Abstract: A graphite steel available as a material for mechanical parts of industrial machines or automobiles, and more particularly, a steel wire for graphitization heat treatment and a graphite steel and methods of manufacturing the same. The graphite steel includes, in percent by weight (wt %), 0.6 to 0.9% of carbon (C), 2.0 to 2.5% of silicon (Si), 0.1 to 0.6% of manganese (Mn), 0.015% or less of phosphorus (P), 0.03% or less of sulfur (S), 0.01 to 0.05% of aluminum (Al), 0.01 to 0.02% of titanium (Ti), 0.0005 to 0.002% of boron (B), 0.003 to 0.015% of nitrogen (N), 0.005% or less of oxygen (O), and the remainder of iron (Fe) and inevitable impurities, and satisfying Equation (1) below: wherein graphite grains are distributed in a ferrite base as a microstructure and a graphitization rate is 100%, (1) ?0.003<[N]?[Ti]/3.43?[B]/0.77<0.003, wherein in Equation (1), [Ti], [N], and [B] are wt % of titanium, nitrogen, and boron, respectively.

Abstract: Provided are stainless steel for a separator of a polymer electrolyte membrane fuel cell, which exhibits enhanced hydrophilicity and enhanced corrosion resistance, and a method of manufacturing the same. In the stainless steel for a separator of a polymer electrolyte membrane fuel cell, which exhibits enhanced hydrophilicity and enhanced corrosion resistance, according to an embodiment of the present invention, a ratio of Cr hydroxide/Cr oxide included in a passivation film of the stainless steel ranges from 0.5 to 1.7, and the passivation film has a contact angle (?) of 70° or less. Thus, not only corrosion resistance may be enhanced by removing a non-conductive film formed on a surface of the stainless steel and forming a new conductive film thereon, but hydrophilicity may also be secured without additional surface treatment such as a separate coating or the like, and thus manufacturing costs may be reduced and productivity may be increased.

Abstract: Provided is an alloy-plated steel material that can be used in home appliances, automobiles, and construction materials and the like and, more particularly, to an alloy-plated steel material having excellent corrosion resistance and high surface quality.

Abstract: A steel material for a low yield ratio, high-strength steel pipe having excellent low-temperature toughness according to an aspect of the present invention comprises, by weight %, 0.03-0.065% of C, 0.05-0.3% of Si, 1.7-2.2% of Mn, 0.01-0.04% of Al, 0.005-0.025% of Ti, 0.008% or less of N, 0.08-0.12% of Nb, 0.02% or less of P, 0.002% or less of S, 0.05-0.3% of Cr, 0.4-0.9% of Ni, 0.3-0.5% of Mo, 0.05-0.3% of Cu, 0.0005-0.006% of Ca, 0.001-0.04% of V, and the balance of Fe and inevitable impurities, wherein a number of deposits having an average diameter of 20 nm or less per unit area in a cross section of the steel material may be 6.5*109/mm2 or greater.

Abstract: Provided is a manufacturing method of a surface-treated Zn—Ni alloy electroplated steel sheet, the method comprising the steps of: preparing a Zn—Ni alloy electroplated steel sheet including a steel sheet and a Zn—Ni alloy-plated layer with an Ni content of 5-20 wt % (S1); preparing an alkaline electrolyte solution in which 4-250 g/L of potassium hydroxide (KOH) or sodium hydroxide (NaOH) or both combined are added in distilled water (S2); and inside the alkaline electrolyte solution, placing the Zn—Ni alloy electroplated steel sheet as an anode and installing another metal sheet as a cathode, and applying 2-10 V of an alternating or direct current to conductor electrochemical etching such that a 3-point average value of the arithmetic average roughness (Ra) of the surface of the Zn—Ni alloy electroplated steel sheet reaches 200-400 nm, thereby producing a surface-treated electroplated steel sheet (S3).

Abstract: Provided is an austenitic stainless steel having excellent hot workability and exhibiting enhanced corrosion resistance of welded parts of hot-rolled and cold-rolled materials. The austenitic stainless steel having excellent corrosion resistance of welded parts according to an embodiment of the present disclosure includes, in percent (%) by weight, 0.02 to 0.07% of C, 0.2 to 0.7% of Si, 2.5 to 4.0% of Mn, 2.5 to 4.0% of Ni, 17.0 to 19.0% of Cr, less than 0.1% of P, less than 0.01% of S, 1.0 to 3.0% of Cu, 0.1 to 0.2% of N, and the remainder of Fe and other inevitable impurities, wherein a crack resistance index (CRN) represented by Formula (1) below is equal to or greater than 0. CRN=542+715C?27Si?1.49Mn+38.8Ni?52.5Cr+35.

