A flatness measuring apparatus for measuring the flatness of a metallic strip, including a measuring roller which has a roller axis and which makes contact with the strip for the measuring the flatness. The measuring roller is connected to a cooling system, using which the measuring roller can be cooled. To ensure that a high degree of measuring accuracy can be maintained even at high temperatures, the cooling system has a nozzle bar that extends parallel to the roller axis. At least one spray nozzle is arranged on the nozzle bar, using which cooling medium can be sprayed on the surface of the measuring roller in a spraying direction. The spraying direction meets a surface section of the measuring roller, and the angle between the spraying direction and the tangent on the measuring roller at the location of the surface section is less than 30°.

A coil skid on which a hot-rolled coil 1 obtained by coiling a hot-rolled steel sheet is placed includes: at least two or more layers of a metal plate 11 and at least two or more layers of a heat insulating material 12 each stacked alternately, in which the metal plate 11 is in contact with the hot-rolled coil 1. The uneven cooling of an outer peripheral portion of the hot-rolled coil caused by the coil skid is prevented while ensuring the strength of the coil skid, to thereby inhibit the uneven hardness in the longitudinal direction of the hot-rolled coil resulting from this uneven cooling.

A coil skid on which a hot-rolled coil 1 obtained by coiling a hot-rolled steel sheet is placed includes: at least two or more layers of a metal plate 11 and at least two or more layers of a heat insulating material 12 each stacked alternately, in which the metal plate 11 is in contact with the hot-rolled coil 1. The uneven cooling of an outer peripheral portion of the hot-rolled coil caused by the coil skid is prevented while ensuring the strength of the coil skid, to thereby inhibit the uneven hardness in the longitudinal direction of the hot-rolled coil resulting from this uneven cooling.

A high-strength thin-gauge checkered steel plate/strip and a manufacturing method therefor, wherein residual elements such as Sn and Cu in steel scrap are fully utilized as alloy elements in the smelting of molten steel, and the steel has selectively added micro-alloy elements such as B; during the smelting process, the alkalinity of the slag, the types of inclusion in the steel and the melting point thereof, the content of free oxygen and the content of soluble aluminum (Als) in the molten steel are controlled; and twin-roll thin-strip continuous casting is performed to cast a cast strip (11); after exiting crystallization rollers (8a, 8b), the cast strip (11) directly enters a lower sealed chamber (10) containing a non-oxidizing atmosphere, and enters an online rolling machine (13) in a sealed manner so as to undergo hot rolling, then after rolling, the strip steel is cooled by means of air atomization. The resultant steel roll can be used directly as hot-rolled checkered plate/strip, or as a finished checkered plate/strip after being cut and finished, and is widely applicable to the fields of architecture, mechanical production, automobile, bridges, transportation, ship building, etc.

A high-strength thin-gauge checkered steel plate/strip and a manufacturing method therefor, wherein residual elements such as Sn and Cu in steel scrap are fully utilized as alloy elements in the smelting of molten steel, and the steel has selectively added micro-alloy elements such as B; during the smelting process, the alkalinity of the slag, the types of inclusion in the steel and the melting point thereof, the content of free oxygen and the content of soluble aluminum (Als) in the molten steel are controlled; and twin-roll thin-strip continuous casting is performed to cast a cast strip (11); after exiting crystallization rollers (8a, 8b), the cast strip (11) directly enters a lower sealed chamber (10) containing a non-oxidizing atmosphere, and enters an online rolling machine (13) in a sealed manner so as to undergo hot rolling, then after rolling, the strip steel is cooled by means of air atomization. The resultant steel roll can be used directly as hot-rolled checkered plate/strip, or as a finished checkered plate/strip after being cut and finished, and is widely applicable to the fields of architecture, mechanical production, automobile, bridges, transportation, ship building, etc.

A flat rolled metal product (1) is first hot-rolled in at least one rolling stand (2), then fed to a cooling zone (5) arranged downstream of the rolling stand (2) and finally cooled in the cooling zone (5). During the rolling in the rolling stand (2), the flat rolled product (1) is oriented horizontally. Before running into the cooling zone (5) and/or when running into the cooling zone (5), the flat rolled product (1) is turned by a first acute angle (a) about an axis running in the transporting direction (x), so that after completion of the turning about the axis the flat rolled product (1) is oriented obliquely. The flat rolled product (1) is cooled in the cooling zone (5) while it is oriented obliquely. The product (1) is then returned to horizontal orientation.

A hot and cold composite formed square and rectangular steel tube and a production method for the same are provided. The radius of an outer corner of the square and rectangular steel tube meets the following conditions: when t is less than or equal to 6 mm, R is greater than 0 and less than 2.0 t; when t is greater than 6 mm and less than or equal to 10 mm, R is greater than 0 and less than 2.5 t; when t is greater than 10 mm, R is greater than 0 and less than 3.0 t, wherein t is the wall thickness of a straight tube part of the square and rectangular steel tube; R is the radius of each of the outer corners of the four corners of the square and rectangular steel tube; and the wall thickness of each corner of the square and rectangular steel tube is between 1.0 t and 1.8 t.

An aluminum foil is formed from an alloy of type AA1xxx, AA3xxx, and/or AA8xxx, which has a cold-solidified state and contains on its surface a rolling oil layer with a polyalkylene glycol or a compound containing a polyalkylene oxide structure. The aluminum foil has a thickness of 4 μm to 100 μm and can be easily coated with an electrode suspension for producing a battery film.

A method for producing a steel tube including the step of the manufacturing a steel tube having an inner tube wall, an outer tube wall, and a free tube cross-section enclosed by the inner tube wall, wherein after the manufacturing, the steel tube includes at least one contaminant on the inner tube wall. After the manufacturing of the steel tube, the inner tube wall is cleaned by introducing liquid or solid CO.sub.2 into the free tube cross-section, and of applying the liquid or solid CO.sub.2 onto the inner tube wall to remove the contaminant therefrom.

A method quenches a steel pipe and an apparatus quenches a steel pipe by which a steel pipe having excellent and uniform quality can be acquired by applying uniform rapid cooling to the steel pipe in a longitudinal direction as well as in a circumferential direction of the steel pipe using a simple unit. Movements of a heated steel pipe in a direction parallel to and in a direction perpendicular to a pipe axis of the steel pipe are stopped, and cooling water is jetted onto an outer surface of the steel pipe from four or more spray nozzles arranged spirally outside the steel pipe while rotating the steel pipe about the pipe axis.