Control and Research of Inclusion in Ultra Low Carbon Steel

In order to solve the problem of large amount of inclusions in ultra-low carbon steel,these measurement such as optimizing the modifier composition,controlling the temperature of RH inlet temperature,adjusting the time interval between adding Al to deoxidize and alloying,and optimizing composition of the slag had been utilized.It was found out that by adjusting the ratio of small particles of lime and aluminum slag,total iron content decreased from 29.5% to 10.9% after the modification.At a reasonable temperature of inlet molten steel the inclusion due to the blowing oxygen during RH process can directly reduced.In RH smelting,when Al and Ti are added without time interval,a large amount of Al-Ti composite inclusions will generate in the molten steel,which will lead to the blockage of the nozzle. Controlling the interval time between adding Al and add Ti alloy more than 150 s can effectively reduce the frequency of nozzle clogging.The percentage of cold rolling inclusion defects had been decreased from 0.33% to 0.15%.