Silicon steel and processing therefore

Claim 1

In a process for producing electromagnetic silicon steel having a cube-on-edge orientation, a permeability of at least 1900 (G/O e ) at 10 oersteds and a core loss of no more than 0.700 watts per pound at 17 kilogauss, which includes the steps of: preparing a melt of silicon steel consisting essentially of, by weight, from 0.02 to 0.06% carbon, from 0.015 to 0.15% manganese, from 0.01 to 0.05% of material from the group consisting of sulfur and selenium, from 0.0006 to 0.0080% boron, up to 0.0100% nitrogen, up to 1.0% copper, no more than 0.008% aluminum, from 2.5 to 4.0% silicon, balance iron; casting said steel; hot rolling said steel; cold rolling said steel; decarburizing said steel; applying a refractory oxide base coating to said steel; and final texture annealing said steel; the improvement comprising the steps of coating the surface of said steel with a refractory oxide base coating consisting essentially of: (a) 100 parts, by weight, of at least one substance from the group consisting of oxides, hydroxides, carbonates and boron compounds of magnesium, calcium, aluminum and titanium; (b) up to 100 parts, by weight, of other substances from the group consisting of boron and compounds thereof, said coating containing at least 0.5%, by weight, of boron; (c) from 0.5 to 40 parts, by weight, of SiO 2 added as colloidal silica; (d) up to 20 parts, by weight, of inhibiting substances; and (e) up to 10 parts, by weight of fluxing agents; and final texture annealing said steel with said coating thereon; said steel's magnetic properties being in part, attributable to the inclusion of boron and SiO 2 in the base coating.