Abstract: The present invention relates to a weld bead inspection device that inspects welding quality by measuring the state of beads formed at a welding part of a metallic or non-metallic pipe, or the like, and more specifically, to a weld bead inspection device that more efficiently inspects a welding part joined by a method such as thermal fusion for connection between pipes or connection between a pipe and a fitting. The weld bead inspection device includes a housing unit that forms an appearance; an imaging unit that images shapes of the weld beads in an inner space that is open downward from a middle inner side of the housing unit; a control unit that is provided in the housing unit to store image data captured by the imaging unit or to calculate external shapes of the weld beads for determining welding quality on the basis of the image data.

Abstract: Provided are a high-strength steel sheet having excellent bendability and formability, and a method for manufacturing same. The steel sheet includes: 0.05 to 0.12% of carbon (C), 2.0 to 3.0% of manganese (Mn), 0.5% or less (excluding 0%) of silicon (Si), 1.0% or less (excluding 0%) of chromium (Cr), 0.1% or less (excluding 0%) of niobium (Nb), 0.1% or less (excluding 0%) of titanium (Ti), 0.0025% or less (excluding 0%) of boron (B), 0.02 to 0.05% of aluminum (sol.Al), 0.05% or less (excluding 0%) of phosphorus (P), 0.01% or less (excluding 0%) of sulfur (S), 0.01% or less (excluding 0%) of nitrogen (N), with a balance of Fe and inevitable impurities, and 35 to 50% of ferrite and 35 to 45% of bainite, and a balance of martensite, the ferrite comprising, by area fraction: 8 to 15% of non-recrystallized ferrite and 27 to 35% of recrystallized ferrite, as a microstructure.

Abstract: The present invention relates to a non-magnetic high manganese steel sheet with high-strength, which has superior strength and moldability, and at the same time, can obtain superior non-magnetic characteristics, and a method for manufacturing the same.

Abstract: A high-ductility, high-strength and high Mn steel strip used for steel strips of automobiles requiring superior formability and high strength, a plated steel strip produced by using the same, and a manufacturing method thereof are disclosed. The high Mn steel strip comprises, by weight %, 0.2˜1.5% of C, 10˜25% of Mn, 0.01˜3.0% of Al, 0.005˜2.0% of Si, 0.03% or less of P, 0.03% or less of S, 0.040% or less of N, and the balance of Fe and other unavoidable impurities. The high-ductility, high-strength and high Mn steel strip, and the plated steel strip produced by using the same have superior surface properties and plating characteristics.

Abstract: A method for manufacturing a steel sheet used for structural members, elements, etc. of automobiles including a front side member, pillar, and the like, and more particularly, a method for manufacturing a steel sheet having a high strength and formability as well as hot-dip galvanizing properties is disclosed. In the method, after an aluminum killed steel slab, which comprises, by weight %: C: 0.05% to 0.25%; Si: 0.1% to 1.5%; S: 0.02% or less; N: 0.01% or less; Al: 0.02% to 2.0%; Mn: 1.0% to 2.5%; P: 0.001% to 0.1%; Sb: 0.005% to 0.10%; the balance of Fe and other unavoidable impurities, is subjected to a homogenization treatment at a temperature range of 1050° C. to 1300° C., the aluminum killed steel slab is subjected to a hot rolling under a finishing hot rolling temperature of 850° C. to 950° C. and a coiling temperature of 400° C. to 700° C., followed by a cold rolling under a cold rolling reduction ration of 30% to 80%, and annealing the cold rolled steel sheet.

Abstract: A high-ductility, high-strength and high Mn steel strip used for steel strips of automobiles requiring superior formability and high strength, a plated steel strip produced by using the same, and a manufacturing method thereof are disclosed. The high Mn steel strip comprises, by weight %, 0.2˜1.5% of C, 10˜25% of Mn, 0.01˜3.0% of Al, 0.005˜2.0% of Si, 0.03% or less of P, 0.03% or less of S, 0.040% or less of N, and the balance of Fe and other unavoidable impurities. The high-ductility, high-strength and high Mn steel strip, and the plated steel strip produced by using the same have superior surface properties and plating characteristics.

Abstract: A method for manufacturing a steel sheet used for structural members, elements, etc. of automobiles including a front side member, pillar, and the like, and more particularly, a method for manufacturing a steel sheet having a high strength and formability as well as hot-dip galvanizing properties is disclosed. In the method, after an aluminum killed steel slab, which comprises, by weight %,: C: 0.05% to 0.25%; Si: 0.1% to 1.5%; S: 0.02% or less; N: 0.01% or less; Al: 0.02% to 2.0%; Mn: 1.0% to 2.5%; P: 0.001% to 0.1%; Sb: 0.005% to 0.10%; the balance of Fe and other unavoidable impurities, is subjected to a homogenization treatment at a temperature range of 1050° C. to 1300° C., the aluminum killed steel slab is subjected to a hot rolling under a finishing hot rolling temperature of 850° C. to 950° C. and a coiling temperature of 400° C. to 700° C., followed by a cold rolling under a cold rolling reduction ration of 30% to 80%, and annealing the cold rolled steel sheet.

Abstract: A method for manufacturing a cold rolled steel sheet for use in a shadow mask is disclosed, in which without adding an expensive alloy element, a short intermediate decarburization annealing is carried out, and despite this fact, a forming defect does not occur after the forthcoming stacked annealing. The method includes the steps of preparing a steel composed of, in weight %, 0.003% or less of C, 0.10-0.20% of Mn, 0.01-0.05% of Al, 0.004% or less of N, and a balance of Fe and other unavoidable impurities. A hot rolling is carried out on the steel at a temperature of above 910° C., and then, a first cold rolling is carried out to form a first cold rolled steel sheet. Then a decarburization is carried out on the first cold rolled steel sheet down to a carbon content of 0.0015% to form a decarburized steel sheet, and then a second cold rolling with a reduction ratio of more than 35% is carried out on the decarburized steel sheet.

Abstract: The present invention is related to the cold rolled steel sheet for making a shadow mask of a cathode ray tube of a color Braun tube for selecting colors and a manufacturing method therefor. Objects of the present invention are to enable production of a cold rolled steel sheet by one-step cold rolling and low-temperature annealing rather than by the conventional two-step cold rolling and decarburization annealing, and to provide a cold rolled steel sheet for a shadow mask and the manufacturing method therefor having better etchability and formability which are required for the material for a shadow mask than those of the conventional cold rolled steel sheets. The manufacturing method of the cold rolled steel sheet of the present invention is comprised of the steps of homogenizing the aluminum killed steel, which is composed in weight % of less than 0.002% of C, 0.20-0.45% of Mn, 0.015-0.020% of S, less than 0.02% of P, less than 0.01% of Si, 0.01-0.03% of Cr, 0.01-0.02% of Al, 0.0010-0.