28results about How to "Improve hardenability" patented technology

The invention relates to the field of metal materials and petroleum machinery, in particular to VBRE low-carbon low-alloy steel for a pressure-bearing part of an ultra-deep well blowout preventer group and a preparation method of the VBRE low-carbon low-alloy steel. The steel comprises the following chemical components in percentage by weight: 0.05 to 0.15 percent of C, 0.05 to 0.35 percent of Si, 0.40 to 0.80 percent of Mn, 2.0 to 3.0 percent of Cr, 0.80 to 1.20 percent of Mo, 0.05 to 0.25 percent of V, 0.0005 to 0.0030 percent of B, 0.0020 to 0.030 percent of RE and the balance of Fe. A series of key technologies such as purification smelting, high-purity rare earth treatment, argon protection pouring, cast ingot high-temperature demolding, high-temperature diffusion annealing, homogeneous forging forming and thermal refining are adopted, and the defects of internal component segregation, shrinkage cavity and porosity, non-metallic inclusion, uneven tissue, unstable performance and the like of the ultra-deep well blowout preventer set pressure-bearing part are greatly reduced; the VBRE low-carbon low-alloy steel for the pressure-bearing part of the blowout preventer group of the ultra-deep well, which has the characteristics of purity, homogeneity, compactness, refinement and the like and excellent obdurability matching, is obtained, and the service performance requirements of high strength, high toughness, heat resistance, corrosion resistance, fatigue resistance and the like are met.

This invention discloses a 440MPa grade steel plate with ultra-low temperature toughness and its preparation method, belonging to the field of steel materials technology. It solves the contradiction between insufficient strength and toughness grades and excessive nickel content in existing low-temperature steels. The composition of the 440MPa grade steel plate with ultra-low temperature toughness, by mass percentage, includes: C: 0.030%–0.085%, Si: 0.18%–0.38%, Mn: 0.95%–1.35%, P: ≤0.010%, S: ≤0.003%, Cr: 0.01%–0.25%, Mo: 0.01%–0.15%, Ni: 3.20%–4.25%, Cu: 0.12%–0.85%, Nb: 0.008%–0.035%, Al: 0.02%–0.036%, Ti: 0.008%–0.022%, with the balance being Fe and other unavoidable impurities. The steel plate of this invention exhibits excellent strength and low-temperature toughness.

A pre-hardened steel plate for a mirror-surface mold, comprising elements as follows: C: 0.28 to 0.36%, Si: 0.50 to 0.80%, Mn: 1.20 to 1.50%, P ≤ 0.020%, S ≤ 0.010%, Cr: 1.30 to 1.80%, Mo: 0.30 to 0.50%, Ni: 0.65 to 0.90%, V: 0.15 to 0.30%, H ≤ 1.5 ppm, and the balance is Fe and inevitable impurities. A pre-hardened steel plate with high hardenability for a mirror-surface mold having is obtained by using a manufacturing method comprising subjecting continuous casting billets to processes such as rolling, offline slow cooling, normalizing and tempering heat treatments. The advantages of the manufacturing method lie in that the production efficiency of continuous casting is high, the manufacturing costs are low. When not quenched-and-tempered, the hardness of the steel plate having a thickness of 20-180 mm reaches 38-42 HRC, the hardness fluctuation of the entire thickness ≤ 2 HRC, and the level of flaw detection satisfies the requirement of of level I in GB / T2970.

The invention relates to the technical field of bolt production, and particularly discloses a high-strength bolt machining process and device. Comprising the following steps: S1, material selection: selecting an alloy steel blank containing C, Si, Mn, Cr, Mo, V and the balance of Fe; s2, cold heading forming is conducted, specifically, the alloy steel blank is placed in a multi-station cold heading machine, and a bolt blank is formed through continuous cold heading and forging; s3, heat treatment is conducted, specifically, the bolt blank is subjected to quenching treatment and then subjected to tempering treatment, and a bolt base body is obtained; and S4, surface treatment is conducted, specifically, phosphating treatment is conducted on the surface of the bolt base body in sequence to form a phosphating layer, the composite coating is coated, and the high-strength bolt is obtained. The high-strength bolt machining process can be used for manufacturing connecting components requiring high reliability under complex working conditions such as heavy load, vibration and impact, and the high-strength bolt machining process has the advantages that the toughness, fatigue resistance and delayed fracture resistance are improved while high strength is kept.

