CSP冷轧镀锌板表面缺陷分析和改进工艺

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

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、SiO_2、Al_2O_3、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、6～7SiO_2、28～32MgO、2.3Al_2O_3),采用结晶器保护渣(%:32CaO、33SiO_2、1NgO、2.8Al_2O_3)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%。

The surface defects of cold rolled 0. 8～1.0 mm sheet （ ≤0. 07% C） produced by compact strip production （CSP） line with 900～1 600 mm ×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 surface defects of sheet were mainly FeO, CaO, SiO2, Al2O3, MgO etc. The average surface defects occurred ratio of cold rolled galvanized sheet from 12.64% in 2006 to 3.15% 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 nozzle from tundish to mold, reasonably improve flow field in tundish, use shield agent 39 ～43CAO, 6 ～7SIO2, 28 ～ 32MgO, 2. 3Al2O3 in tundish and shield slag main ingredient 32CAO, 33SIO2, 1MgO, 2. 8Al2O3 in mold,