202 results about "Cementite" patented technology

The invention relates to the field of screw forming, and discloses a screw cold heading forming process which is characterized by comprising the following steps: step 1, wire preparation and surface pretreatment: based on the requirement of screw forming on the surface quality of raw materials, a metal wire is treated by adopting a mechanical wiredrawing and chemical phosphating and saponifying composite process, and the surface of the metal wire is treated; surface oxide skin is removed, a lubricating film layer is formed, and the forming flowability and the service life of the die in the subsequent cold heading process are effectively improved. A raw material is subjected to spheroidizing annealing treatment in a continuous spheroidizing annealing furnace, internal pearlite is converted into spherical cementite, the ductility and deformation uniformity of the material are improved, then a continuous wire drawing machine is adopted for multi-stage drawing diameter reduction, a three-stage chemical phosphating-saponification treatment process is matched, a low-friction and high-adhesion lubricating film layer is formed, and the service life of the lubricating film layer is prolonged. And a stable material basis and a lubricating environment are provided for the subsequent cold heading process, so that the problems that the friction resistance generated in the forming process of a screw material is large, and a mold is quickly worn are solved.

The invention discloses steel for a low-temperature high-speed rotating shaft and a heat treatment process of the steel. The steel is prepared from, by mass, 0.2%-0.3% of C, 2.5%-4.2% of Ni, 1.5%-3.2% of Cr, 0.15%-0.6% of Mn, 0.2%-0.3% of Si, 0.2%-0.4% of Mo, 0.08%-0.2% of V and the balance Fe through matching, mixing, smelting, slab continuous casting to form a cast ingot, and hot rolling; the obtained steel ingot is cooled after being quenched, then tempering cooling is carried out for more than or equal to three times, in the non-head-tail tempering cooling process, the tempering temperature of at least one time is higher than the dissolution temperature of cementite, and the other tempering temperatures are all lower than the dissolution temperature of the cementite; the heat preservation time of each tempering is 1-3 hours; the invention relates to a martensite castable which is composed of tempered martensite and cementite which are evenly distributed, the tempered martensite is in a lath shape, the width of the lath is smaller than 1 micrometer, the cementite is in a spherical and / or film shape, and the size of the cementite is smaller than 100 nm. The obtained material can keep good obdurability at extremely low temperature, and is suitable for low-temperature gas compressors and other scenes.

The invention discloses a controlled cooling method of a steel wire rod 87Mn for a bridge cable. The rolling temperature, the spinning temperature and the roller way speed are accurately controlled, the Stelmor air cooling control cooling technology is adopted, it is ensured that the temperature of a wire rod is evenly distributed in the cooling process, and too fast or too slow local cooling is avoided. A sectional controlled cooling process is adopted, network cementite is prevented from being generated through first-section rapid cooling, uniform transformation of the structure is ensured through second-section slow cooling, the structure is stabilized through third-section natural cooling, the process design is reasonable, and operation is easy and convenient. The finally obtained 87Mn hot-rolled wire rod is free of martensite and network cementite in the core, the sorbite rate is larger than or equal to 93%, and the 87Mn hot-rolled wire rod has high strength, high plasticity and good drawing performance and is suitable for the high-requirement field such as bridge cables.

The invention relates to gray cast iron and a smelting method thereof, in particular to high-strength gray cast iron and a smelting method thereof. According to the high-strength gray cast iron and the smelting method thereof, the defect that in the prior art, alloying is adopted for improving the strength of the gray cast iron, and consequently the texture of the gray cast iron is poor is overcome, the tensile strength of an attached casting test bar of the high-strength gray cast iron is larger than 300 MPa, and the hardness is larger than 190 HB; the metallographic structure of the high-strength gray cast iron in an as-cast state can achieve more than 98% of pearlite, less than 1% of cementite and more than 90% of A-type graphite, and the strength and the metallographic structure of the alloyed gray cast iron are effectively improved.

The invention relates to the technical field of oil and gas well cementation engineering, in particular to a well cementation cement stone micro-crack self-repairing material and a preparation method and application thereof. The well cementation cement stone micro-crack self-repairing material is prepared from the following raw materials in parts by weight: 30 parts of deionized water, 3 to 12 parts of monomer, 0.03 to 0.09 part of cross-linking agent, 0.06 to 0.3 part of initiator, 3 to 20 parts of natural latex, 1.5 to 3 parts of surfactant and 0.03 to 1.5 parts of filler, and is prepared by adopting an emulsion copolymerization method. The obtained self-repairing material is high in liquid absorption rate in a weak acid solution, high in expansion rate when meeting carbon dioxide and excellent in mechanical property, can be doped into a well cementation fluid system, is used for two corrosive medium environments of supercritical CO2 and CO2 formation water in a water wet environment, seals a shaft leakage channel, and improves the sealing integrity of a shaft.

