69 results about "Yield ratio" patented technology

The invention discloses a production method of thick-wall pipeline steel X65MS for polar regions, which adopts ultra-low carbon and high Ni + casting blank secondary cogging extreme cooling + steel plate online ultrafast cooling, breaks the component design of the conventional pipeline steel standard, solves the problem of poor drop hammer low-temperature toughness of thick-wall acid-resistant pipeline steel at-55 DEG C, and has the transverse and longitudinal yield strength of 460-560MPa, the tensile strength of 590-650MPa, the yield ratio of less than or equal to 0.80, the tensile strength of 590-650MPa and the tensile strength of less than or equal to 0.80. The uniform elongation is 10%-12%, the impact value at-55 DEG C is 400-500 J, and the drop weight at-55 DEG C is 90%-95%; when the product is soaked in an NACE solution for 96 hours in an HIC test, CLR, CTR and CSR are all 0; sSC test: four-point bending constant load nominal yield is 90%, and the sample is soaked for 720 hours, and the surface of the sample has no crack; the CTOD value of the crack tip opening displacement of the CTOD test material at-55 DEG C is greater than or equal to 0.6 mm.

The invention discloses a high-toughness low-yield-ratio steel plate for a bridge and a preparation method of the high-toughness low-yield-ratio steel plate, and relates to the technical field of low-alloy high-strength structural steel, and the steel plate for the bridge comprises the following chemical components in percentage by weight: 0.05% < = C < = 0.09%, 0.20% < = Si < = 0.30%, 1.50% < = Mn < = 1.70%, 0.50% < = Cr < = 0.60%, 0.35% < = Cu < = 0.50%, 0.4% < = Ni < = 0.6%, 0.2% < = Mo < = 0.3%, 0.03% < = Nb < = 0.05%, 0.01% < = Ti < = 0.02%, 0 < = B < = 30 ppm, and the balance of Fe and inevitable impurities. The production method comprises the steps of billet heating and heat preservation; controlled rolling and controlled cooling; the yield strength of the produced steel plate is larger than or equal to 870 MPa, the tensile strength is larger than or equal to 780 MPa, the yield ratio is smaller than or equal to 0.86, the ductility is larger than or equal to 15%, and the impact energy at the temperature of minus 40 DEG C is larger than or equal to 150 J. On the basis that the alloy cost is remarkably reduced, the performance combination of high strength, high toughness and low yield ratio is obtained at the full thickness through process regulation and control, and the steel plate is suitable for the scene of outdoor bridge steel.

Provided is a steel sheet that may be used for automobile parts and the like, and to a steel sheet having an excellent balance of strength and ductility, an excellent balance of strength and hole expansion ratio, and an excellent yield ratio evaluation index, and a method for manufacturing the same. The steel sheet includes: by wt %, C: 0.1 to 0.25%, Si: 0.01 to 1.5%, Mn: 1.0 to 4.0%, Al: 0.01 to 1.5%, P: 0.15% or less, S: 0.03% or less, N: 0.03% or less, B: 0.0005 to 0.005%, a balance of Fe, and unavoidable impurities; and as microstructures, bainite, tempered martensite, fresh martensite, retained austenite and unavoidable structures.

Provided is an angular steel pipe having a low yield ratio and excellent low-temperature toughness and ductility. This angular steel pipe has a prescribed steel component composition, and the steel structure in the center of the plate thickness of the flat plate section has ferrite as the main phase, the area ratio of a second phase comprising one or more elements selected from pearlite, pseudo-pearlite, and upper bainite is 5-30%, and the average crystal grain size is 10.0-30.0 [mu] m. The number of pearlites and pseudo pearlites having an equivalent circle diameter of 2-20 [mu] m inclusive is 500 / mm2 or more, the yield strength of the flat plate section is 295 MPa or more, the tensile strength of the flat plate section is 400 MPa or more, the yield ratio of the flat plate section is 0.85 or less, the uniform elongation of the flat plate section is 8.0% or more, the elongation at break of the flat plate section is 27.0% or more, and the Charpy absorption energy of the corner section at-10 DEG C is 80 J or more. And the ductile-brittle transition temperature of the corner section is-10 DEG C or less.

