汽车钢板表面线状缺陷控制技术

针对线状缺陷是制约汽车钢板表面品质的关键问题,对汽车钢种热轧板和冷轧板的表面缺陷进行SEMEDS分析。研究发现保护渣是引起汽车板线状缺陷的主要原因。提高钢液洁净度可以缓解水口堵塞,进而减少保护渣卷入与内壁大尺寸夹杂物脱落,此外优化结晶器流场也可以防止卷渣的发生。某钢厂通过工艺优化,使加铝前钢液溶解氧降低明显,并有效减少连铸过程钢液的二次氧化,提高了钢液洁净度。此外还通过对浸入式水口结构进行优化,降低了结晶器上回流强度,使液面波动明显减小。采取上述工艺优化,轧板表面线状缺陷的发生率显著降低。

Control technology of surface sliver defects for automobile steel sheets

For challenge of sliver defects restricting surface quality of automobile steel sheets,the surface defects on hot rolled sheets and cold rolled sheets of automobile steel were analyzed by SEM-EDS.The results show that mold fluxes are the main causes of sliver defects of automobile steel sheets.Improving the cleanliness of molten steel can alleviate nozzle clogging,thereby the entrapped slags in the mold and the large size inclusions which dropped from inner will decrease.In addition,slag entrapment in the mold would also be prevented by optimizing the flow field.By the optimized process in a steel mill,dissolved oxygen content in molten steel before aluminum addition obviously decreases and reoxidation of molten steel during casting process significantly reduces,and the cleanliness of molten steel is improved.In addition,through the optimization of submerged nozzle structure,inten-sity of up flow in the mold declines and level fluctuation of liquid obviously decreases.Through the above opti-mized processes,surface sliver defects on rolled sheets significantly declines.