Abstract: The causes of RH slag oxidation in ultra-low carbon steel and its impact on steel quality, as well as the principles, concrete methods, and implementation effects of the main control process currently dominated by deoxygenation and modification, were summarized. The difficulties and shortcomings of the process control were analyzed. A new control technology with isolation as the main idea and RH vacuum chamber slag-making as the operation method was put forward, its basic principle and theoretical advantages were described, and the preliminary production test and application results were introduced. Both theoretical analysis and practical results indicate that the new control process using RH vacuum chamber slag-making as operation method has the advantages of easy stability control and good effect.And the TFe mass fraction of the bottom layer slag in top slag can be stably controlled to below 4%, which has potential advantages over the current deoxidation and modification process.

Key words: ultra-low carbon steel, oxidation of top slag, deoxygenation and modification, RH slagging, isolate