The Purity of Ferrosilicon and Its Influence on Inclusion Cleanliness of Steel.

The effect of impurities such as Al and Ca on the type and amount of inclusions formed during deoxidation of liquid steel has been studied on a laboratory scale. The microstructure of different grades of ferrosilicon and the occurrence of impurities (Al, Ca, Ti and P) were also studied. The results show that impurities are present primarily in intermetallic phases in the ferrosilicon and that oxide inclusions are very rare. The grade of ferrosilicon has a direct impact on the composition and amount of inclusions in the liquid steel. An increased content of aluminium results in the formation of alumina inclusions, while high purity ferrosilicon results in the formation of silicates which are removed more slowly from the melt.