44 results about "Equivalent weight" patented technology

The invention relates to large-thickness high-homogeneity polar region ship low-temperature steel and a preparation method thereof. The steel plate comprises the following chemical components in percentage by weight: 0.06%-0.12% of C, 0.15%-0.35% of Si, 1.10%-1.40% of Mn, less than or equal to 0.008% of P, less than or equal to 0.008% of S, 0.020%-0.050% of Nb, 0.020%-0.040% of Al, 0.010%-0.020% of Ti, 0.04%-0.08% of residual element Mo and the balance of Fe and inevitable impurity elements. The carbon equivalent CEV is less than or equal to 0.38%, and the cold crack sensitivity index Pcm is less than or equal to 0.20%. The manufacturing process of the steel plate comprises the steps of KR, BOF smelting, LF, RH, slab continuous casting, slab slow cooling, heating, rolling, steel plate pile slow cooling and heat treatment, the matrix structure of the obtained steel plate is a uniform and fine ferrite and tempered pearlite mixed structure, and the grain size ranges from 8 micrometers to 15 micrometers. The yield strength of the transverse tensile property at the 1 / 4 position of the steel plate ranges from 376 MPa to 392 MPa, the tensile strength ranges from 528 MPa to 553 MPa, the ductility is larger than or equal to 27.0%, the yield strength of the transverse tensile property at the 1 / 2 position ranges from 359 MPa to 375 MPa, the tensile strength ranges from 524 MPa to 537 MPa, the ductility is larger than or equal to 26.5%, and the steel plate is excellent in performance, excellent in whole plate uniformity, good in plate shape and easy to weld.

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.

Provided is a steel sheet that simultaneously achieves a strength of TS: 1310 MPa or more and excellent delayed fracture resistance. The steel sheet has a defined chemical composition and a complex structure consisting mainly of martensite and bainite, where carbides in the grains of martensite and bainite are 5% or more and 25% or less, the average circle equivalent diameter of carbides is 10 nm or more and 80 nm or less, and the particle size distribution of carbides satisfies Expression (1).

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.

Provided is a steel sheet characterized by having a prescribed chemical composition, and by having a depth of 3-100 [mu] m at which the areal proportion of pearlite in the sheet thickness direction from the surface is 0-20%, and by having an areal proportion of pearlite having an equivalent circle diameter of 5 [mu] m or more at a depth of 0-20% of the areal proportion of pearlite in the sheet thickness direction, the areal proportion of pearlite is 0-30%. Further provided is a hot press molded article characterized by having a prescribed chemical composition, having an average C concentration of 0.20 mass% or less from the surface to 20 [mu] m in the thickness direction, and containing 90% or more of martensite in terms of areal proportion.

To provide an assembly for brazing heat treatment.SOLUTION: First members 3, 4, 5 comprise a core material and a brazing material made of a melting member cladded on the core material, and a second member 2 comprises a substrate made of a member to be molten, wherein the melting member contains Si in an amount of 1.5 mass% or more and 14.0 mass% or less, one of V and Ti in an amount of 0.010 mass% or more and 1.5 mass% or less, with the balance consisting of Al and inevitable impurities, the member to be molten contains the other one of V and Ti in an amount of 0.010 mass% or more and 0.5 mass% or less, with the balance consisting of Al and inevitable impurities, an RD-TD parallel surface of the melting member has less than 5 intermetallic compounds containing one of V and Ti having a diameter of 10.00 μm or more in a circle equivalent diameter in an observation visual field of 10000 μm2, and an RD-TD parallel surface or an ED-TD parallel surface of the member to be molten has 10 or more intermetallic compounds containing the other one of V and Ti having a diameter of 0.01 μm or more and less than 5.00 μm in a circle equivalent diameter in an observation visual field of 10000 μm2.SELECTED DRAWING: Figure 1

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.

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 %.

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.

