Patent ID: 8277573
Filing Date: 2012-10-02
Classification: C21D,C22C

Abstract:
1. A process for the production of grain oriented magnetic strip wherein a silicon steel is continuously cast to form a slab, solidified and subjected to the following operations in sequence: hot-rolling of the slab to obtain a hot-rolled sheet; cooling of the hot-rolled sheet and coiling thereof; optional annealing of the hot-rolled sheet; cold-rolling the hot-rolled sheet until obtaining a cold-rolled strip; decarburization annealing and primary recrystallization of the cold-rolled strip; applying of an annealing separator onto a surface of the cold-rolled strip; secondary recrystallization annealing of the cold-rolled strip, and wherein the hot-rolled sheet and/or the cold-rolled strip is optionally nitrided, characterised in that: the steel comprises the following components, expressed in weight concentration: Si between 2.3% and 5.0%, N in the range of 20-200 ppm, S and/or Se so that (S+(32/79)Se) be in the range of between 30 and 350 ppm, at least two elements of the series B, Al, Cr, V, Ti, W, Nb, Zr and at least one of the elements of the series Mn, Cu, such that the two quantities: where [X] in represents the weight concentration of element expressed in ppm and M x the related atomic weight, is such as to satisfy the following relationships: optionally C up to 800 ppm, Sn, Sb, As in concentrations such that their sum does not exceed 1500 ppm and/or P, Bi, in concentrations such that their sum does not exceed 300 ppm, the remaining part being iron and unavoidable impurities, and in that the slab, solidified in a time less than 6 minutes, is subjected, in the absence of a heating prior to the hot-rolling, to the following operations in sequence: