29 results about "Equivalent weight" patented technology

The hydrogen transmission pipeline steel comprises the following chemical components in percentage by mass: 0.020%-0.045% of C, 0.11%-0.19% of Si, 1.45%-1.65% of Mn, less than or equal to 0.0010% of S, less than or equal to 0.008% of P, 0.015%-0.045% of Al, 0.040%-0.060% of Nb, 0.020%-0.035% of Ti, 0.30%-0.50% of Cr, 0.0040%-0.0080% of RE, less than or equal to 0.004% of N, less than or equal to 0.0015% of O, less than or equal to 0.0001% of H and the balance of Fe and other inevitable impurities, the conditions that the carbon equivalent Ceq = C + Mn / 6 + (Cr) / 5 is less than or equal to 0.35%, the Nb / Ti = the rare earth element is selected from at least one of lanthanum, cerium and neodymium. The invention aims to solve the technical problems that the existing hydrogen transmission pipeline steel is easy to generate hydrogen embrittlement, short in fatigue life and high in production cost in a high-pressure hydrogen environment, and meets the core requirements of hydrogen energy long-distance transmission pipeline engineering on high strength, high hydrogen embrittlement resistance, high fatigue performance and low cost of materials.

The invention discloses a Q460 crack-arrest steel plate with the thickness of 150-220 mm and a manufacturing method thereof. The steel plate comprises the following chemical components in percentage by weight: 0.05-0.10% of C, 0.10-0.50% of Si, 0.8-1.8% of Mn, 0-0.05% of Nb, 0-0.05% of V, 0-0.03% of Ti, 0.02-0.07% of Al, 0-0.5% of Ni, 0-0.10% of Cu, 0.4-0.8% of Cr, 0-0.4% of Mo, 0-0.0020% of B, 0.010-0.030% of Ca, less than or equal to 0.010% of P, less than or equal to 0.001% of S, less than or equal to 0.0020% of O, less than or equal to 0.0030% of N, less than or equal to 0.0001% of H and the balance of Fe and And the carbon equivalent CEV is less than or equal to 0.48%. The manufacturing method comprises the steps of smelting, external refining, vacuum degassing, Ca treatment, continuous casting, heating, rolling, heat treatment and the like. The thickness of the steel plate reaches 150-220 mm, the yield strength is larger than or equal to 420 MPa, the tensile strength is 520-670 MPa, the ductility is larger than or equal to 18%, the Z-direction area reduction rate is larger than or equal to 50%, the-40 DEG C low-temperature impact Akv is larger than or equal to 100 J, the-20 DEG C CTOD value is larger than or equal to 1.0, and the steel plate has excellent obdurability and crack arrest performance and can be widely applied to the fields such as ocean engineering and harbor machinery which have strict requirements for material performance.

The invention discloses low-carbon high-toughness high-crack-arrest 500MPa-grade steel for ocean engineering and a production method of the low-carbon high-toughness high-crack-arrest 500MPa-grade steel. The steel plate comprises the following chemical components in percentage by mass: 0.06%-0.09% of C, 0.15%-0.20% of Si, 1.00%-1.50% of Mn, less than or equal to 0.008% of P, less than or equal to 0.002% of S, 0.10%-0.20% of Mo, 0.03%-0.08% of Nb, less than or equal to 0.005% of Ti, 0.30%-0.50% of Ni, 0.10%-0.20% of Cu and the balance of F and inevitable impurities, wherein the carbon equivalent CEV is less than or equal to 0.41%, the strengthening equivalent Req is 0.40%-0.62%, and the fracture toughness equivalent Feq is 0.10%-0.12%. The yield strength of the core part of the steel plate is larger than or equal to 420 MPa, the tensile strength is larger than or equal to 550 MPa, the percentage elongation after fracture is larger than or equal to 22%, the impact energy at the temperature of-80 DEG C is larger than or equal to 250 J, the steel plate is welded under the heat input quantity of 20-50 kJ / cm, and the impact energy at the temperature of-40 DEG C of a welded joint after welding is larger than or equal to 100 The method comprises the key process steps of smelting, heating, controlled rolling and controlled cooling, and the steel which is good in crack arrest performance and can meet the requirements of ocean engineering equipment is obtained.

