Grain-oriented silicon steel sheet and process for production thereof

A process for producing a grain-oriented silicon steel sheet having superior coating and magnetic properties in a surface layer of said sheet,

• said process comprising the steps of hot-rolling a silicon steel slab containing about C:
• 0.030-0.12 wt %, Si:
• 2.0-4.5 wt %, acid-soluble Al:
• 0.01-0.05 wt %, N:
• 0.003-0.012 wt %, Mn:
• 0.02-0.5 wt %, and Bi:
• 0.005-0.20 wt %, cold-rolling the hot-rolled sheet once or twice or more with intermediate annealing interposed, performing decarburization annealing to the final cold rolled sheet,
• applying an annealing separator to said surface of said decarburized steel sheet,
• applying final finishing annealing to said sheet, including secondary recrystallization annealing to said sheet,
• applying purifying annealing to the resulting separator-applied sheet, and
• providing said steel slab with a content of about 0.1-1.0 wt % of Cr so that a Cr spinel oxide is formed in a subscale oxide film under said surface layer of said steel sheet in the course of said decarburization annealing.