Patent ID: 7887645

Claim:
A method for producing a high permeability grain oriented electrical steel, consisting essentially of the steps of: providing a strip having a thickness of from about 1.5 to about 4 mm, the strip composition comprising about 2.0 to about 4.5% silicon, greater than 0.25 to about 1.2% chromium, about 0.01 to about 0.08% carbon, about 0.01 to about 0.05% aluminum, the strip having a volume resistivity of at least about 45 μΩ-cm, and an austenite volume fraction (γ1150° C.) of at least about 20%, annealing said strip to provide an isomorphic layer thickness of at least about 2% of the total thickness of the annealed strip, rapidly cooling the annealed strip to ensure that the austenite is transformed into a hard second phase, cold rolling the cooled and annealed strip in one or more stages to provide a cold rolled strip, said cold rolling providing a final reduction of at least 80%, decarburization annealing the cold roll strip sufficiently to prevent magnetic aging, coating at least one surface of the decarburization annealed strip with an annealing separator coating, and final annealing the coated strip to effect secondary grain growth and thereby provide a permeability measured at 796 A/m of at least 1840.