The invention provides a TMCP delivery 550MPa-grade steel plate for engineering machinery and a preparation method thereof, and the steel plate comprises the following components in percentage by mass: the balance of Fe and inevitable impurities. The 550MPa-grade ultra-thin specification steel plate is stable in mechanical property, good in internal quality, good in strength, toughness and plasticity and low in yield ratio, flaw detection meets the national standard requirement, especially the carbon equivalent is low, the welding performance is excellent, and the 550MPa-grade ultra-thin specification steel plate has high industrial application and popularization value.

The application provides a low yield ratio and 370MPa-grade marine atmosphere corrosion resistant heavy steel plate without coating and a manufacturing method thereof. The steel plate is composed of the following components in percentage by weight: C: 0.04% to 0.06%, Si: 0.10% to 0.30%, Mn: 0.30% to 0.50%, P: less than or equal to 0.012%, S: less than or equal to 0.005%, Ni: 2.7% to 3.5%, Cu: 0.35% to 0.85%, Mo: 0.05% to 0.15%, Nb: 0.005% to 0.015%, Ti: 0.006% to 0.030%, Al: 0.015% to 0.040%, B: 0.0008 to 0.0016%, and the balance of iron and inevitable impurities. The components satisfy 22 <= 15[Mo]+6[Ni]+5[Cu] <= 26, the Pcm value (%) is less than or equal to 0.19%, the production method of the steel plate comprises smelting, slab continuous casting, slab heating, controlled rolling, controlled cooling and heat treatment. The yield strength of the steel plate is greater than or equal to 370MPa, the tensile strength is greater than or equal to 510MPa, the elongation after fracture is greater than or equal to 20%, the yield ratio is less than or equal to 0.77, the KV2 impact energy at-40 DEG C is greater than or equal to 200J, the corrosion rate of the steel plate in a marine atmosphere environment in a one-year period is 0.024mm / a to 0.030mm / a, and the thickness of the steel plate is 100mm to 130mm.

The purpose of the present invention is to provide a technology relating to: a steel sheet which still has high collision resistance characteristics after being subjected to cold pressing and being formed into a component; and a method for producing the steel sheet.　Disclosed is a steel sheet which has a specific component composition and a specific steel structure, and has a yield ratio of 0.80 or less, wherein: in a tensile test according to JIS Z2241, the retained austenite that disappears during the period from the start of the tensile test to the processing of imparting 1% strain in terms of nominal strain is 0.8% or more in terms of the area ratio with respect to the entire steel structure; and when the processing of imparting 1% strain and a heat treatment at a temperature of 100°C are performed, the amount of increase in YS obtained by subtracting YS before (the processing and the heat treatment) from YS after (the processing and the heat treatment) is 200 MPa or more, and El after (the processing and the heat treatment) is not less than 0.9 × (El before (the processing and the heat treatment)). YS and El represent the yield stress and total elongation of the steel sheet, respectively.

The invention belongs to the technical field of steel smelting, and relates to steel for a low-temperature U-shaped bolt and a smelting method of the steel. The steel comprises the following chemical components in percentage by weight: 0.33%-0.38% of C, 0.20%-0.30% of Si, 0.60%-0.70% of Mn, less than or equal to 0.010% of P, less than or equal to 0.005% of S, 0.95%-1.10% of Cr, 0.18%-0.22% of Mo, 0.020%-0.050% of Al, less than or equal to 0.0010% of O and the balance of Fe and inevitable residual elements. The tensile strength of produced steel is larger than or equal to 980 MPa, the yield ratio Rel / Rm is larger than or equal to 0.9, the percentage elongation after fracture A is larger than or equal to 12%, the percentage reduction of area Z is larger than or equal to 45%, the impact absorbing energy AKV at the temperature of-20 DEG C is larger than or equal to 80 J, and the austenite grain size reaches the grade 7 or above.

The application discloses a rare earth low-alloy high-strength corrosion-resistant low-temperature-resistant low-yield ratio hot-rolled H-shaped steel for large-span steel structures, which comprises the following components: C 0.09%-0.13%, Si 0.40%-0.50%, Mn 1.20%-1.30%, P 0.01%-0.03%, S≤0.010%, V 0.04%-0.05%, Cr 0.25%-0.30%, Ni 0.13%-0.15%, Cu 0.25%-0.30%, Ce 0.0010%-0.0030%, N 0.0050%-0.0070% and O≤0.0025%. A manufacturing method thereof is also disclosed. The H-shaped steel manufactured by the application satisfies the following conditions: lower yield strength ReL≥380MPa, tensile strength Rm≥520MPa, yield ratio≤0.75, impact toughness at-60 DEG C≥80J and elongation after fracture≥30%.