This invention relates to a 1900MPa grade ultra-high strength and toughness stainless gear steel and its preparation method. The chemical composition of the 1900MPa grade ultra-high strength and toughness stainless gear steel, by mass percentage, is: C 0.08-0.11%, Cr 10-12%, Ni 2-4%, Mo 2-5%, Co 10-13%, V 0.2-0.6%, Nb 0.02-0.05%, Al 0.5-1.0%, with the balance being Fe and unavoidable impurities. Its composition design must meet the following requirements: Chromium equivalent Cr... eq It is 17~18, with a nickel equivalent (Ni). eq The martensitic transformation point is 14-15. s The temperature range is 240~280℃. Its beneficial effects are: strengthening through the composite precipitation of intermetallic compounds NiAl and M₂C carbides, combined with Cr... eq Ni eq M s A synergistic design incorporating 5%–10% metastable austenite achieves an excellent balance between strength and toughness. The resulting steel exhibits tensile strength ≥1900 MPa, yield strength ≥1550 MPa, elongation ≥13%, fracture toughness ≥80 MPa·m¹ / ², and bending fatigue limit reaching 920 MPa. It is particularly suitable for manufacturing critical structural components requiring high load-bearing capacity and high reliability, such as aircraft engines, and has broad application prospects.

A steel material according to the present disclosure has a chemical composition containing, in terms of mass%, 0.10-0.40% C, 0.01-0.45% Si, 0.30-0.95% Mn, not more than 0.030% P, not more than 0.025% S, more than 0.50 and up to 1.80% Cr, 0.005-0.100% Al, not more than 0.0250% N, and not more than 0.0050% O with the remainder being Fe and impurities, wherein: the total area ratio of ferrite and pearlite in the microstructure is not less than 95%; an average equivalent circle diameter DN of nitrides having an equivalent circle diameter of not less than 20 nm is not more than 70 nm; and a sample standard deviation SDN of the equivalent circle diameter of the nitrides is not more than 45 nm.

The invention discloses a low-cost alloyed Q460C / D steel plate and a production method thereof. The low-cost alloyed Q460C / D steel plate comprises the following chemical components: 0.06-0.0.08% of C, 0.1-0.3% of Si, 1.50-1.60% of Mn, less than or equal to 0.010% of P, less than or equal to 0.003% of S, 0.025-0.035% of Als, 0.020-0.030% of Nb, 0.008-0.015% of Ti and the balance of Fe and residual elements, Ceq is less than or equal to 0.35, and meanwhile, the carbon equivalent (Ceq = C + Mn / 6 + Si / 24 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14) is controlled. The steel plate is prepared by the following steps: (1) KR molten iron pretreatment: ensuring that S in molten iron is less than or equal to 0.005%, the desulfurization period is less than or equal to 25 minutes, and the desulfurization temperature drop is less than or equal to 25 DEG C; (2) smelting and casting: under the vacuum degree of 67 Pa, the pressure maintaining time is longer than or equal to 20 min, and meanwhile, the molten steel turning effect in the pressure maintaining process is required to be good; the VD off-station temperature is 1570 to 1575 DEG C; (3) heating: the heating temperature of the steel billet is 1180-1230 DEG C, and the heating time is 1 min / mm, and (4) high-temperature recrystallization direct rolling: after rolling is finished, DQ + ACC cooling is adopted, the cooling speed is controlled to be 10-20 DEG C / s, and the water outlet temperature is controlled to be 370-400 DEG C. The steel plate obtained through the method has the advantages in the aspect of cost economy, and the urgency of market requirements is improved.

The present application provides a steel sheet and a method for manufacturing the same. The steel sheet of the present application contains, in mass%, C: 0.03 to 0.15%, Si: 0.50% or less, Mn: 0.3 to 2.5%, P: 0.030% or less, S: 0.0050% or less, Ni: 0.01 to 5.00%, Al: 0.005 to 0.100%, N: 0.0100% or less, and O: 0.0100% or less, Ceq satisfies 0.300 to 0.550%, the remainder is Fe and inevitable impurities, the hardness of the center segregation portion of the steel sheet satisfies formula (3), the number density of segregation particles with an equivalent circle diameter of 100 μm or more is 2.0 pieces / mm 2 Hereinafter, the average effective crystal grain diameter of the center portion of the sheet thickness is 20 μm or less. Hv max / Hv ave ≤1.35+0.006 / [C]‑t / 500...(3)