A steel plate for a box of a large mining dump truck in an extremely cold zone and a manufacturing method therefor. The steel plate is divided into a composite-layer steel plate and a base-layer steel plate. The composite-layer steel plate and the base-layer steel plate are metallurgically bonded. The composite-layer steel plate comprises the following chemical components: 0.19-0.29 wt.% of C; 0.15-0.75 wt.% of Si; 0.55-1.55 wt.% of Mn; 0.10-0.70 wt.% of Cr; less than or equal to 0.030 wt.% of P; less than or equal to 0.010 wt.% of S; 0.010-0.060 wt.% of Al; 0.0005-0.0050 wt.% of B; any one or more selected from 0.01-0.60 wt.% of Mo, 0.01-0.08 wt.% of RE, 0.005-0.060 wt.% of Nb, 0.01-0.10 wt.% of V, and 0.005-0.060 wt.% of Ti; and the balance of Fe and inevitable impurities. The base-layer steel plate comprises the following chemical components: 0.08-0.13 wt.% of C; 0.15-0.55 wt.% of Si; 0.70-1.70 wt.% of Mn; 0.05-0.55 wt.% of Cr; 0.10-0.55 wt.% of Mo; 1.25-2.55 wt.% of Ni; less than or equal to 0.030 wt.% of P; less than or equal to 0.010 wt.% of S; 0.010-0.080 wt.% of Al; 0.0005-0.0050 wt.% of B; any one or more selected from 0.01-0.08 wt.% of RE, 0.005-0.060 wt.% of Nb, 0.01-0.10 wt.% of V, and 0.005-0.060 wt.% of Ti; and the balance of Fe and inevitable impurities. By means of the design of the steel element components, the composite-layer steel plate has relatively high strength and hardness, and the base-layer steel plate has excellent low-temperature toughness while having relatively high strength and hardness. According to the steel plate compounded by a rolling process, the steel plates of the layers are metallurgically bonded, so that the integrity of the steel plate can be ensured, and the characteristics of the steel plates of the layers can be exerted, and thus, the whole composite plate has excellent comprehensive mechanical properties. In addition, the contents of carbon and alloy elements are controlled, thereby reducing the carbon equivalent, thus ensuring that the steel plate has good welding performance.

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.

Free-cutting steel includes a specific composition, with an A value defined by a following formula (1) satisfying 4.0 or more and 20.0 or less, and remainder having Fe and an unavoidable impurity; and texture with 1000 or more sulfide particles with an equivalent circle diameter of less than 1 μm per mm2, 500 or more sulfide particles with an equivalent circle diameter of 1 μm or more and 5 μm or less per mm2, and 1000 or more Pb particles with an equivalent circle diameter of 1 μm or less per mm2, whereinA value=(Mn+5Cr) / S  (1)here, symbols of elements in the formula indicate contents (% by mass) of the elements.

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).

To provide a brazing sheet.SOLUTION: A brazing sheet has a brazing material cladded on at least one surface of a core material, wherein the brazing material contains Si in an amount of 1.5 mass% or more and 14.0 mass% or less, one of V and Ti in an amount of 0.010 mass% or more and 1.5 mass% or less, with the balance consisting of Al and inevitable impurities, the core material contains the other one of V and Ti in an amount of 0.010 mass% or more and 0.5 mass% or less, with the balance consisting of Al and inevitable impurities, an RD-TD parallel surface of the brazing material has less than 5 intermetallic compounds containing one of V and Ti having a diameter of 10.000 μm or more in a circle equivalent diameter in an observation visual field of 10000 μm2, and an RD-TD parallel surface of the core material has 10 or more intermetallic compounds containing the other one of V and Ti having a diameter of 0.01 μm or more and less than 5.00 μm in a circle equivalent diameter in an observation visual field of 10000 μm2.SELECTED DRAWING: None

This steel sheet is for liquefied CO2 transport tanks, has a prescribed chemical composition, and has an α value of 1.00-1.50 mass%, a β value of 10.00-15.00, a γ value of 0.70-1.50 mass%, a Ceq value of 0.550-0.620 mass%, a yield strength of 670-870 MPa, a tensile strength of 780-940 MPa, a thickness of 25-60 mm, an average hardness at the t / 4 position of 265 Hv-290 Hv with a standard deviation of 20 or less, and a maximum hardness HVmax in the central segregation area of 400 Hv or less. The segregation degree in the center of the plate thickness satisfies a prescribed range. Of inclusion particles found in a cross section in the sheet thickness direction, in rectangular regions with a side length of 4 mm, the rectangular regions each being centered at the t / 4 and t / 2 positions, the inclusion particles having a circular equivalent diameter of 0.5 μm or more and having Ti at 20 mass% or more, 99% or more of the inclusion particles by number have a circular equivalent diameter of 4.0 μm or less. The average crystal grain diameter at the center of the plate thickness is 15.0 μm or less.

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 %.