104 results about "Ferrite pearlite" patented technology

The invention relates to a high-performance non-quenched and tempered steel bar for a fan shaft and a manufacturing method of the high-performance non-quenched and tempered steel bar, and belongs to the field of iron-based alloys. The steel comprises the following chemical components in percentage by weight: 0.37 to 0.43 percent of C, 0.30 to 0.60 percent of Si, 1.20 to 1.70 percent of Mn, less than or equal to 0.025 percent of P, 0.030 to 0.070 percent of S, less than or equal to 0.50 percent of Cr, 0.10 to 0.30 percent of Ni, less than or equal to 0.30 percent of Mo, less than or equal to 0.30 percent of Cu, 0.010 to 0.030 percent of Al, 0.005 to 0.025 percent of Ti, 0.05 to 0.15 percent of V, 0.0100 to 0.0200 percent of N, less than or equal to 0.0002 percent of H, less than or equal to 0.0015 percent of O and the balance of Fe and inevitable impurity elements. The manufacturing process comprises the steps of converter / electric furnace smelting, LF furnace refining, RH / VD furnace vacuum degassing, continuous casting, casting blank reheating, cogging rolling, flame cleaning, intermediate blank finishing, intermediate blank heating, bar rolling, cooling and stress relief tempering. The total cross-section structure of the bar is a ferrite and pearlite structure. The bending degree per meter is smaller than or equal to 0.5 mm, the surface defect depth is smaller than or equal to 0.10 mm, and the internal quality meets the A-level requirement of the GB / T4162 standard.

The application discloses a low-carbon-equivalent 355MPa grade normalized rolled thick plate organization uniformity control method, wherein the temperature of the billet before charging is less than or equal to 400 DEG C, the temperature of the soaking furnace is 1130-1150 DEG C, the time of the soaking section is 45-55 minutes, the total furnace time is 170-185 minutes, the second opening temperature of the billet is 880-940 DEG C, the finishing rolling is 6-8 passes, the cumulative reduction is 60-70%, and the final rolling temperature is 860-900 DEG C; the steel plate cooling is realized by adopting a laminar flow cooling system, the full-automatic water pouring control cooling mode is adopted, the water inlet temperature is 720-740 DEG C, the red temperature is 640-660 DEG C, and the surface temperature of the steel plate after cooling is monitored. The head and tail and the full-thickness organization type of the normalized rolled steel plate are all 'ferrite + pearlite' organizations, the grain size level is all above 9.0, there is no obvious banded structure and no bainite structure, and the problem of the organization difference of the 355MPa grade thick plate product caused by the normalized rolling is solved.

Provided in the present invention are a hardness evaluation method and system for a heat affected zone of a multi-layer and multi-pass welded joint of hull steel. The method comprises: establishing a finite element model of a welded joint, and acquiring welding thermal cycles at nodes in a heat affected zone of the finite element model; performing solving to obtain critical temperatures for microstructural transformations of a study object, and performing solving to obtain volume fractions of transformation products during the thermal cycles, and a volume fraction of an austenite-ferrite-pearlite mixture after all the thermal cycles; acquiring hardness values of a martensite and a bainite in each thermal cycle, and a hardness value of the austenite-ferrite-pearlite mixture after all the thermal cycles; and on the basis of the acquired hardness values of the martensite and the bainite in each thermal cycle, and the the acquired hardness value of the austenite-ferrite-pearlite mixture after all the thermal cycles, acquiring a comprehensive hardness value of the heat affected zone. The present invention can accurately reproduce heat conduction and a microstructure transformation process in a heat affected zone during multi-layer and multi-pass welding of full steel, thereby assisting engineers in evaluating a welding temperature field and the structure distribution of the heat affected zone.

The invention discloses a high-toughness anti-fatigue high-pressure-resistant seamless steel tube and a gradient preparation method thereof, and relates to the technical field of metal material processing. The seamless steel tube forms a performance gradient from the inner wall to the outer wall in the wall thickness direction; the seamless steel pipe sequentially comprises a ferrite-pearlite structure layer, a transition structure layer and a tempered martensite structure layer from the inner wall to the outer wall, a Fe4N nitride layer and a Ni-Ti alloy layer are arranged on the inner wall, and a reinforced surface layer is formed on the outer wall through ceramic coating treatment. According to the seamless steel pipe, the performance gradient is formed along the wall thickness, the inner wall has high toughness and corrosion resistance, and the outer wall has high strength and fatigue resistance and adapts to complex working conditions; the gradient preparation method solves the problems that a traditional technology is large in heating temperature difference, uneven in rolling deformation, asynchronous in heat treatment phase change and the like, the comprehensive performance is improved, the technology is based on the prior art, the improvement cost is low, and industrial production is facilitated.

