. The current range of spot welding of lubricant GA is similar to that of the uncoated GA, but the burning trace of spot welding is inferior to that of the uncoated GA in the oiling condition. The alkaline degreasability of lubricant GA shows 100% in alkaline degreasing condition of automotive company. The size and shape of the phosphated coating layer are similar to those of the uncoated GA sheet. The powdering property of the lubricant GA gives rise to 20∼50% improved property compared with the uncoated GA sheet.

Challenges in the Production of Thin Coatings at High Line Speed

  • Michel, Dubois;Luc, Warichet;Jose, Callegari
    • Corrosion Science and Technology
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    • v.9 no.1
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    • pp.1-7
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    • 2010
  • Cost reduction of products is and will always be a key objective of industrials. However, it is well identified that the wiping process reaches its limits at high line speed in general and especially thin coatings. If wiping models predict that it is possible to reach 32-37 g/$m^2$ of pure Zinc at 180 m/min provided the nozzle to strip distance can be reduced to 6mm, the possibility to reach that process window industrially with sufficient robustness is debated. 3 key problems are reviewed and analyzed: Zinc splashing and liquid drop emissions of various forms, the production of skimming and the noise generated by the nozzles. The available data and models are firstly used to predict phenomena. Secondly, videos and pictures from the lines showing what really happens on the edges especially in case of a strip width change are analyzed. Whereas the predicted level of skimming to remove from the pot is expected very high, it turns out that the target may be very close to the full splashing phenomena and that the most critical industrial situation is related to strip specification changes. It is then expected that the industrial feasibility of the 32-37 g/$m^2$ at 180 m/min will depend strongly on the amount of incoming strip with the same width that can be processed continuously.

Characteristics of Zn-Ni Electrodeposition of 60 kgf/$\textrm{mm}^2$ Grade Transformation Induced Plastic Steel Sheets for Automotive Body (60 kgf/$\textrm{mm}^2$급 자동차용 변태유기소성강화강 Zn-Ni 전기도금 특성 연구)

  • Kim D. H.;Kim B. I.;Jeon Y. T.;Jeong Y. S.
    • Journal of the Korean institute of surface engineering
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    • v.37 no.5
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    • pp.263-272
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    • 2004
  • High strength steels such as transformation induced plastic steel, dual phase and solid solution Hardening have been developed and continuously improved due to the intensified needs in the automotive industry. But silicon and manganese in transformation induced plastic steels were known to exhibit harmful effects on galvannealing reaction by oxide film formed during heat treatment. Therefore, in this work, the applicability of Zn-Ni electrodeposition instead of hot dip galvannealed coating to transformation induced plastic steels was evaluated and optimum electroplating condition was investigated. Based on these investigations optimized electroplating conditions were proposed and Zn-Ni electrogalvanized steel sheet was produced by EGL (electrogalvanized line). Its perfomance properties for automotive steel was evaluated.

The corrosion behavior of galvanized steel sheets at the cut edges (용융아연도금강판의 단면부 부식특성)

  • 남궁성;허보영
    • Journal of the Korean institute of surface engineering
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    • v.34 no.4
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    • pp.297-302
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    • 2001
  • As GA (Hot dip galvannealed steel sheet) has good corrosion resistance, weldability and paintability as well as excellent formability, it's demand is rapidly increasing for automotive panels. The GA coated layers are composed of several kinds of brittle Fe-Zn Metallic compounds which are susceptible to powdering during the press forming, however, very careful controls of manufacturing conditions such as galvannealing heat-treatment or bath composition are essential to meet with the required quality of automotive use. In this study the required characteristics of automotive panel are practically surveyed in detail and the appropriate manufacturing conditions of galvannealing or bath composition have experimentally investigated by using the various analyzing and simulating equipments. The result in this study indicated that the corrosion resistance at the cut edges was improved by increasing of coating weight and decreasing of thickness of sheet steels.