This invention discloses a heat treatment method for improving the yield strength ratio of steel used in continuous extrusion dies. Specifically, the steel is subjected to the following sequential heat treatments: high-temperature normalizing, low-temperature normalizing, spheroidizing annealing, high-temperature quenching, high-temperature tempering, and low-temperature tempering. The high-temperature normalizing temperature is 1070℃~1100℃; the low-temperature normalizing temperature is 710℃~730℃; the spheroidizing annealing temperature is 840℃~870℃; the high-temperature quenching temperature is 1070℃~1100℃; the high-temperature tempering temperature is 620℃~640℃; and the low-temperature tempering temperature is 530℃~550℃. The yield strength ratio of the die steel after heat treatment using this method is ≥0.91, and the hardness is 48~52 HRC.

The high-strength steel plate comprises the following components in percentage by weight: 0.03-0.06% of C, 0.10-0.25% of Si, 0.3-0.8% of Mn, less than or equal to 0.005% of S, less than or equal to 0.006% of P, 8.5-10.0% of Ni, 0.5-2.0% of Cu and the balance of Fe and other inevitable impurities, and the components also need to simultaneously meet the following conditions: 30C + 4Mn + 1.5 Cu + Ni is more than or equal to 12.5% and less than or equal to 16%. The steel plate has high strength, excellent low-temperature toughness and low yield ratio at the same time, and has higher deformation allowance in a low-temperature environment of not lower than-196 DEG C, so that the steel plate has very high service safety; the yield strength of the steel plate is larger than or equal to 690 MPa, the tensile strength is 770-940 MPa, the ductility is larger than or equal to 18%, the impact energy at the temperature of-196 DEG C is larger than or equal to 100 J, the yield ratio is smaller than or equal to 0.90, and the steel plate is suitable for manufacturing liquefied natural gas (LNG) containers, ships, storage tanks and various low-temperature structures.

The invention relates to a low-yield-ratio 785MPa-grade ultra-high-strength thin plate and a preparation method thereof, belongs to the technical field of ultra-high-strength steel, and solves the problem of high yield ratio of existing ultra-high-strength steel. The invention discloses a low-yield-ratio 785MPa-grade ultra-high-strength thin plate. The low-yield-ratio 785MPa-grade ultra-high-strength thin plate comprises the following chemical components in percentage by mass: 0.08-0.12% of C, 0.10-0.20% of Si, 0.5-1.0% of Mn, 5.5-6.5% of Ni and the balance of Fe. 0.5 to 1.0 percent of Cr, and 0.5 to 1.0 percent of Mo; 0.06% to 0.10% of V; ti: 0.008% to 0.015%; p < = 0.005%; ni * Mn is greater than or equal to 3.0 * 10 <-4 > and less than or equal to 6.5 * 10 <-4 >. The yield ratio of the steel is not higher than 0.90, and the steel has the comprehensive characteristics of high strength, excellent low-temperature toughness and the like.

The invention relates to a low-cost A630-420H hot-rolled steel bar and a production method thereof. The low-cost A630-420H hot-rolled steel bar comprises the following components in percentage by mass: 0.45-0.52% of C, 0.10-0.40% of Si, 0.50-0.80% of Mn, less than or equal to 0.045% of P, less than or equal to 0.045% of S, 0.015-0.020% of N and the balance of Fe and inevitable impurities. The production method comprises the steps of continuous casting, casting blank heating, rolling and cooling. According to the invention, steel-making and steel-rolling process parameters are strictly controlled, so that an A630-420H hot-rolled steel bar product with strength, plasticity and other technical indexes meeting NCh 204: 2020 standard requirements and low cost is obtained, the yield strength is 440-520 MPa, the tensile strength is 650-730 MPa, the yield-strength ratio is 1.40-1.55, and the percentage elongation after fracture is 13.5-17.5%.

The invention relates to the technical field of dual-phase steel, in particular to 800MPa-grade hot-rolled dual-phase steel with excellent reaming performance and a production method thereof, and the 800MPa-grade hot-rolled dual-phase steel comprises the following chemical components in percentage by mass: 0.045%-0.055% of C, 0.50%-1.00% of Si, 1.50%-2.50% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, 0.03%-0.05% of Alt, 0.25%-0.55% of Cr, 0.01%-0.03% of Ti and the balance of Fe and inevitable impurities. The martensite with high-proportion toughness is prepared, and the hole expansion rate reaches up to 55%-75%. And the addition amount of alloy elements is small, and the alloy cost is greatly reduced. The yield strength of the dual-phase steel ranges from 550 MPa to 580 MPa, the tensile strength ranges from 820 MPa to 870 MPa, the percentage elongation after fracture ranges from 16% to 22%, and the yield ratio ranges from 0.64 to 0.74.