The steel sheet has a prescribed chemical composition, and in the metallographic structure at a position 1 / 4 of the sheet thickness from the surface, the steel sheet contains, in area%, 60.0% or more but less than 90.0% of bainite, more than 10.0% but 40.0% or less of martensite, and 10.0% or less in total of ferrite, pearlite and retained austenite, with the balance being Fe and unavoidable impurities. The value obtained by dividing the standard deviation of the aspect ratio of the old austenite crystal grains by the average value of the aspect ratio of the old austenite crystal grains is 0.50 or less, and the average grain diameter of the old austenite crystal grains is 30 [mu] m or less.

The invention relates to a thick hot-rolled spring wide steel plate, and belongs to the field of iron-based alloys. The steel comprises the following chemical components in percentage by mass: 0.47 to 0.55 percent of C, 0.17 to 0.37 percent of Si, 0.70 to 1.10 percent of Mn, 0.90 to 1.20 percent of Cr, 0.10 to 0.25 percent of V, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S and the balance of Fe and inevitable impurities, and the structure is uniform ferrite and pearlite. The production thickness ranges from 41 mm to 55 mm, the width is larger than 2000 mm, and the length is not smaller than 6000 mm; the straightness is less than or equal to 3mm / m, and the thickness tolerance range is within 1mm. The hardness is smaller than 280 HBW, the inclusions A, B, C and D are all smaller than 1.5 grades, and the sum of the inclusions A, B, C and D is smaller than or equal to 3.0 grades and is larger than or equal to 2.0 grades. High purity, longitudinal and transverse performance uniformity and accurate thickness control of the large-size spring steel plate are achieved, the thickness machining amount of the steel plate is reduced by four times compared with that of a forging technology, the higher yield is achieved, and the production cost of large-size springs is greatly reduced.

The application discloses a production method of a mining rare-earth wear-resistant GN-14A hot-rolled round steel, and a steelmaking process is as follows: a converter is operated with double-slag, and an end-point basicity is controlled at 2.5; the end-point control target of the converter is C >= 0.08%, and P <= 0.020%; a VD deep vacuum time is >= 15 min, and a soft blowing time is >= 20 min; a superheat degree is <= 25 DEG C, a caster pulling speed is 0.55 m / min <= 0.60 m / min; a casting blank slow cooling time is >= 24 hours; and a rolling process is as follows: 1020 DEG C <= open rolling temperature <= 1050 DEG C; 780 DEG C <= final rolling temperature <= 850 DEG C; 450 DEG C <= entering slow cooling pit temperature <= 550 DEG C; and 50 DEG C <= exiting slow cooling pit temperature <= 150 DEG C. The hot-rolled round steel prepared by the application has a structure of ferrite + pearlite structure, inclusion levels of A class <= 1.5 level, B class <= 1.5 level, C class <= 1.0 level, D class <= 1.5 level, and austenite grain size >= 5 level.

The application discloses a method for improving the production efficiency of normalized rolling Q420NE wind power steel, and the chemical components of the Q420NE wind power steel are as follows in percentage by weight: C: 0.16-0.18%; Si: 0.20-0.30%; Mn: 1.45-1.65%; Nb: 0.035-0.045%; V: 0.035-0.045%; Ti: 0.010-0.020%; P: less than or equal to 0.015%; S: less than or equal to 0.005%; Ca: 0.0008-0.0020%; Als: 0.015-0.030%; O: less than or equal to 0.0035%; N: less than or equal to 0.0052%; and the rest is iron and inevitable impurities; and a specific preparation process and control parameters are disclosed. The prepared steel plate has good strength, plasticity and toughness, and the structure is fine ferrite+pearlite+behenite.

