JPS6483618A - Production of light-gaged grain oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To produce a light-gaged grain oriented silicon steel sheet having a high magnetic flux density and low iron loss value by decreasing the longitudinal draft of a steel sheet coil at the time of cold rolling to the draft smaller in the second half part than in the front half part at the time of subjecting the hot rolled sheet of a silicon steel to cold rolling, decarburization annealing and final finish annealing. CONSTITUTION:The silicon steel slab contg. 0.020wt.% C and 2.5-4.0wt.% Si is heated and hot rolled to the hot rolled sheet having 2mm thickness; thereafter, the steel sheet is annealed, pickled and coiled. This steel sheet is made into a thin sheet having 0.10-0.23mm final sheet thickness by >=2 passes of cold rolling including intermediate annealing and is then subjected to decarburization annealing in a wet hydrogen atmosphere; further an annealing and separating agent essentially consisting of MgO is coated thereon and the steel sheet is subjected to the final finish annealing in the hydrogen atmosphere. The finish cold rolling draft of the hot rolled sheet is decreased to the draft lower by 2-30% in the second half part of the hot rolled coil than in the first half part within this stage, by which the grain oriented silicon steel sheet having the high magnetic flux density and the low iron loss value as well as the excellent magnetic characteristics is produced.