CSP冷轧镀锌板表面缺陷分析和改进工艺

通过扫描电镜和能谱分析了马钢900～1600 mm×90～50 mm铸坯CSP(紧凑式带材生产线)冷轧0.8～1.0 mm薄板(≤0.07%C)的表面缺陷。分析结果表明,薄板表面缺陷处夹杂物主要为FeO、CaO、SiO2、Al2O3、MgO等。通过控制120 t LF吹氩量≤200 L/min,钢包到中间包用长水口,中间包到结晶器用浸入式水口,合理改善中间包流场,采用中间包覆盖剂(%:39～43CaO、6～7SiO2、28～32MgO、2.3Al₂O₃),采用结晶器保护渣(%:32CaO、33SiO₂、1NgO、2.8Al₂O₃)等改进工艺措施,使冷轧镀锌板平均表面缺陷发生率从2006年的12.64%降至2007年的3.15%。

An Analysis on Surface Defect of CSP Cold Rolled Galvanized Sheet and Process Improvement

The surface defects of cold rolled 0.8~1.0 mm sheet(≤0.07%C)produced by compact strip production (CSP)line with 900～1600mm×90～50 mm cast slab at Masteel have been analyzed by scanning electron microscope and energy dispersion spectrum analysis.Analysis results showed that the inclusions at surace defects of sheet were mainly Fe0,CaO,SiO₂,Al₂0₃,MgOetc.The average surface defects occured ratio of cold rolled galvanized sheet from 12.64% in 2006 to3. 15% in 2007 by using improved process measures such as to control 120 t LF argon blown rate ≤ 200 L/min,use long nozzle from ladle to tundish,use immersed nozale from tundish to mold,reasonably improve flow field in tundish, use shieid agent 39～43Ca0,6~7SiO₂,28～32MgO,2.3Al₂O₃ in tundish and shield slag main ingedient 32CaO,33SiO₂,1MgO,2.8Al₂0₃ in mold.