Formation mechanism of Fe-Al inhibition layer on hot-rolled galvanized sheet

doi:10.13251/j.issn.0254-6051.2025.05.050

Abstract

Abstract: Using kinetic and thermodynamic calculations, the formation mechanism of the Fe-Al inhibition layer on hot-rolled substrates during galvanizing process was investigated. The effects of the temperature and surface roughness of the substrate entering the zinc bath on the formation of the inhibition layer were analyzed. The results show that the main component of the Fe-Al inhibition layer on the hot-rolled galvanized sheet is Fe₂Al₅. The process of Fe₂Al₅ inhibition layer formation involves the dissolution of Fe atoms on the sheet surface into the zinc liquid, nucleation of the Fe-Al phase, and subsequent growth of the Fe-Al phase nuclei to form a complete inhibition layer. The main process parameters affecting the Fe₂Al₅ inhibition layer are the substrate temperature and the number of Fe atoms per unit area of the substrate, while the number of Fe atoms is influenced by the surface roughness of the substrate. The higher the substrate temperature, the higher the initial nucleation rate of Fe₂Al₅, and the faster and more complete the formation of the Fe₂Al₅ inhibition layer, with an increase in coating thickness. The smoother the substrate surface, the fewer the number of Fe atoms per unit area, resulting in a straighter and more uniform Fe₂Al₅ inhibition layer, smaller fluctuations in coating thickness, and better coating surface quality.

Key words: hot-rolled galvanized sheet, Fe-Al inhibition layer, Fe₂Al₅, roughness, hot-rolled sheet temperature

CLC Number:

TG174.443

Li Shiming, Zhang Ziyue, Zhang Jie, Li Yuanpeng, Chen Binkai, Zhang Qifu. Formation mechanism of Fe-Al inhibition layer on hot-rolled galvanized sheet[J]. Heat Treatment of Metals, 2025, 50(5): 322-327.

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