To provide an Al-Mg-Si based aluminum alloy sheet capable of obtaining excellent surface properties and formability even in the case the temperature rising rate and heating temperature at the time of intermediate annealing are made low.SOLUTION: The Al-Mg-Si-based aluminum alloy sheet contains Si: 0.50 mass% or more and 1.60 mass% or less, Mg: 0.25 mass% or more and 1.00 mass% or less, Fe: 0.05 mass% or more and 0.50 mass% or less, Mn: 0.01 mass% or more and 0.30 mass% or less, and Cu: 0.001 mass% or more and 0.30 mass% or less, with the balance being Al and inevitable impurities. When the Mg content is represented by [Mg] in mass%, [Mg] / [Si] is more than 0.50, the area ratio of Cube orientation is 9% or less, and the number densities of compounds having equivalent circle diameters of 1.5 μm or more are 1000 particles / mm2 or more and 10000 particles / mm2 or less.SELECTED DRAWING: None

Provided is a steel material having excellent SSC resistance. The steel material of the present invention has a chemical composition, in terms of mass%, of C: 0.035% or less, Si: 1.00% or less, Mn: 1.00% or less, P: 0.030% or less, S: 0.0050% or less, sol. Al: 0.005 to 0.100%, N: 0.001 to 0.020%, Ni: 5.00 to 7.50%, Cr: 10.00 to 14.00%, Cu: 0.01% or more and less than 1.50%, Mo: 1.50 to 3.50%, V: 0.01 to 1.00%, Ti: 0.02 to 0.30%, Co: 0.01 to 0.50%, Ca: 0.0003 to 0.0030%, O: 0.0050% or less, W: 0 to 1.50%, Nb: 0 to 0.50%, B: 0 to 0.0050%, Mg: 0 to 0.0050%, rare earth elements (REM): 0 to 0.020%, and the balance being Fe and impurities, and the total of Mn sulfides having a circle equivalent diameter of 1.0 μm or more and Ca sulfides having a circle equivalent diameter of 2.0 μm or more is 0.50 pieces / mm 2 The following.

A steel consists of, in mass %, C: 0.25 to 0.45%, Si: 0.10 to 0.50%, Mn: 0.40 to 0.70%, P: 0.015% or less, S: 0.005% or less, Cr: 0.80 to 1.50%, Mo: 0.17 to 0.30%, V: 0.24 to 0.40%, Al: 0.005 to 0.100%, N: 0.0300% or less, O: 0.0015% or less, and the balance being Fe and impurities, and satisfies Formula (1) to Formula (4) described in the present specification, wherein: its microstructure is composed of ferrite and pearlite having a total area fraction of 5.0 to 100.0%, and a hard phase having a total area fraction of 0 to 95.0%; a proportion of a total area of CaO—CaS—MgO—Al2O3 composite oxides with respect to a total area of oxides in the steel is 30.0% or more; and a number density of oxides having an equivalent circle diameter of 20.0 μm or more is 15.0 pieces / mm2 or less.

The stainless steel contains 0.0001 mass % or more and 0.15 mass % or less of C, 0.30 mass % or more and 2.0 mass % or less of Si, 0.1 mass % or more and 15 mass % or less of Mn, 5 mass % or more and 30 mass % or less of Ni, 0.0001 mass % or more and 0.01 mass % or less of S, 16 mass % or more and 25 mass % or less of Cr, 0 mass % or more and 5 mass % or less of Mo, 0 mass % or more and 0.005 mass % or less of Al, 0 mass % or more and 0.0010 mass % or less of Mg, 0.0010 mass % or more and 0.0060 mass % or less of O, and 0.0001 mass % or more and 0.5 mass % or less of N, and at least includes an inclusion with an equivalent circle diameter of 5 μm or more, having the average composition of 5 mass % or more of MnO, 20 mass % or more of Cr2O3+Al2O3, 1 mass % or more of Al2O3, and 5 mass % or less of CaO. The number density of the inclusion having the composition is 0.5 inclusions / mm2 or less.

