Establishment of Optimum Production Regimes for Extra-Furnace Processing of Low-Alloy Steels in Order to Ensure their Good Corrosion Resistance in Aqueous Media through Formation of Favorable Non-Metallic Inclusions

Optimum production regimes are established for steel extra-furnace treatment providing not only low contamination with non-metallic inclusions (NI), but also formation of NI with favorable morphology not having a deleterious effect on steel corrosion resistance. It is shown that this is achieved by controlled input of Al in steel alloying and deoxidation stages, limiting its content in steel, limiting the temperature for additionof aluminum and calcium in the final treatment stage, and also the duration of the flushing period. For steel micro- alloyed with titanium it is also possible to form another type of NI that does not adversely affect steel corrosion resistance. The oxide component of these NI with a high content of calcium and titanium acquires a rounded shape. Formation of such NI is achieved by the controlled addition of Al, Ti, and Ca in the concluding treatment stage.