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The Characteristics of Cr-Free Coating Hot Dip Galvanized Sheet Steel

  • Kim, Jong-Gi;Moon, Man-Been;Yun, Jeong-Mo
    • Corrosion Science and Technology
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    • v.10 no.1
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    • pp.24-29
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    • 2011
  • The greatest purpose of chromate treatment is to improve anti-corrosion by stabilizing a metal surface. Because metal surface forms a compound by absorbing oxygen or water in the air by being generally unstable, it is necessary to improve anti-corrosion of the metal by forming the metal surface with a stable film. When considering the economical efficiency and requirements together because the film of the metal surface treated with chromate has good anti-corrosion and the stability also in the air by being compact and strong, Chromate treatment has been used most up to the electronics industry from the auto industry. However, these days, because hexavalent chromium is both a toxic agent to be able to cause cancers and deadly poisonous environmental pollutant, the strong legal controls on its use is being imposed all over the world. Because of this reason, a new anti-corrosion method is being required. Also, by users' various demands, the passivations that have recently been developed require various characteristics such as conductivity, chemical resistance, alkali cleaning resistance as well as anti-corrosion. We could confirm the results such as excellent anti-corrosion compared to chromate, conductivity, chemical resistance and detergent resistance as the result of analysis of various characteristics of the galvannealed sheet steels coated with Cr-Free solution developed in this research.

Effect of Dewpoints on Annealing Behavior and Coating Characteristics in IF High Strength Steels Containing Si and Mn (Si, Mn함유 IF 고강도강의 소둔거동 및 도금특성에 미치는 이슬점 온도의 영향)

  • Jeon, Sun-Ho;Shin, Kwang-Soo;Sohn, Ho-Sang;Kim, Dai-Ryong
    • Korean Journal of Metals and Materials
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    • v.46 no.7
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    • pp.427-436
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    • 2008
  • The effect of dewpoints on annealing behavior and coating characteristics such as wettability and galvannealing kinetics was studied by annealing 0.3wt%Si - 0.1~0.4wt% Mn added interstitial-free high strength steels(IF-HSS). The 0.3wt%Si-0.1wt%Mn steel exhibited good wettability with molten zinc and galvannealing kinetics after annealing when the dewpoint of $H_2-N_2$ mixed gas was above $-20^{\circ}C$. It is shown that the wettability and galvannealing kinetics are directly related to the coverage of the external(surface) oxide formed by selective oxidation during annealing. At $N_2-15%H_2$ annealing atmosphere, the increase of dewpoint results in a gradual transition from external to internal selective oxidation. The decrease of external oxidation of alloying elements with a concurrent increase of their subsurface enrichment in the substrate, showing a larger surface area that was free of oxide particles, contributed to the improved wettability and galvannealing kinetics. On the other hand, the corresponding wettability and galvannealing kinetics were deteriorated with the dewpoints below $-20^{\circ}C$. The continuous oxide layer of network and/or film type was formed on the steel surface, leading to the poor wettability and galvannealing kinetics. It causes a high contact angle between annealed surface and molten zinc and plays an interrupting role in interdiffusion of Zn and Fe during galvannealing process.

Analysis of Performance of Multi-functioned frictional force measuring instrument using adaptive smoothing (적응화 평활화법을 이용한 다기능 마찰력 측정기의 성능 분석)

  • Kim, Tae-Soo;Kim, Gwang-Su
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.12 no.2
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    • pp.113-119
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    • 2019
  • We have developed the multi-functioned friction measuring instrument for the previous research. In here, we improved the performance of friction measuring instrument by applying the adaptive smoothing method and analyzed the friction of plate and monitoring function of friction surface through scratch tests. We substituted lubricant steel plate to lubricant oil used for reducing the friction when fabricating steel plate because lubricant oil was regarded as one of the major causes for the environmental pollution. In particular, the functions of various plate such as galvannealed steel sheets were analyzed because friction coefficient could be changed depending on the type of organic/inorganic plate or state of coating layer. Therefore, we demonstrated that adaptive smoothing method could enhance the accuracy of measuring instrument which eliminate the noise. As a result of using the method, it showed the reduction rate 0.0417% for the friction coefficient 0.16.