热浸镀铝硅钢板表面点状缺陷分析及改进

为提高铝硅镀层钢板表面质量,利用光学显微镜(OM)、扫描电镜(SEM)及能谱(EDS)对镀铝硅钢板表面出现的点状缺陷的显微形貌及成分进行分析。结果表明,铝硅镀层钢板表面产生的点缺陷主要分为4类,第I类点缺陷成分主要为Al-Si氧化物和氧化锌,由铝渣及锌灰粘附在镀层表面所致;第II类点缺陷产生原因为镀层表面压入铝渣或异物;第III类点缺陷由Al-Fe-Si氧化物、Al-Si氧化物及W-C、Co-C化合物组成,为沉没辊涂层磨损后与铝渣共同粘附在镀层表面造成;第IV类点缺陷处呈中间凹陷、边缘微凸起的微观形貌,产生原因为镀层表面受异物划伤。针对以上缺陷的产生原因提出严格控制铝锅温度、增加捞渣频次、降低炉鼻内氧含量等措施。

Analysis and improvement of point defects on surface of hot dip aluminum-silicon plated steel sheet

In order to improve the surface quality of aluminum-silicon plated steel sheet,the microscopic morphology and composition of the point-like defects appeared on the surface of aluminum-silicon plated steel sheet were analyzed by using optical microscope(OM),scanning electron microscope(SEM)and energy spectrum(EDS).The results show that the point defects generated on the surface of the aluminumsilicon plated steel sheet are mainly divided into four categories.The typeⅠpoint defect components are mainly Al-Si oxide and zinc oxide,which are caused by the adhesion of aluminum dross and zinc dust on the coating surface.The cause of typeⅡpoint defects is that aluminum slag or foreign matter is pressed into the surface of the coating.The typeⅢpoint defects are composed of Al-Fe-Si oxides,Al-Si oxides and W-Co-C alloy compounds,which are caused by co-adhesion with the aluminum dross on the surface of the coating.The type IV point defects have the microscopic morphology of middle depression and edge slight bulge,which are caused with surface scratching by foreign objects.In view of the above causes of the defects,some measures are proposed,such as strict controlling of the temperature of the aluminum pot,increasing the frequency of slag fishing,and reducing the oxygen content in the furnace nose.