Rare earth metal treated cold rolled, non-oriented silicon steel and method of making it

A cold rolled, non-oriented, semi-processed silicon steel having a composition comprising in percent by weight from about 0.5 to about 4% silicon, up to about 0.8% aluminum, from about 0.05 to about 0.5% manganese, about 0.012% maximum sulfur, less than about 0.010% carbon and up to about 400 ppm. cerium, the balance being iron.

A cold rolled, non-oriented, fully processed silicon steel having a composition comprising in percent by weight from about 0.5 to about 4% silicon, up to about 0.8% aluminum, from about 0.05 to about 0.5% manganese, about 0.012% maximum sulfur, less than about 0.005% carbon and up to about 400 ppm. cerium, the balance being iron.

A method of preparing a refined silicon steel melt for semi-processed and fully processed cold rolled, non-oriented silicon steels comprising the steps of melting a heat of silicon steel tapping said melt into a ladle, adding ferro-silicon, ferro-manganese silicon and aluminum for deoxidizing and alloying purposes, mixing said melt by argon stirring, subjecting said melt to a vacuum degassing treatment, adding aluminum and a substance chosen from the class consisting of a rare earth metal and a rare earth metal compound for final deoxidation and desulfurization of said melt, continuing said vacuum degassing treatment for a period of time sufficient for at least one complete volume exchange within said ladle to permit adequate flotation of inclusions formed during said final deoxidation and desulfurization, said refined melt comprising in percent by weight from about 0.5 to about 4% silicon, up to about 0.8% aluminum, from about 0.5 to about 4% silicon, up to about 0.8% aluminum, from about 0.05 to about 0.5% manganese, about 0.012% maximum sulfur, up to about 0.1% maximum carbon and up to about 400 ppm. cerium, the balance being iron.

A method of preparing a refined silicon steel melt for semi-processed and fully processed cold rolled, non-oriented silicon steels comprising the steps of melting a heat of silicon steel, tapping said melt into a first ladle, adding ferro-silicon, ferro-manganese silicon and aluminum for deoxidation purposes, teeming said first ladle into a second ladle, adding ferro-silicon to said second ladle for alloying purposes, subjecting said second ladle to a vacuum degassing treatment, adding aluminum and a substance chosen from the class consisting of a rare earth metal and a rare earth metal compound for final deoxidation and desulfurization of said melt, continuing said vacuum degassing treatment for a period of time sufficient for at least one complete volume exchange within said ladle to permit adequate flotation of inclusions formed during said final deoxidation and desulfurization, said refined melt comprising in percent by weight from about 0.5 to about 4% silicon, up to about 0.8% aluminum, from about 0.05 to about 0.5% manganese, about 0.012% maximum sulfur, up to about 0.1% maximum carbon and up to about 400 ppm. cerium, the balance being iron.