This steel sheet has a prescribed chemical composition, wherein: the microstructure at a 1 / 4 thickness position that is the position at 1 / 4 the plate thickness in the plate thickness direction from the surface, is composed of, in area%, retained austenite: 3-10%, ferrite: 0-10%, pearlite: 0-5%, and martensite and bainite: 75-95% in total; and, in a cross section parallel to the plate thickness direction, when a region measuring 80 μm × 80 μm centered at the 1 / 4 thickness position in the plate thickness direction and measuring 80 μm in a direction perpendicular to the plate thickness direction is divided into 16 parts each measuring 20 μm × 20 μm, and the area ratio of retained austenite in each divided region is determined, σ1 / γave is 0.20 or less, where σ1 is the standard deviation and γave is the average of the area ratio of retained austenite in each divided region.

This invention discloses a ship plate steel with high plasticity, excellent impact toughness, and excellent weldability, and its production method. The composition of the ship plate steel includes C, Si, Mn, Als, P, S, Re, and the balance Fe and impurities. The preparation method includes: heating the billet at a temperature of 1150–1250℃, a heating rate of 8–12 min / cm, and a furnace exit temperature in the range of 1170±30℃; rolling: the first-stage rolling temperature is ≥1050℃, the intermediate billet thickness is 3 times the thickness H of the finished steel plate, and the second-stage rolling temperature is ≤960℃. The final rolling temperature is 830±30℃; the red-hot temperature after rolling is determined according to the thickness H of the finished steel plate. When H≤16mm, the red-hot temperature after rolling is 620±40℃; when 16<H≤25mm, the red-hot temperature after rolling is 640±30℃. The maximum thickness of the finished steel plate obtained by this invention is 25mm, the yield strength ReH≥320MPa, the tensile strength Rm≥420MPa, the elongation A≥30%, the longitudinal impact energy KV2≥200J at 0℃, and the steel plate microstructure is ferrite + pearlite. It is an economical high-plasticity ship plate steel.

The present application relates to a kind of thickness > 250 ~ 300mm low compression ratio S355NL extra-thick steel plate and its manufacturing method, the chemical composition of the steel plate: C:0.08 ~ 0.12%, Si:0.20 ~ 0.40%, Mn:1.45 ~ 1.65%, P:≤0.005%, S:≤0.001%, Al:0.02 ~ 0.05%, Nb:0.02 ~ 0.05%, V:0.03 ~ 0.06%, Ni:0.25 ~ 0.45%, Ti:0.01 ~ 0.03%, the balance is Fe and inevitable impurity element, carbon equivalent Ceq≤0.45%.Production using large thickness thick continuous casting slab, rolling compression ratio is less than 2.0.The internal quality and mechanical property of steel plate meet: yield strength ≥275Mpa, tensile strength ≥450Mpa, elongation after fracture ≥22%, the Charpy impact energy of transverse direction at-50 ℃ single value ≥100J, thickness direction tensile reduction of area ≥35%.Steel plate UT flaw detection can meet the requirement of NB / T47013.3 I level.The metallographic microstructure of steel plate is uniform fine ferrite + pearlite structure.

The present application relates to a kind of wind turbine gear box bearing steel and its production method, belong to the field of wind power steel.The steel is φ180-φ250mm round steel, metallographic structure is ferrite+pearlite, and a small amount of bainite.Adopting molten iron pretreatment-converter or electric arc furnace smelting-LF refining-RH or VD furnace vacuum degassing-large section continuous casting CCM large billet-rolled into round steel-finishing production process.The macrostructure of round steel: loose center ≤1.5 level, general loose ≤1.0 level, center crack ≤1.0 level, center segregation ≤1.0 level, no shrinkage cavity and subsurface crack.Inclusion: B fine ≤1.5 level, B coarse ≤0.5 level, D fine ≤1.0 level, D coarse ≤0.5 level, Ds ≤1.5 level.Macroscopic inclusion: image defect density ≤10mm / dm³, image single defect length ≤3mm, except 15% D in the center of bar.The banded structure is ≤3 levels.The present application is a kind of wind power steel with excellent purity, uniformity and density.