This application provides a quenched and tempered steel plate and its production method. The quenched and tempered steel plate comprises the following components by mass percentage: C: 0.15–0.20%; Si: 0.20–0.40%; Mn: 1.20–1.50%; Cr: 0.20–0.50%; Ni: 0.10–0.20%; Nb: 0.020–0.040%; Ti: 0.010–0.040%; Mo: 0.30–0.50%; B: 0.0010–0.0025%; P≤0.015%, S≤0.004%; N≤0.004%, Als: 0.010–0.060%, with the remainder being Fe and unavoidable impurities. This application manufactures a thick, high-strength quenched and tempered steel plate with high surface quality by adjusting the elemental composition and content of the quenched and tempered steel plate, specifically by adding certain amounts of Ni, Cr, and B.

The application discloses a 27MnTiB high-strength wear-resistant steel plate and a production method thereof. By adopting a reasonable controlled rolling and controlled cooling process, cooperating with on-line quenching, stacking slow cooling and rapid low-temperature tempering, the 27MnTiB steel plate can not only obtain relatively high hardness and strength, but also obtain relatively high impact toughness, directly meeting the requirements of high-strength wear-resistant steel, with the yield strength being greater than or equal to 1500MPa, the tensile strength being greater than or equal to 1650MPa, the elongation being greater than or equal to 9%, the impact energy being greater than or equal to 60J, and the hardness being greater than or equal to 450HB. Meanwhile, the processing and manufacturing process is simplified, and the processing cost is reduced.

The application discloses a Ti-V-Zr-Cr-Al system ultrahigh-strength near-beta titanium alloy and a preparation method thereof, and belongs to the technical field of titanium alloy materials. The ultrahigh-strength near-beta titanium alloy contains 5.0-5.5% of Al, 11.0-11.5% of V, 2.5-3.0% of Cr, 4.5-5.0% of Zr, and the balance of Ti and inevitable impurity elements according to mass percentage. In the preparation process, firstly, the alloy ingot is subjected to open forging, and then is subjected to upsetting and drawing forging after being cooled to a phase transition point, so that a certain amount of primary alpha phase is formed in the alloy and is uniformly distributed in beta grains, thereby obtaining a titanium alloy forging blank; and then, the titanium alloy forging blank is sequentially subjected to solid solution treatment and aging treatment, thereby obtaining a near-beta ultrahigh-strength titanium alloy with a duplex structure. The titanium alloy has a tensile strength of more than 1800 MPa, a yield strength of 1780 MPa, a fracture elongation of more than 3.2%, and a uniform elongation of more than 2.8%. In particular, the tensile strength reaches 1800 MPa, and the titanium alloy can meet the requirements of the fields of aerospace, energy industry and the like, and has high use value and popularization value.

The invention discloses a production method for improving the impact toughness stability of thick-specification high-strength steel Q690D. The thick-specification high-strength steel Q690D comprises the following chemical components in percentage by weight: 0.13-0.15% of C; 0.25 to 0.35 percent of Si; mn: 1.40% to 1.50%; 0.080% to 0.110% of Nb, V and Ti; 0.85 to 1.05 percent of Cr, Mo and Ni; less than or equal to 0.015% of P; s < = 0.005%; b: 0.0008% to 0.0015% of the total weight of the The content of Als is 0.015 to 0.030 percent; o: < = 0.0035%; n: less than or equal to 0.0050%; the production method comprises the steps of KR desulfurization, converter smelting, LF refining, RH refining, continuous casting, heating, rolling and heat treatment. The invention aims to meet the depth requirement of the through quenching layer of the thick steel plate, ensure the strength performance of the high-strength steel Q690D and avoid great fluctuation of low-temperature toughness caused by the boron element.

