A spot welded joint of at least two steel sheets is provided. At least one of the steel sheets presents yield strength above or equal to 600 MPa, an ultimate tensile strength above or equal to 1000 MPa, uniform elongation above or equal to 15%. The base metal chemical composition includes 0.05≤C≤0.21%, 4.0≤Mn≤7.0%, 0.5≤Al≤3.5%, Si≤2.0%, Ti≤0.2%, V≤0.2%, Nb≤0.2%, P≤0.025%, B≤0.0035%, and the spot welded joint contains a molten zone microstructure containing more than 0.5% of Al and containing a surface fraction of segregated areas lower than 1%, said segregated areas being zones larger than 20 μm.sup.2 and containing more than the steel nominal phosphorus content.

A method for combined rolling and extruding of cast billet is proposed. When implementing the method for combined rolling and extruding of metals or alloys, a cast billet with a predetermined temperature is fed to the working gauge, in which it is rolled and then to the die, through which the cast billet is extruded. When the cast billet is fed into the working gauge, a cladding layer of metal or alloy is created on the surfaces of the rolls by extruding the cast billet through the gaps formed between the surfaces of the rolls and the die. This invention makes it possible to improve the quality of the resulting products, as well as to increase the efficiency of the process as a whole.

An aluminum alloy contains equal to or more than 0.005 mass % and equal to or less than 2.2 mass % of Fe, and a remainder of Al and an inevitable impurity. In a transverse section of the aluminum alloy wire, a surface-layer void measurement region in a shape of a rectangle having a short side length of 30 μm and a long side length of 50 μm is defined within a surface layer region extending from a surface of the aluminum alloy wire by 30 μm in a depth direction, and a total cross-sectional area of voids in the surface-layer void measurement region is equal to or less than 2 μm.sup.2.

The present invention is a superconducting wire including: a wire formed of a superconducting material; and a superconducting stabilization material disposed in contact with the wire, in which the superconducting stabilization material is formed of a copper material which contains: one or more types of additive elements selected from Ca, Sr, Ba, and rare earth elements in a total of 3 ppm by mass to 400 ppm by mass; a balance being Cu and inevitable impurities, and in which a total concentration of the inevitable impurities excluding O, H, C, N, and S which are gas components is 5 ppm by mass to 100 ppm by mass.

The present invention is a superconducting wire including: a wire formed of a superconducting material; and a superconducting stabilization material disposed in contact with the wire, in which the superconducting stabilization material is formed of a copper material which contains: one or more types of additive elements selected from Ca, Sr, Ba, and rare earth elements in a total of 3 ppm by mass to 400 ppm by mass; a balance being Cu and inevitable impurities, and in which a total concentration of the inevitable impurities excluding O, H, C, N, and S which are gas components is 5 ppm by mass to 100 ppm by mass.

A primary object of the present invention is to provide a continuous-cast slab where central porosity is reduced by surly crushing the slab, and a method and apparatus of manufacturing the same.

The continuous-cast slab 1 having horizontally symmetrical granular equiaxed crystals at least in the center in the thickness direction includes a first reduction dent 2 and a second reduction dent 3 that further dents from the bottom surface of the first reduction dent 2 and is narrower than the first reduction dent 2 at least on one long side surface. Such a configuration can makes it possible to achieve the continuous-cast slab 1 of no more than 2.5×10.sup.−4 cm.sup.3/g in a maximum porosity volume while segregation is reduced.

Steel production plant to obtain long products such as rods, bars or sections, with overall productivity comprised between 0.7-3.0 Mton/year, preferably between 1.0 and 3.0 Mton/year, comprising at least two co-rolling lines (11a, 11b).

A horizontal continuous casting apparatus includes a fluid supply pipe for supplying a lubricating fluid to the hollow portion of the mold, which is arranged on one end side of the mold; and, a cooling water cavity for accommodating cooling water cooling an inner peripheral surface of the hollow portion of the mold, which is formed outside the inner peripheral surface, wherein the inner peripheral surface and the inner bottom surface of the cooling water cavity facing the inner peripheral surface form parallel surfaces with each other, and a cooling wall of the mold between the inner peripheral surface and the inner bottom surface is formed so that the heat flux value per unit area from the molten aluminum alloy to the cooling water is 10×10.sup.5 W/m.sup.2 or more.

A continuous casting and rolling line for casting, rolling, and otherwise preparing metal strip can produce distributable metal strip without requiring cold rolling or the use of a solution heat treatment line. A metal strip can be continuously cast from a continuous casting device and coiled into a metal coil, optionally after being subjected to post-casting quenching. This intermediate coil can be stored until ready for hot rolling. The as-cast metal strip can undergo reheating prior to hot rolling, either during coil storage or immediately prior to hot rolling. The heated metal strip can be cooled to a rolling temperature and hot rolled through one or more roll stands. The rolled metal strip can optionally be reheated and quenched prior to coiling for delivery. This final coiled metal strip can be of the desired gauge and have the desired physical characteristics for distribution to a manufacturing facility.

A production apparatus for short-process metal composite plate manufacturing, the apparatus including a metal supply device including an uncoiler (1), pinch roll (2), shot blasting machine (3), welding device (4), welding pinch roll (5), induction heating apparatus (6), metal delivery machine (7), two crystallization cooling rolls (8), secondary cooling leveling roll (9), rolling mill pinch roll (10), rolling mill (11), on-line cooling apparatus (12), straightener (13), and at least one of a dividing shear (14) and a recoiling machine (15). Also disclosed is a production method for short-process metal composite plate manufacturing. The apparatus and method combine continuous casting, rolling, and heat-treating means for single material production with continuous and large-scale production of composite plate strips, and production efficiency of composite plates is sharply improved. Single-sided or double-sided composite plate production having different thickness specifications can be performed, the optional range of a base layer or cladding material is wide.