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针对厚度规格2.0 mm以上的LACK系列热镀锌产品,在客户折弯成形过程中易出现锌层起皱问题,通过SEM对缺陷位置的形貌组织进行了观察,发现基板表面晶粒尺寸粗大,造成带钢最表层强度下降,并随着晶粒尺寸的增大,裂纹形成需要的外加切应力及裂纹扩展的最大正应力均减小。采用有限元软件对成形过程中的应力情况进行分析发现,锌层起皱位置为成形过程中等效拉应力最大的位置。最后,提出了优化热轧工艺的措施来有效消除带钢表面粗晶和起皱现象。
For LACK series hot-dip galvanized products with a thickness of 2.0 mm or more, zinc wrinkle easily occurs during the bending process of the customer. The morphology and microstructure of the defect location are observed through SEM, and the grain size of the substrate surface is coarse, Resulting in the decrease of the maximum strength of the strip. With the increase of the grain size, the additional normal shear stress required for crack formation and the maximum normal stress of crack propagation decrease. Finite element software was used to analyze the stress during the forming process. It was found that the zinc wrinkle position is the position with the highest equivalent tensile stress in the forming process. Finally, the measures to optimize the hot rolling process are proposed to effectively eliminate the coarse grain and wrinkle on the surface of the strip.