The invention belongs to the technical field of cold forging steel rolling, and particularly relates to a hot-rolled wire rod and a method for improving the plastic deformation capacity of the hot-rolled wire rod. The method comprises the following steps that S1, a first steel billet is obtained, and shot blasting treatment is conducted on the first steel billet to obtain a second steel billet; s2, the second steel billet is preheated, heated and subjected to heat preservation, and a third steel billet is obtained; s3, the third steel billet is subjected to first dephosphorization, rough rolling, second dephosphorization, rolling of a finishing mill, rolling of a reducing sizing mill, spinning and curling, and then a first hot-rolled wire rod is obtained; and S4, the first hot-rolled wire rod is put into a Stelmor cold conveying line to be cooled, and the hot-rolled wire rod is obtained. According to the hot-rolled wire rod and the preparation method thereof, structure regulation and control of the hot-rolled wire rod are achieved through cooperation of component optimization and process adjustment, transformation from coarse grain and high bainite proportion to fine grain and uniform ferrite and pearlite is achieved, the plastic deformation capacity of the hot-rolled wire rod is remarkably improved, the requirement of the downstream one-annealing and two-drawing process is met, and the production efficiency and the product percent of pass are greatly improved.

The invention relates to the technical field of metallographic analysis and detection, and particularly discloses a display method for accurately distinguishing multi-phase structures of a W780X hot rolled plate. Performing hot inlaying; performing grinding; polishing is conducted; corroding, namely soaking and corroding the polished sample in an aggressive agent sodium thiosulfate solution for 10-200 seconds, taking out, wiping the surface by using a hydrochloric acid alcohol cotton ball to remove a corrosion product on the surface, washing by using alcohol, and drying by blowing; the morphology, size and distribution state of ferrite, pearlite and martensite can be clearly displayed through metallographic microscope observation. Compared with the prior art, the etchant adopted by the invention is a solution prepared from 8-15g of sodium thiosulfate and 77-90ml of water, the three structures can be clearly displayed after corrosion, the cost is low, the etchant is safe and non-toxic, the preparation is convenient, and the morphology and distribution state of ferrite, pearlite and martensite in the metallographic structure of the W780X hot-rolled plate can be clearly and completely displayed; the method has the characteristics of low detection cost, rapidness, simplicity and accuracy.

The invention relates to a 45 steel plate for punch forming of a high-strength chain wheel and a preparation method of the 45 steel plate. The steel comprises the following chemical components: 0.42%-0.48% of C, 0.20%-0.30% of Si, 0.55%-0.65% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.015%-0.025% of V, 0.15%-0.20% of Cr and the balance of Fe and impurities. The metallographic structure of the finished steel plate is a ferrite and pearlite mixed structure, and the volume fraction ratio of ferrite to pearlite is (45%-55%): (55%-45%); and the grain size grade is 8.0-10.0 grade. On the basis of traditional 45 steel components, a small amount of V and Cr elements are added, a specific controlled rolling and controlled cooling process is combined, under the condition that follow-up heat treatment is not carried out, hot-rolled strip steel which is small in grain size, uniform in structure and excellent in obdurability matching is directly obtained, and the finished steel product is particularly suitable for punch forming of chain wheels.

The present invention provides: a continuously cast slab in which slab season cracking does not occur during cooling of the continuously cast slab even if the continuously cast slab has a low toughness; and a method for manufacturing the same. Disclosed is a continuously cast slab for high-strength steel, which has a specific component composition, the continuously cast slab being characterized in that: the average prior austenite grain size ratio (d20 / d10) of the average prior austenite grain size d20 at the position of 20 mm below a surface layer of the continuously cast slab to the average prior austenite grain size d10 at the position of 10 mm below the surface layer of the continuously cast slab is 1.0 to 4.0 inclusive; the microstructure is composed of ferrite, pearlite, bainitic ferrite, tempered martensite, quenched martensite, and retained austenite; and the microstructure at the position of 10 mm below the surface layer of the continuously cast slab and the microstructure at the position of 20 mm below the surface layer of the continuously cast slab are formed of a structure that has a specific area ratio.

The high-performance carbon steel comprises the following components in percentage by weight: 0.05 to 0.25 percent of C, 0.10 to 0.40 percent of Si, 0.55 to 2.0 percent of Mn, 0.01 to 0.05 percent of N, less than or equal to 0.020 percent of S, less than or equal to 0.018 percent of P, less than or equal to 0.005 percent of As, less than or equal to 0.008 percent of Sb, less than or equal to 0.008 percent of Sn and the balance of Fe and inevitable impurities, and the elements also need to simultaneously meet the following conditions: less than or equal to 0.020 percent of P, less than or equal to 0.020 percent of As, less than or equal to 0.020 percent of Sb and less than or equal to 0.008 percent of Sn; the inevitable impurities comprise Cr, Mo and Mn, and (Cr + Mo + Mn) * N is controlled to be greater than or equal to 0.010%; the microscopic structure of the high-performance carbon steel is ferrite and pearlite, the high-performance carbon steel can be directly used in a hot rolling state, the postweld heat treatment inhibition performance is stable, the room-temperature yield strength is larger than or equal to 240 MPa, the tensile strength is larger than or equal to 415 MPa, the high-temperature instantaneous tensile yield strength at 350 DEG C is larger than or equal to 175 MPa, and the tensile strength is larger than or equal to 350 MPa.

