GRAIN ORIENTED STEEL STRIP WITH HIGH MAGNETIC CHARACTERISTICS, AND MANUFACTURING PROCESS OF THE SAME

摘要

A method for the production of hot-rolled steel strip comprising the following steps : - providing a steel slab comprising, in weight percentages : Si : 2.5 to 3.5%, C : 0.05 to 0.1 %, Mn : 0:05 to 0.1 %, Als : 0.015 to 0.026%, N : 0.0050 to 0.0100%, and further comprising S and/or Se so that S+ (32/79) Se is in an amount of 0.018 to 0.030 %, and optionally comprising one or more elements chosen among Sb in an amount of 0.015 to 0.035%, Cu in an amount of 0.08% to 0.25%, Sn in an amount of 0.06% to 0.15%, P in an amount of 0.005% to 0.015%, the balance being iron and unavoidable impurities, - reheating said slab to a temperature between 1300°C and 1430°C, - roughing hot-rolling said slab to produce a blank having a thickness below 50 mm, - finishing hot-rolling of said blank to produce a hot rolled strip in three rolling passes or more, the temperature of said blank during the first pass being above 1 150°C and at least one rolling pass being performed with a reduction of 40% or more and being immediately followed by a holding of more than 20 sec, the average interpass holding temperature Tav being settled between 1000 and 1200°C, the total finishing hot rolling time t being controlled so that the value of Tav for any portion of said strip further respects the under mentioned equation : Tav > T1 + a1(t-78) [eq. 1 ] with T1= 992.2 + 1493(Als) and a1=1.204 + 24.9(Als), Tav and being expressed in °C, t in seconds and Als in weight %, - cooling of said hot-rolled strip from the finish rolling temperature to a temperature below 600°C in less than 10 sec and - coiling of said hot-rolled strip.