Patent ID: 6287392
Filing Date: 2001-09-11
Classification: C21D,C22C

Abstract:
A process for producing a grain-oriented silicon steel sheet wherein said sheet has a surface layer having superior coating and magnetic properties,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 %, said slab having a content of about 0.1-1.0 wt % of Cr,cold-rolling the hot-rolled sheet once or twice or more with intermediate annealing interposed,performing decarburization annealing to the final cold rolled sheet in an oxidizing atmosphere to form a Cr spinel oxide subscale under said surface layer of said steel sheet in the course of said decarburization annealing, which subscale provides said steel with a content of about 0.1-1.0 wt % of Cr,applying an annealing separator to said surface of said decarburized steel sheet,applying final finishing annealing with secondary recrystallization annealing to said sheet, andapplying purifying annealing to the resulting separator-applied sheet.