Effect of CaO–Al 2 O 3 –SiO 2 –MgO(–CaF 2 ) refining slag system on inclusions in silicon–manganese deoxidized spring steel

In order to make the refined slag match various grades of spring steel, high-temperature equilibrium experiments were conducted in the laboratory to study the effect of CaO–Al 2 O 3 –SiO 2 –MgO refining slag with varying basicity, Al 2 O 3 content, and CaF 2 additives on inclusions containing Al (Al 2 O 3 ) in silicon–manganese-deoxidised steel. The results show that the control effect of low basicity refining slag on inclusions is better than that of high basicity slag. The soluble aluminium increases with the increase of the basicity of steel slag and the Al 2 O 3 content in inclusions is positively correlated with the Al 2 O 3 content in slag. When the relative adsorption capacity of the refined slag is 6 × 10 −3 , the area density of Al-containing inclusions in steel is at a low level. Low basicity slag with low Al 2 O 3 is good, and it is more suitable for producing high-end spring steel. To produce middle- and low-end spring steel, the refining slag system with a basicity of about 2–2.5, Al 2 O 3 , MgO, and CaF 2 content is about 10% can be used. Among them, a small amount of CaF 2 improves the liquidity of steel liquid, improves its relative adsorption capacity to Al-containing inclusions, and can control the production of Al-containing inclusions in the steel.