The present invention relates to a radiant tube apparatus disposed in a heat treatment facility to perform a heat treatment of a strip and a method for manufacturing the same. The radiant tube apparatus includes a tube having an internal pipe, wherein the tube has a first continuous pattern and a second continuous pattern extending side by side and spaced apart from each other at a predetermined distance on a surface, and, in each of the first continuous pattern and the second continuous pattern, a plurality of unit patterns having a predetermined height from the surface are connected to each other in a longitudinal direction.

The present disclosure relates to a high-strength hot-dip galvanized steel sheet having excellent surface quality and electrical resistance spot weldability, and a method for manufacturing the same. A galvanized steel sheet according to an aspect of the present disclosure is a galvanized steel sheet including a base steel sheet and a zinc-based plating layer formed on a surface of the base steel sheet, wherein a ratio (a/b) of a hardness of a surface layer portion (a) to a hardness of an internal portion (b) of the base steel sheet may be less than 0.95.

A direct flame furnace burner unit for furnaces for the thermo-chemical treatment of steel strips in continuous hot-dip galvanizing plants includes a burner with a combustion head provided with a combustion chamber having an outlet opening of the combustion flame, and a body to which the combustion head is fixed. The body includes a first chamber which is in communication with the combustion chamber, a first lance for the injection of a fuel into the combustion chamber, a mixing chamber provided with at least a first inlet and a second inlet opening which is connectable to a second supply source, at least a second lance for the injection of the mixture into the combustion chamber. The burner is operable in two distinct operating modes, a diffusive flame combustion mode and a premixed flame combustion mode.

Equipment for the continuous hot dip-coating of a metal strip 9 including an annealing furnace, a tank 2 containing a liquid metal bath 3, a snout connecting the annealing furnace and tank 2, through which the metal strip 9 runs in a protective atmosphere and the lower part of the snout, the sabot 5, is at least partly immersed in the liquid metal bath 3 in order to define with the surface of the bath, and inside this snout, a liquid seal 6, an overflow 7 not connected to the snout, the overflow 7 including at least one tray 8, placed in the vicinity of the strip 9 when entering the liquid metal bath 3 and encompassed by liquid seal 6.

A bridle device and a method for producing a steel strip in which snaking of a steel strip that occurs during production of a high-silicon steel strip is suppressed. The bridle device includes a pair of upper and lower rotatable endless belts or a pair of upper and lower rotatable caterpillars configured to pinch a steel strip. The bridle device is movable or swingable in a steel strip width direction by using a steering mechanism. The bridle device further includes a rolling reduction mechanism configured to perform rolling reduction on a pinched portion of the steel strip by using the pair of upper and lower endless belts or the pair of upper and lower caterpillars. The steering mechanism moves or swings the bridle device in the steel strip width direction, and the rolling reduction mechanism performs rolling reduction on one of end portions in the steel strip width direction.

A method for manufacturing a metal sheet comprising pinching the metal sheet in rapid quenching between a pair of pinch rolls in the range where the temperature of the metal sheet is from (T.sub.Ms+150) (° C.) to (T.sub.Mf−150) (° C.), wherein the Ms temperature of the metal sheet is T.sub.Ms (° C.) and the Mf temperature thereof is T.sub.Mf (° C.), as well as a rapid quenching unit comprising a pair of pinch rolls capable of use in such a method.

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 device for determining the microstructure of a metal product during metallurgical production of the metal product, the device having at least one X-ray source, at least one X-ray detector and at least one accommodating chamber, inside which the X-ray source and/or the X-ray detector is/are arranged and which has at least one window which is transparent to X-ray radiation. To allow reliable determination of the microstructure of a metal product during the metallurgical production thereof, the device includes at least one cooling installation for actively cooling the accommodating chamber.

A method for manufacturing a sheet metal component including: annealing a flat steel product comprising 0.05-0.5% C, 0.5-3% Mn, 0.06-1.7% Si, ≤0.06% P, ≤0.01% S, ≤1.0% Al, ≤0.15% Ti, ≤0.6% Nb, ≤0.01% B, ≤1.0% Cr, ≤1.0% Mo, ≤1.0% Cr+Mo, ≤0.2% Ca, ≤0.1% V, remainder iron and impurities in a continuous furnace under an atmosphere consisting of 0.1-15% hydrogen and remainder nitrogen with a specific dew point and temperature profile; applying a coating consisting of ≤15% Si, ≤5% Fe, in total 0.1-5% of at least one alkaline earth or transition metal and a remainder Al and unavoidable impurities; heating the fat steel product to >Ac3 and ≤1000° C. for a time sufficient to introduce a heat energy quantity>100,000-800,000 kJs; hot-forming the flat steel product to form the component; and cooling at least one section of the component at a cooling rate sufficient to generate hardening structures.

Provided is a high-strength steel sheet suitable for automobile structural members, etc., and a method for manufacturing same, wherein the high-strength steel sheet has a low yield ratio and high strength and has excellent formability through improvement of ductility that may prevent processing defects such as cracks, wrinkles, or the like, during press forming.