连铸夹渣类缺陷的成因分析和控制措施

分析了产生冷轧板卷夹渣类缺陷的连铸工序因素。结果表明,150 t转炉-吹氩站-LF-CAS或RH-(900～1 020) mm×210 mm连铸流程生产低碳铝镇静钢时,水口插入深度130～155 mm时热轧板缺陷指数远低于水口插入深度125 mm和160 mm时缺陷指数;浇铸时钢包水口自开和烧氧打开钢中平均总氧含量T[O]分别为15×10^-6和25×10^-6;通过下渣检验仪控制钢包至中间包的下渣量,热轧夹渣类缺陷指数显著降低。通过控制中间包钢水量,改进中间包水口结构;优化浸入式水口插入深度,提高钢包自开率和下渣检测使用率,采用低钠结晶器保护渣,使热轧板夹渣翘皮指数由原先的3.45降到0.73。

Analysis on Formation of Slag Entrapment Defects in Concasting and Control Measures

Concasting process factors to form the cold rolled coil defect related slag entrapment have been analyzed. Results show that with production of low carbon aluminium-killed steel by 150 t converter-argon blowing station-LF-CAS or RH-(900 ~ 1 020)mm x210 mm casting process, the defect index of hot rolled plate with nozzle merging depth 130 ~ 155 mm is far less that with nozzle merging depth 125 mm and 160 mm； the average total oxygen content T[O] in steel with ladle nozzle self-open and oxygen lance open is respectively 15 x 10^-6 and 25 x 10^-6; slag entrapment defect index of hot rolled plate decreases obviously by using slagging detector to control slagging amount from ladle to tundish. The index of slag inclusion-skin defect of hot rolled plate decreases from original 3. 45 to 0. 73 by controlling amount of liquid in tundish, improving nozzle structure of tundish, optimizing merging depth of submerging nozzle, increasing ratio of ladle self-open and operating ratio of control tundish slagging amount detector, and using low sodium mold powder.