This application relates to a hot-rolled pickled duplex steel and its preparation method, belonging to the field of strip steel production technology. The chemical composition of the duplex steel, by mass fraction, is: C: 0.05%~0.15%, Si: 0.15%~1.50%, Mn: 1.0%~2.0%, Al: 0.02%~0.10%, P≤0.015%, S≤0.006%, Cr: 0.1%~0.5%, Nb: 0.01%~0.05%, Ti: 0.01%~0.03%, Ni: 0.01%~0.40%, V: 0.001%~0.050%, with the remainder being Fe and unavoidable impurities. Through optimized C-Si-Mn-Cr-Nb-Ni composition system design, combined with controlled rolling and staged laminar flow cooling processes, a multiphase microstructure composed of ferrite and martensite was successfully obtained in the hot-rolled pickled duplex steel. This multiphase microstructure enables hot-rolled and pickled duplex steel to maintain high strength while retaining high elongation. Furthermore, a specific component ratio effectively suppresses softening in the weld heat-affected zone. This hot-rolled and pickled duplex steel is particularly suitable for passenger car chassis manufacturing, achieving a balance between lightweight design, high safety performance, and good manufacturability.

The application relates to the technical field of alloy steel, in particular to a 90 ksi steel grade alloy steel for extra-high voltage wellhead equipment and a preparation method thereof. The raw material components of the alloy steel include, by mass percentage, C: 0.25-0.35%, Si: 0.15-0.35%, Mn: 0.40-0.90%, P<=0.020%, S<=0.010%, Cr: 1.90-2.50%, Ni<=0.10%, Mo: 1.00-1.50%, V: 0.01-0.10%, Nb: 0.01-0.10%, Al: 0.01-0.10%, B: 30-60 ppm, and the rest is Fe and inevitable impurities. The 90 ksi steel grade alloy steel for extra-high voltage wellhead equipment provided by the application has high strength and good hydrogen sulfide corrosion resistance as a wellhead forging material.

A martensitic stainless steel sheet for a brake disc rotor, characterized by containing predetermined components and having, in a mother phase, precipitates with a particle size of 2 µm or less and a density of 0.01 to 20 pieces / µm2. The precipitates finely present in hot rolling and hot-rolled sheet annealing improves productivity in hardening, improves temper softening resistance of the steel sheet in use as a component, inhibits cracking in hot stamping, and inhibits reduction in high-temperature strength. Accordingly, the martensitic stainless steel sheet excellent in temper softening resistance, hardenability, formability, and high-temperature strength that is applicable to the disc rotor is provided.

The application relates to the technical field of welding materials, in particular to a continuous oil pipe butt welding gas protection solid core welding wire and a welding method; the chemical components of the solid core welding wire include the following: C: 0.08%-0.14%, Si: 0.2%-0.3%, Mn: 0.7%-1.0%, Ni: 0.15%-0.25%, Cu: 0.25%-0.35%, Cr: 0.5%-0.7%, Mo: 0.10%-0.15%, Nb: 0.02%-0.03%, Ti: 0.01%-0.02%, and the rest is Fe and inevitable impurities; by adopting low-carbon components, the fatigue performance of a weld is reduced, then the Mn, Ni, Mo, Cr and Cu systems are adopted, and i and Nb trace elements are added at the same time, so that the solid solution strengthening, fine-grain strengthening and precipitation strengthening methods can be comprehensively utilized to improve the strength of the weld, the hardenability of the weld metal is improved, the generation of bainite is promoted, the toughness and strength of the metal weld are improved, and therefore the fatigue resistance of a pipe-pipe butt welding joint is comprehensively improved.

The invention discloses a rolling method for improving the hardness of a steel rail with standard strength. The production process comprises the following steps: molten iron in a steelmaking process, converter smelting, LF (ladle furnace) refining, VD (vacuum degassing) and continuous casting to ensure the purity and component uniformity of molten steel; rolling and subsequent processes: heating by a stepping furnace, descaling by high-pressure water, rolling by a universal rolling mill, cooling and pre-bending by a cooling bed, straightening, carrying out ultrasonic flaw detection, processing, checking and warehousing; the steel rail comprises the following chemical components in percentage by mass: 0.81-0.86% of C; s : 0.52%-0.59%; mn: 1.17 to 1.25%; less than or equal to 0.020% of P; less than or equal to 0.020% of S; 0.23 to 0.28% of Cr; 0.03 to 0.05 percent of N ; and the balance Fe and impurities. The low-cost and high-quality high-speed steel rail steel is prepared by optimizing the chemical components of the steel grade and customizing the controlled rolling and controlled cooling process, and the hardness, strength and toughness of the high-speed steel rail steel all meet the American standard requirements.