Abstract: Provided is a manufacturing method of a grain-oriented electrical steel sheet including preparing a hot-rolled sheet by hot-rolling a slab; removing some of scales formed on the hot-rolled sheet and leaving a scale layer having a thickness of 10 nm or more to prepare a hot-rolled sheet on which the scale layer remains; preparing a cold-rolled sheet by cold-rolling the hot-rolled sheet on which the scale layer remains; preparing the decarburization annealed cold-rolled sheet by decarburization annealing the cold-rolled sheet; coating an annealing separator on the decarburization annealed cold-rolled sheet to form a metal oxide layer; and final annealing the steel sheet on which the metal oxide layer is formed, wherein the annealing separator includes magnesium oxide (MgO) or magnesium hydroxide (MgOH) and fluoride.

Abstract: Provided is a surface-treated metallic material with easy control of glossiness and a manufacturing method therefor, the surface-treated metallic material comprising: a metallic material; and a coating layer which is formed on at least one side of the metallic material and on which an ultraviolet curable coating composition is cured, wherein the coating layer consists of a plurality of protrusions, which have a volume of 3 to 16 pico liters and are arranged at a density of 5 to 610 per 1 mm2 of the metallic material. As such, the surface-treated steel sheet is excellent in adhesion, scratch resistance and corrosion resistance, and has easy control of glossiness.

Abstract: A grain-oriented electrical steel sheet incudes a groove formed on a surface and a solidified alloy layer formed under the groove, wherein the solidified alloy layer includes particles of a certain average diameter.

Abstract: A clad steel plate, having excellent strength and formability, may include a base material; and a cladding material provided on both side surfaces of the base material, wherein the base material is austenitic high-manganese steel comprising, by weight, 0.3% to 1.4% of C, 12% to 25% of Mn, and a remainder of Fe and inevitable impurities, the cladding material is a martensitic carbon steel comprising, by weight, 0.09% to 0.4% of C, 0.3% to 4.5% of Mn, and a remainder of Fe and inevitable impurities.

Abstract: A method for preparing a porous carbon material by using coal tar generated in a coke oven gas (COG) process is provided. The method includes: removing quinoline insoluble (QI) by mixing tetrahydrofuran (THF) with coal tar generated in a COG purification process; distilling coal tar by adding a phenolic resin to the QI-removed coal tar, and heating the same at a temperature of 100° C. to 330° C.; carbonizing the distilled coal tar by heating the same at 350° C. to 600° C.; mixing a carbide after the carbonization step and the coal tar, which has been distilled before the carbonization, and grinding/granulating the same; mixing the ground/granulated carbide and the coal tar, which has been distilled before the carbonization, with a pore forming agent, and heat treating the same at 300° C. to 500° C.; and forming pores by making the heat treated carbon material come into contact with water vapor at 700° C. to 1000° C.

Abstract: A wear-resistant steel having excellent hardness and impact toughness and a method for producing same can include: 0.29-0.37 wt % of carbon, 0.1-0.7 wt % of silicon, 0.6-1.6 wt % of manganese, 0.05 wt % or less of phosphorus, 0.02 wt % or less of sulfur, 0.07 wt % or less of aluminum, 0.1-1.5 wt % of chromium, 0.01-0.8 wt % of molybdenum, 0.01-0.08 wt % of vanadium, 50 ppm or less of boron, and 0.02 wt % or less of cobalt; and optionally one or more of 0.5 wt % or less of nickel, 0.5 wt % or less of copper, 0.02 wt % or less of titanium, 0.05 wt % or less of niobium, and 2-100 ppm of calcium; with the remainder of Fe and other inevitable impurities.

Abstract: Provided are a hot-dip zinc plated steel material and a method for preparing same, the hot-dip zinc plated steel material comprising: base iron comprising 0.01-1.6 wt % of Si and 1.2-3.1 wt % of Mn; a Zn—Al—Mg alloy plating layer; and an Al-rich layer formed on the interface of the base iron and Zn—Al—Mg alloy plating layer, wherein the rate of occupied surface area of the Al-rich layer is 70% or higher (including 100%).

