• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.191-191
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• 2013

최근 차량 경량화와 승객의 안전성을 위하여 고성형/고강도강의 수요가 급격히 증가하고, 이를 위한 강종 개발로 고강도 및 고버링성 소재가 개발되고 있으며, 또한 차량의 자동차의 사용환경이 점차 가혹해지고 장수명화 됨에 따라 자동차 강판에서 방청방식의 중요성이 크게 대두되고 있어, 이를 충족시키기 위한 합금화융융아연도금 열연강판(HGA)의 사용이 증대되고 있다. 따라서 본 연구는 고강도/고버링성의 합금화용융도금열연강판 개발을 목적으로 하였으며, 합금 성분 및 PGL의 열처리 조건에 따른 기계적 물성 을 평가하였으며, SEM,OM등을 통한 미세조직 관찰 및 홀확장성 평가를 실시 하였다.

• 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.

• Corrosion Science and Technology
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• v.7 no.1
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• pp.1-5
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• 2008

The gas atmosphere in continuous annealing and galvanizing lines alters both composition and microstructure of the surface and sub-surface of sheet steel. The formation and morphology of the oxides of alloying elements in High Strength Interstitial Free (HS-IF), Dual Phase (DP) and Transformation-Induced Plasticity (TRIP) steels are strongly influenced by the furnace dew point, and the presence of specific oxide may result in surface defects and bare areas on galvanized sheet products. The present contribution reviews the progress made recently in understanding the selective formation of surface and subsurface oxides during annealing in hot dip galvanizing and conventional continuous annealing lines. It is believed that the surface and sub-surface composition and microstructure have a pronounced influence on galvanized sheet product surface quality. In the present study, it is shown that the understanding of the relevant phenomena requires a combination of precise laboratory-scale simulations of the relevant technological processes and the use of advanced surface analytical tools.

• Korean Journal of Materials Research
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• v.14 no.9
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• pp.676-681
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• 2004

In-situ observation in SBM on the microfracture behavior of coating layer was performed for GA steel sheets that have various Fe contents and thickness of coating layer. In case of cross sectional side of coating layer that was in a tensile stress state during bending, fine perpendicular crack pre-induced during galvannealing grew and propagated rapidly toward the coating surface with the increase of strain. And then it grew and propagated along the ${\Gamma}/Fe$ matrix interface, and combined with the nearest another perpendicular crack. Consequently, flaking occurred. The more Fe content and thickness of coating layer increased, the more average crack interval and flaking resistivity increased. Exfoliation was little observed at coating surface in a tensile stress state.