Abstract: A heating furnace according to an embodiment of the present invention includes: a furnace body that has an inlet at the upper portion through which a steel sheet blank is inserted from a wound coil and an outlet at the lower portion through which the steel sheet blank is discharged, and has a cylindrical structure having a space for conveying the steel sheet blank; a conveyer that is spirally disposed on the inner circumference of the furnace body and sequentially conveys the steel sheet blank from the inlet at the upper portion and the outlet at the lower portion; and a clamping means that is disposed at one side of the conveyer and selectively clamps the steel sheet blank.

Abstract: Provided is a high manganese nitrogen-containing steel sheet. The high manganese nitrogen-containing steel sheet according to the present invention comprises 0.5 to 1.0 wt % of carbon, 10 to 20 wt % of manganese, 0.02 to 0.3 wt % of nitrogen, with a remainder of Fe and unavoidable impurities. The high manganese nitrogen-containing steel sheet according to the present invention produces an austenite phase at room temperature, in which the stacking fault energy is effectively controlled by adding chrome and nitrogen. Accordingly, the high manganese nitrogen-containing steel sheet of the present invention produces a mechanical twin during the plastic deformation of the steel sheet, thereby increasing the work hardening rate, tensile strength, and workability.

Abstract: The present invention relates to an apparatus for centering a submerged entry nozzle. The present invention includes: a plurality of laser beam generators 20 that is disposed above a mold 3 for continuous casting to radiate a laser beam toward the center of the mold; a tundish moving unit 15 that moves a tundish 1 above the mold 3; and a control unit that is linked with the laser beam generators 20 and controls the tundish moving unit 15 to center the installation position of the submerged entry nozzle 5 provided at the lower portion of the tundish, in response to signals transmitted from the laser beam generators 20. According to the present invention, in addition to accurately and quickly centering the submerged entry nozzle 5, it is possible to maintain the submerged entry nozzle that has been centered, such that it is possible to minimize a channeling phenomenon of molten steel. Accordingly, it can be expected to improve the quality of a slab.

Abstract: The quenchable steel sheet has an alloy composition including carbon (C) in an amount of 0.15˜0.30 wt %, silicon (Si) in an amount of 0.05˜0.5 wt %, manganese (Mn) in an amount of 1.0˜2.0 wt %, boron (B) in an amount of 0.0005˜0.0040 wt %, sulfur (S) in an amount of 0.003 wt % or less, phosphorus (P) in an amount of 0.012 wt % or less, one or more selected from among calcium (Ca) in an amount of 0.0010˜0.0040 wt % and copper (Cu) in an amount of 0.05˜1.0 wt %, two or more selected from among cobalt (Co), zirconium (Zr) and antimony (Sb), and iron (Fe). Alloy elements are controlled to increasing hot ductility and enabling pressing at 600˜900° C. so that a tensile strength of 1400 MPa or more and an elongation of 8% or more are obtained after pressing.

Abstract: Disclosed herein is a method for reducing edge serration defects in a thin slab, including: reheating a thin slab having an alloy composition including carbon (C), niobium (Nb), aluminum (Al), iron (Fe) and inevitable impurities to uniformalize the thin slab into an austenite structure; controlling precipitates that occur in the reheated thin slab by controlling an temperature of the thin slab discharged from a heat-treatment furnace at a temperature at which niobium carbide (NbC) start to precipitate; and hot-rolling the thin slab. The method is advantageous in that the temperature of a thin slab discharged from a heat-treatment furnace is controlled, so that the edge serration defects in the thin slab can be reduced, thereby improving the productivity of the thin slab.

Abstract: The present invention relates to an apparatus for centering a submerged entry nozzle. The present invention includes: a plurality of laser beam generators 20 that is disposed above a mold 3 for continuous casting to radiate a laser beam toward the center of the mold; a tundish moving unit 15 that moves a tundish 1 above the mold 3; and a control unit that is linked with the laser beam generators 20 and controls the tundish moving unit 15 to center the installation position of the submerged entry nozzle 5 provided at the lower portion of the tundish, in response to signals transmitted from the laser beam generators 20. According to the present invention, in addition to accurately and quickly centering the submerged entry nozzle 5, it is possible to maintain the submerged entry nozzle that has been centered, such that it is possible to minimize a channeling phenomenon of molten steel. Accordingly, it can be expected to improve the quality of a slab.

Abstract: The present invention relates to a mold powder supply apparatus using the waste heat of a tundish, which can collect waste heat from molten steel in the tundish, and preheat and dry mold powder. The mold powder supply apparatus using the waste heat of a tundish according to an embodiment of the present invention includes: a powder hopper that is mounted to a frame close to a tundish to absorb heat radiated from the top of the tundish, through one side; an agitator that agitates mold powder filled in the powder hopper; and a supply pipe that is connected to the bottom of the powder hopper to supply the powder hopper into a mold.

Abstract: The present invention relates to a method of continuous hardening press and an apparatus thereof. The process of continuous press hardening, includes: slab casting that makes a slab by continuous-casting molten steel refined by an electric furnace or a blast furnace, and then reheats and hot-rolls the slab into a hot-rolled steel sheet; blanking that conveys the hot-rolled steel sheet to a blank through a sealed oven and blanks the hot-rolled steel sheet, after the slab casting; and press hardening that conveys the hot-rolled steel sheet to a press die and presses the hot-rolled steel sheet, after the blanking. According to the embodiments of the present invention, since a high-temperature steel sheet formed by hot rolling is directly put into press hardening, reheating is not required such that the entire process is simplified and reduction of manufacturing cost can be expected.

Abstract: A heating furnace according to an embodiment of the present invention includes: a furnace body that has an inlet at the upper portion through which a steel sheet blank is inserted from a wound coil and an outlet at the lower portion through which the steel sheet blank is discharged, and has a cylindrical structure having a space for conveying the steel sheet blank; a conveyer that is spirally disposed on the inner circumference of the furnace body and sequentially conveys the steel sheet blank from the inlet at the upper portion and the outlet at the lower portion; and a clamping means that is disposed at one side of the conveyer and selectively clamps the steel sheet blank.

Abstract: The present invention relates to an apparatus for a press hardening die which has a structure improved to decrease cooling rate of trimming portions in pressing a steel plate blank for manufacturing a part for press hardening. A press hardening die cooling device according to an embodiment of the present invention includes: a press hardening die composed of upper and lower dies equipped with cooling water suppliers therein to press a steel plate blank from the top and the bottom; and a cooling water temperature adjuster disposed between the cooling water suppliers of the upper and lower dies and the contact surface of the steel plate blank to adjust temperature of cooling water supplied to the steel plate blank.

Abstract: A method of manufacturing a cold-rolled steel sheet includes: adding, by weight %, carbon (C) 0.005% or less, nitrogen (N) 0.002 to 0.005%, manganese (Mn) 0.1 to 1.0%, phosphorous (P) 0.005 to 0.1%, niobium (Nb) 0.015 to 0.04%, silicon (Si) 0.30 or less, sulfur (S) 0.02% or less, aluminum 0.001 to 0.03%; adjusting the atomic ratio of Nb/C to 1 or more and the atomic ratio of Al/N to 0.5 to 1.5, homogenizing a steel containing iron (Fe) and elements inevitably contained in manufacturing the steel as the remainder at temperature of 1150 to 1300° C., setting the final hot-rolling temperature to 890 to 950° C. that is over an Ar3 critical point; and hot-winding the hot-rolled steel sheet and cold-rolling the hot-rolled steel sheet at 40 to 80% cold reduction ratio.