BRIGHT ANNEALING METHOD FOR COLD ROLLED FERRITIC STAINLESS STEEL STRIP

摘要

PURPOSE:To form a bright finished surface having excellent rust preventiveness by subjecting a cold rolled ferritic stainless steel strip contg. Cr at a specific compsn. ratio to bright annealing under adequate conditions in a gaseous mixture atmosphere composed of N2 and H2. CONSTITUTION:The cold rolled ferritic stainless steel strip contg. 12-20wt% Cr is heated under the conditions of the region where the average heating rate between 400-800 deg.C is upper than the curve connecting successively the coordinate points A-F in the orthogonal coordinates having the dew point of the atmosphere in the furnace and average heating-up rate at the coordinate axes in a method for subjecting the above-mentioned stainless steel strip to bright annealing in a gaseous atmosphere of N2:H2=1:3. The steel strip after the heating is then held for 2-20 seconds in a 800-880 deg.C temp. range. The steel strip is thereafter cooled at =400 deg.C/min cooling rate in a 800-400 deg.C temp. range. The pitting arising from the circumferential edge of the non-metallic inclusions insoluble in water on the bright surface of the resulted steel strip is thereby prevented.