A primary object of the present invention is to provide a technique of avoiding occurrence of surface defects caused by an electromagnetic brake while checking internal defects with this electromagnetic brake, so that cleanliness of a cast steel can be improved compared with prior arts, and the present invention provides a method for continuously casting steel, the method comprising supplying molten steel into a mold while applying an electromagnetic brake to an outlet flow discharged from an outlet port of an immersion nozzle, wherein magnetic flux density (B) of the electromagnetic brake is within a range of the following (Formula 1):

[00001]$\begin{array}{cc}{B}_{\min }\le B\le B_{\max },.Math.B_{\min }=\frac{800.Math.{\left(\frac{D_{\max }}{D_0}\right)}^3.Math.\left(\frac{H_{\mathrm{SEN}}}{H_0}\right)}{\left(v.Math.\sin .Math..Math.\theta \right)},\mathrm{and}.Math..Math.B_{\max }=\frac{3000.Math.{\left(\frac{D_{\max }}{D_0}\right)}^3.Math.\left(\frac{H_{\mathrm{SEN}}}{H_0}\right)}{{\left(v.Math.\sin .Math..Math.\theta \right)}^2}.& \left(\mathrm{Formula}.Math..Math.1\right)\end{array}$

A primary object of the present invention is to provide a technique of avoiding occurrence of surface defects caused by an electromagnetic brake while checking internal defects with this electromagnetic brake, so that cleanliness of a cast steel can be improved compared with prior arts, and the present invention provides a method for continuously casting steel, the method comprising supplying molten steel into a mold while applying an electromagnetic brake to an outlet flow discharged from an outlet port of an immersion nozzle, wherein magnetic flux density (B) of the electromagnetic brake is within a range of the following (Formula 1):

[00001]$\begin{array}{cc}{B}_{\min }\le B\le B_{\max },.Math.B_{\min }=\frac{800.Math.{\left(\frac{D_{\max }}{D_0}\right)}^3.Math.\left(\frac{H_{\mathrm{SEN}}}{H_0}\right)}{\left(v.Math.\sin .Math..Math.\theta \right)},\mathrm{and}.Math..Math.B_{\max }=\frac{3000.Math.{\left(\frac{D_{\max }}{D_0}\right)}^3.Math.\left(\frac{H_{\mathrm{SEN}}}{H_0}\right)}{{\left(v.Math.\sin .Math..Math.\theta \right)}^2}.& \left(\mathrm{Formula}.Math..Math.1\right)\end{array}$

Process control of intense stirring along a solidification front and adjustments in casting speeds during direct chill casting of 7xxx series alloys can decrease an ingot’s cracking susceptibility. Intense stirring control is used to reduce the thickness of the solidification front, promote agglomeration of hydrogen gas rejected at the solidification front, remove impurities rejected at the solidification front, and improve grain size. Intense stirring control is used to operate at faster casting speeds without risk of increasing the thickness of the solidification front. Optional reheating during casting to promote dispersoid formation is used to generate a high-strength zone of dispersoid-strengthened solidified metal in the outer periphery of the ingot, which can further decrease the ingot’s susceptibility to cracking.

A continuous casting method includes, conveying a cast slab from a casting mold, stirring a non-solidified portion in the cast slab with a first electromagnetic stirring device, stirring the non-solidified portion with a second electromagnetic stirring device disposed downstream of the first electromagnetic stirring device in a conveyance direction of the cast slab, and subsequently, rolling the cast slab with a reduction roll, in which, the first electromagnetic stirring device alternately imparts the cast slab with electromagnetic force in one direction to cause the non-solidified portion to flow toward one width direction side of the cast slab at a flow rate of at least 5 cm/s, and with electromagnetic force in another direction to cause the non-solidified portion to flow toward another width direction side of the cast slab at a flow rate of at least 5 cm/s.

A continuous casting method includes, conveying a cast slab from a casting mold, stirring a non-solidified portion in the cast slab with a first electromagnetic stirring device, stirring the non-solidified portion with a second electromagnetic stirring device disposed downstream of the first electromagnetic stirring device in a conveyance direction of the cast slab, and subsequently, rolling the cast slab with a reduction roll, in which, the first electromagnetic stirring device alternately imparts the cast slab with electromagnetic force in one direction to cause the non-solidified portion to flow toward one width direction side of the cast slab at a flow rate of at least 5 cm/s, and with electromagnetic force in another direction to cause the non-solidified portion to flow toward another width direction side of the cast slab at a flow rate of at least 5 cm/s.

A molten metal purification device for purifying molten metal flowing through a flow body having a flow path formed by a pair of opposed side walls and a bottom wall. The device includes internal and external members provided inside and outside the flow body, respectively. The internal member includes an electrode body provided inside the path made of a conductive member and has a pair of opposed electrodes provided in the path where current flows across the electrodes through the molten metal and a non-conductive filter. The external member is configured as a magnetic field device having an upper surface side magnetized to an N or S pole and disposed below the flow body. Lines of magnetic force coming out from the N pole or entering the S pole intersect with the current to generate Lorentz force for driving the molten metal along a flowing direction in the path.

A molten metal purification device for purifying molten metal flowing through a flow body having a flow path formed by a pair of opposed side walls and a bottom wall. The device includes internal and external members provided inside and outside the flow body, respectively. The internal member includes an electrode body provided inside the path made of a conductive member and has a pair of opposed electrodes provided in the path where current flows across the electrodes through the molten metal and a non-conductive filter. The external member is configured as a magnetic field device having an upper surface side magnetized to an N or S pole and disposed below the flow body. Lines of magnetic force coming out from the N pole or entering the S pole intersect with the current to generate Lorentz force for driving the molten metal along a flowing direction in the path.

Electromagnetic stirring device in a mould for casting aluminium or aluminium alloys, wherein the electromagnetic stirring device has a winding core of conductive coils intended for the circulation of a current generating an electromagnetic field of stirring of the molten metal inside the mould. A mould, casting machine and casting plant provided with such an electromagnetic stirring device are also provided. A stirring method in a mould for casting aluminium or aluminium alloys is disclosed, including a phase of supply of phase-shifted currents on an electromagnetic stirring device in a mould.

Electromagnetic stirring device in a mould for casting aluminium or aluminium alloys, wherein the electromagnetic stirring device has a winding core of conductive coils intended for the circulation of a current generating an electromagnetic field of stirring of the molten metal inside the mould. A mould, casting machine and casting plant provided with such an electromagnetic stirring device are also provided. A stirring method in a mould for casting aluminium or aluminium alloys is disclosed, including a phase of supply of phase-shifted currents on an electromagnetic stirring device in a mould.

The present invention discloses a wire rod for an ultrahigh-strength steel cord and a manufacturing method thereof. The manufacturing method includes: smelting molten steel where inclusions in sizes ≥5 μm are at a number density ≤0.5/mm.sup.2 and sizes of inclusions are ≤30 μm; casting the molten steel into an ingot blank with a center carbon segregation value of 0.92-1.08; cogging the ingot blank into an intermediate blank with a center carbon segregation value of 0.95-1.05; rolling the intermediate blank into a wire rod; and performing temperature control cooling on the wire rod to obtain a wire rod with high purity, high homogeneity and tensile strength ≤1,150 MPa. The wire rod may be used for an ultrahigh-strength steel cord with single tensile strength ≥3,600 MPa.