Provided is a steel sheet that has excellent quenching properties and cold-working properties. This steel sheet comprises, by mass%, 0.50%–0.90% of C, 0.01%–0.50% of Si, 0.20%–1.30% of Mn, no more than 0.100% of P, no more than 0.100% of S, no more than 0.100% of Al, 0.01%–1.20% of Cr, and no more than 0.0150% of N, the remainder being Fe and impurities. The total area ratio of ferrite and cementite particles is at least 95%, the average particle diameter of the ferrite is 5.0–20.0 μm, the Cr concentration [Cr]θ in the cementite particles is less than 2.00%, the Mo concentration [Mo]θ in the cementite particles is no more than 1.00%, the average particle diameter of the cementite particles is no more than 1.50 μm, and the spheroidization rate of the cementite particles is at least 85%.

Provided is a steel sheet that has excellent quenching properties and cold-working properties. This steel sheet comprises, by mass%, 0.50%–0.90% of C, 0.01%–0.50% of Si, 0.20%–1.30% of Mn, no more than 0.100% of P, no more than 0.100% of S, no more than 0.100% of Al, 0.01%–1.20% of Cr, and no more than 0.0150% of N, the remainder being Fe and impurities. The total area ratio of ferrite and cementite particles is at least 95%, the average particle diameter of the ferrite is 5.0–20.0 μm, the Cr concentration [Cr]θ in the cementite particles is less than 2.00%, the Mo concentration [Mo]θ in the cementite particles is no more than 1.00%, the average particle diameter of the cementite particles is no more than 1.50 μm, and the spheroidization rate of the cementite particles is 75% or more but less than 85%.

Provided is a cold-rolled steel sheet consisting of carbon (C): 0.23 wt% to 0.35 wt%, silicon (Si): 0.05 wt% to 0.5 wt%, manganese (Mn): 0.3 wt% to 2.3 wt%, phosphorus (P): more than 0 wt% and not more than 0.02 wt%, sulfur (S): more than 0 wt% and not more than 0.005 wt%, aluminum (Al): 0.01 wt% to 0.05 wt%, chromium (Cr): more than 0 wt% and not more than 0.8 wt%, molybdenum (Mo): more than 0 wt% and not more than 0.4 wt%, titanium (Ti): 0.01 wt% to 0.1 wt%, boron (B): 0.001 wt% to 0.005 wt%, a balance of iron (Fe), and unavoidable impurities, wherein a final microstructure of the cold-rolled steel sheet includes cementite, a transition carbide, and a fine precipitate, the transition carbide including ε-carbide having an atomic ratio of a substitutional element selected from Fe, Mn, Cr, and Mo, to C of 2.5:1, or η-carbide having an atomic ratio of the substitutional element to C of 2:1, and the fine precipitate having an atomic ratio of an alloying element selected from Mo and Ti, to C of 1:1.

Provided is a hot rolled steel sheet having a predetermined chemical composition and a microstructure comprising, by area ratio, pearlite: 90 to 100% and pro-eutectoid ferrite: 0 to 10%, wherein the pearlite has an average lamellar spacing of 0.08 to 0.30 μm, and the percentage of cementite in the pearlite having a major axis length of more than 0.3 μm and an aspect ratio of less than 3.0 is less than 15%.

The invention deals with a hot worked and annealed graphitic steel product having a composition comprising in weight percent: 0.70 % ≤ C ≤ 1.1 %, 0.35 % ≤ Mn ≤ 0.80 %, 1.0 % ≤ Si ≤ 3.0 %, 0.010 % ≤ Ti ≤ 0.090 %, 0.001 % ≤ Al ≤ 0.09 %, P ≤ 0.090 %, S ≤ 0.2, 0.0090 ≤ N ≤ 0.0150 and comprising optionally one or more of the following elements, by weight percent: 0 % ≤ B ≤ 0.006 %, 0 % ≤ Cr ≤ 1 %, 0 % ≤ Mo ≤ 0.5 %, 0 % ≤ V ≤ 0.2 %, 0 % ≤ Nb ≤ 0.1 %, 0 % ≤ Ni ≤ 3.0 %, 0 % ≤ Co ≤ 3.0 %, 0 % ≤ Cu ≤ 3.0 %, 0 % ≤ Sn ≤ 0.1 %, 0 % ≤ Ce ≤ 0.1 %, 0 % ≤ Mg ≤ 0.1 %, 0 % ≤ Zr ≤ 0.1 % the remainder of the composition being iron and unavoidable impurities resulting from the smelting, said steel having a microstructure comprising 1 to 10% in area fraction of free graphite particles, up to 5% optional cementite, the balance being ferrite.