The invention discloses a production method of a Q620qE steel plate with a low yield ratio. The steel comprises the following chemical components in percentage by weight: 0.07%-0.08% of C, 0.25%-0.3% of Si, 1.5%-1.55% of Mn, less than or equal to 0.012% of P, less than or equal to 0.002% of S, 0.035%-0.045% of Nb, 0.01%-0.02% of Ti, 0.25%-0.3% of Mo, 0.45%-0.55% of Cr and 0.2%-0.3% of Ni. The process comprises the steps of smelting, continuous casting, heating, controlled rolling and controlled cooling and tempering. A Q620qE steel plate with the thickness reaching 50 mm is produced through a continuous casting billet with the section of 260 mm, the structure of the steel is bainite and ferrite, the yield strength Rp0.2 is larger than or equal to 620 MPa, the tensile strength Rm is larger than or equal to 720 MPa, the ductility A is larger than or equal to 15%, the yield ratio is smaller than or equal to 0.85, and the Charpy impact energy at the temperature of-40 DEG C is larger than or equal to 120 J. A welding evaluation test shows that under the submerged-arc welding heat input of 35 kJ / cm, the impact energy at the temperature of-40 DEG C of a heat affected zone is larger than or equal to 120 J, and the impact energy at the center of a welding seam is larger than or equal to 100 J.

The invention discloses a novel high-strength steel bar process control method which comprises the following steps: (1) firstly, in order to ensure that the strength and the yield ratio reach the standard, presetting the weight percentage of C, Si, Mn, V, Nb and Ceq in initial components of steelmaking, and presetting the temperature of a heating furnace, the steel throwing temperature, the heating time and the continuous casting cooling speed; (2) test rolling is conducted, and when the yield strength does not reach the standard, adjustment is conducted according to whether the tensile strength has allowance or not till the yield strength is larger than 635 Mpa, and the yield-strength ratio is larger than 1.26; (3) whether Agt reaches the standard or not and the bending brittle failure condition are checked, and then adjustment is conducted according to a small-specification steel bar technology and a large-specification steel bar technology so that it can be guaranteed that the yield strength and the yield strength ratio reach the standard; and (4) on the basis of the adjustment, the small-specification reinforcing steel bar technology and the large-specification reinforcing steel bar technology are solidified respectively. The high-strength steel bar can be prepared, and meanwhile the problems that the yield strength is not up to the standard, the strength-to-yield ratio is not up to the standard, Agt is not up to the standard and bending is prone to brittle failure are solved.

The invention discloses 540 MPa-grade low-silicon hot-rolled high-strength dual-phase steel and a manufacturing method thereof. The 540 MPa-grade low-silicon hot-rolled high-strength dual-phase steel comprises, by weight, 0.04%-0.15% of C, smaller than or equal to 0.03% of Si, 1.0%-2.0% of Mn, 0.02%-0.22% of Al, 0.005%-0.025% of Nb, 0.005%-0.025% of Ti, 0.01%-0.10% of V, smaller than or equal to 0.015% of P, smaller than or equal to 0.02% of S and the balance Fe and inevitable impurities. The elements also need to meet the condition that C + Si / 24 + Mn / 6 is greater than or equal to 0.20% and less than or equal to 0.49%; 0.5 < = (Nb + V + Ti) / C < = 1.5. The requirements that the steel plate has high strength and plasticity, low yield ratio and high formability are met at the same time, the high surface requirement is met, the tensile strength of the obtained dual-phase steel is larger than or equal to 540 MPa, the ductility is larger than or equal to 22%, the yield ratio is smaller than or equal to 0.72, and the hole expansion rate is larger than or equal to 40%.

