Device (10) and method for winding/unwinding rolled products (20). The device (10) is interposed between a rolling unit located upstream (102) and a rolling unit located downstream (105). The device (10) comprises a heating furnace (11) and a support structure (16) disposed outside the heating furnace (11). On the support structure (16), substantially in a diametrically opposite position, two winding/unwinding drums (18a, 18b) are assembled, positioned inside the furnace (11). The support structure (16) is selectively rotating to alternatively dispose a first of the two drums (18a or 18b) in its winding position or in its unwinding position of a reel (29). A second of the two drums (18b or 18a) consequently assuming the opposite unwinding or winding position.

Disclosed is a continuous thermal treatment line for a steel strip. The strip passes through consecutive thermal treatment chambers, is quickly cooled in at least one of the chambers by spraying liquid onto the strip, or by spraying a fluid made up of gas and liquid or spraying a combination of gas and liquid forming a mist. After quick cooling, a protective metal layer is deposited on the strip by dip coating. The cooling fluid strips iron oxides or other alloy elements contained in the steel to be treated, minimizing oxidation and reducing the oxides on the strip. Spray pressure and distance are chosen to facilitate the stripping property and the mechanical action of the sprayed fluid, reducing the layer of oxides on the strip. The temperature of the strip at the end of the cooling step is the temperature necessary for carrying out the desired treatment cycle.

Disclosed is a continuous thermal treatment line for a steel strip. The strip passes through consecutive thermal treatment chambers, is quickly cooled in at least one of the chambers by spraying liquid onto the strip, or by spraying a fluid made up of gas and liquid or spraying a combination of gas and liquid forming a mist. After quick cooling, a protective metal layer is deposited on the strip by dip coating. The cooling fluid strips iron oxides or other alloy elements contained in the steel to be treated, minimizing oxidation and reducing the oxides on the strip. Spray pressure and distance are chosen to facilitate the stripping property and the mechanical action of the sprayed fluid, reducing the layer of oxides on the strip. The temperature of the strip at the end of the cooling step is the temperature necessary for carrying out the desired treatment cycle.

Provided is a method of easily producing a non-oriented electrical steel sheet that contains substantially no Al and contains large amounts of Si and Mn and has low iron loss, comprising hot rolling a slab having a specified chemical composition to obtain a hot-rolled sheet; coiling the hot-rolled sheet; cold rolling the hot-rolled sheet once or twice with intermediate annealing being performed therebetween, to obtain a cold-rolled sheet; and subjecting the cold-rolled sheet to final annealing, wherein the hot-rolled sheet after the hot rolling is cooled at an average cooling rate from 800° C. to 650° C. of 30° C./s or more, and thereafter the coiling is performed at 650° C. or less.

Provided is a method of easily producing a non-oriented electrical steel sheet that contains substantially no Al and contains large amounts of Si and Mn and has low iron loss, comprising hot rolling a slab having a specified chemical composition to obtain a hot-rolled sheet; coiling the hot-rolled sheet; cold rolling the hot-rolled sheet once or twice with intermediate annealing being performed therebetween, to obtain a cold-rolled sheet; and subjecting the cold-rolled sheet to final annealing, wherein the hot-rolled sheet after the hot rolling is cooled at an average cooling rate from 800° C. to 650° C. of 30° C./s or more, and thereafter the coiling is performed at 650° C. or less.

The present invention provides a steel product that has excellent oxidation resistance on a surface thereof that is to come into contact with a steel material and that also has excellent weldability. The steel product for use in contact with a steel material according to the present invention is a steel product for use in contact with a steel material, the steel product including a centrifugally-cast portion formed on a surface of the steel product that is to come into contact with the steel material, the centrifugally-cast portion being made through centrifugal casting, and a statically-cast portion to which the centrifugally-cast portion is welded, the statically-cast portion being formed through static casting, the centrifugally-cast portion containing, in terms of mass %, C: 0.2% to 0.7%; Si: more than 0% and 2.0% or less; Mn: more than 0% and 3.0% or less; Cr: 15.0% to 40.0%; Ni: 18.0% to 55.0%; Al: 1.0% to 5.5%; and at least one type selected from the group consisting of Ti: 0.01% to 0.6% and/or Nb: 0.1% to 1.8%, the balance being composed of Fe and inevitable impurities.

The present invention provides a steel product that has excellent oxidation resistance on a surface thereof that is to come into contact with a steel material and that also has excellent weldability. The steel product for use in contact with a steel material according to the present invention is a steel product for use in contact with a steel material, the steel product including a centrifugally-cast portion formed on a surface of the steel product that is to come into contact with the steel material, the centrifugally-cast portion being made through centrifugal casting, and a statically-cast portion to which the centrifugally-cast portion is welded, the statically-cast portion being formed through static casting, the centrifugally-cast portion containing, in terms of mass %, C: 0.2% to 0.7%; Si: more than 0% and 2.0% or less; Mn: more than 0% and 3.0% or less; Cr: 15.0% to 40.0%; Ni: 18.0% to 55.0%; Al: 1.0% to 5.5%; and at least one type selected from the group consisting of Ti: 0.01% to 0.6% and/or Nb: 0.1% to 1.8%, the balance being composed of Fe and inevitable impurities.

Provided is a non-oriented electrical steel sheet that contains substantially no Al and contains large amounts of Si and Mn and has low iron loss, comprising a chemical composition containing C: 0.0050% or less, Si: 2.0% or more and 6.0% or less, Mn: 1.0% or more and 3.0% or less, P: 0.20% or less, S: 0.0050% or less, N: 0.0050% or less, Al: 0.0050% or less, and one or more selected from B: 0.0001% or more and 0.0050% or less, Nb: 0.0001% or more and 0.0050% or less, and V: 0.0005% or more and 0.0500% or less, with a balance consisting of Fe and inevitable impurities, wherein a number density of Si—Mn nitrides with an average diameter of 50 nm or more and 500 nm or less is 1 or less per μm.sup.3.

Provided is a non-oriented electrical steel sheet that contains substantially no Al and contains large amounts of Si and Mn and has low iron loss, comprising a chemical composition containing C: 0.0050% or less, Si: 2.0% or more and 6.0% or less, Mn: 1.0% or more and 3.0% or less, P: 0.20% or less, S: 0.0050% or less, N: 0.0050% or less, Al: 0.0050% or less, and one or more selected from B: 0.0001% or more and 0.0050% or less, Nb: 0.0001% or more and 0.0050% or less, and V: 0.0005% or more and 0.0500% or less, with a balance consisting of Fe and inevitable impurities, wherein a number density of Si—Mn nitrides with an average diameter of 50 nm or more and 500 nm or less is 1 or less per μm.sup.3.

A steel sheet has a composition containing, by mass %, C: 0.04% to 0.20%, Si: 0.6% to 1.5%, Mn: 1.0% to 3.0%, P: 0.10% or less, S: 0.030% or less, Al: 0.10% or less, N: 0.010% or less, one, two, or all of Ti, Nb, and V in an amount of 0.01% to 1.0% each, and the balance being Fe and inevitable impurities, a microstructure including, in terms of area ratio, 50% or more of ferrite, in which an average grain diameter at a position located 50 μm from a surface of the steel sheet in a thickness direction is 3000×(tensile strength TS (MPa)).sup.−0.85 μm or less, C precipitates having a grain diameter of less than 20 nm formed in steel is 0.010 mass % or more, and a amount of precipitated Fe is 0.03 mass % to 1.0 mass %, and a roughness Ra of 3.0 μm or less.