IN2015DN02521A - - Google Patents

Abstract

A method of production of grain-oriented electrical steel sheet comprising heating a silicon steel material containing, by mass%, Si: 0.8 to 7%, C: 0.085% or less, acid soluble Al: 0.01 to 0.065%, and N: 0.012% or less, and optionally at least one selected from Mn: 1% or less, Cr: 0.3% or less, Cu: 0.4% or less, P: 0.5% or less, Sn: 0.3% or less, Sb: 0.3% or less, Ni: 1% or less, and S and Se in a total of 0.015% or less, and a balance consisting of Fe and unavoidable impurities, at a temperature of 1280°C or less, then hot rolling it, annealing the obtained hot rolled sheet, then cold rolling it once or cold rolling it several times with intermediate annealing to obtain steel sheet of the final sheet thickness, decarburization annealing this steel sheet, then coating an annealing separator, applying final annealing, and applying treatment to increase an amount of nitrogen of the steel sheet from the decarburization annealing to the start of secondary recrystallization of the final annealing, wherein, in the annealing process of the hot rolled sheet, decarburizing the steel sheet to 0.002 to 0.02 mass% of the amount of carbon before decarburization annealing to thereby control a lamellar spacing in the surface layer grain structure after annealing to 20 µm or more and performing only an induction heating in the temperature elevation process in the decarburization annealing of the steel sheet of the final sheet thickness by a heating rate of 40°C/s or more, in the temperature range of a steel sheet temperature of 550°C to 720°C.