The invention relates to the technical field of steel rail welding, in particular to a heat treatment method for improving network cementite in a steel rail welding heat affected zone, which comprises the following steps: A) cooling a welding joint which is formed by welding a hypereutectoid pearlite steel rail and has the surface temperature of 800-1000 DEG C; (B) the surface temperature of the welding joint is increased to 1000-1080 DEG C, and heating is stopped; c) cooling the welding joint; d) stopping heating when the surface temperature of the welding joint is increased to 930-980 DEG C; e) cooling the welding joint; the cooling rate and the final cooling temperature of a welding joint rail head heat affected zone and the cooling rate and the final cooling temperature of a welding joint rail waist heat affected zone are limited; and F) the welded joint is cooled for the fourth time to 20-30 DEG C. The method can improve the mechanical property of the steel rail, which is reduced due to welding, and eliminate a network cementite structure which possibly exists, so that the service performance of a steel rail welding joint is ensured.

The invention discloses a divorced eutectoid transformation fine-grained pressure vessel steel plate and a manufacturing method thereof, and belongs to the technical field of steel preparation. The chemical composition of the divorced eutectoid transformation fine-grained pressure vessel steel plate of the invention is as follows by weight percentage: C: 0.20-0.30%, Si: 0.15%-0.40%, Mn: 0.90%-1.50%, P≤0.015%, S≤0.005%, Cr: 1.0%-2.0%, Ni: 0.20%-0.30%, Mo: 1.0%-2.0%, Nb: 0.01-0.02%, Ti: 0.02-0.03%, Cu: 0.80-0.90%, V: 0.02-0.03%, B: 0.0 01~0.002%, Als: 0.025%~0.035%, N: 0.06%~0.08%, the balance is Fe and inevitable impurities, and the microstructure refinement technology such as chromium-copper alloying + high temperature short-time homogenization treatment + two-stage rolling + short-time normalizing is adopted to realize the refinement of the micro-composite structure of the medium carbon container steel plate, and obtain a perfect global microstructure. The cementite grain size reaches 1.0~2.5μm, and the ferrite grain size reaches 0.5~2.0μm. At the same time, it has good comprehensive mechanical properties, which makes it expected to be widely used in the field of pressure vessel equipment manufacturing.

A steel wire for machine structural parts, may include Fe, inevitable impurities, and, by mass: 0.05 to 0.60% C; 0.005 to 0.50% Si; 0.30 to 1.20% Mn; more than 0 to 0.050% P; more than 0 to 0.050% S; 0.001 to 0.10% Al; more than 0 to 1.5% Cr; and more than 0 to 0.02% N. An area of cementite present at ferrite grain boundaries in an area of all cementite of the steel wire may be 32% or more. When a C content (% by mass) of a steel is expressed as [C], an average circular-equivalent diameter of all the cementite is (1.668-2.13 [C]) μm or more and (1.863-2.13 [C]) μm or less.

The invention belongs to the technical field of heat treatment of metal materials, and relates to high-strength hot-rolled medium manganese steel and a preparation method of the high-strength hot-rolled medium manganese steel. A matrix structure of the obtained high-strength hot-rolled medium manganese steel comprises 49-61 vol% of austenite and 39-51 vol% of martensite, a precipitated phase is a cementite and vanadium carbide double-nanometer precipitated phase, and the yield strength of the high-strength hot-rolled medium manganese steel at the room temperature is 850-920 MPa, the tensile strength is 1190-1570 MPa, and the ductility is 14.5-19.0%.

A steel wire according to one embodiment of the present invention can be a high-strength and high-corrosion-resistant steel wire comprising, by wt%, 0.50-0.75% of carbon (C), 0.5-0.9% of manganese (Mn), 0.2-0.5% of silicon (Si), 0.03-0.18% of molybdenum (Mo), and the balance of iron (Fe) and inevitable impurities, wherein an average diameter of a pearlite block of the steel wire is 25 μm or less, and a carbon content of cementite in pearlite is 18 at% or higher.

