A structural steel having excellent brittle fracture resistance according to an aspect of the present invention comprises, by weight %, 0.02-0.12% of C, 0.01-0.8% of Si, 1.5-2.5% of Mn, 0.005-0.5% of Al, 0.02% or less of P, 0.01% or less of S, 0.0015-0.015% of N, and the remainder of Fe and unavoidable impurities, wherein an outer surface layer portion and an inner central portion are microstructurally divided along the thickness direction, the surface layer portion comprises tempered bainite as a matrix structure, the central portion comprises bainitic ferrite as a matrix structure, and the NDT temperature by the NRL drop-weight test may be −70° C. or lower.

A structural steel having excellent brittle fracture resistance according to an aspect of the present invention comprises, by weight %, 0.02-0.12% of C, 0.01-0.8% of Si, 1.5-2.5% of Mn, 0.005-0.5% of Al, 0.02% or less of P, 0.01% or less of S, 0.0015-0.015% of N, and the remainder of Fe and unavoidable impurities, wherein an outer surface layer portion and an inner central portion are microstructurally divided along the thickness direction, the surface layer portion comprises tempered bainite as a matrix structure, the central portion comprises bainitic ferrite as a matrix structure, and the NDT temperature by the NRL drop-weight test may be −70° C. or lower.

A cooling bar (1) for cooling rolled material (5) being moved in a transport direction (3) and in particular for reducing temperature differences in the temperature of the rolled material (5) transversely to the direction of transport (3). The cooling bar (1) has several full jet nozzles (11) by means of which a coolant beam of a coolant with an approximately constant jet diameter can be distributed to the rolling stock (5) in the direction of distribution (15). A cooling device has at least two cooling bars (1) of that type. The cooling bars extend transversely to a transport direction, one behind the other. Each cooling bar has a respective different pattern of jet nozzles and selection of applicable pattern of jet nozzles in their respective bars selectively cools the rolled material transversely to the transport direction.

A cooling bar (1) for cooling rolled material (5) being moved in a transport direction (3) and in particular for reducing temperature differences in the temperature of the rolled material (5) transversely to the direction of transport (3). The cooling bar (1) has several full jet nozzles (11) by means of which a coolant beam of a coolant with an approximately constant jet diameter can be distributed to the rolling stock (5) in the direction of distribution (15). A cooling device has at least two cooling bars (1) of that type. The cooling bars extend transversely to a transport direction, one behind the other. Each cooling bar has a respective different pattern of jet nozzles and selection of applicable pattern of jet nozzles in their respective bars selectively cools the rolled material transversely to the transport direction.

The invention relates to a method for producing a metallic strip or sheet (1), in which the strip or sheet (1) is rolled in a multi-stand rolling mill (11) and is discharged downstream of the last roll stand (14) of the rolling mill (11) in the conveying direction (F), wherein the strip or sheet (1) is cooled in the multi-stand rolling mill (11) and/or downstream of the rolling mill (11) as viewed in conveying direction (F), wherein a temperature of the strip or sheet (1) is measured upstream of the last roll stand (14) of the rolling mill (11) as viewed in conveying direction (F). Based on this measured temperature, a temperature for the strip or sheet (1) at the exit (A) of the last roll stand (14) of the rolling mill (11), is then determined purely by calculation with the aid of a temperature calculation model, with which temperature further processes of the manufacturing method can be controlled or regulated after a comparison with a predetermined reference value.

A method for operating a storage device for two rolls in a roll stand for rolling metal. The storage device is component part of the roll stand or can be positioned relative to the roll stand so that the rolls can be transferred from the roll stand into the storage device or vice versa. A measuring system is provided which detects the temperatures and/or the diameters of the rolls individually and independently of one another, at least at predefined detection positions, as viewed in the direction of the roll axes. After transmission to an automation unit that controls the roll stand, the unit can adapt a roll model, by means of which it repeatedly determines the temperatures and/or the diameters of the rolls, at predefined determination positions, in the direction of the roll axes, using operating data of the roll stand for the rolls of the same type.

A method for operating a storage device for two rolls in a roll stand for rolling metal. The storage device is component part of the roll stand or can be positioned relative to the roll stand so that the rolls can be transferred from the roll stand into the storage device or vice versa. A measuring system is provided which detects the temperatures and/or the diameters of the rolls individually and independently of one another, at least at predefined detection positions, as viewed in the direction of the roll axes. After transmission to an automation unit that controls the roll stand, the unit can adapt a roll model, by means of which it repeatedly determines the temperatures and/or the diameters of the rolls, at predefined determination positions, in the direction of the roll axes, using operating data of the roll stand for the rolls of the same type.

The device has a short production line, and all components are reasonably configured. A multifunctional cooling control device is adopted to integrate high-pressure water descaling and intermediate billet cooling functions, which is simpler and more efficient. Layout of a 4R+(3−4)F rolling mill, four thermos-detectors and short-distance underground coilers are use. The method includes the steps: carrying out continuous casting to manufacture a slab, high-pressure water rotating descaling, rough rolling by a four-stand high reduction rough rolling unit, machining by a drum shear, cooling after high-pressure water descaling in the multifunctional cooling control device, finish rolling by a three-stand or four-stand finish rolling unit, air cooling, dividing coils by a high-speed flying shear, and coiling by underground coilers, wherein temperature monitoring is respectively carried out after rough rolling, before finish rolling, after finish rolling, and before coiling by the underground coiler.

The device has a short production line, and all components are reasonably configured. A multifunctional cooling control device is adopted to integrate high-pressure water descaling and intermediate billet cooling functions, which is simpler and more efficient. Layout of a 4R+(3−4)F rolling mill, four thermos-detectors and short-distance underground coilers are use. The method includes the steps: carrying out continuous casting to manufacture a slab, high-pressure water rotating descaling, rough rolling by a four-stand high reduction rough rolling unit, machining by a drum shear, cooling after high-pressure water descaling in the multifunctional cooling control device, finish rolling by a three-stand or four-stand finish rolling unit, air cooling, dividing coils by a high-speed flying shear, and coiling by underground coilers, wherein temperature monitoring is respectively carried out after rough rolling, before finish rolling, after finish rolling, and before coiling by the underground coiler.

A framework cooler (20) for cooling a steel strip (50), installed in a roller framework (11), in place of the work rolls (5) and their associated installation pieces (5a and 5b). The framework cooler (20) is sized to be installed into the roller framework (11) through the operator-side roller stands (1) of the roller framework (11). The cooler (20) includes a lower (21b) and an upper water tank (21a), each having a connection (22) for a coolant, and includes a plurality of cooling nozzles (23), or cooling tubes (23a) arranged in the depth direction (T) of the framework cooler (20) or at least one cooling slot (24) extending in the depth direction (T). The bottom and top sides of the steel strip (50) may be cooled.