METHOD FOR PRODUCING GRAIN-ORIENTED MAGNETIC STEEL SHEET HAVING GOOD BLANKING WORKABILITY WITHOUT APPLYING PRIMING COATING

摘要

PROBLEM TO BE SOLVED: To provide a method for stably producing a grain-oriented magnetic steel sheet by solving particularly such a problem as bending characteristics in the magnetic steel sheet without forsterite coating.;SOLUTION: The grain-oriented magnetic steel sheet which has no priming coating which mainly contains the forsterite (Mg₂SiO₄) is produced by the steps of: hot-rolling a silica-containing steel slab with sol. Al reduced to ≤100 ppm and N to ≤ 50 ppm; applying cold-rolling once or twice or more interposing an intermediate annealing; recystallizing and annealing the resultant product in the atmosphere having ≤ 40°C dew point; and performing last finish-annealing in the atmosphere having ≤ 40°C dew point. In soaking at ≥ 800°C for ≥ 20 hr during the last finish-annealing, the steel sheet is maintained under a prescribed staying time ratio in both of nitriding atmosphere and non-nitriding atmosphere.;COPYRIGHT: (C)2005,JPO&NCIPI