The invention discloses a fixed flash welding and joint heat treatment method for a U75VH online heat treatment steel rail for a heavy haul railway, which can ensure that a fixed flash welding joint of the U75VH online heat treatment steel rail for the heavy haul railway is a normal pearlite structure by optimally designing parameters of a joint fixed flash welding process and a joint heat treatment heating process. Abnormal structures such as bainite, martensite and secondary cementite do not exist, the strength, hardness and toughness of the joint are matched with the performance of a base material, and the requirement of a heavy haul railway for the smoothness of the steel rail joint can be met. And the risk that the steel rail is fractured due to'saddle-shaped 'abrasion caused by too large hardness difference of a welding area or a microscopic abnormal structure of a joint in the line service process is improved, and the line operation safety is guaranteed.

The present invention addresses the problem of providing a welded joint in which LME cracks during production are suppressed. This welded joint is characterized by being provided with a high-strength steel plate having a tensile strength of 780 MPa or more, the high-strength steel plate having a prescribed chemical composition, and in a non-heat-affected part located at a distance of 5 mm or more from the outer end of a spot-welded part, the depth at which the C concentration measured by GDS is 0.01% or less in the depth direction of the high-strength steel plate is 3 [mu] m or more, and the thickness of the high-strength steel plate is 10 [mu] m or more. The roughness of the surface of the high-strength steel sheet exceeds 3.0 [mu] m, and the thickness of a layer having an area ratio of cementite of 10% or less in the depth direction of the high-strength steel sheet is 8 [mu] m or more in a heat-affected part located 0-100 [mu] m from the welding shoulder.

[Problem] To provide a method for producing cementite, capable of suppressing carbon precipitation and stably producing cementite over a long period of time. [Solution] Hematite (Fe2O3) is put into a reactor as an iron oxide serving as an iron source, and a carbonized gas formed from a mixed gas of carbon monoxide and carbon dioxide is supplied to the reactor. Cementite (Fe3C) can be efficiently produced for a long period of time without precipitating carbon by adjusting the carbon activity so that ac = 1 to 10 and subjecting the carbonized gas and hematite to a reduction reaction.

The invention discloses an online spheroidizing annealing process and system for a hot-rolled wire rod, and belongs to the technical field of wire heat treatment in the metallurgical industry. The process combines controlled rolling, controlled cooling and on-line spheroidizing annealing, and specifically comprises the following steps: after a steel billet is heated, rolling is completed in an austenite and ferrite two-phase region, and the steel billet is immediately cooled to 20-30 DEG C higher than the Ar3 temperature through water; the whole coil of the hot-rolled wire rod enters a tunnel type annealing furnace by utilizing waste heat of the hot-rolled wire rod, heat preservation is conducted for 0.4-0.6 h at the temperature 60-80 DEG C below the A1 temperature, the form and number of separated cementite in austenite are controlled, and nucleation points are formed; the temperature is increased to 20-50 DEG C below the temperature A1, heat preservation is conducted for 8-12 h, and cementite is gathered and grows up through spheroidization; and finally, slowly cooling to below 550 DEG C at the speed of 10-20 DEG C / h, and discharging. The rolling waste heat is fully utilized, the long heating process of traditional annealing is omitted, energy consumption is remarkably reduced, the annealing time is shortened, and the production efficiency is improved.

The present invention addresses the problem of providing a steel sheet and a plated steel sheet having high LME resistance. A steel sheet and a plated steel sheet according to the present invention are characterized by having a prescribed chemical composition, having a depth of 3 [mu] m or more at which the C concentration measured by GDS is 0.01% or less in the depth direction from the surface of the steel sheet, and having a thickness of 5 [mu] m or more at which the area ratio of cementite is 10% or less in the depth direction from the surface of the steel sheet. The surface roughness of the steel sheet is 3.0 [mu] m or less in terms of arithmetic average roughness Ra.

The invention provides high-spheroidization-rate medium-carbon steel based on medium-low annealing temperature and a production method thereof.The method comprises the steps of a hot rolling process, specifically, a medium-carbon steel blank is subjected to hot continuous rolling, the hot rolling coiling temperature is controlled to be 650 + / -20 DEG C, and a lamellar pearlite structure is obtained; a cold rolling process: carrying out cold rolling on the hot rolled coil, controlling the total cold rolling reduction rate to be not less than 35%, and introducing high-density dislocation and distortion defects into a pearlite structure; the cold-rolled steel plate is placed in a cover annealing furnace, under the full hydrogen protection atmosphere, the cold point temperature in the furnace is controlled to be 700 + / -10 DEG C, the hot point temperature is 710 + / -10 DEG C, the heat preservation time is 4-8 hours, and the flaky cementite is fully spheroidized; according to the method, the spheroidization rate of the medium carbon steel reaches 90% or above successfully under the upper limit condition of the annealing temperature of 720 DEG C, the contradiction between insufficient equipment capacity and high-end product requirements is solved, and remarkable economic benefits are achieved.

