Method of producing non-oriented electromagnetic steel strip having superior magnetic properties and appearance

摘要

A method of producing a non-oriented electromagnetic steel strip by subjecting a low-carbon steel slab to hot-rolling, cold rolling at a small reduction and first annealing. In order to improve magnetic flux density and surface appearance of the product, specific conditions are employed so as to coarsen the crystalline structure to obtain a controlled and moderate crystal grain size after the annealing. The slab is cold-rolled at a rolling reduction of about 5 to 15% and is subjected to first annealing by heating at a rate of about 3 DEG C./sec or higher and holding the strip for about 5 to 30 seconds at 850 DEG C. to the A3 transformation temperature of the steel, while controlling the crystal grain size to about 100 to 200 mu m after first annealing.