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 dual hardness steel article comprises a first air hardenable steel alloy having a first hardness metallurgically bonded to a second air hardenable steel alloy having a second hardness. A method of manufacturing a dual hard steel article comprises providing a first air hardenable steel alloy part comprising a first mating surface and having a first part hardness, and providing a second air hardenable steel alloy part comprising a second mating surface and having a second part hardness. The first air hardenable steel alloy part is metallurgically secured to the second air hardenable steel alloy part to form a metallurgically secured assembly, and the metallurgically secured assembly is hot rolled to provide a metallurgical bond between the first mating surface and the second mating surface.

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 method for collecting mill scale from a hot rolling mill is provided. The hot rolling mill includes a flume. The method includes transporting mill scale particles in wastewater, retrieving the wastewater from a flume of the hot rolling mill and separating the mill scale particles from the wastewater using a separator. A hot rolling mill and a method for retrofitting a hot rolling mill are also provided.

A process may be used to produce a composite material in a rolling plant. The process may involve providing a first workpiece and a second workpiece, which workpieces are configured in the form of a temporary composite. The process may further involve producing a planar connection between the first and second workpieces in the temporary composite by prerolling. Still further, the process may involve rolling, in particular hot rolling, the temporary composite to form the composite material after the planar connection has been produced by prerolling. The process may also involve heating the temporary composite before and/or after the prerolling.

Provided is a continuous casting and rolling method, which includes: a continuous casting operation of producing a slab; and a rolling operation of pressing the slab after a front end portion of the slab passes a first rolling stand into which the front end portion of the slab, which is provided as a continuous body to the slab produced in the continuous casting operation, initially enters.

A method for processing a press hardenable steel includes first heating a slab of the press hardenable steel. The slab is heated to a re-heat furnace temperature of approximately 2300 F. The slab is subjected to rolling into a steel sheet having a predetermined thickness. The temperature of the slab during rolling corresponds to a rolling temperature that is greater than or equal to 1600 F. The steel sheet is coiled. The temperature of the steel sheet during coiling corresponds to a coiling temperature of approximately 1050 F.

A steel sheet for heat treatment having a chemical composition including, by mass %: C: 0.05 to 0.50%; Si: 0.50 to 5.0%; Mn; 1.5 to 4.0%; P: 0.05% or less; S: 0.05% or less; N: 0.01% or less; Ti: 0.01 to 0.10%; B: 0.0005 to 0.010%; Cr: 0 to 1.0%; Ni: 0 to 2.0%; Cu: 0 to 1.0%; Mo: 0 to 1.0%; V: 0 to 1.0%; Ca: 0 to 0.01%; Al: 0 to 1.0%; Nb: 0 to 1.0%; REM: 0 to 0.1%; and the balance: Fe and impurities, wherein a maximum height roughness Rz on a surface of the steel sheet is 3.0 to 10.0 ?m, and a number density of carbide being present in the steel sheet and having circle-equivalent diameters of 0.1 ?m or larger is 8.0?10.sup.3/mm.sup.2 or lower.

Electric resistance welded steel pipe securing the high strength and high toughness demanded from oil well pipe in recent years. The metal structure in a region having a width of 0.5 mm in both the thickness directions from a reference point, when using a point defined as a point of the thickness in the thickness direction from the surface in the base material part of the steel pipe as the reference point, consists of polygonal ferrite: 10 area % or less and a balance: bainitic ferrite. The thickness is 15 mm or more.