To provide a steel pipe for an airbag and a method for producing the steel pipe that ensure strength and low-temperature toughness without performing quenching and tempering.SOLUTION: A steel pipe for an airbag has a chemical composition comprising C: 0.10 to 0.25%, Si: 0.01 to 0.50%, Mn: 1.00 to 3.00%, P: 0.030% or less, S: 0.020% or less, Cr: 0.01 to 1.00%, Al: 0.010 to 0.060%, N: 0.0020 to 0.0200%, and V: 0.05 to 0.30%, optionally containing Mo: 0.30% or less as an optional element, with the balance being Fe and unavoidable impurities, having a metal structure mainly composed of a ferrite structure and cementite, in which an average crystal grain size of the ferrite structure is 1.5 μm or less, satisfying, with respect to tensile strength TS and elongation at break EL, Formula A: TS≥850 MPa and Formula B: TS×EL≥10000 MPa%, and having a fracture appearance transition temperature vTrs of -50°C or less.SELECTED DRAWING: None

The invention discloses a method for accurately measuring the phase content in stainless steel. The method is suitable for stainless steel containing at least one phase of ferrite, austenite, cementite and martensite. The method comprises the following steps: S1, cutting, grinding and polishing a stainless steel sample to obtain a bright surface; s2, pre-judging the type and the number of contained phases through metallographic structure observation in combination with component analysis and a heat treatment process; and S3, directional detection is conducted according to the pre-judgment result, ferrite is measured through metallographic software after being subjected to electrolytic corrosion through a KOH electrolyte, austenite is measured through an X-ray diffraction technology, cementite is measured through a laser confocal microscope after being subjected to acid etching, and martensite is obtained by subtracting the sum of the measured phase content by 100%. The method integrates various technical advantages, is simple and convenient to operate, wide in detection range and high in precision, and can provide accurate data support for stainless steel process optimization and material development.

The invention discloses a high-toughness corrosion-resistant pearlite steel wire with an adjustable honeycomb structure characteristic as well as a preparation method and application of the high-toughness corrosion-resistant pearlite steel wire, and belongs to the technical field of pearlite steel wire processing. The surface of the steel wire is provided with an aluminum alloy coating which is metallurgically bonded with a base body and has the thickness of 8-10 microns; the steel wire is subjected to ultrasonic treatment to generate a structure with a honeycomb characteristic, and the obtained cementite lamella serves as a hard phase to form a regular'honeycomb wall ', so that a core supporting effect is achieved; the ferrite serving as a plastic phase is coordinated and deformed under the action of external force by forming a honeycomb unit with uniform size, so that more energy is absorbed and crack propagation is hindered; and an Al2O3 protective film is instantaneously formed on the surface of the aluminum alloy coating, so that the aluminum alloy coating has excellent corrosion resistance and better mechanical properties. The Vickers hardness of the aluminum alloy reaches up to 830-850 HV < 0.1 >, the tensile strength of the aluminum alloy reaches 3100-3200 MPa, and the ductility of the aluminum alloy reaches 16-20%.

A steel part for the transmission system of an automobile comprising a core made of the following elements0.15% ≦ C ≦ 0.25%;1.0% ≦ Mn ≦1.6%; 0.4% ≦ Si ≦ 0.9%; 0.001% ≦ Al ≦ 0.1 %; 0.10% ≦ Mo ≦ 0.5%; 1% ≦ Cr ≦ 1.5 %; 0 ≦ P ≦ 0.09%; 0 ≦ S ≦ 0.09%; 0% ≦ N ≦ 0.09%; 0 ≦ Nb ≦ 0.06%; 0% ≦ Ni ≦ 1%; 0% ≦ V≦ 0.2%; 0% ≦ Ti ≦ 0.1%; 0% ≦ Cu≦ 1%; 0% ≦ B ≦ 0.008%; 0% ≦ Sn≦ 0.1%; 0% ≦ Ce ≦ 0.1%; 0% ≦ Mg ≦ 0.10%; 0% ≦ Zr ≦ 0.10%; the remainder composition being composed of iron and unavoidable impurities caused by processing, the microstructure of the core of said steel part comprising, by area percentage, at least 90% of Martensite, with a cumulative optional presence of any one or more from Residual Austenite, Pearlite, ferrite and Bainite from 1% to 10% and precipitates of Aluminum and / or Niobium in form of AlN and / or Nb (C,N), wherein the percentage of grains with prior austenite grains size from 3 to 5 is limited to a maximum of 10% of the total grains, such steel part comprising a martensite­deficient layer till the depth of 1mm or less on all its surfaces, such martensite­ deficient layer comprising from 55% to 72% of martensite, 10% to 40% of bainite and the remainder being any one or more from residual austenite, ferrite or cementite.

