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 method for producing a metal ingot by using an electron-beam melting furnace having an electron gun and a hearth that accumulates a molten metal of a metal raw material, wherein the metal raw material is supplied to the position on a supply line disposed along a second side wall of the hearth that accumulates the molten metal of the metal raw material. A first electron beam is radiated along a first irradiation line that is disposed along the supply line and is closer to a central part of the hearth relative to the supply line on the surface of the molten metal, wherein a surface temperature (T2) of the molten metal at the first irradiation line is made higher than an average surface temperature (T0) of the entire surface of the molten metal in the hearth.

Grain size of a deliverable metal product can be improved by pre-setting recrystallization-suppressing dispersoids during casting. The outer regions of a direct chill cast embryonic ingot can undergo reheating before casting is complete. Through unique wiper placement and/or other reheating techniques, the temperature of the ingot can be permitted to reheat (e.g., up to approximately 410° C. to approximately 420° C.), allowing dispersoids to form. Stirring and/or agitation of the molten sump can facilitate formation of a deeper sump and desirably fine grain size as-cast. The formation of dispersoids during and/or immediately after casting can pin the grain boundaries at the desirably fine grain size, encouraging the same grain sizes even after a later recrystallization and/or solutionizing step.

Apparatus to control continuous casting, including a mold provided with at least one entrance end through which liquid metal is introduced. Furthermore, the apparatus to control continuous casting includes at least one electromagnetic brake associated with the mold, configured to induce in the liquid metal recirculation flows, and a control and command unit connected at least to the electromagnetic brake and configured to manage the functioning thereof.

Systems and methods may utilize magnetic rotors to heat molten metal in the corner regions of a mold during casting (e.g., casting of an ingot, billet, or slab). The magnetic rotors are positioned adjacent to the corners of the mold and heat the molten metal in the corner region to increase the temperature of the molten metal adjacent the corners. The increased temperature of the molten metal in the mold corners can prevent intermetallics from forming in the molten metal or otherwise reduce such formation.

A tundish upper nozzle structure and a continuous casting method make it possible to cause inclusions to float within a tundish. A flange-shaped member having an outside dimension greater than that of an upper end of a tundish upper nozzle is provided along a part or the entirety of the circumference of the upper end of the tundish upper nozzle, and one or more gas discharge holes are provided in one or more of the following surfaces: a lower surface, an outer peripheral surface and a top surface of the flange-shaped member, and a region of an outer peripheral surface of the tundish upper nozzle below the flange-shaped member. A length in the tundish upper nozzle structure is adjusted to cause almost all gas to float upwardly, or to adjust the flow rate of gas flowing downwardly toward the inner bore of the tundish upper nozzle, and the flow rate of gas floating upwardly.

A tundish upper nozzle structure and a continuous casting method make it possible to cause inclusions to float within a tundish. A flange-shaped member having an outside dimension greater than that of an upper end of a tundish upper nozzle is provided along a part or the entirety of the circumference of the upper end of the tundish upper nozzle, and one or more gas discharge holes are provided in one or more of the following surfaces: a lower surface, an outer peripheral surface and a top surface of the flange-shaped member, and a region of an outer peripheral surface of the tundish upper nozzle below the flange-shaped member. A length in the tundish upper nozzle structure is adjusted to cause almost all gas to float upwardly, or to adjust the flow rate of gas flowing downwardly toward the inner bore of the tundish upper nozzle, and the flow rate of gas floating upwardly.

The invention relates to a method for manufacturing a metal ingot by continuous casting, comprising the following steps: S1: melting the metal, S2: transferring the liquid metal (2) by pouring it into a crucible (12), S3: moving the base plate (14) of the crucible (12), S4: progressive solidification of the liquid metal (2) from the base plate (14) of the crucible (12), and S5: during the step S3 of moving the base plate (14), applying a compression force to the metal (3) which is present between the base plate (14) and the side wall (13), the compression force being applied along a second axis (X2) parallel to the first axis (X1) so as to deform the metal and to obtain an ingot (3) which has a smaller width (L2).

A hot-pressed member having excellent bending collapsibility, a method for manufacturing the same, and a method for manufacturing a steel sheet for the hot-pressed member. The hot-pressed member includes a steel sheet as a base material, the steel sheet having a specified chemical composition. The hot-pressed member has a microstructure in which a martensite microstructure is present in a volume fraction of 70% or greater, and a number density of inclusions having a longest diameter of 25 μm or greater is 0.02/mm.sup.2 or less. The hot-pressed member has a tensile strength of 1.8 GPa or greater.

The present invention provides a method for casting a slab having a good cast surface. The method includes heating the surface of molten metal on a metal inlet side of a mold by a first heat source so that the following formulas: q≧0.87 and c≦11.762q+0.3095 are satisfied where c is a cycle time [sec] of turning movement of the first heat source, and q is an average amount of heat input [MW/m.sup.2] determined by accumulating an amount of heat input applied by at least the first heat source to the contact region between the upper surface of the slab on the metal inlet side and the mold, along the path of turning movement of the first heat source, and dividing the resultant accumulated value by the cycle time c.