连退FD表面缺陷控制研究

Research on Surface Defect Control of Continuous Annealing FD Products

1—10月份连退FD带出品率平均为7.0%,是镀锌FD的2倍,是普通表面级别超低碳钢的7倍,给公司制造成本、交货期管理带来较大负面影响,根据取样分析发现,连退FD钢卷表面缺陷主要成分为Al_(2)O_(3)夹杂(20%)和保护渣(80%)。鉴于此,从减少连铸过程二次氧化入手,开展中间包全密封保护浇注、开发中间包高吨位开浇和恒吨位浇注技术,使中间包全氧均值(质量分数)降低约0.5×10^(-6);通过提高保护渣黏度和表面张力,降低了卷渣发生几率;对炼钢品质判定模型中FD板坯挑选规则进行优化,使连退FD缺陷降级率从6月的6.3%降至10月的4.1%。

From January to October,the average yield of FD with reflow is 7.0%,which is twice as much as that of galvanized FD and 7 times as much as that of general surface grade ultra-low carbon steel.According to SEM analysis,the main components of surface defects of continuous annealing FD steel coil are Al_(2)O_(3) inclusion(20%)and mold flux(80%).In order to reduce the secondary oxidation in the continuous casting process,full-seal protective casting and high-tonnage start casting and constant-tonnage casting technology were developed in tundish.In addition,the slag entrainment rate is reduced by increasing the viscosity and surface tension of the flux.At the same time,the rule of FD Slab selection was optimized,and the rate of FD defect degradation decreased from 6.3% in June to 4.1% in October.