11 results about "Lower yield" patented technology

The invention belongs to the field of steel for automobiles, and particularly relates to low-yield-ratio 1180MPa-grade cold-rolled martensitic steel for automobiles and a preparation method. The steel comprises the following components in percentage by weight: 0.145%-0.175% of C, 0.20%-0.45% of Si, 1.75%-2.00% of Mn, less than or equal to 0.020% of P, less than or equal to 0.0050% of S, 0.08%-0.12% of Al, less than or equal to 0.0050% of N, 0.005%-0.008% of B, 0.03%-0.04% of Nb and the balance of Fe and other inevitable impurities. Through brand new matching design of component design and a heat treatment process, martensite serves as a matrix, a small amount of ferritic structures are introduced, the performance characteristic of the low yield ratio is successfully achieved, and the forming capacity of the 1180MPa-grade martensitic steel in the application process is effectively improved.

This invention provides a high-strength steel with a low yield strength ratio of 1100MPa and its production method. The steel plate has the following chemical composition by mass percentage: C 0.15~0.17%, Si 0.58~0.6%, Mn 2.53~2.6%, Cr 0.53~0.8%, Ni 1.44~1.6%, Mo 0.2~0.6%, Nb 0.052~0.08%, V 0.02~0.08%, Ti 0.019~0.03%, Al 0.01~0.05%, Cu 0.83~1.5%, with the balance being Fe and unavoidable impurities. The steel plate has a yield strength ≥1100MPa, a yield strength ratio ≤0.88, an elongation ≥14%, and an impact energy ≥30J at -40℃. The finished steel plate has a thickness of 15mm and a microstructure of tempered lath martensite. The high-strength steel plate of this invention, with a yield strength ≥1100MPa, yield strength ratio ≤0.88, elongation ≥14%, and impact energy ≥30J at -40℃, exhibits a low yield-to-tensile ratio. The advantage of this invention lies in the fact that the salt bath Q&P heat treatment process achieves a good balance between high strength and a low yield-to-tensile ratio.

The application discloses a kind of low yield ratio high toughness 9Ni steel and its short process preparation method, belong to high-performance special steel manufacturing field.9Ni steel chemical composition is as follows according to percentage by mass: C:0.03~0.06%, Si:0.10~0.25%, Mn:0.50~0.80%, P≤0.003%, S≤0.001%, Ni:8.70~9.70%, Mo:0.08~0.15%, Ti:0.010~0.025%, Ca:0.0010~0.0030%, Alt:0.030~0.060%, N:0.003~0.006%, O≤0.0015%, the rest is Fe and inevitable impurity.Preparation method uses the short process technology of '' controlled rolling + online direct quenching + offline tempering'', and steel plate has high safety, high toughness and high quality, is suitable for LNG storage tank and other fields.

The present invention relates to a steel material for use as a material for building structures, ship structures, marine structures, and the like. More specifically, the present invention relates to a low-yield-ratio steel material having excellent toughness in a welding heat-affected zone, and a method for manufacturing the same.

This invention relates to the field of high-toughness energy steel manufacturing technology, specifically to thin-gauge, low-yield-strength-ratio L245-L450 pipeline steel, its preparation method, and applications. The thin-gauge, low-yield-strength-ratio L245-L450 pipeline steel, by mass fraction, contains 0.04-0.08% C, 0.10-0.25% Si, 0.70-1.40% Mn, P≤0.015%, S≤0.010%, 0.010-0.035% Nb, 0.010-0.020% Ti, 0-0.20% Cr, 0.010-0.035% Als, N≤0.0060%, with the remainder being Fe and unavoidable impurities. This invention aims to provide microstructure control targets and suitable composition-processes for a series of pipeline steel products with low yield strength ratios (L245-L450). By optimizing the alloy element ratios and laminar flow cooling process parameters (e.g., controlling the average cooling rate of the water-cooled section to 10-20℃ with 3-8 sets of centrally opened front-end manifolds), a feasible standardized common technology is formed, which stably controls the yield strength ratio of the product within the range of 0.82-0.86. This meets the PSL2 grade performance requirements specified in the national standard "Hot-rolled wide steel strip for oil and gas transmission pipelines" while also possessing low carbon equivalent, excellent low-temperature toughness, and a wide process window, ensuring the comprehensive mechanical properties of the material.

