电镀锌板表面斑状缺陷形成机理分析

采用扫描电镜对电镀锌板表面一类斑状缺陷从微观组织及成分等角度进行了分析,对其形成机理进行了探讨。结果表明:电镀锌板表面缺陷呈被局部碾压形貌,且缺陷部位粘附大量小黑点,小黑点的微区成分主要由C、O、Mg、S、Ca、Si、Mn等组成。通过产线排查及特征元素追溯发现缺陷来自于连续退火基板,导致缺陷产生的根本原因是富集在连续退火线水淬槽及与其相连水管内壁的水垢类异物粘附在板面上。通过清理连续退火线水淬槽及相连水管内壁后,基板表面质量得到控制,缺陷得以消除。

Analysis on formation mechanism of spot defects on surface of electrogalvanized steel sheet

Microstructure and composition of a kind of spot-like defects on the surface of electrogalvanized steel sheet were analyzed by SEM, and its formation mechanism was discussed. The results show that the surface defects of the electrogaivanized steel sheet are locally rolled, and a large number of small black spots are adhered to the defect parts. The composition of the defects is mainly composed of C, O, Mg, S, Ca, Si, Mn, etc. Through production line investigation and further tracing of characteristic elements, it is found that the defects come from the base sheet. The root cause of the defects is the foreign matters adhering to the base sheet surface, which come from their accumulation in the water quenching tank and the inner wall of the water pipe connected with it. The surface quality of the base sheet can be controlled by cleaning the inner wall of water quenching tank and connected water pipe, so that the defects are eliminated.