A steel sheet for hot stamping includes a composition including at least, in mass %, C: 0.100% to 0.600%, Si: 0.50% to 3.00%, Mn: 1.20% to 4.00%, Ti: 0.005% to 0.100%, B: 0.0005% to 0.0100%, P: 0.100% or less, S: 0.0001% to 0.0100%, Al: 0.005% to 1.000%, and N: 0.0100% or less, with a balance of Fe and impurities, surface roughness of the steel sheet satisfies Rz>2.5 m, and 50 mg/m.sup.2 to 1500 mg/m.sup.2 of coating oil is applied to a surface.

A steel sheet for hot stamping includes a composition including at least, in mass %, C: 0.100% to 0.600%, Si: 0.50% to 3.00%, Mn: 1.20% to 4.00%, Ti: 0.005% to 0.100%, B: 0.0005% to 0.0100%, P: 0.100% or less, S: 0.0001% to 0.0100%, Al: 0.005% to 1.000%, and N: 0.0100% or less, with a balance of Fe and impurities, surface roughness of the steel sheet satisfies Rz>2.5 m, and 50 mg/m.sup.2 to 1500 mg/m.sup.2 of coating oil is applied to a surface.

Provided is a warm-pressed member comprising, by weight %, C: 0.01% to 0.5%, Si: 3.0% or less (excluding 0%), Mn: 3% to 15%, P: 0.0001% to 0.1%, S: 0.0001% to 0.03%, Al: 3.0% or less (excluding 0%), N: 0.03% or less (excluding 0%), and the balance of Fe and inevitable impurities. After a warm press forming process and a cooling process, the warm-pressed member has a microstructure comprising: 5 volume % to 50 volume % of retained austenite; and at least one of ferrite, martensite, tempered martensite, and bainite as a remainder.

Provided is a warm-pressed member comprising, by weight %, C: 0.01% to 0.5%, Si: 3.0% or less (excluding 0%), Mn: 3% to 15%, P: 0.0001% to 0.1%, S: 0.0001% to 0.03%, Al: 3.0% or less (excluding 0%), N: 0.03% or less (excluding 0%), and the balance of Fe and inevitable impurities. After a warm press forming process and a cooling process, the warm-pressed member has a microstructure comprising: 5 volume % to 50 volume % of retained austenite; and at least one of ferrite, martensite, tempered martensite, and bainite as a remainder.

A device and a method for producing a continuous strip-shaped composite material. For this purpose, a base material, which is produced using at least one casting machine as a continuous strand, in particular made of steel, and providing at least one cladding material, which is unwound in the form of at least one metal strip by a coil unwinding unit are provided. Subsequently, a slab which has formed by solidification from the strand produced by the casting machine and the metal strip unwound by the coil unwinding unit, in the hot state are brought together, wherein the materials, which are moved in the direction toward one another, formed from the slab and the unwound metal strip are hot rolled, so that a single continuous strip-shaped composite material is thus produced by roll cladding. The base material is continuously cast in the vertical direction in the casting direction.

A device and a method for producing a continuous strip-shaped composite material. For this purpose, a base material, which is produced using at least one casting machine as a continuous strand, in particular made of steel, and providing at least one cladding material, which is unwound in the form of at least one metal strip by a coil unwinding unit are provided. Subsequently, a slab which has formed by solidification from the strand produced by the casting machine and the metal strip unwound by the coil unwinding unit, in the hot state are brought together, wherein the materials, which are moved in the direction toward one another, formed from the slab and the unwound metal strip are hot rolled, so that a single continuous strip-shaped composite material is thus produced by roll cladding. The base material is continuously cast in the vertical direction in the casting direction.

A primary object of this invention is to provide a continuous casting method by which a slab of excellent internal quality can be obtained even if the casting speed is changed. In this invention, upon continuous casting with two pairs of the reduction rolls arranged along a casting direction and support rolls arranged between the reduction rolls, when a casting speed is reduced compared to a state where combination of reduction with reduction rolls at a first stage on an unsolidified portion of the slab and reduction with reduction rolls at a second stage on a solidified portion thereof is employed, the combination is switched to combination of reduction with the reduction rolls at the first stage on a portion of the slab at an end of solidification and the reduction with the reduction rolls at the second stage on the solidified portion thereof.

A primary object of this invention is to provide a continuous casting method by which a slab of excellent internal quality can be obtained even if the casting speed is changed. In this invention, upon continuous casting with two pairs of the reduction rolls arranged along a casting direction and support rolls arranged between the reduction rolls, when a casting speed is reduced compared to a state where combination of reduction with reduction rolls at a first stage on an unsolidified portion of the slab and reduction with reduction rolls at a second stage on a solidified portion thereof is employed, the combination is switched to combination of reduction with the reduction rolls at the first stage on a portion of the slab at an end of solidification and the reduction with the reduction rolls at the second stage on the solidified portion thereof.

A system for producing flat rolled products from thick-cast metal slabs includes: a continuous casting device, by which a flat continually cast product with a thickness of at least 160 mm can be continually cast; a separating device, arranged so as to adjoin the continuous casting device for separating the flat continually cast product into individual thick slabs; a hot-rolling mill, by which the thick slabs can be rolled to form the flat rolled product; a thick slab supplying device arranged transversely to the transport direction and positioned between the separating device and the rolling train; and an electric heating device arranged in front of the hot-rolling mill, for a direct hot charging process, said electric heating device allowing at least the thick slabs coming from the continuous casting device arranged in the common transport line to be heated to a hot-rolling temperature.

A system for producing flat rolled products from thick-cast metal slabs includes: a continuous casting device, by which a flat continually cast product with a thickness of at least 160 mm can be continually cast; a separating device, arranged so as to adjoin the continuous casting device for separating the flat continually cast product into individual thick slabs; a hot-rolling mill, by which the thick slabs can be rolled to form the flat rolled product; a thick slab supplying device arranged transversely to the transport direction and positioned between the separating device and the rolling train; and an electric heating device arranged in front of the hot-rolling mill, for a direct hot charging process, said electric heating device allowing at least the thick slabs coming from the continuous casting device arranged in the common transport line to be heated to a hot-rolling temperature.