This invention discloses a low-alloy angle steel (Q355B) with micro-niobium and low-manganese content, and its efficient short-process production method. The chemical composition of the angle steel is: C 0.14%~0.21%, Si 0.20%~0.45%, Mn 1.00%~1.25%, Nb 0.005%~0.014%, P≤0.025%, S≤0.020%, N≤0.009%, with the balance being Fe and unavoidable impurities. This method uses scrap steel as raw material, sequentially processing it through electric arc furnace smelting, LF refining, and continuous casting to obtain a high-temperature billet. The high-temperature billet is then directly conveyed to the heating furnace, achieving hot charging and hot delivery. Compared with existing technologies, this invention omits the billet cooling and secondary heating processes, significantly reducing energy consumption, shortening the production cycle, and reducing the formation of iron oxide scale. By substituting a small amount of Mn with Nb, and utilizing the dispersed precipitation of Nb(C,N) to simultaneously achieve grain refinement and precipitation strengthening, a ferrite + pearlite microstructure with an average grain size of 15~23μm is obtained, resulting in angle steel with excellent mechanical properties. This invention, while ensuring the strength and toughness of angle steel, also possesses the comprehensive advantages of energy saving, cost reduction, and efficiency control, and has promising prospects for industrial application.

The invention provides a wire rod for enhancing the service performance of a high-strength tire bead wire and a structure control method. The wire rod comprises the following components in percentage by weight: 0.06%-0.12% of [C], 0.15%-0.25% of [Si], 0.50%-0.60% of [Mn], less than or equal to 0.015% of [P], 0.0030%-0.010% of [S], 0.0010%-0.0030% of total oxygen, 0.0005%-0.0015% of [Als], 0.0001%-0.0009% of [V] and 0.0002%-0.0011% of [Mg]. And the balance of Fe and inevitable impurities. The steel wire rod structure control method comprises the steps of smelting, continuous casting, heating, rolling, steel wire rod rolling and steel wire rod cooling. According to the wire rod produced through the method, the grain size is not larger than 25 microns, and the grain size difference is not larger than 2 levels. The wire rod structure is composed of ferrite and pearlite, and the ferrite content is larger than 90%. The tensile strength of the wire rod is 410-450 MPa, and the ductility is 30%-40%.

The invention discloses a production method of a high-toughness high-resistivity low-alloy steel medium plate. Steel comprises the following chemical components in percentage by weight: 0.06%-0.10% of C, 0.90%-1.30% of Si, 1.45%-1.7% of Mn, less than or equal to 0.015% of P, less than or equal to 0.004% of S, 0.020%-0.060% of Alt, 0.008%-0.020% of Ti, 1.3%-1.5% of Mn / Si, more than or equal to 3.42% of Ti / N and the balance of Fe and inevitable impurities. Through high-temperature finish rolling, the finish rolling temperature is 50 DEG C or above higher than the Ar3 temperature point, and complete recrystallization is ensured; after rolling, double-stage controlled cooling is adopted, the pearlite transformation temperature is skipped to 650-700 DEG C through fast cooling, and ferrite is promoted to grow sufficiently through slow cooling; the microstructure of the finally obtained steel plate is 85%-92% of ferrite and 8%-15% of pearlite, the grain size of the ferrite is 10-12 grades, high toughness and high resistivity are well matched, the alloy production cost is low, and the process is simple.