The application discloses a low-cost thick-gauge 460MPa nickel-free weather-resistant steel and a manufacturing method thereof. The chemical components of the steel are as follows: C: 0.04-0.07%, Si: 0.55-0.75%, Mn: 0.43-0.63%, P: 0.010-0.014%, S: less than or equal to 0.003%, Cu: 0.3-0.5%, Cr: 0.3-0.5%, Ti: 0.020-0.030%, V: 0.020-0.030%, B: 0.0007-0.0013%, Al: 0.020-0.030%, Zr: 0.0009-0.0015%, and the balance of Fe and other inevitable impurities; and the chemical components need to meet the following conditions simultaneously: a welding crack sensitivity index Pcm is less than or equal to 0.17%; a carbon equivalent CEV is less than or equal to 0.32%; a weather resistance index I is greater than or equal to 6.0; Cu / P+5*Si is greater than or equal to 25; and 0.06% is less than or equal to (Al+Ti+V) and is less than or equal to 0.085%. The obtained weather-resistant steel has the characteristics of high strength and weather resistance, good surface quality, low yield ratio and easy welding without adding Ni, the thickness of the steel can reach 60 mm at most, the use range of the high-strength weather-resistant steel is widened, and the weather-resistant steel can be widely used for manufacturing corrosion-resistant structural parts.

The invention discloses low-cost thick-specification 590 MPa nickel-free weathering steel and a manufacturing method thereof. The low-cost thick-specification 590 MPa nickel-free weathering steel comprises the following chemical components in percentage by weight: 0.06 to 0.09 percent of C, 0.65 to 0.85 percent of Si, 0.53 to 0.83 percent of Mn, 0.010 to 0.014 percent of P, less than or equal to 0.003 percent of S, 0.3 to 0.5 percent of Cu, 0.3 to 0.5 percent of Cr, 0.020 to 0.030 percent of Ti, 0.020 to 0.030 percent of V, 0.0015 to 0.0020 percent of B, 0.020 to 0.030 percent of Al, 0.0015 to 0.0020 percent of Zr and the balance of Fe and other inevitable impurities. The chemical components need to simultaneously meet the following requirements: the welding crack sensitive index Pcm is less than or equal to 0.22%; the carbon equivalent CEV is less than or equal to 0.35%; the weather-proof index I is greater than or equal to 6.2; cu / P + 5 * Si > = 25; 0.06% < = (Al + Ti + V) < = 0.085%. According to the weathering steel, the yield strength is larger than or equal to 590 MPa, the tensile strength is larger than or equal to 710 MPa, the impact energy at the temperature of-20 DEG C is 190-360 J, the yield ratio is smaller than or equal to 0.85, and no copper brittleness crack exists on the surface of a steel plate.

The present invention aims to provide a colloidal silica containing silica particles having a proper true specific gravity, a high aggregation ratio, and a high alkoxyl group content at a high purity, and a production method capable of easily producing the colloidal silica and reducing the production cost. The present invention relates to a colloidal silica characterized in that the silica particles contained in the above colloidal silica have an average primary particle diameter of 33 nm or more, an aggregation ratio of 1.2 or more, a true specific gravity of 1.95 or more, contain 1000 mass ppm or more of an alkoxyl group per 1 g of the silica particles, have a proportion of the number of silica particles having a circular equivalent diameter of less than 20 nm of less than 15%, and contain 5 μmol or more of a primary amine per 1 g of the silica particles.

The present invention relates to a composition, preferably for bonding together metal sheets, comprising:a. 1 part by mole of at least one linear epoxy resin with an average epoxy equivalent weight of 600 to 5,000 g / mole and an epoxy functionality of 2,b. 0.4 to 0.8 parts by mole of at least one non-linear epoxy resin having an average epoxy equivalent weight of 180 to 350 g / mole and an average epoxy functionality of at least 3,c. 0.8 to 1.3 parts by mole of at least one basic hardener comprising at least two free amine-bonded hydrogen atoms, andd. 0.9 to 1.2 parts by mole of at least one crosslinker comprising at least two blocked isocyanate groups.

The invention discloses a production method for optimizing impact performance of a thick E ship plate, which comprises the following chemical components in percentage by mass: 0.06-0.09% of C, 0.15-0.23% of Si, 1.5-1.6% of Mn, 0.020-0.05% of Al, 0.010-0.02% of Ti, 0.020-0.030% of Nb, less than or equal to 0.02% of P, less than or equal to 0.003% of S, less than or equal to 0.006% of N and the balance of iron and inevitable impurity elements, and the carbon equivalent Ceq in the steel plate is controlled to be less than or equal to 0.36%. Wherein Ceq = [C + Mn / 6 + (Cr + Mo + V) / 5 + (Cu + Ni) / 15]. The rolling reduction in the rough rolling process is strictly controlled, meanwhile, the structure is promoted to be further refined through the ACC technology, a uniform structure with ferrite and pearlite as main components is obtained, the performance uniformity is guaranteed, and therefore good obdurability and impact resistance are obtained.

