Abstract: The present invention has as objective a procedure for the oriented-grain magnetic sheet that provides particular operative hot rolling mill conditions of silicon steel slabs, by means which it is possible to highly contain the heterogeneities of hot rolled sheet re-crystallization. The use of these operative conditions permits to reduce the growing tendency of the crystallized grain during the annealing of the sheets at a final thickness that precedes the secondary oriented re-crystallization. Contemporarily, the particular operational conditions of hot rolling mill according to the invention permit a fine precipitation of secondary phases useful to the control of the grain growing, starting from a quantity of sulphur (S) and nitrogen (N) in matrix lower than corresponding provided by the conventional technologies and consequently disposable in metallic solid solution before the rolling after the heating of the slabs at temperature values lower than 1300° C.

Abstract: 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 1150° C.

Abstract: The present invention has as objective a procedure for the oriented-grain magnetic sheet that provides particular operative hot rolling mill conditions of silicon steel slabs, by means which it is possible to highly contain the heterogeneities of hot rolled sheet re-crystallization. The use of these operative conditions permits to reduce the growing tendency of the crystallized grain during the annealing of the sheets at a final thickness that precedes the secondary oriented re-crystallization. Contemporarily, the particular operational conditions of hot rolling mill according to the invention permit a fine precipitation of secondary phases useful to the control of the grain growing, starting from a quantity of sulphur (S) and nitrogen (N) in matrix lower than corresponding provided by the conventional technologies and consequently disposable in metallic solid solution before the rolling after the heating of the slabs at temperature values lower than 1300° C.

Abstract: Process for the production of grain-oriented magnetic sheets, wherein a slab made of steel having a thickness of ?100 mm, containing Si in the range comprised between 2.5 and 3.5% by weight, is subjected to a thermo-mechanical cycle comprising the following operations:—optional first heating to a temperature T1 no higher than 1250° C.·first rough hot-rolling, in a first rough hot rolling mill, to a temperature T2 comprised between 900 and 1200° C., the reduction ratio (% Rid) applied to the first rough hot-rolling being adjusted so as to be:—of at least 80%, in the absence of a subsequent heating to a temperature T3—determined by the following relationship % Rid=80 (T3?T2)/5, in the presence of a subsequent heating to a temperature T3—optional second heating to a temperature T3 >T2·second finishing hot-rolling, in a second fmishing hot rolling mill, to a temperature T4<T3 to a thickness of the rolled section comprised in the range of 1.5 mm-3.

Abstract: A process for the production of grain oriented electrical Fe—Si strips in which a Si-containing alloy is directly cast as a strip between 2.5-5.0 mm thick and cold rolled in one stage, or in more stages with intermediate annealing, to a final thickness of between 0.15-1.0 mm. The strip is then continuously annealed to carry out the primary recrystallization and then annealed to carry out the oriented secondary recrystallization. The process further includes that after solidification of the strip, and before its coiling, a phase transformation from Ferrite to Austenite is induced into the metal matrix for a volume fraction between 25-60%, obtained by controlling the alloy composition so that the Austenite fraction is allowed within the stability equilibrium between the two phases. The strip is then deformed by rolling in-line with the casting step to obtain a deformation higher than 20% in the temperature interval 1000-1300° C.

Abstract: In the production of electrical steel strips, a special islab-reheating treatment before hot rolling is carried out so that the maximum temperature within the furnace is reached by the slab well before its extraction from the furnace. During the heating stage and performance at the highest temperatures of the thermal cycle, second phase particles are dissolved and segregated elements are distributed in the metallic matrix, while during cooling and temperature equalising steps of the slab in the furnace a controlled amount of small second phases particles are more homogeneously re-precipitated from the metallic matrix. Differently from all the conventional processes for the production of electrical steels, the slab reheating furnace become a site in which it is performed the precipitation of a controlled amount of second phases particles for the necessary grain growth control during the successive process steps.

Abstract: The present invention refers to a process for the production of electrical steel strips, in which a strip directly cast from molten steel and containing alloy elements apt to generate a precipitation of sulphides and/or nitrides apt to inhibit the grain growth, is hot rolled in-line with the casting operation, at a temperature comprised between (1250) and (1000)° C., and in which said strip is coiled after hot rolling at a temperature of less than (780)° C. if sulphides are utilised, or at a temperature of less than (600)° if nitrides, or nitrides plus sulphides, are utilised. A final product is thus obtained having excellent and constant magnetic properties.

Abstract: Process for the production of oriented grain electrical steel strips, in which a silicon steel, comprising at least 30 ppm of S, is directly cast as strip 1.5-4.5 mm thick and cold rolled to a final thickness of between 1.0 and 0.15 mm; characterised by the following staged: Cooling and deformation of the solidified strip to obtain a second phases distribution in which 600 cm−1<Iz<1500 cm−1 and Iy=1.9 Fv/r (cm−1), Fv being the volume fraction of second phases stable at temperatures of less than 800° C., and r being the precipitates mean radius, in cm.; Hot rolling between solidification and coiling of the strip at a temperature of not less than 750° C., with a reduction ratio of between 15 and 60%; Cold rolling with reduction ratio of 60-92%; Cold rolled strip annealing at 750-1100° C., with increase of the nitrogen content of at least 30 ppm with respect to the initial composition at the strip core, in nitriding atmosphere.