Analysis of large inclusions in 430 stainless steel continuous casting slabs under unsteady state
In order to investigate the effect of unsteady state continuous casting on large inclusions in stainless steel,the hot rolling and ultrasonic flaw detection method was used to study the types,sources,sizes,quantities,distri-bution in the 430 stainless steel continuous casting slab under the fluctuation of mold liquid level,as well as the in-fluence on the surface quality of the cold-rolled plate.The results show that there are mainly four types of large in-clusions,41.3％of them originate from the nodule at the mold nozzle,38.7％of them are caused by the entrapment of mold protective slag,13.3％of them are caused by the entrapment of refined slag,and 6.7％of them are endoge-nous inclusions.The inclusion of nozzle nodules,refining slag entrapment,and endogenous inclusions are generally generated before the molten steel exits the crystallizer nozzle,and their distribution is mainly concentrated at the dis-tance of 1/3 to 1/4 from the inner arc surface in the thickness direction of the casting slab and near the narrow sur-face.The slag entrapment of protective slag is generated within the mold,and there is a certain area of aggregation.The nozzle nodule type inclusions which belong to brittle inclusions with large dimensions,have the greatest harm to the surface quality of the cold plate.Accordingly,attention should be paid to the fluctuation of residual active ele-ments such as[Al],[Mg],[Ti],[Ca],and the temperature of molten steel during the continuous casting process,and these fluctuations should be reduced to avoid large inclusions caused by the structural changes in nozzle nodules.Using the hot rolling and flaw detection method can obtain information on the type,size,distribution,and other characteristics of large inclusions in continuous casting slabs.Based on the deformation characteristics of inclusions,their harmfulness can be intuitively judged,but the accuracy is easily affected by other factors.
NETL
NSTL
万方数据