Provided is a martensite-based free-cutting stainless steel bar that is characterized by: having a chemical composition of C at 0.60% exclusive to 1.00% inclusive, Si at 0.10% to 2.0%, Mn at 0.10% to 3.0%, S at 0.050% or less, P at 0.10% or less, and Cr at 11.0% to 16.0%, the balance being Fe and impurities; and having: an average Cr carbide equivalent spherical diameter of no greater than 1.20 μm, a Cr carbide number density of at least 0.10 particles / μm2, an average Cr nitride equivalent spherical diameter of no greater than 0.80 μm, and a Cr nitride number density of at least 0.05 particles / μm2.

The invention relates to a novel method for measuring the epoxy equivalent of epoxy resin, which comprises the following steps of: 1, preparing a sample, weighing a certain mass of epoxy sample to be measured until the weight is 0.0001 g, and putting the epoxy sample into a dry titration container; step 2, dissolving the sample, adding a strong polar solvent into a titration container containing the sample, then adding excessive HCl standard liquid, and uniformly mixing to obtain a to-be-detected sample solution; step 3, reacting at room temperature in a dark place for a certain time; step 4, adding an indicator, namely adding 4-6 drops of a phenolphthalein indicator into the sample solution; step 5, titration: filling the calibrated NaOH standard solution into a basic burette until the color of the solution is changed from colorless to purple red, namely a titration end point, and recording the volume of the consumed NaOH standard solution; and step 6, carrying out a blank experiment, namely carrying out the blank experiment according to the steps 1-5, namely, not adding the epoxy sample to be measured, then titrating by using a NaOH standard solution, and recording the volume of the consumed NaOH standard solution. The method can effectively improve the accuracy and stability of the epoxy equivalent measurement result.

Provided is a forged steel roll having excellent wear resistance. The forged steel roll according to the present disclosure has a chemical composition containing, in terms of mass%, 0.85%-1.05% of C, 0.60%-1.20% of Si, 0.30%-0.60% of Mn, 0.020% or less of P, 0.020% or less of S, 0.001%-0.050% of Al, 0.001%-0.020% of N, 0.0050% or less of O, 4.00%-6.00% of Cr, 0.20% to less than 1.00% of Mo, 1.00%-2.00% of V, 0.40% or less of Cu, and 0.30%-0.60% of Ni, with the balance being Fe and impurities. The forged steel roll satisfies formula (1), and the number ratio of an MC-type carbide in the total carbide having an equivalent circle diameter of 0.5-5.0 μm is 30% or more.　(1): (V + 2Mo) / (Cr + Ni) ≥ 0.400 The content in mass% of the corresponding element in the chemical composition is plugged in for each chemical symbol in formula (1).

An ultra-high solids content primer coating composition comprising:(i) 5.0 to 50 wt % of at least one bisphenol F epoxy resin;(ii) 1.5 to 12 wt % of at least one silane;(iii) 0 to 20 wt % of at least one hydrocarbon resin;(iv) 0 to 15 wt % of at least one reactive diluent;(v) at least one curing agent;wherein said composition has a solids content of at least 90 wt % according to ASTM D5201-05;wherein said composition has a viscosity of 200 to 800 cps at 23° C. and 50% RH (ASTM D4287);and wherein the ratio between hydrogen equivalents in the curing agent and epoxy equivalents of the coating composition is in the range 50:100 to 120:100.

An embodiment of the present invention provides steel for hot forming, a hot-formed member, and methods for manufacturing same, the steel comprising, by wt %, 0.06-0.1% of C, 0.05-0.6% of Si, 0.6-2% of Mn, 0.05% or less of P, 0.02% or less of S, 0.01-0.1% of Al, 0.01-0.8% of Cr, 0.01-0.5% of Mo, 0.02% or less of N, and the remainder of Fe and inevitable impurities, wherein an alloy factor represented by relational expression 1 below is 7 or more, and the number of carbides having a circular equivalent diameter of 0.5 μm or greater is 105 / mm2 or less.Alloy⁢ factor=I⁡(Mn)×I⁡(Si)×I⁡(Cr)×I⁡(Mo)[Relational⁢ expression⁢ 1]where the I values for the components are I(Mn)=3.34×Mn+1, I(Si)=0.7×Si+1, I(Cr)=2.16×Cr+1, and I(Mo)=3×Mo+1, respectively, and the content of each component is expressed as wt %.