The invention discloses 690MPa-grade low-yield-ratio bridge steel with excellent fracture resistance and crack arrest performance and a manufacturing method thereof. The 690MPa-grade low-yield-ratio bridge steel comprises the following chemical components in percentage by weight: 0.03-0.13% of C, 0.10-0.30% of Si, 0.50-1.50% of Mn, less than or equal to 0.010% of P, less than or equal to 0.002% of S, 1.20-2.00% of Ni, 0.015-0.060% of Alt, 0.020-0.080% of Nb, 0.30-0.80% of Mo, 0.015-0.050% of Ti, 0.0020-0.0050% of Ca, less than or equal to 0.004% of N and the balance of Fe and other inevitable impurities, and the following requirements are met: 1.8% < = C + Mn + Ni < = 3.5% The steel for the bridge, disclosed by the invention, has the advantages of excellent fracture resistance and crack arrest capability, low yield ratio, high strength and high toughness, the yield ratio is less than or equal to 0.85, and the steel for the bridge has good toughness, tensile property and fracture resistance and crack arrest capability.

The invention discloses low-yield-ratio and high-toughness bridge steel and a preparation method, relates to the technical field of low-alloy and high-strength structural steel, and aims to solve the problems that bridge construction has higher requirements on steel performance when developing towards the directions of light weight, large span, high speed, heavy load and the like, and traditional bridge steel is high in yield ratio and cost due to the fact that a large amount of Cr, Mo and other alloy elements are added. The bridge steel with excellent comprehensive mechanical properties is developed by optimizing the alloy element ratio, combining offline quenching, two-phase region treatment and tempering processes and accurately regulating and controlling structure transformation and the proportion of all phases, the yield strength of the bridge steel is larger than or equal to 780 MPa, the tensile strength is larger than or equal to 870 MPa, the yield ratio is smaller than or equal to 0.85, the ductility is larger than or equal to 16%, the impact energy at the temperature of 40 DEG C below zero is larger than or equal to 120 J, and the steel can be used for manufacturing bridges. The high-strength and low-yield-ratio bridge steel has high strength, low yield ratio and good welding performance, breaks through the bottleneck of the traditional technology, provides key material support for bridge steel and structural industry upgrading, and promotes green and efficient bridge construction development.

The invention relates to a low-temperature-resistant high-tensile-yield-ratio high-strength steel bar which comprises the following chemical components in percentage by mass: 0.10-0.35% of C, 0.60-1.00% of Si, 1.30-2.00% of Mn, 0.20-0.25% of V, 0.02-0.03% of N, 0.03-0.05% of Nb, 0.1-0.3% of Ni, 0.05-0.2% of Cu, 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] and [Nb] of V and Nb elements with fixed N atoms meets the condition that [N] / (0.42 [C] + 0.3 [V] + 0.13 [Nb]) is larger than or equal to 0.10 and smaller than or equal to 0.17. The microstructure of the steel is ferrite, pearlite and bainite, the average grain size of the microstructure is smaller than or equal to 12 micrometers, the content of the ferrite is 50% by volume or above, and the content of the bainite is 20-35% by volume. The steel bar has the advantages of high strength, good strength and plasticity matching, low temperature resistance, excellent high-tensile-yield ratio and the like.

The utility model relates to the technical field of structural wires, and discloses an elliptical structural wire, which comprises an elliptical outer layer, a core wire is fixedly arranged in the outer layer, the core wire is positioned on the innermost layer of the elliptical structural wire, the core wire is of a core steel belt structure, the width of the elliptical structural wire is 1.0 mm-4. 0mm, and the thickness of the elliptical structural wire is 0.8 mm-2. 5mm. According to the elliptical structural wire, the rectangular or elliptical core wire structure is adopted to provide enough support and have a good supporting area, the outer layer is wrapped outside the core wire, and the outer layer is uniformly wrapped on the core wire, so that the safety of a steel belt is ensured, the strength and the elasticity of the structural wire are increased, and the forming effect of the structural wire is improved; the core wire is resistant to high temperature and prevented from being in contact with air, a zinc layer can be plated on the outer side of the core wire so that the corrosion resistance effect of the core wire can be guaranteed, red rust cannot be generated after a neutral salt spray test is conducted for 96 hours or above, the overall corrosion resistance of the structural wire is improved, meanwhile, the tensile strength of the structural wire is good, the yield ratio is larger than 93%, the percentage elongation after fracture is larger than 2%, and the overall performance is excellent.

