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Surface Characteristics of the Galvannealed Coating in Interstitial-Free High Strengthen Steels Containing Si and Mn  

Jeon, Sun-Ho (POSCO Technical Research Laboratories)
Chin, Kwang-Geun (POSCO Technical Research Laboratories)
Kim, Dai-Ryong (Materials Science & Metallurgical Engineering, Kyungpook National University)
Publication Information
Korean Journal of Metals and Materials / v.46, no.2, 2008 , pp. 58-64 More about this Journal
Abstract
Surface-void defects observed on the galvannealed(GA) steel sheets in Interstitial-free high-strengthened steels containing Si and Mn have been investigated using the combination of the FIB(Focused Ion Beam) and FE-TEM(Field Emission-Transmission Electron Microscope) techniques. The scanning ion micrographs of cross-section microstructure of defects showed that these defects were identified as craters which were formed on the projecting part of the substrate surface. Also, those craters were formed on the Si or Mn-Si oxides film through the whole interface between galvannealed coating and steel substrate. Interface enrichments and oxidations of the active alloying elements such as Si and Mn during reduction annealing process for galvanizing were found to interrupt Zn and Fe interdiffusion during galvannealing process. During galvannealing, Zn and Fe interdiffusion is preferentially started on the clean substrate surface which have no oxide layer on. And then, during galvannealing, crater is developed with consumption of molten zinc on the oxide layer.
Keywords
hot-dip galvannealed steel(GA); crater; selective oxidation; Si oxide; Mn oxide;
Citations & Related Records
Times Cited By KSCI : 2  (Citation Analysis)
Times Cited By Web Of Science : 7  (Related Records In Web of Science)
Times Cited By SCOPUS : 5
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