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 heating device and a method for the inductive heating of a flat steel strip in a hot rolling mill. The heating device is between two rolling trains of the hot rolling mill and the flat steel strip runs at a speed through the heating device in a transporting direction. The heating device includes: transverse-field modules arranged one after the other along the transporting direction of the flat steel strip; longitudinal-field modules arranged one after the other along the transporting direction of the flat steel strip and arranged before or after the transverse-field modules along the transporting direction; a first power supply supplying at least one transverse-field module with a first alternating voltage; and a second power supply supplying at least one longitudinal-field module with a second alternating voltage. The power supplies have a converter and an electrically connected capacitor bank with multiple capacitors connected in parallel.

A heating device and a method for the inductive heating of a flat steel strip in a hot rolling mill. The heating device is between two rolling trains of the hot rolling mill and the flat steel strip runs at a speed through the heating device in a transporting direction. The heating device includes: transverse-field modules arranged one after the other along the transporting direction of the flat steel strip; longitudinal-field modules arranged one after the other along the transporting direction of the flat steel strip and arranged before or after the transverse-field modules along the transporting direction; a first power supply supplying at least one transverse-field module with a first alternating voltage; and a second power supply supplying at least one longitudinal-field module with a second alternating voltage. The power supplies have a converter and an electrically connected capacitor bank with multiple capacitors connected in parallel.

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 steel pipe for line pipe has a composition of, in mass %: C: 0.02 to 0.11%; Si: 0.05 to 1.0%; Mn: 0.30 to 2.5%; P: up to 0.030%; S: up to 0.006%; Cr: 0.05 to 0.36%; Mo: 0.02 to 0.33%; V: 0.02 to 0.20%; Ti: 0.001 to 0.010%; Al: 0.001 to 0.100%; N: up to 0.008%; Ca: 0.0005 to 0.0040%; and other elements and satisfies Cr+Mo+V0.40, the chemical symbols in the equation substituted by the content of the corresponding element in mass %. The pipe contains tempered martensite and/or tempered bainite and further contains ferrite in at least one of a portion between a steel pipe outer surface and a depth of 1 mm from the outer surface, and a portion between a steel pipe inner surface and a depth of 1 mm from the inner surface.

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.

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.

A X80 pipeline steel with good strain-aging performance comprises (wt. %): C: 0.02-0.05%; Mn: 1.30-1.70%; Ni: 0.35-0.60%: Ti: 0.005-0.020%; Nb: 0.06-0.09%; Si: 0.10-0.30%; Al: 0.01-0.04%; N0.008%; P0.012%; S0.006%; Ca: 0.001-0.003%, and balance iron and unavoidable impurities.

A X80 pipeline steel with good strain-aging performance comprises (wt. %): C: 0.02-0.05%; Mn: 1.30-1.70%; Ni: 0.35-0.60%: Ti: 0.005-0.020%; Nb: 0.06-0.09%; Si: 0.10-0.30%; Al: 0.01-0.04%; N0.008%; P0.012%; S0.006%; Ca: 0.001-0.003%, and balance iron and unavoidable impurities.