This invention discloses a method for producing 780MPa grade bridge steel with low yield strength ratio and high toughness. The chemical composition of the steel (by mass percentage) is: C = 0.05~0.06%, Si = 0.1%~0.2%, Mn = 1.30%~1.40%, P ≤ 0.006%, S ≤ 0.002%, Nb = 0.015%~0.025%, Ti ≤ 0.008%, Al... T =0.02%~0.05%, Cr=0.4%~0.5%, Ni=0.5%~0.6%, Cu=0.5%~0.6%, Mo=0.2%~0.3%, B=0.0035%~0.0040%, N≤30PPM, the remainder being Fe and unavoidable impurities, with a carbon equivalent Ceq≤0.50% and a crack sensitivity index Pcm≤0.23%. The process steps include: slab heating temperature of 1120~1150℃, two-stage rolling, finishing rolling temperature of 840~880℃ in the two-phase region; followed by online quenching with DQ to 260~300℃, and then tempering heat treatment at 500℃ to obtain a 780MPa grade bridge steel with low yield strength ratio and high toughness of lath bainitic + martensitic structure.

This invention discloses a thin-gauge, low-yield, high-toughness 5Ni steel with the following chemical composition and mass percentages: C: 0.04–0.08%, Si: 0.15–0.25%, Mn: 0.30–0.60%, Ni: 4.75–4.95%, S≤0.005%, P≤0.008%, Alt: 0.020–0.050%, O≤20ppm, N≤40ppm, H≤2ppm, Cr+Cu+Mo≤0.30%, with the balance being Fe and impurities. The advantage of this invention is that it enables the steel to meet both low yield strength and high toughness requirements, while simultaneously ensuring excellent weldability and formability.

The present application relates to a kind of low X90 grade pipeline steel hot-rolled coil of ratio of yield strength, chemical composition includes by weight percentage:C 0.05-0.07%, Si 0.20-0.40%, Mn 1.50-1.90%, Nb0.05-0.09%, Ti 0.01-0.02%, Cr 0.10-0.30%, Mo 0.10-0.20%, Ni 0.10-0.20%, 0≤P≤0.012%, 0≤S≤0.005%, Als 0.015-0.035%, the rest is Fe and inevitable impurities.The present application also relates to a kind of low X90 grade pipeline steel hot-rolled coil of ratio of yield strength manufacturing method.Through the technical scheme of the present application, the present application can effectively reduce the yield ratio in the production and application of X90 grade pipeline steel hot-rolled coil.

The invention discloses a bridge steel plate and a manufacturing method thereof, and belongs to the technical field of steel, the bridge steel plate comprises the following chemical components in percentage by weight: 0.08-0.11% of C, 0.30-0.50% of Si, 1.50-1.70% of Mn, 0.030-0.060% of Nb, 0.040-0.070% of V, 0.010-0.040% of Ti and 0.015-0.050% of Als, a Mn-Nb-V-Ti component system is adopted, a low yield ratio control technology of a TMCP + T state bridge steel plate is developed, and by optimizing controlled cooling after rolling, the yield ratio of the steel plate is controlled to be smaller than that of the steel plate. The volume fraction of ferrite and bainite in a steel plate structure is effectively controlled, the high-performance requirement for the low yield ratio of the high-strength bridge steel plate is met, and stable batch economical production of the bridge steel plate with the thickness of 6-64 mm is achieved.

This invention discloses an isotropic bridge steel with low yield strength ratio and high toughness, and its manufacturing method. Its chemical composition by weight percentage is: C: 0.02–0.05%, Si: 0.25–0.45%, Mn: 1.00–1.40%, P≤0.01%, S≤0.003%, Nb: 0.02–0.05%, Ni: 0.40–0.70%, Cu: 0.25–0.45%, Mo: 0.10–0.20%, Cr: 0.50–0.80%, Ti: 0.005–0.02%, B: 0.001–0.0025%, Al: 0.01–0.04%, CEV: 0.36–0.52%, Pcm: 0.13–0.20%, I≥6.30, with the balance being iron and unavoidable impurities. The steel of this invention has excellent weather resistance and weldability, uniform overall plate performance, and minimal differences in transverse and longitudinal properties.

Provided are a square steel pipe having high strength, a low yield ratio, and excellent low-temperature toughness, a method for manufacturing the same, and a building structure having excellent earthquake resistance even in a low-temperature environment. Provided is a square steel pipe having flat plate parts and corner parts, the square steel pipe having a predetermined component composition, and containing, in a location at the center of the plate thickness of the flat plate parts, 80-95% ferrite by area ratio and a total of 5-20% by area ratio of at least one selected from the group consisting of pearlite, pseudo pearlite, and upper bainite, and having a microstructure in which the average crystal grain size df of ferrite is 5.0-20.0 µm, the average crystal grain size dp of pearlite and pseudo-pearlite is 3.0-18.0 µm, the ratio dp / df of dp to df is 0.60-1.00, and the total number density of pearlite and pseudo pearlite is 2,000 / mm2 or greater.