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 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 invention relates to a hot stamped component, a precoated steel sheet used for hot stamping, and a hot stamping process. The hot stamped component of the present invention is provided with a coating of aluminium or an aluminium alloy on at least one surface of the base steel, the coating is produced by interdiffusion between the base steel and a precoating of aluminium or aluminium alloy, and the coating has a thickness of 6 to 26 μm.

The present invention relates to a hot stamped component, a precoated steel sheet used for hot stamping, and a hot stamping process. The hot stamped component of the present invention is provided with a coating of aluminium or an aluminium alloy on at least one surface of the base steel, the coating is produced by interdiffusion between the base steel and a precoating of aluminium or aluminium alloy, and the coating has a thickness of 6 to 26 μm.

Provided is a grain-oriented electrical steel sheet having both low iron loss and good magnetostrictive properties, with which a transformer having excellent properties can be manufactured. The grain-oriented electrical steel sheet of the present disclosure has a linear strain region extending linearly in a direction intersecting the rolling direction, where the linear strain region has a region having compressive stress in the rolling direction, and a region adjacent in a rolling direction to the region having compressive stress has a region having tensile stress in the rolling direction.

Provided is a grain-oriented electrical steel sheet having both low iron loss and good magnetostrictive properties, with which a transformer having excellent properties can be manufactured. The grain-oriented electrical steel sheet of the present disclosure has a linear strain region extending linearly in a direction intersecting the rolling direction, where the linear strain region has a region having compressive stress in the rolling direction, and a region adjacent in a rolling direction to the region having compressive stress has a region having tensile stress in the rolling direction.

In some embodiments, a coating applied to steel reinforcement bar (e.g., steel rebar) that could considerably extend the lifetime of concrete structures by reducing steel rebar corrosion is disclosed. The coating includes a thin, passivating steel (e.g., stainless steel) layer that is applied to the outside of conventional steel rebar. The coating can be applied in-line through metal cold spray manufacturing, which is a high throughput coating technique that can be integrated into existing steel manufacturing plants. Furthermore, a novel, high performance ferritic steel with tailored resistance to corrosion from chlorides is described. The new ferritic steel is distinct from other commercial and experimental steels, and is better suited for coating low-cost steel structures like rebar. Multiple alloying elements including Cr, Al, and Si will each form protective oxides independently, increasing the total amount of protection and extending it over much wider ranges of pH and electrical potential.

Steel sheets for hot stamping accommodated in a far-infrared radiation multi-stage type heating furnace are stably supported over a long period of time using steel sheet support members having a small projected area and inhibited from thermally deforming. The far-infrared radiation multi-stage type heating furnace includes: heating units and a ceiling unit arranged in a vertical direction with multiple stages to accommodate aluminum-coated steel sheets or zinc- coated steel sheets for hot stamping; and far-infrared radiation heaters disposed within the heating units and the ceiling unit to heat the steel sheets for hot stamping to a temperature ranging from the Ac.sub.3 transformation temperature to 950° C. Steel sheet support members are mounted to the heating units to support the steel sheets for hot stamping by point contact or line contact with the steel sheets for hot stamping.

Steel sheets for hot stamping accommodated in a far-infrared radiation multi-stage type heating furnace are stably supported over a long period of time using steel sheet support members having a small projected area and inhibited from thermally deforming. The far-infrared radiation multi-stage type heating furnace includes: heating units and a ceiling unit arranged in a vertical direction with multiple stages to accommodate aluminum-coated steel sheets or zinc- coated steel sheets for hot stamping; and far-infrared radiation heaters disposed within the heating units and the ceiling unit to heat the steel sheets for hot stamping to a temperature ranging from the Ac.sub.3 transformation temperature to 950° C. Steel sheet support members are mounted to the heating units to support the steel sheets for hot stamping by point contact or line contact with the steel sheets for hot stamping.

A heating system for drill steel pipe billet includes a feedback device configured to control distances d.sub.1 and d.sub.2 of three flamethrowers, a propulsion device, a positioning device, a heating device, a temperature measuring device and a conveying device. Heating temperature of the flamethrowers is controlled by an oxygen distribution box and a gas distribution box. A heating method for the drill steel pipe billet is also provided, in which a rolling forming method of gradient flame heating is adopted to control density of the rolled pieces and avoid internal defects of the drill steel caused by the same deformation of the traditional uniformly heated pipe billets. A radial temperature of the drill steel pipe billet is accurately controlled through the feedback device. Only one set of flamethrowers corresponding to drill steel pipe billets of different dimensions is required, and other devices are universal components, which will not be replaced.