Abstract: A steel having few alumina clusters prepared by casting liquid steel deoxidized with Al, with the addition of one or more rare-earth metals (REM) selected from the group of Ce, La, Pr and Nd in which: (a) The REM-oxide-content in oxide-based inclusions consisting mainly of alumina and REM-oxides is 0.5 to 15 mass % of said oxide-based inclusions, or (b) The mass ratio of total REM to total oxygen (T.O.), REM/T.O., in liquid steel is not less than 0.05 and not more than 0.5, in addition to (a), or (c) The total REM-content is not less than 0.1 ppm and less than 10 ppm and the dissolved-REM-content is less than 1 ppm.

Abstract: A steel having few alumina clusters prepared by casting liquid steel deoxidized with Al, with the addition of one or more rare-earth metals (REM) selected from the group of Ce, La, Pr and Nd in which: (a) The REM-oxide-content in oxide-based inclusions consisting mainly of alumina and REM-oxides is 0.5 to 15 mass % of said oxide-based inclusions, or (b) The mass ratio of total REM to total oxygen (T.O.), REM/T.O., in liquid steel is not less than 0.05 and not more than 0.5, in addition to (a), or (c) The total REM-content is not less than 0.1 ppm and less than 10 ppm and the dissolved-REM-content is less than 1 ppm.

Abstract: An iron scrap having a composition comprising iron and iron-soluble elements in the sum of 100 mass %, and containing Cu, elements of the Groups IIIa, VIII, Ib, IIb, IIIb, IVb and Vb having affinity with Cu, and unavoidable impurities, is melted in an oxygen-containing atmosphere. A predetermined amount of C, and whenever necessary, a predetermined amount of at least one of Cr and Mo and/or a predetermined amount of at least one of Mn, V and Ti, are added to the molten steel. The molten iron is then separated into an Fe-enriched layer and a Cu-enriched layer under the molten state. Cu and the above elements having affinity with Cu are separated and precipitated into the Cu-enriched layer by utilizing the difference of the specific gravity between the layers. According to this method, impurity elements detrimental to the stable production of a steel material having a homogeneous property, such as Cu, Sn, etc., can be removed economically and efficiently when the iron scrap is recycled.

Abstract: A casting C obtained by solidification of molten metal by using a pair of water cooled casting rolls 2a, 2b is subjected to temperature adjustment in a temperature zone so that an austenite structure exists in its matrix. Thereafter, the casting is rolled by an in-line rolling mill 5 at a temperature ranging from 850.degree. C. to less than 1,350.degree. C. and at a reduction of 5 to 50%. In this way, overall variance of elongation of the steel material is kept within 5% in terms of the standard deviation.

Abstract: The present invention provides a thin cast strip or a thin steel sheet having good cast strip properties and mechanical properties from a molten steel containing a large amount of iron scrap containing Cu and Sn. The thin cast strip or thin steel sheet is characterized by being a thin cast strip or thin steel sheet of a common carbon steel comprising 0.15 to 10% by weight of Cu and 0.03 to 0.5% by weight of Sn, the primary dendrite spacing on a surface layer portion being in the range of from 5 to 100 .mu.m.

Abstract: An Fe-Cu alloy sheet manufactured by a thin plate continuous casting method so as to be used as a material of electronic and magnetic parts. The alloy sheet has an alloy structure of high uniformity which contains 20 to 90% Cu, 1 to 10% Cr, 0 to 10% Mo, and one or more of alloying elements selected from the group consisting of Al, Sc, Y, La, Si, Ti, Zr and Hf whose amount or total amounts are not less than a calcualtion value of the following equation and not more than 10%, the balance being essentially Fe: ##EQU1## wherein .alpha.=1,.beta.=51-(%Cu) (in the case where Cu=20 to 50%),.beta.=-19 +0.4 (% Cu) (in the case where Cu=50 to 90%).Boron and/or carbon take substantially the same effects as the above-mentioned elements such as Al.

Abstract: In a continuous casting process in a twin-roll system, a gap is provided between end faces of cooling rolls and side gates or between the circumferential surface of the cooling rolls and side faces of the side gates. A DC magnetic field is applied to the molten metal in a pouring basin in the vicinity of the side gates in a vertical direction to the molten metal and direct current (DC) is intensively fed to the end portion of the molten metal to generate an electromagnetic force mainly at a corner portion of the molten metal. The electromagnetic force is directed toward the center portion of the molten metal, and thereby prevents leakage of molten metal from the gap, penetration into the gap or the formation of hot bands. In order to intensively feed the direct current to the end portion of the molten metal, an electrode is placed in sliding contact with the end face of the cooling roll.

Abstract: A twin roll-type sheet continuous casting apparatus includes a nozzle for supplying molten metal; a pair of casting rolls for casting the molten metal supplied from the nozzle into a sheet, the casting rolls being horizontally disposed in parallel relation to each other, being cooled, and rotated in opposite directions, respectively; a coiler; and a support sheet extending generally horizontally below the pair of casting rolls for receiving the cast sheet and transferring it to the coiler, and being taken up by the coiler along with the cast sheet placed therein. Since tension is not applied to the cast sheet, even a brittle material can be continuously cast into a sheet. Also, a dummy sheet requested for starting the casting of the sheet becomes unnecessary, and even when a rupture of the sheet occurs, the apparatus can be continuously operated without stopping the operation.

Abstract: A method of manufacturing an austenitic stainless steel sheet having reduced minute surface concavities and convexties ropings and gloss unevenness and a manufacturing system for carrying out the same are provided. The method comprises (a) a casting process of casting a molten austenitic (.gamma.) stainless steel into a thin cast plate by a twin-roll thin plate casting method employing a pair of cooled rolls disposed opposite to each other, (b) a cooling process of cooling the cast thin plate in a single phase state of the .gamma. phase, (c) a cast plate in a dual phase state of the .delta. and .gamma. phase or a single phase state of the .delta. phase and then cooling the thin cast plate to restore the single phase state of the .gamma. phase, and (d) a cold-rolling process of cold-rolling the heat-treated thin cast plate.

Abstract: MnS is finely dispersed and precipitated in a steel, and the steel obtained has highly improved characteristics such as HAZ toughness, cold cracking resistance, and corrosion resistance. This steel is obtained by continuously casting a component-adjusted molten steel having a dissolved oxygen concentration of 20 to 60 ppm and containing 0.01 to 0.05% by weight of a deoxidizing element, at a specific cooling rate.

Abstract: In a method for controlling solidification segregation in casting of carbon steel containing 0.53 wt. % or less of carbon, .alpha.-phase stabilizing elements and .gamma.-phase stabilizing elements of the carbon steel are separated from each other at inter-dendritic portions by adding 2 wt. % or less of at least one element selected from the group consisting of Be, Cr, Nb, Sn, Ti, Mo, and V into the molten steel.

Abstract: The .alpha.-stabilizing element, e.g. P, and the .gamma.-stabilizing element, e.g. Mn, do not segregate at an identical site of a casting. Castings are cooled at a rate of 40.degree. C./min or less in a temperature range of the peritectic reaction and/or the Ar.sub.4 transformation, thereby condensing P and Mn into .delta. and .gamma. phases, respectively.