彩涂钢板表面微小点锈原因分析

Cause analysis of tiny rust spot defects on prepainted steel sheet

针对彩涂板表面出现的一种微小点锈缺陷进行了详细的微观分析,根据漆膜表面、漆膜剥离后的基板表面和截面的形貌及能谱分析结果,发现该微小点锈缺陷表面存在铁的锈蚀,但漆膜未出现鼓泡,漆膜下方镀层完整,镀层下方钢基体未发生锈蚀;同时根据缺陷位置漆膜中的压痕、裂纹及局部氧化铁嵌入漆膜的特征,明确了该微小点锈缺陷的起因是漆膜表面的铁屑或氧化铁屑压入。

A detailed microscopic analysis was carried out for a type of tiny spot rust defects on prepainted steel sheet.Based on the morphology and energy spectrum analysis results of the paint surface,the substrate surface after the paint film was peeled off and the cross section,the root cause of the defect was determined.Firstly,no blister in the paint was observed and neither the zinc coating nor the steel substrate under the paint was damaged.Therefore,the rust product at the spot defect did not originate from the substrate corrosion.Secondly,according to the characteristics of the indentation,cracks and local iron oxide embedded in the paint film at the spot defect position,it was figured out that the tiny spot rust defect was caused by the iron or iron oxide scraps on the surface of the paint film.