On the Role of Ferroalloys in Steelmaking

Ferroalloys are added in steel to improve properties like tensile strength, ductility, fatigue strength and corrosion resistance. Additionally, there can be several other tasks for ferroalloys like in refining, deoxidation, control of non-metallic inclusions and precipitates. The short history of ferroalloys is introduced parallel to the development of different steel types. Then the latest innovations like development of new low- and high-alloyed (HSLA and stainless) steels are discussed. Influences of ferroalloys and special requirements in different stages in steelmaking process from melting to casting are considered. The eventual influence of oxide impurities in ferroalloys to steel cleanliness was examined. It was observed that concerning primary alloying in early stage of ladle treatments the influence of ferroalloys is hardly decisive. Trimming additions close to casting start are more critical but on the other hand the additions are quite small and thus do not markedly influence the steel composition. However, the possible risk of ending up macro-inclusions to solidifying steel should be considered. Finally, some novel potential developments of ferroalloys as master alloys carrying nanoparticles are discussed.