The invention discloses an atmospheric corrosion resistant steel plate with a yield ratio lower than 0.75. The atmospheric corrosion resistant steel plate comprises the following chemical components in percentage by mass: 0.08 to 0.13 percent of C, 0.40 to 0.65 percent of Si, 0.30 to 0.70 percent of Mn, 0.070 to 0.130 percent of P, less than or equal to 0.010 percent of S, 0.30 to 0.55 percent of Cr, 0.10 to 0.30 percent of Ni, 0.20 to 0.45 percent of Cu, 0.010 to 0.035 percent of Nb, 0.005 to 0.030 percent of Ti, 0.020 to 0.045 percent of Alt and the balance of Fe and impurities. The steel plate has the advantages that the steel plate has a low yield ratio, good plasticity and toughness are obtained, the production cost is reduced, and meanwhile stable product performance is guaranteed.

The invention discloses a low-yield-ratio, high-toughness and low-cost L485M pipeline steel coil plate and a manufacturing method thereof, and the low-yield-ratio, high-toughness and low-cost L485M pipeline steel coil plate comprises the following chemical components in percentage by weight: 0.045 to 0.070 percent of C, 0.045 to 0.075 percent of Nb, 0.028 to 0.045 percent of V, 0.008 to 0.018 percent of Ti, 0.15 to 0.28 percent of Cr, 0.012 to 0.045 percent of Als, 0.0010 to 0.0025 percent of Mg, 0.0008 to 0.0018 percent of Ca and 0.6 to 1.2 percent of Ca / Mg. A C-Mn-Nb-Mg-Ca design is adopted, the yield strength of a rolled plate is 530-600 MPa, the tensile strength is 630-730 MPa, the elongation is larger than or equal to 28%, the Akv mean value at the temperature of-40 DEG C is larger than or equal to 280 J, the DWTT mean value at the temperature of-20 DEG C is larger than or equal to 90%, the hardness value HV10 is smaller than or equal to 220, and the yield ratio is smaller than or equal to 0.82. The problems that an existing rolling technology is complex, the rolling pass multi-procedure cost is high, the product low-temperature toughness index is loose, and the yield ratio is high are solved.

The purpose of the present invention is to provide: a zinc-plated steel sheet and a member that are excellent in tensile characteristics and collision characteristics; and a method for manufacturing the zinc-plated steel sheet and the member.　The zinc-plated steel sheet comprises a steel sheet having a prescribed steel structure, and a zinc plating layer on a surface of the steel sheet, wherein: after the zinc-plated steel sheet is subjected to U-bending for a bending radius of R=4 mm at a stroke speed of 1,500 mm / min, a spacer having a thickness of 5 mm is installed on the inner side (compression side) of the bent portion of the zinc-plated steel sheet; when the bent portion has been subjected to bending until the two surfaces of the steel sheet that are present at locations each facing toward an individual one of the upper and lower surfaces of the spacer in the thickness direction comes into close contact with the spacer, no cracks are produced on the outer side (tension side) of the bent portion; the tensile strength is at least 780 MPa and less than 1,180 MPa; and the yield ratio is 65-95%.

The present invention relates to a thick-walled high-toughness low-yield-ratio steel for a petroleum casing pipe, a petroleum casing pipe, and a manufacturing method for the petroleum casing pipe. In addition to Fe and inevitable impurities, the steel further comprises the following chemical components in percentage by mass: C: 0.30-0.40%, Si: 0.10-0.25%, Mn: 1.0-1.5%, Ti: 0.01-0.10%, Cr: 0.1-1.0%, Al: 0.015-0.035%, Ni≤0.2%, Nb: 0.010-0.040%, P≤0.015%, S≤0.003%, and N≤0.005%, satisfying the following relational expressions: C+Mn+5Cr-2Si+Ti+Nb≥1.8%, preferably 1.800-6.288%, and C+Mn / 6+Cr / 10+Ni / 15≤0.65%, wherein element symbols in the expressions are substituted with the mass percentage contents of the corresponding elements. The steel of the present invention has a yield strength of 379-552 MPa, a tensile strength of greater than or equal to 655 MPa, a yield ratio of less than or equal to 0.700, and a 0°C transverse Charpy impact energy of more than 50 J. The steel of the present invention can be used for producing a petroleum casing pipe having stable performance and a wall thickness of greater than or equal to 14 mm, wherein the petroleum casing pipe has a yield ratio of less than or equal to 0.750.