This invention discloses a high-strength, high-toughness Nb-containing steel and its nano-phase controlled rolling and cooling preparation method, belonging to the field of iron and steel metallurgy and rolling technology. The chemical composition of the steel plate, by mass percentage, is as follows: C: 0.12~0.20%, Si: 0.55~0.65%, Mn: 1.40~1.50%, Nb: 0.030~0.080%, N: 0.0080~0.0110%, Al: 0.020~0.050%, P≤0.030%, S≤0.025%, with the balance being Fe and unavoidable impurities; and the Nb / N mass ratio is controlled at 3.6~10.0, and the carbon equivalent C≤0.45%. The preparation method includes smelting, refining, continuous casting, heating, two-stage controlled rolling, and segmented controlled cooling steps. Through precise Nb / N ratio combined with controlled rolling and controlled cooling processes, nanoscale Nb(C,N) precipitates with a size of 20~80nm are induced, with a volume fraction ≥0.2%. The resulting steel plate has a microstructure of ferrite + bainite, a tensile strength ≥600MPa, a lower yield strength ≥450MPa, an elongation after fracture ≥18%, an impact absorption energy of ≥40J at -20℃, and a crack incidence rate ≤0.3%. This invention achieves a synergistic improvement in high strength, high toughness, and excellent crack resistance.

Provided in the present invention is a one-component structural adhesive including: 47 to 61 weight percent of a first epoxy resin, the first epoxy resin having an epoxide equivalent weight of less than 240 grams per equivalent; 27 to 41 weight percent of a difunctional mercaptan; and 1 to 14 weight percent of a latent catalyst, wherein the total weight of the one-component structural adhesive is taken as 100 weight percent. The one-component structural adhesive according to the technical solution of the present invention can achieve fast curing at low temperatures, and the cured product thereof has high elongation-at-break and adhesion strength.

The application discloses a 200-210mm thick high-strength low-welding-crack-sensitivity A514 steel plate and a production method thereof. The A514 steel plate comprises the following chemical components (unit, wt%): C: 0.10-0.12, Si: 0.10-0.15, Mn: 0.90-1.0, P≤0.010, S≤0.003, Als: 0.020-0.040, Nb: 0.040-0.050, V: 0.18-0.20, Cr: 0.7-0.75, Ni: 2.01-2.3, Cu: 0.22-0.26, Mo: 0.45-0.50, B: 0.002-0.0030, Re: 0.0015-0.0025, and other Fe and residual elements, and the carbon equivalent Ceq≤0.7%. The 1015-1125mm thick steel ingot is adopted to ensure a large compression ratio, the cogging rolling and the secondary heating rolling are adopted to fully break the original cast structure and refine the grains, so that the internal quality of the steel plate reaches the level of a forged piece, and the rolling is used to replace the forging; the twice circulating quenching is adopted to reduce the mechanical property difference of different thickness layers of the steel plate, the differential temperature tempering process is adopted after the quenching to eliminate the residual stress in the quenched steel, the impact toughness and the strength uniformity of the whole plate are improved, and the performance of the A514 heavy steel plate under the low-temperature condition meets the use requirement.

Provided is a steel material having excellent cold forgeability. This steel material has a prescribed component composition and a structure in which the area ratio of martensite is not more than 10.0% and the remainder contains at least bainite, the number density of sulfide-based inclusions having an equivalent circle radius of 1-20 [mu] m is not less than 10.0 / mm2, and the number density of sulfide-based inclusions having an equivalent circle radius of not less than 1 mm is not more than 0.10 / mm2.

