A roll-transport device including: a roll that comes into contact with the base material; a support shaft that rotatably supports the roll; and a bearing that is disposed on an outer peripheral surface of the support shaft and has an end surface on one side in an axial direction, which faces an inside of a furnace, and an end surface on the other side in the axial direction, which is positioned on a side of an inner portion (space surrounded by the roll). A purge gas is caused to circulate from the end surface on the other side toward the end surface on the one side of the bearing, and the purge gas is discharged into the furnace from the end surface on the one side of the bearing.

A resistance annealing furnace for annealing a metal wire, strand, string, wire rod or strap having at least two electric axes provided with respective pulleys to convey the metal wire and a DC voltage generator suppliable with an AC voltage to generate an annealing voltage applied between the two electric axes so as to provoke the annealing due to Joule effect. The DC voltage generator has active supplying means supplied with the AC voltage so as to generate an intermediate DC voltage, a pulse width modulator to transform the intermediate voltage into a first PWM voltage with the same amplitude, a voltage transformer to transform the first PWM voltage into a second PWM voltage with a smaller amplitude, and a voltage rectifier stage to transform the second PWM voltage into the annealing voltage.

An apparatus for continuously treating metal strip of aluminum, an aluminum alloy, a nonferrous metal, or a nonferrous-metal alloy, has at least one heat-treatment device through which the metal strip passes in a strip-travel plane in a travel direction without contact from an upstream inlet end to a downstream outlet end and having a heating zone at the upstream end and a cooling zone formed by a row extending in the direction of at least two cooling subzones. A strip-centering device between the cooling subzones adjusts a position of the metal strip in the strip-travel plane and transverse thereto.

Provided is a hearth roll for supporting and conveying a steel sheet in a continuous annealing furnace, wherein all of a shaft portion and a roil main body are made from one or more ceramic materials, preferably constituted with concentric ceramic layers of different ceramic materials centering on the rotation shaft of the roll. The hearth roll has not only an excellent pickup resistance but also a long roll life free from maintenance for long periods. Also provided is a continuous annealing facility using the hearth roll in at least one of a heating zone, a soaking zone and a cooling zone.

An apparatus for annealing alloy ribbon, the apparatus comprising: an unwinder unwinding an alloy ribbon from a spool of the alloy ribbon; a heating member comprising a first flat surface, on which the alloy ribbon unwound by the unwinder runs while contacting the first flat surface, the heating member heating the alloy ribbon running while contacting the first flat surface through the first flat surface; a cooling member comprising a second flat surface, on which the alloy ribbon heated by the heating member runs while contacting the second flat surface, the cooling member cooling the alloy ribbon running while contacting the second flat surface through the second flat surface; and a winder winding the alloy ribbon cooled by the cooling member.

A hearth roll for heat treatment furnaces has excellent build-up resistance, has a hexavalent-chromium-free thermal spray coating film formed on the roll surface thereof and is safe for the environment. A method for manufacturing a hearth roll for continuous annealing furnaces includes a first step of applying an aqueous solution containing chromium phosphate onto a thermal spray coating film formed on the roll surface of a hearth roll or impregnating the thermal spray coating film with the aqueous solution; and a second step of burning the hearth roll.

Provided are a high-strength steel sheet having high strength of a yield strength of 550 MPa or more and a method for manufacturing the same.

The high-strength steel sheet has a specified chemical composition and a microstructure, where observed in a cross section in a thickness direction perpendicular to a rolling direction, including a martensite phase having a volume fraction of 50% to 80%, and a ferrite phase having an average grain diameter of 13 m or less, wherein a volume fraction of ferrite grains having an aspect ratio of 2.0 or less with respect to the whole ferrite phase is 70% or more, and wherein an average length in a longitudinal direction (in a width direction of the steel sheet) of the ferrite grains is 20 m or less, and a yield strength (YP) of 550 MPa or more.

A steel-strip production apparatus adapted to produce a hot-dip-plated steel strip and a cold-rolled steel strip includes a continuous annealing furnace, a snout connected to the continuous annealing furnace, a contact-type seal plate device and a noncontact-type seal roll device, a hot-dip-plating tank that is movable, and a roll configured to turn the path direction of the steel strip after passing through the snout, wherein a hot-dip-plated steel strip production unit configured to produce a hot-dip-plated steel strip by bringing the steel strip continuously annealed in the continuous annealing furnace into the hot-dip-plating tank; and a cold-rolled steel strip production unit configured to produce a cold-rolled steel strip by transferring the steel strip continuously annealed in the continuous annealing furnace without causing the steel strip to pass through the hot-dip-plating tank, are configured to be switchable with one another.

A heat treatment plant for continuous heat treatment of a metal strip has an annealing furnace and a subsequent over-ageing chamber that can be heated. In this plant, the metal strip is guided over several deflector rolls spaced vertically apart in the over-ageing chamber so that it passes through the over-ageing chamber in a meandering path. At least one deflector roll can be moved in vertical direction so that the strip length and the retention time of the metal strip in the over-ageing chamber can be set. A method for heat-treating a metal strip is also disclosed.

A method for forming a film on a surface of a steel sheet includes applying a treatment solution for forming a film containing a fibrous material to the surface of the steel sheet by using a coater under a condition in which a difference between a speed of the steel sheet and a speed of an applicator of the coater is 1.0 m/min or more, inclining the surface of the steel sheet, to which the treatment solution for forming a film has been applied, at an angle of 10? or more with respect to a horizontal plane until drying is started, and thereafter drying the steel sheet.