取向硅钢表面白条缺陷成因分析

Causes analysis of the surface white stripe defect on grain oriented silicon steel

对取向硅钢成品表面白条缺陷形成原因进行分析,采用三维视频显微镜观察表面微观形貌,场发射扫描电镜观察截面形貌及酸洗后缺陷区域表面形貌,能谱仪进行能谱成分分析。研究表明:白条缺陷微观观察都存在椭圆状绝缘涂层脱落,缺陷区的硅酸镁底层生成异常,厚度远超正常区域,白条缺陷区在涂氧化镁之前已损伤。白条缺陷区经酸洗后发现含有以O、Al、Si为主要成分的针状物,该针状物来源于脱碳退火炉中的耐火纤维,耐火纤维在脱碳退火时掉落并粘附到钢带表面,二次轧制时耐火纤维压入钢带表面,破坏了氧化膜,导致硅酸镁底层的生成受到影响,高温退火后产品表面产生了白条缺陷。通过改进保温耐火纤维使用方法,消除了该缺陷。

The causes of white stripe defects on the surface of grain oriented silicon steel were analyzed.The surface morphology was observed by three-dimensional video microscope,the crosssection morphology of the steel and the surface morphology of the defect area after pickling were observed by field emission scanning electron microscope,and the energy spectrum composition was analyzed by energy spectrum analyzer.The analysis result showed that there was elliptical insulation layer falling off in the white stripe defect,and the magnesium silicate substrate in the defect area was abnormal,of which the thickness was much thicker than the normal area.It indicated that the white stripe defect area had been damaged before coating magnesium oxide.After pickling,the spicules with the main composition of O,Al and Si were found in the defect area of white stripe.It was found that the spicules originated from the refractory used in decarburization annealing furnace.The refractory fiber fell and adhered into the surface of the steel strip during decarburization annealing,and was pressed into the strip surface in the process of secondary rolling,which destroyed the oxide film,and affected the formation of the magnesium silicate substrate,and caused the white strip defect on the surface of the steel production after high temperature annealing.This kind of defect has been eliminated by improving the use method of insulating refractory fiber.