The application provides a rare earth-titanium-boron composite vacuum seal welding high-density cored wire and a preparation method thereof, and belongs to the technical field of metallurgical auxiliary materials. The preparation method comprises the following steps: weighing lanthanum-cerium rare earth alloy powder, titanium powder and boron powder for batching, and then uniformly mixing under a protective atmosphere to obtain mixed powder; filling the mixed powder into a low-carbon steel cylinder after pretreatment under a protective atmosphere, and then preliminarily sealing to obtain a composite blank; performing a reduction reaction on the composite blank in hydrogen, and then performing seal welding under a vacuum condition to obtain a composite blank after vacuum seal welding; heating the composite blank after vacuum seal welding, and then performing hot drawing to obtain the cored wire. The cored wire provided by the application realizes stable composite addition of rare earth, titanium and boron with high recovery rate, and significantly improves the structure and performance of 20Mn2 steel and the like, and solves the problems of cold heading cracking, insufficient toughness and aging embrittlement.

A pre-hardened steel plate for a mirror-surface mold, comprising elements as follows: C: 0.28 to 0.36%, Si: 0.50 to 0.80%, Mn: 1.20 to 1.50%, P ≤ 0.020%, S ≤ 0.010%, Cr: 1.30 to 1.80%, Mo: 0.30 to 0.50%, Ni: 0.65 to 0.90%, V: 0.15 to 0.30%, H ≤ 1.5 ppm, and the balance is Fe and inevitable impurities. A pre-hardened steel plate with high hardenability for a mirror-surface mold having is obtained by using a manufacturing method comprising subjecting continuous casting billets to processes such as rolling, offline slow cooling, normalizing and tempering heat treatments. The advantages of the manufacturing method lie in that the production efficiency of continuous casting is high, the manufacturing costs are low. When not quenched-and-tempered, the hardness of the steel plate having a thickness of 20-180 mm reaches 38-42 HRC, the hardness fluctuation of the entire thickness ≤ 2 HRC, and the level of flaw detection satisfies the requirement of of level I in GB / T2970.

This disclosure provides a steel sheet with excellent hardenability and excellent cold workability. The steel sheet disclosed herein has the following composition by mass %: C: 0.15~0.50%, Si: 0.01~0.50%, Mn: 0.20~1.30%, P: less than 0.100%, S: less than 0.100%, Al: less than 0.100%, Cr: 0.01~1.20%, N: less than 0.0150%, and the balance being Fe and impurities. The total surface area of ​​ferrite and cementite particles is 95% or more, the average grain size of ferrite is 5.0~20.0 μm, and the Cr concentration in the cementite particles is [Cr]. θ and Mo concentration [Mo] θ To satisfy equation (1), the average particle size of the cementite particles is less than 1.50 μm, the spheroidization rate of the cementite particles is greater than 70% and less than 85%, and the dispersion DI of the number of cementite particles in a small square partition with a side length of 10 μm, as defined by equation (2), is less than 45%. 2[Cr] θ +3[Mo] θ ≤3 / √C (1) DI=σ θ / N θ ×100 (2)

This invention belongs to the field of casting technology and mainly relates to a production method for thick-walled cast steel parts, including the following steps: design of the chemical composition of the cast steel parts; design of the heat treatment process: the cast steel parts are treated with a heat treatment method of high-temperature annealing + quenching + high-temperature tempering in sequence. By adjusting the content of a wide range of constituent elements required by the customer, and adding trace elements Nb and B strengthening elements when designing and optimizing the internal control composition, the hardenability of the cast steel material is significantly improved; and combined with the heat treatment process of high-temperature annealing + quenching + high-temperature tempering, the relevant parameter ranges and steps of each heat treatment process are designed reasonably to ensure that the entire cross-section of the cast steel part obtains a uniform tempered sorbite structure, and that the strength, plasticity, and average Akv of the surface, half radius, and core of the cast steel part all meet the standard requirements; the performance compliance rate of the finally obtained cast steel parts is 100%.

