New types of unfavorable nonmetallic inclusions based on MgO-[Al.sub.2][O.sub.3] and metallurgical factors governing their content in metal. Part 1. Reasons and mechanisms for formation in steel of nonmetallic inclusions based on alumina magnesia spinel

Reasons and basic mechanisms are considered for formation and transformation of non-metallic inclusions based on alumina magnesia spinel, and the unfavorable effect on corrosion resistance of carbon and low-alloy steels in aqueous chlorine-containing media. Basic approaches are demonstrated making it possible to reduce the content of the inclusions in question in steel aimed both at reducing the content of inclusions during steel smelting, and on limiting the possibility of their transformation during steel continuous casting and hot rolling. Key words: low-alloy carbon steels, corrosion-active non-metallic inclusions, ladle treatment, reaction with lining, slag.