Abstract: The present invention relates to a steel sheet which is suitable to be used as the material of a part such as a friction plate for a vehicle automatic transmission. More specifically, the present invention relates an ultra-high strength steel sheet having excellent shear workability and a method for manufacturing same.

Abstract: A plating steel sheet for hot press forming includes: a base steel sheet; an Al—Zn-based plating layer formed on at least one surface of the base steel sheet; and an Fe—Al-based surface alloy layer formed between the base steel sheet and the Al—Zn-based plating layer, wherein the Al—Zn-based plating layer can include 10-30 wt % of Zn, 1 wt % or less of Fe, and the balance of Al and impurities.

Abstract: A roll stamping apparatus includes sets of rollers that rotate while facing each other so as to press opposite surfaces of a material which is continuously supplied to move between the rollers. The sets of rollers have molding portions with a stamping structure applied to outer surfaces so as to mold the material, wherein a plurality of sets of rollers are disposed along a movement direction of the material, the respective molding portions of the sets of rollers are formed to sequentially change a cross section of the material along the movement of the material, and the molding portion of at least one set of rollers before a final set of rollers through which the material finally passes is a set of over-molding rollers having a length in a circumferential direction longer than the molding portions of the final set of rollers.

Abstract: Provided is a high-strength steel sheet including, in % weight, carbon (C): 0.04 to 0.15%, silicon (Si): 0.01 to 1.0%, manganese (Mn): 1.8 to 2.5%, molybdenum (Mo): 0.15% or less (excluding 0%), chromium (Cr): 1.0% or less (excluding 0%), phosphorus (P): 0.1% or less, sulfur (S): 0.01% or less, aluminum (Al): 0.01 to 0.5%, nitrogen (N): 0.01% or less, boron (B): 0.01% or less (excluding 0%), antimony (Sb): 0.05% or less (excluding 0%), one or more of titanium (Ti): 0.003 to 0.06% and niobium (Nb): 0.003 to 0.06%, a balance of Fe and other unavoidable impurities, and contents of the C, the Si, the Al, the Mo and the Cr satisfy the following Expression 1: Expression 1: {(2×(Si+Al))+Mo+Cr}/C?20. The high-strength steel sheet comprises: a ferrite phase, a bainite phase, a martensite phase, and a residual austenite phase, the ferrite phase being less than 40% of area fraction in the microstructure.

Abstract: Provided is a high-strength steel sheet including, in % weight, carbon (C): 0.04 to 0.15%, silicon (Si): 0.01 to 1.0%, manganese (Mn): 1.8 to 2.5%, molybdenum (Mo): 0.15% or less (excluding 0%), chromium (Cr): 1.0% or less (excluding 0%), phosphorus (P): 0.1% or less, sulfur (S): 0.01% or less, aluminum (Al): 0.01 to 0.5%, nitrogen (N): 0.01% or less, boron (B): 0.01% or less (excluding 0%), antimony (Sb): 0.05% or less (excluding 0%), one or more of titanium (Ti): 0.003 to 0.06% and niobium (Nb): 0.003 to 0.06%, a balance of Fe and other unavoidable impurities, and contents of the C, the Si, the Al, the Mo and the Cr satisfy the following Expression 1: Expression 1: {(2×(Si+Al))+Mo+Cr}/C?15. The high-strength steel sheet comprises: a ferrite phase, a bainite phase, a martensite phase, and a residual austenite phase, the ferrite phase being less than 40% of area fraction in the microstructure.

Abstract: Provided is a solution composition for steel sheet surface treatment, comprising 30 wt % to 60 wt % of a trivalent chromium compound containing chromium phosphate (A) and chromium nitrate (B); 0.2 wt % to 0.4 wt % of a rust-inhibiting and corrosion-resisting agent; 0.1 wt % to 0.3 wt % of a molybdenum-based compound; 5 wt % to 10 wt % of a water-soluble cationic urethane resin; 0.5 wt % to 2.0 wt % of a silane coupling agent; and 27.3 wt % to 64.2 wt % of water, a zinc-based plated steel sheet surface-treated with the same, and a manufacturing method therefor, the zinc-based plated steel sheet surface-treated with the solution composition for steel sheet surface treatment containing trivalent chromium may have an excellent effect on corrosion resistance, blackening resistance, fingerprint resistance, oil resistance, and alkali resistance.

Abstract: One aspect of the present invention relates to a plated steel sheet for hot press forming, having an excellent impact property.