Effect of Basicity and Al2O3 Content in Slag on Cleanliness of Electroslag Ingot

Abstract

In order to clarify the mechanism for the increase in oxygen content during electroslag remelting, this paper analyzes in detail the effect of slag components on the gas content and number, size and composition of inclusions in electroslag ingots. The results show that, when the CaF2-MgF2-CaO-MgO-SiO2 slag system is used for electroslag remelting, the oxygen content in electroslag ingots decreases clearly with the increase in slag basicity. When the basicity is 14~3.3, the oxygen content in electroslag ingots is only 9~11 ppm. When the basicity drops to 2.3, the oxygen content increases to 20 ppm. The slag with high basicity also leads to a decrease in the number and size of inclusions with high Ca content. When the CaF2-MgF2-CaO-MgO-SiO2-Al2O3 slag system is used for electroslag remelting, with the increase in the Al2O3 content in slag with the same basicity, the oxygen content and inclusions in electroslag ingots gradually increase. However, the Al content in inclusions increases and the Ca content decreases. The decomposition of SiO2 and Al2O3 in slag is the main reason for the decrease in the cleanliness of electroslag ingots.