NONORIENTED SILICON STEEL SHEET HAVING EXCELLENT SURFACE PROPERTIES AND ITS MANUFACTURE

• Main Authors: NISHIMOTO AKIHIKO, HOSOYA YOSHIHIRO, URABE TOSHIAKI
• Format: Patent
• Language: English
• Published: 04.09.1990
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PURPOSE:To manufacture the nonoriented silicon steel sheet having excellent surface properties by subjecting a continuously cast slab having specified compsn. constituted of C, Si, Mn, Al, S, P, B and Fe to specified hot rolling and annealing and thereafter executing cold rolling and final annealing. CONSTITUTION:A continuously cast slab constituted of, by weight, <=0.005% C, 1.2 to 3.5% Si, 0.1 to 0.5% Mn, 0.1 to 2.0% Al, <0.005% S, 0.001 to 0.1% P and 0.001 to 0.01% B (furthermore <=4.0% Si+Al, exp (0.6Si+Al-4.7)<=P+10B are satisfied) and the balance Fe with inevitable impurities is subjected to hot rolling at 1050 to 1200 deg.C slab-heating temp., 750 to 850 deg.C finish temp. and <=620 deg.C coiling temp. The obtd. steel strip is annealed so that the unrecrystallized ferritic region in the direction of sheet thickness is regulated to <=30%. After that, the steel strip is subjected to cold rolling and final annealing. In this way, the nonoriented silicon steel sheet having excellent magnetic properties and excellent surface properties free from ridging can be obtd.