A weakly deoxidized Q420MPa grade marine climate corrosion resistant steel, its composition and wt% are as follows: C: 0.05-0.15%, Si: 0.10-0.30%, Mn: 1.00-1.70%, P: 0.050-0.100%, S≤0.002%, Cu: 0.15-0.35%, Ni: 0.10-0.30%, Nb: 0.020-0.050%, Ti: 0.005-0.020%, O: 0. 0.010~0.025%, 0.020%≤Ce+La≤0.050%, 10%≤Si / O≤20%, 5%≤Mn / Si≤10%, CEV≤0.45, CEV=C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15; Production process: After desulfurization of molten iron, it is smelted in a conventional converter; after casting, the billet is heated; high-pressure water descaling; rough rolling; finish rolling; cooling to coiling temperature; coiling; and conventional subsequent processes. This invention achieves a stable ferrite + pearlite + bainite microstructure by ensuring a yield strength ≥410MPa, tensile strength ≥550MPa, and elongation after fracture ≥27%, using a low C, high P, and high O composition, adding certain amounts of Mn, Cu, Ni, Nb, Ti, Ce, La, etc., and achieving a low-temperature impact energy of -60℃ ≥170J and an annual corrosion rate of ≤1.3mm / y in marine climates.

This steel sheet includes: a base steel sheet having a predetermined chemical composition; and a zinc-plated layer formed on a surface of the base steel sheet, in which, when a sheet thickness of the base steel sheet is denoted by t, a metallographic structure at a t / 4 position, which is a position at t / 4 from the surface in a cross section in a sheet thickness direction of the base steel sheet, contains, by volume percentage, tempered martensite: 85% or more, residual austenite: 7% or more, and one or more selected from ferrite, pearlite, bainite, and fresh martensite: 0% or more and 8% or less, a metallographic structure in a surface layer region, which is a range from the surface to a position of 50 μm in the cross section in the sheet thickness direction, contains, by volume percentage, 30% or more of bainite, and a remainder including one or more selected from ferrite, pearlite, tempered martensite, fresh martensite, and residual austenite, in the surface layer region, a diameter of prior austenite grains in the sheet thickness direction is 10.0 μm or less, and a tensile strength of the steel sheet is 1,470 MPa or more.

The invention relates to low-cost easy-to-form hot-rolled automobile steel and a production method thereof. The steel comprises the following chemical components in percentage by mass: 0.04-0.08% of C, less than or equal to 0.50% of Si, 1.20-1.80% of Mn, less than or equal to 0.030% of Als, 0.040-0.110% of Ti, less than or equal to 0.020% of P, less than or equal to 0.010% of S, less than or equal to 0.0040% of N and the balance of Fe and inevitable inclusions. The metallographic structure of the finished steel plate is ferrite, pearlite and a small amount of bainite. Aiming at high-forming-performance and low-cost production of the 510-700MPa-grade hot-rolled automobile steel, a full-process control technology is adopted, on the premise that a product has good forming performance, the narrow standard requirement is met, and meanwhile the beneficial effects of low cost and the like are achieved; and heating process rhythm control and powerful dephosphorization water spraying are adopted, so that the surface quality and performance of a finished product are ensured, and meanwhile, the production cost is reduced.

The application discloses a high-strength and high-toughness medium-carbon ferrite-pearlite type non-quenched and tempered steel and a preparation method thereof. The chemical component of the steel is as follows: C: 0.40-0.48%; Si: 0.20-0.60%; Mn: 1.20-1.60%; Ti: 0.010-0.020%; Zr: 0.005-0.020%; P: less than or equal to 0.025%; S: less than or equal to 0.015%; N: 0.010-0.025%, and the rest is Fe and inevitable impurities. The preparation method comprises the following steps: continuous casting of a large square billet, heating in a heating furnace, rough rolling, finish rolling, air cooling on a cooling bed, sawing and bundling. The non-quenched and tempered steel can improve the strength and toughness matching while reducing the cost.

A sulfur-resistant and corrosion-resistant low-carbon alloy coiled tubing and a preparation method therefor. The sulfur-resistant and corrosion-resistant low-carbon alloy coiled tubing has a metallographic structure of ferrite and pearlite, and is prepared by means of the butt joint of steel strip plates, coiling molding, tube blank welding, extrusion molding, a welding seam heat treatment and cooling. In the preparation method, welding seam grains of the steel strips are refined by means of a plasma welding method, such that the structure is uniform, and the strength is stable; and the heat treatment process refines the welding seam grains, makes the structure more uniform, and improves the strength and corrosion resistance of a coiled tubing.