A manufacturing method of an alloy steel for cold-forging according to an embodiment of the present disclosure comprises homogenizing a steel material, furnace-cooling the steel material, and segmentation-annealing the steel material, in which the segmentation-annealing may be performed at least once and is optionally repeated one or more times.An alloy steel for cold-forging according to an embodiment of the present disclosure may comprise segmented cementite.A gear for cold-forging according to an embodiment of the present disclosure may have a gear surface grain boundary oxide layer of 19 μm or less.

The invention relates to the technical field of full mold casting, and provides a casting method of a large-scale automobile covering part GGG70L nodular cast iron stamping die, which comprises the following steps: firstly, manufacturing a model, and then manufacturing conformal chillers according to the molded surface of the model, and arranging the conformal chillers in a large area; smelting molten iron, adding alloy raw materials, and regulating and controlling the proportion of the alloy raw materials; then molten iron is subjected to spheroidizing inoculation and then is poured, after pouring, cooling in the eutectic stage is accelerated through external forced blowing heat dissipation, and through large-area use of shape-following chilling blocks, the profile cooling speed in the eutectic cooling stage is increased, the graphitization reaction is remarkably inhibited, growth of carburizing body nucleation and pearlite is promoted, and the pearlite nucleation rate is remarkably increased; ferrite precipitation is inhibited, and finally the pearlite content in a molded surface area is stabilized to be 90% or above; and finally, cooling to 200 DEG C, opening the sand box, taking down the test bar on the casting, and carrying out stretching detection and metallographic inspection. And multi-dimensional cooperative regulation and control are realized, so that the pearlite content is greatly increased, and the balance of mechanical properties is realized.

To provide a machine structure wire rod applicable to automobiles, construction components, and the like, and a manufacturing method therefor, and to provide a wire rod having excellent drawability, and a method for manufacturing the same.SOLUTION: The present invention is a wire rod which, in weight%, consists of C: 0.8-1.2%, Si: 0.01-0.6%, Mn: 0.1-0.6%, Cr: 0.8-2.0%, Al: 0.01-0.06%, N: 0.02% or less (excluding 0), with the remainder being Fe and inevitable impurities, wherein a microstructure includes proeutectoid cementite in a pearlite main structure, includes 20 or more AlN having an average particle size of 30 nm or less per unit area (μm2), and includes a microstructure satisfying the following relational expression 1, wherein [Relational Expression 1] is [(average size of block crystal grains(μm))2 / (length of proeutectoid cementite(μm / 1200 μm2))≤0.5].SELECTED DRAWING: Figure 1

The present invention relates to a free-cutting steel and a method for manufacturing same and, more specifically, to a steel wire and a method for manufacturing same, wherein the steel wire comprises, in weight%, C: 0.60%-0.85%, Si: 1.50%-1.99%, Mn: 0.10%-0.60%, S: 0.010%-0.150%, Cr: 0.005%-0.050%, Ti: 0.005%-0.020%, N: 0.003%-0.015%, and the balance of Fe and other impurities, and has a microstructure including ferrite, graphite particles, and cementite particles after graphitization heat treatment.

A hot-pressed member having a specified chemical composition in which Ti / Sb 2.0≤Ti / Sb≤20.0 is satisfied and a method for producing the hot-pressed member. The hot-pressed member has a microstructure in which a volume fraction of martensite is 95% or more, an average grain size of prior austenite is 7 μm or less, the number of cementite grains with a grain size of 0.10 μm or more is 2 grains / μm2 or more, and the number of Ti-based carbide grains with a grain size of 0.10 μm or less is 0.20 grains / μm2 or more, and a tensile strength of 2100 MPa or higher.