Study on mechanism of oxygen increase and countermeasure to control oxygen content during electroslag remelting process

Abstract

This study analyses the mechanism of oxygen increase during the electroslag remelting (ESR) process and proposes a countermeasure to control oxygen content of electroslag ingots. The results show that when the oxygen in the electrode is high, the oxygen in the ingots decreases after the ESR process. However, when the oxygen in the electrode is low, the oxygen in the ingots increases after the ESR process. Oxygen increase is closely related to the slag system that was used during the process. According to the experiment and the theoretical analysis, the [Al]-[O] reaction is the control reaction, and the oxygen content of the ingots is determined by the Al2O3 activity in the slag pool when Al in the electrode is kept constant. Based on this finding, the new slag system that decreases the oxygen content of the electroslag ingot is designed and it contains the following components: 63–67%CaF2, 4–6%Al2O3, 18–22%CaO, 8–12%RExOy or 43–47%CaF2, 4–6%Al2O3, 18–22%CaO, 8–12%MgO and 18–22%RExOy.