The invention relates to a high-strength weather-resistant steel bar, which is characterized in that the steel bar comprises the following chemical components in percentage by mass: 0.32 to 0.45 percent of C, 0.60 to 1.00 percent of Si, 1.40 to 2.00 percent of Mn, 0.25 to 0.30 percent of V, 0.02 to 0.03 percent of N, 0.03 to 0.10 percent of RE and the balance of Fe and inevitable impurity elements, the microstructure of the steel bar is a complex phase of ferrite, pearlite and bainite, the content of the pearlite is more than 70 volume percent, and the content of the ferrite is 5 to 25 volume percent. The excellent mechanical property and weather resistance of the reinforcing steel bar are realized by controlling the types and contents of the elements, especially the ratio of the elements V to the elements C, and combining the preparation process.

A steel sheet comprising a steel microstructure containing, by volume fraction, tempered martensite: 85% or more, retained austenite: from 5% or more to less than 15%, and ferrite, pearlite, bainite, and freshly tempered martensite less than 10% in total, where the Mn and C contents in the retained austenite are denoted as MnA and CA and the Mn and C contents in the matrix are denoted as MnM and CM, respectively, satisfies the following formulas (1) to (3), and the number of carbides having an equivalent circle radius of 0.1 µm or more is 100 or less in a measurement region of 20,000 µm², and the steel sheet has a tensile strength of 1100 MPa or more. The steel sheet is excellent in terms of impact resistance and formability. MnA / MnM=1.2 (1) CA / CM=5.0 (2) CA=1.0 (3).

The invention relates to the technical field of metal material processing and heat treatment, and discloses an anti-seismic reinforcing steel bar and a production process thereof, and the production process comprises the following steps: carrying out surface instantaneous micro-quenching on a high-temperature reinforcing steel bar subjected to controlled rolling forming to form a martensite thin layer; then applying a high-frequency electromagnetic field for disturbance treatment; coating a layer of functional precursor powder on line; then in-situ tempering and surface alloying are achieved by applying on-line shear deformation; and finally, the whole steel bar is subjected to speed-controlled cooling so as to complete core structure phase change. According to the method, precise in-situ tempering is conducted on a quenched surface layer through plastic deformation heat induced by shear stress, a functional precursor is synchronously driven to react in situ to form an alloying modified layer, and the structure transformation condition is optimized under the assistance of electromagnetic disturbance; an integrated composite gradient structure with the core being ferrite-pearlite and the surface being tempered martensite and a functional modification layer is achieved, and the problems that according to a traditional technology, strength and toughness matching is difficult, and performance is unstable are solved.

The application provides a kind of steel and its preparation method, steel for packaging, metal can, belongs to the field of steel preparation.The chemical composition of the steel includes: C, Si, Mn, Alt, P, S, N and Fe;Among them, the content of C is 0.12%~0.15% by mass fraction, the content of Si is ≤0.03%, the content of Mn is 0.50%~0.80%, the content of Alt is 0.030%~0.060%, the content of P is <0.012%, the content of S is <0.010%, the content of N is ≤0.003%;The microstructure of the steel includes: ferrite, pearlite and tertiary cementite;The content of ferrite is 80%~88% by volume fraction, the content of pearlite is 10%~15%, and the content of tertiary cementite is 2%~5%.Low-carbon component design is adopted, without adding other alloy elements, refined ferrite grains and small interlamellar spacing pearlite structure are obtained to realize high strength and high plasticity of the material, the strength of the material is significantly improved, and the forming property of the material is improved.

The invention relates to a high-strength steel bar with excellent low-temperature performance and welding performance, which is characterized in that the steel bar comprises the following chemical components in percentage by mass: 0.25-0.30% of C, 0.60-1.00% of Si, 1.30-1.80% of Mn, 0.20-0.25% of V, 0.02-0.03% of N, less than 0.35 ppm of H and the balance of Fe and inevitable impurity elements, and the relationship between the mass percentage content [N] of N in the steel and the mass percentage content [V] of a V element with fixed N atoms meets the following condition: [N] / (0.16 [C] + 0.275 [V]) is more than or equal to 0.2 and less than or equal to 0.3, and the balance of Fe and inevitable impurity elements. The microstructure of the steel is ferrite, pearlite and bainite, the average grain size of the microstructure is smaller than or equal to 10 micrometers, the content of the ferrite is 60% by volume or above, and the content of the bainite is 10-30% by volume. The steel bar provided by the invention simultaneously meets the requirements of high strength, excellent weldability, good strength and plasticity matching and good low-temperature performance.