Influence Of Fluoride Containing Slag On Inclusions In Electroslag Steel And Numerical Simulation Of Droplet Behavior Of ESR Process

As a mean of smelting high quality ingot, electroslag remelting technology has irreplaceable superiority than other steelmaking process due to its excellent metallurgical reaction conditions and special way of crystallization. With the development of science and technology, requirements of electroslag steel with higher quality and performance are also constantly improved. As the inclusions has a great influence on the mechanical properties of steel, strictly control the number of the non-metallic inclusions in steel becomes one of the main means to improve mechanical properties of steel. Through the slag-steel equilibrium experiment, inclusions dissolve experiment and plant experiment, this article investigates the evolution regulation and solve mechanism of non-metallic inclusions in the ESR slag, and analyses the formation and distribution of droplet in electroslag remelting process by numerical simulation.Slag-steel equilibrium experiment and plant experiment show that inclusions in MC5 steel change from CaO-MgO-Al2O3-SiO2 type and oxygen and sulfur compound inclusions of electrode to MgO-Al2O3 type inclusions and Al2O3 inclusions. More MgO-Al2O3 inclusions were found in the steel after CaF2-CaO-Al2O3-MgO-SiO2 slag melting. More Al2O3 inclusions were found in the steel after CaF2-Al2O3 slag melting. Inclusions with bigger size are less found in CaF2-CaO-Al2O3-MgO-SiO2 slag melting than in CaF2-Al2O3 slag melting. Argon atmosphere is not fit for the removal of sulfide inclusion, but it benefits the removal of total inclusions. Larger filling ratio contributes to reducing the number of inclusionsAlumina particles in CaF2-Al2O3 slag system become two kinds of intermediate products:CaO-Al2O3 and CaO-6Al2O3 with CaF2 in the slag. The compact interphase layer formed by intermediate product hinders the further reaction. Alumina particles in CaF2-CaO-Al2O3-MgO-SiO2 slag system react into MgO-Al2O3 with MgO in the slag. The dissolution of alumina is layer by layer with the dissolution of MgO-Al2O3 into the slag.The shape of electrode tip is the most significant factor that affects the size of droplet. Electrode insertion depth and low viscosity of the slag will make a taper angle of the electrode tip, and form a larger droplet. The increase of the interfacial tension also makes a larger size of the droplet at the electrode tip.