热镀铝锌钢板表面横向条纹缺陷原因分析及解决方案

Solution for transverse streak of surface defect on 55% Al-Zn-Si hot dip strip

热镀铝锌钢板具有优异的耐腐蚀能力、良好的光热反射能力等,在建筑、家电等行业广泛应用。宝钢生产的热镀铝锌钢板表面存在垂直轧制方向的横向条纹缺陷。横向条纹缺陷是由于锌锅内稳定辊位置发生变化,导致带钢通道线位置改变,引起气刀距离变化、镀层厚度变化,宏观呈现条纹。稳定辊的打滑,导致摩擦力矩、摩擦偏角的变化,使稳定辊位置发生变化。铝锌液密度小,使得铝锌锅内的稳定辊处于游离的不稳态,打滑不断重复发生。一定范围内,锌层厚度越厚、带钢规格越厚,横向条纹越明显。通过提高辊面粗糙度、采用空心辊等可以解决横向条纹缺陷问题。

Since the 55% Al-Zn-Si coated steel product( GALVALUME) sheets exhibit excellent corrosion resistance and heat reflection,their use in construction and home appliance is expanding. A streak of surface defect on galvalume product is perpendicular to rolling direction. The transverse streak is the result of regular variation of coating thickness after proved by oil stone polishing,due to the passline position variation of the strip and the air knife distance variation. The position variation of stabilizing roll in pot during hot dip coating process is caused by the friction torque and contact angle change. The stabilizing roll in pot is free and unstable due to the lower AlZn-Si liquid density,and makes fluttering. The thicker the zinc thickness,the more obvious the transverse streak defectis. The thicker the strip,the more obvious the transverse streak defectis. It turns out that the solution for this defect is using hollow rolls or the greater surface roughness of stabilizing roll.