The invention discloses a preparation technology of hot work die steel with high thermal strength, and belongs to the technical field of die steel, the preparation technology is based on ultra-low phosphorus and sulfur pure iron, ferrotungsten, 4.5-5.5% of W, 1.8-2.2% of ferromolybdenum, 4.9-5.25% of ferrochromium, 4.9-5.25% of Cr, 0.5-0.8% of V, and the carbon content is dynamically adjusted through a carbon equivalent formula, namely Ceq = C + 1 / 7Cr + 1 / 5Mo + 1 / 8W + 1 / 4V = 0.95-1.05, so that the carbon content is controlled within the range of 0.38-0.42%; in the preparation stage, the gas content is controlled through electric arc furnace-LF-VD triple refining, so that the content of the O element is smaller than or equal to 12 ppm, then the structure is refined through electroslag remelting, multidirectional forging is conducted after diffusion annealing is conducted for 12 h at the temperature of 1200 DEG C, and the target that the total forging ratio is not smaller than 9 is achieved; and finally, through a combined process of quenching at the temperature of 1080 DEG C, stepped tempering at the temperature of 580-600 DEG C and ion nitriding at the temperature of 520 DEG C for 24 hours, the hot work die steel which is high in red hardness, namely the hardness of the hot work die steel is not smaller than 48 HRC at the temperature of 600 DEG C, and the hot work die steel has excellent thermal fatigue performance can be obtained. Therefore, the technical problem of how to improve the material performance of the hot work die steel is solved.

Provided is a steel bar or wire rod with which it is possible to obtain excellent heat cracking resistance and excellent machinability. This steel bar or wire rod has a chemical composition described in the description, and Fn1 defined by formula (1) is 1.2-5.0. Furthermore, the number density of sulfides having an equivalent circle diameter of 1 [mu] m or more is less than 660 / mm2 at a position 0.16 R depth from the surface of the steel bar or wire in a longitudinal section parallel to the central axis of the steel bar or wire and including the central axis. Furthermore, the number density of sulfides having an equivalent circle diameter of 1 [mu] m or more at a depth position of 0.65 R in the vertical section is 660 / mm2 or more. Fn1 = Mn / S (1). Here, the content (mass%) of the corresponding element is substituted at each element symbol in the formula.

A method of 3D concrete printing, comprises the steps of providing a set- delayed flowable construction material, conveying the construction material to a deposition head, placing the construction material through an outlet of the deposition head in order to form a layer of construction material, before placing the construction material, incorporating into the set-delayed construction material a setting accelerator agent selected from the group of SA-1), which is a setting accelerator comprising a water-soluble silicate source, SA-2), which is a setting accelerator comprising a source of aluminum ions, SA-3), wherein both of setting accelerator agents SA-1) and SA-2) are separately incorporated into the set-delayed construction material, wherein the set control agent comprises (i) a retarder comprising (i-a) an α-hydroxy monocarboxylic acid or a salt thereof, and, optionally, (i-b) a polycarboxylic acid having a carboxylic acid equivalent weight of 333 or less, or a salt thereof; and (ii) an oxyanion source selected from a borate source, a carbonate source, the carbonate source having an aqueous solubility of 15.0 g·L-1 or more at 25 °C, and mixtures thereof; wherein the weight ratio of (ii) to (i) is in the range of from 1.2 : 25, and wherein in the construction material the ratio of the dosage of the set control agent to the dosage of the setting accelerator agent is determined by the following inequation (1): 3 ≤ Dosage set control agent / (1 / 3.5 * Dosage SiO2 + 2.5 / 3.5 * Dosage Al) ≤ 42.0.

The present invention relates to an X80 heavy-gauge high-strength high-strain pipeline steel, a UOE welded pipe, and a manufacturing method therefor. In addition to Fe and inevitable impurities, the pipeline steel further comprises the following chemical components in percentage by weight: 0.051-0.09% of C, 0.1-0.4% of Si, 1.5-1.9% of Mn, P ≤ 0.015%, S ≤ 0.002%, Cu ≤ 0.19%, 0.05-0.19% of Ni, 0.11-0.35% of Cr, Mo ≤ 0.13%, 0.02-0.08% of Nb, 0.005-0.035% of Ti, 0.001-0.004% of Ca, 0.010-0.045% of Alt, N ≤ 0.006%, B ≤ 0.0003%, O ≤ 0.005%, and H ≤ 0.0002%, wherein the carbon equivalent CEIIW is 0.41-0.47%, and 0.60% ≤ Ni + 3Cr ≤ 1.10%, each element symbol in the expression being substituted for the mass percentage content of the corresponding element. The UOE welded pipe of the present invention has a wall thickness of 25-40 mm and a caliber of φ 1016 to φ 1422 mm, and has a yield strength of 555-665 MPa, a tensile strength ≥ 625 MPa, a low-temperature impact energy higher than 1600 J at -20ºC, and a full-wall-thickness DWTT shear fracture area percentage greater than 85% at -10ºC, as well as a longitudinal yield strength of 530-640 MPa, a yield ratio ≤0.85, and a uniform elongation ≥7%.