热基镀锌钢板漏镀缺陷原因及形成机理分析

doi:10.13251/j.issn.0254-6051.2025.09.045

摘要/Abstract

摘要： 某钢厂的热基连续镀锌板在生产过程中经常出现漏镀缺陷,严重影响了产品质量。通过系统的表面检测、微观结构分析和化学成分测试,并结合退火过程中氧化皮还原反应温度的理论计算,探讨了漏镀缺陷成因和机理。结果表明,热基镀锌钢板表面漏镀处存在氧化物,这些氧化物中的O元素在入锌锅前以氧化铁的形式存在于钢板表面。该厂退火炉最高加热温度为540 ℃,低于理论计算还原温度(≥550 ℃),导致氧化物在退火炉中得不到充分还原。热轧基板表面的印痕边缘区域的微裂纹受热轧终轧后氧化皮厚度影响,且对退火炉内的露点非常敏感,通过带入退火炉水分,使局部露点上升,引发氧化。当热轧基板进入锌锅后,其表面的氧化铁会导致镀锌过程中的润湿性降低,从而产生漏镀或镀层孔洞。通过平整(平整压下率为2.5%)降低粗糙度,并控制退火炉露点在-50 ℃以下,显著提升了该厂热基镀锌钢板表面质量,解决了漏镀问题。

关键词: 热基镀锌, 漏镀, 露点, 微裂纹, 氧化铁

Abstract: In the production process of hot-rolled galvanized sheets at a steel plant, bare spot defects frequently occur, severely affecting the product quality. The causes and mechanisms of these bare spot defects were investigated through systematic surface inspection, microstructural analysis, chemical composition testing, and theoretical calculations of the oxide scale reduction reaction temperature during the annealing process. The results show that oxide residues are present on the surface of the steel sheets at the locations of bare spots. The oxygen (O) in these oxides exists as iron oxides on the steel surface before entering the zinc pot. The annealing furnace in the plant has a maximum heating temperature of 540 ℃, which is lower than the theoretically required reduction temperature (≥550 ℃), preventing complete oxide reduction during annealing. Microcracks at the edges of surface indentations on the hot-rolled substrate are influenced by the thickness of the oxide scale formed after final rolling. These areas are highly sensitive to the dew point in the annealing furnace. The moisture introduced into the furnace increases the local dew point, promoting oxidation. When the hot-rolled substrate enters the zinc pot, the remaining iron oxides impair the wettability of the molten zinc, leading to bare spots or coating porosity. By implementing skin-pass rolling (2.5% reduction rate) to reduce the surface roughness and controlling the annealing furnace dew point below -50 ℃, the plant significantly improves the surface quality of hot-rolled galvanized steel sheets and resolves the bare spot issue.

Key words: hot-rolled galvanized, bare spot defects, dew point, microcracks, iron oxides

中图分类号:

TG174.443

李士明, 张杰, 张子月, 陈斌锴, 于邦超, 张启富. 热基镀锌钢板漏镀缺陷原因及形成机理分析[J]. 金属热处理, 2025, 50(9): 287-292.

Li Shiming, Zhang Jie, Zhang Ziyue, Chen Binkai, Yu Bangchao, Zhang Qifu. Analysis of causes and formation mechanisms of bare spot defects in hot-rolled galvanized steel sheets[J]. Heat Treatment of Metals, 2025, 50(9): 287-292.

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