The invention discloses an anisotropic 700MPa-grade steel plate with low yield ratio and low longitudinal and transverse strength and a manufacturing method thereof. The anisotropic 700MPa-grade steel plate comprises the following components in percentage by weight: 0.070-0.11% of C, less than or equal to 0.20% of Si, 1.30-1.70% of Mn, less than or equal to 0.013% of P, less than or equal to 0.003% of S, 0.30-0.65% of Cr, 0.10-0.30% of Mo, 0.018-0.040% of Nb, 0.008-0.015% of Ti, 0.030-0.060% of Als, less than or equal to 0.0050% of N, less than or equal to 0.0004% of B, 0.0010-0.0035% of Mg and the balance of Fe and inevitable impurities. The ratio of (% Als) / [(% N)-0.292 (% Ti)] is greater than or equal to 27.5; (% C) * [(6.53 (% Si) + 5.17 (% Als) + 1.55 (% Mn) + 10.67 (% P) + 26.39 (% S)] < = 0.36, Mg treatment is performed, the Mg / S ratio is controlled to be 1.0-3.0, and (% Mg) * (% S) 0.28 < = 1.5 * 10 <-3 >. According to the steel plate, the yield strength is larger than or equal to 605 MPa, the tensile strength is larger than or equal to 700 MPa, the single value of Charpy impact energy KV2 at the temperature of-40 DEG C is larger than or equal to 120 J, the single value of KV2 of a welding heat affected zone HAZ-40 DEG C is larger than or equal to 47 J, the yield ratio is smaller than or equal to 0.85, and the low longitudinal and transverse strength anisotropy, namely the longitudinal / transverse strength difference is smaller than or equal to 30 MPa.

The application discloses a kind of mechanical properties prediction system after hot-rolled steel bar heat treatment, the system includes database communication module, process control module, machine learning algorithm module, physical metallurgy model module.The system real-time monitoring collection field production data, and according to the production data of different steel rolling process, it is not under the condition of heat treatment to predict its mechanical properties after heat treatment according to national standard heat treatment process, including tensile yield strength, tensile tensile strength, tensile elongation after fracture, tensile yield ratio test, surface shrinkage.The application realizes the on-line prediction of the mechanical properties of 42CrMo steel bar after heat treatment by using deep convolutional neural network, and the relevant prediction results can be used to replace the actual heat treatment inspection process to reduce production cost.

A collision-resistant steel plate for butane pressure vessels, comprising the following components (wt%): C: 0.10–0.20%, Si: 0.20–0.45%, Mn: 1.60–1.80%, Al: 0.025–0.045%, P≤0.015%, S≤0.005%, V: 0.065–0.085%, Nb: 0.027–0.045%. The process involves: smelting, casting into a billet, heating the billet, rough rolling, finish rolling, cooling, normalizing, and stress relief. The static yield strength Rel of this invention is 460–500 MPa, and the dynamic yield strength Re is 510–760 MPa; the tensile strength is 610–700 MPa; the yield ratio is ≤0.85; and the static elongation after fracture A is 29–41% and the dynamic elongation after fracture A... d The strength-ductility product is 18995–27798 MPa·% at 28–41%; the drop hammer tear (DWTT) energy is 15–19 kJ; when the impact velocity is 5–50 m / s and the impact displacement is 1.5 m, the energy absorbed by the steel plate is 3.57–3.89 kJ, and the grain size of ferrite does not exceed 0.008 μm.

The invention discloses a simulated postweld heat treatment method for improving-80 DEG C impact performance stability of a steel plate core, a simulated postweld stress relief method comprises the processes of heating, heat preservation, cooling and cooling, the charging temperature of the steel plate is lower than 400 DEG C, the heating speed is 50-55 DEG C / h when the temperature is higher than 400 DEG C, the heat preservation temperature is 580-600 DEG C, and the heat preservation time is 3-12 hours; and when the temperature is higher than 400 DEG C, the cooling speed is 10-30 DEG C / h, the steel plate is discharged from the furnace when the discharging temperature is lower than 400 DEG C, and air blowing cooling is performed after discharging. By strictly controlling heating, heat preservation, cooling and cooling parameters, it is guaranteed that the steel plate has the excellent core mechanical property after stress relief after simulation welding, the yield strength is larger than or equal to 310 MPa, the tensile strength is 450-520 MPa, the percentage elongation after fracture is larger than or equal to 30%, the yield ratio is 0.70-0.80, and the impact energy at the temperature of-80 DEG C is larger than or equal to 180 J. The device solves the problem that the room-temperature tensile strength and-80 DEG C impact energy of the core part of the steel plate are obviously reduced after stress relief after welding is simulated, and provides a basis for a user to reasonably set a stress relief system after welding of the steel plate.