Method for manufacturing high silicon non-oriented electrical steel sheet with superior magnetic properties

摘要

PURPOSE: A method for effectively manufacturing high silicon non-oriented electrical steel sheet having superior electrical characteristics by diffusion annealing a steel sheet at a high temperature after coating a siliconizer coating composition on the surface of intermediate annealing treated steel sheet is provided. CONSTITUTION: In a non-oriented electrical steel sheet manufacturing process comprising the steps of hot rolling the reheated steel slab after reheating a steel slab, controlling thickness of the steel sheet by annealing and cold rolling the hot rolled steel sheet, and recrystallization annealing the cold rolled steel sheet, the method for manufacturing high silicon non-oriented electrical steel sheet comprises the processes of controlling the total oxygen amount in an oxide layer on the surface of the intermediate annealed steel sheet to 210 to 420 parts per million by intermediate annealing the cold rolled steel sheet in the temperature range of 950 to 1,100 deg.C at an atmosphere of nitrogen gas containing 50% or more of hydrogen and a humidity atmosphere having a dew point (PH2O/PH2) of 0.06 to 0.30; drying the coating composition coated steel sheet after coating a coating composition comprising 100 weight parts of Fe-Si based calcined powder having a particle size corresponding to a sieve size of 325 mesh and containing 20 to 70 wt.% of Si and a colloidal silica solution containing 15 to 30 weight parts of silica solid for 100 weight parts of the Fe-Si based calcined powder on the surface of the intermediate annealed steel sheet; and diffusion annealing the dried steel sheet in the temperature range of 1,050 to 1,200 deg.C at an atmosphere of nitrogen gas containing 20% or more of hydrogen.