Provided is a method of, in ladle refining treatment of a molten steel, accurately estimating the molten steel temperature after the ladle refining treatment. An operation method of ladle refining treatment by which ladle refining treatment of a molten steel is performed while continuously measuring a molten steel temperature during operation of the ladle refining treatment of the molten steel comprises setting a time earlier than a scheduled ending time of the ladle refining treatment in a continuous measurement period of the molten steel temperature as a determination timing, and estimating the molten steel temperature at the scheduled ending time on the basis of a change with time of the molten steel temperature in continuous measured data of the molten steel temperature from a start of continuous measurement of the molten steel temperature to the determination timing.

Disclosed is a continuous rapid solidification apparatus, which comprises a cooling roll configured to cool a molten metal supplied to an outer circumference surface thereof; a crucible configured to supply the cooling roll with the molten metal; a molten metal supply configured to melt a raw material metal and supply the crucible with the molten metal; a first chamber configured to form a sealed space where the molten metal supplied from the crucible is cooled by the cooling roll; and a second chamber configured to be formed of a space separated from the first chamber and to form a sealed space where the molten metal is supplied to the crucible by the molten metal supply.

Disclosed is a continuous rapid solidification apparatus, which comprises a cooling roll configured to cool a molten metal supplied to an outer circumference surface thereof; a crucible configured to supply the cooling roll with the molten metal; a molten metal supply configured to melt a raw material metal and supply the crucible with the molten metal; a first chamber configured to form a sealed space where the molten metal supplied from the crucible is cooled by the cooling roll; and a second chamber configured to be formed of a space separated from the first chamber and to form a sealed space where the molten metal is supplied to the crucible by the molten metal supply.

Disclosed is a continuous rapid solidification apparatus, which comprises a cooling roll configured to cool a molten metal supplied to an outer circumference surface thereof; a crucible configured to supply the cooling roll with the molten metal; and two or more molten metal supplies configured to melt raw material metal and sequentially supply the crucible with the molten metal.

A method for manufacturing carbon fiber reinforced aluminum composites is provided. Particularly, the method uses a stir casting process during a melting and casting process and reduces a contact angle of carbon against aluminum by inputting carbon fibers while supplying a current to liquid aluminum to induce the carbon fibers to be spontaneously and uniformly distributed in the liquid aluminum and inhibits a formation of an aluminum carbide (Al.sub.4C.sub.3) phase on an interface between the aluminum and the carbon fiber, thereby manufacturing carbon fiber reinforced aluminum composites having excellent electrical, thermal and mechanical characteristics.

A method for manufacturing carbon fiber reinforced aluminum composites is provided. Particularly, the method uses a stir casting process during a melting and casting process and reduces a contact angle of carbon against aluminum by inputting carbon fibers while supplying a current to liquid aluminum to induce the carbon fibers to be spontaneously and uniformly distributed in the liquid aluminum and inhibits a formation of an aluminum carbide (Al.sub.4C.sub.3) phase on an interface between the aluminum and the carbon fiber, thereby manufacturing carbon fiber reinforced aluminum composites having excellent electrical, thermal and mechanical characteristics.

Provided are a high-strength steel sheet having a specified chemical composition, in which a Mn-segregation degree in a region within 100 m from a surface thereof in a thickness direction is 1.5 or less, in a plane parallel to the surface of the steel sheet in a region within 100 m from the surface of the steel sheet in the thickness direction, the number of oxide-based inclusion grains having a grain long diameter of 5 m or more is 1000 or less/100 mm.sup.2, a proportion of the number of oxide-based inclusion grains having a chemical composition containing alumina of 50 mass % or more, silica of 20 mass % or less, and calcia of 40 mass % or less to the total number of oxide-based inclusions having a grain long diameter of 5 m or more is 80% or more, a specified metallographic structure, and a TS of 980 MPa or more, a high-strength galvanized steel sheet, and a manufacturing method thereof.

Provided are a high-strength steel sheet having a specified chemical composition, in which a Mn-segregation degree in a region within 100 m from a surface thereof in a thickness direction is 1.5 or less, in a plane parallel to the surface of the steel sheet in a region within 100 m from the surface of the steel sheet in the thickness direction, the number of oxide-based inclusion grains having a grain long diameter of 5 m or more is 1000 or less/100 mm.sup.2, a proportion of the number of oxide-based inclusion grains having a chemical composition containing alumina of 50 mass % or more, silica of 20 mass % or less, and calcia of 40 mass % or less to the total number of oxide-based inclusions having a grain long diameter of 5 m or more is 80% or more, a specified metallographic structure, and a TS of 980 MPa or more, a high-strength galvanized steel sheet, and a manufacturing method thereof.

Disclosed is a continuous rapid solidification apparatus, which includes a cooling roll configured to cool a molten metal supplied to an outer circumference surface thereof; a crucible configured to supply the cooling roll with the molten metal; and two or more molten metal supplies configured to melt raw material metal and alternately supply the crucible with the molten metal.

Disclosed is a continuous rapid solidification apparatus, which includes a cooling roll configured to cool a molten metal supplied to an outer circumference surface thereof; a crucible configured to supply the cooling roll with the molten metal; and two or more molten metal supplies configured to melt raw material metal and alternately supply the crucible with the molten metal.