快换浸入式水口异常对钢板内部质量的影响

Effects of Submerged Entry Nozzle Quick Changing Failure during Continuous Casting on Steel Plate Disqualification in Flaw Detection

本论文通过连铸中间包浸入式水口快速更换发生过的生产实践以及产生批量钢板探伤不合格实例,对探伤不合格钢板取样进行金相显微镜和扫描电镜分析研究。结果表明:快速更换中间包水口吸气产生氧化物夹杂是导致钢板探伤不合格的主要原因。经过讨论,采取措施规定:当连浇过程发生浸入式水口异常情况仅允许快换一次,且对快换浸入式水口后的炉次在结晶器内取气体样,通过与真空后钢液取样对比氮氧含量,判断快换浸入式水口滑板面是否吸气。并对连浇过程快换浸入式水口后的铸坯进行封锁,依据气体分析对封锁铸坯采取降级等处置等措施,有效的控制和避免了快换浸入式水口异常产生的批量探伤不合重复性质量事故。

Based on quick-changing practice of tundish submerged entry nozzle during continuous casting and flaw detection disqualification instances of steel plate in batch,the research is performed on specimens taken from disqualified steel plate in flaw detection by means of metallographic microscope and scanning electron microscope.The results show that oxide inclusions formed due to gas ingress at tundish submerged nozzle during quick-changing are the major causes of disqualified steel plate in flaw detection.After discussion,measures are taken to stipulate that in case of abnormal situation of submerged entry nozzle in continuous casting process,quick change is allowed only once,and gas samples are taken in the mould for the heat after quick change of submerged entry nozzle.By com⁃paring nitrogen and oxygen content with that of liquid steel after vacuum,judge whether the sliding plate surface of quick change submerged entry nozzle inhales air.In the continuous casting process,the billets after the quick change of the submerged entry nozzle are blocked.According to the gas analysis,the blocked billets are degraded and other measures are taken to effectively control and avoid the repetitive quality accident of unqualified batch flaw detection caused by the abnormal quick change of the submerged nozzle.