Abstract: The influence of two slag systems on the type, size and morphology of inclusions in hot work die steel was studied in a 10 t protective atmosphere electroslag remelting furnace. The results show that the mass fraction of T.O in molten steel increases to 0.001 6% and the size of inclusions increases when S2 slag is used for electroslag remelting. The inclusions after S2 slag electroslag remelting are mainly Al₂O₃, while the inclusions after S1 slag are mainly MgO-Al₂O₃. The S1 slag has higher optical basicity and stronger desulfurization ability. The difference in the content of Al_s and Mg in steel is related to the basicity of the two slag. The calculation model of molten slag was established and the activity of Al₂O₃ in slag was calculated. According to the Al-O equilibrium relationship, the content of oxygen in molten steel can be controlled by reducing the activity of Al₂O₃ in slag and increasing the basicity of slag, so as to produce ingots with low oxygen content.

Key words: electroslag remelting, inclusion, basicity, activity, calculation model of molten slag