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Laboratory and industrial studies were carried out to investigate non-metallic inclusions in high strength alloy steel refined by high basicity and high Al_2O_3 slag.It was found that the steel/slag reaction time largely affected non-metallic inclusions.With the reaction time increased from 30 min to 90 min in laboratory study,MgO-Al_2O_3 spinels were gradually changed into CaO-MgO-Al_2O_3 system inclusions surrounded by softer CaO-Al_2O_3 surface layers.By using high basicity slag which contained as much as 41%Al_2O_3 in the laboratory study,ratio of low melting temperature CaO-MgO-Al_2O_3 system inclusions was remarkably increased to above 80%.In the industrial experiment,during the secondary refining,the inclusions changed in order of “Al_2O_3→MgO-Al_2O_3→CaO-MgO-Al_2O_3”.Through the LF and RH refining,most inclusions could be transferred to lower melting temperature CaO-Al_2O_3 and CaO-MgO-Al_2O_3 system inclusions.
Laboratory and industrial studies were carried out to investigate non-metallic inclusions in high strength alloy steel refined by high basicity and high Al 2 O 3 slag. It was found that the steel / slag reaction time largely affected by non-metallic inclusions. W the the reaction time increased from 30 min to 90 min in laboratory study, MgO-Al_2O_3 spinels were gradually changed into CaO-MgO-Al_2O_3 system inclusions surrounded by softer CaO-Al_2O_3 surface layers. By using high basicity slag which contained as much as 41% Al_2O_3 in the laboratory study , the ratio of low melting temperature CaO-MgO-Al 2 O 3 system inclusions was remarkably increased to above 80%. In the industrial experiment, during the secondary refining, the inclusions changed in order of “Al 2 O 3 → MgO-Al 2 O 3 → CaO-MgO-Al 2 O 3 ”. Through the LF and RH refining, most inclusions could have been transferred to the lower melting temperature CaO-Al 2 O 3 and CaO-MgO-Al 2 O 3 system inclusions.