Patent ID: 6153019
Filing Date: 2000-11-28
Classification: C21D

Abstract:
A process for producing grain-oriented magnetic steel sheeting in which a slab made from a steel containing (in mass %)more than 0.005 to 0.10% C,2.5 to 4.5% Si,0.03 to 0.15% Mn,more than 0.01 to 0.05% S,0.01 to 0.035% Al,0.045 to 0.012% N,0.02 to 0.3% Cu,the remainder being Fe, including unavoidable impurities is heated through a temperature below the solubility temperature for manganese sulphide, at any rate however below 1320.degree. C. but above the solubility temperature for copper sulphides; subsequently hot rolled to a final thickness of the hot strip between 1.5 and 7.0 mm, with an initial temperature of at least 960.degree. C. and with a final temperature in the range of 880 to 1000.degree. C.; the hot strip is subsequently annealed for 100 to 600 s at a temperature ranging from 880 to 1150.degree. C. and immediately cooled at a cooling rate in excess of 15 K/s and cold rolled in one or several cold-rolling steps to the final thickness of the cold strip; subsequently the cold strip is subjected to a recrystallizing annealing process in a humid atmosphere containing hydrogen and nitrogen, with synchronous decarburisation, and after applying on both sides a parting agent, essentially containing MgO, it is annealed at high temperature and after applying an insulating layer, it is subjected to final annealing, characterized in that the cold strip--for said high-temperature annealing--is heated in an atmosphere comprising less than 25 vol. % H.sub.2, the remainder being nitrogen and/or a noble gas, at least until the holding temperature of 1150 to 1200.degree. C. is reached.