Early oxidation of the dimple area leading to darkening hot-dip galvanized sheet. (November 2022)

• Record Type: Journal Article
• Authors: Zhao, Zhiyang; Song, Renbo
• Is Part Of: Vacuum. Volume 205(2022)
• Publication Date: 2022-11
• Subjects: Hot dip galvanizing -- Corrosion -- Leveling process -- Zinc layer -- Free solidification; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2022.111457
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: The surfaces of hot-dip galvanized sheets are microscopically uneven, whose dimple areas show weaker corrosion resistance and earlier oxidation than high-altitude leveled areas. The anode-affected area, coinciding with neutral wire-cutting electrolyte coverage areas, shows gray macroscopically after wire electric discharge machine (WEDM) process, being darker than the metallic silver-white in the original high-altitude areas. The corrosion behavior by WEDM is mainly concentrated in the dimple area, mainly showing dense corroded micro-hillocks. The metal shows free solidification behavior there lacking leveling stress rolling, resulting in weak corrosion resistance. The investigation reveals the initial oxidation behavior of the hot-dip galvanized sheet surface; applying thorough leveling stress on each dimple micro-area will be useful to improve the corrosion resistance there. Graphical abstract: Image 1 Highlights: Gloss main supplier, priority corrosion in pits, leveling effect were discussed. The early stage of oxidation behavior on hot-dip galvanized coatings was found. Dense oxide particles appeared in dimple areas, causing coating losing gloss.