This invention discloses a high-plasticity, high-strength mold steel alloy powder for SLM (Sequencing Molding Machine) processes. Its composition, by weight percentage, includes: C 0.09-0.13%, Mn 0.05-0.2%, Cr 12.1-12.6%, Ni 13.0-15.2%, Mo 0.7-1.0%, Al 0.8-1.0%, B 0.002-0.004%, Si 0.1-0.15%, and Ti, with the balance being Fe; wherein the Ti / (Si+B) ratio is 0.7-0.8. This invention also discloses a preparation process for the high-plasticity, high-strength mold steel. By adjusting the contents of Ti, B, and other elements, and selecting a Ti / (Si+B) ratio of 0.7-0.8, combined with a suitable preparation process, this invention refines the grains and increases hardenability, ultimately obtaining a high-plasticity, high-strength mold steel.

The application discloses a 785MPa-grade steel plate with ultralow-temperature toughness and a preparation method thereof, and belongs to the technical field of steel materials, and solves the contradiction between the insufficient toughness level of the ultrahigh-strength steel and the excessive matching of the nickel content in the prior art.The 785MPa-grade steel plate with ultralow-temperature toughness comprises the following components in percentage by mass: C: 0.08% to 0.15%, Si: 0.02% to 0.18%, Mn: 0.60% to 1.63%, P: ≤0.010%, S: ≤0.004%, Cr: 0.35% to 0.95%, Mo: 0.32% to 0.60%, Ni: 3.15% to 4.35%, Cu: 0.75% to 1.85%, V: 0.04 to 0.12%, Nb: 0.008% to 0.035%, Al: 0.017% to 0.036%, Ti: 0.008% to 0.022%, and the balance of Fe and other inevitable impurities.The 785MPa-grade steel plate with ultralow-temperature toughness has excellent strength and low-temperature toughness.

A low-cost Q690D steel plate and its online quenching-tempering production method belong to the field of steel heat treatment technology. Its chemical composition and mass content are: C 0.14-0.17%, Si 0.25-0.35%, Mn 1.35-1.55%, P≤0.01%, S≤0.005%, Cr 0.30-0.50%, Nb 0.020-0.035%, Ti 0.015-0.025%, V 0.02-0.04%, B 0.0015-0.0025%, with the remainder being iron and unavoidable impurities. The production method includes controlled rolling, online quenching, and tempering processes. This invention does not add precious metal elements such as Ni, Mo, and Cu, resulting in low alloy cost, short process time, and a steel plate with a yield strength ≥690MPa and an impact energy ≥120J at -20℃, exhibiting good strength and toughness matching.

This application relates to a wire rod, an arc-sprayed wire, and a preparation method thereof, belonging to the technical field of arc-sprayed materials. The chemical composition of the wire rod, by mass fraction, is: C: 0.08%~0.14%, Si: 0.10%~0.60%, Mn: 1.50%~2.00%, P≤0.020%, S≤0.020%, Cr≤0.10%, Ni≤0.10%, Mo≤0.05%, Cu≤0.10%, Ti≤0.010%, Al≤0.020%, N≤0.010%, TO≤0.010%, with the remainder being Fe and unavoidable impurities. The wire is prepared by optimizing the chemical composition of the alloy wire rod through processes such as smelting, continuous casting, rolling, surface treatment, rough drawing, copper plating, and fine drawing. The mass fraction of Cu is 0.10%~0.25%, and the other elements are the same as those in the wire rod. This wire material has excellent wear and corrosion resistance and adhesion strength to the aluminum alloy substrate. It can form a stable protective coating on the inner wall of the engine cylinder, taking into account both the advantages of engine lightweighting and high performance requirements, and effectively supporting long-term service.

This disclosure provides a steel sheet with excellent hardenability and excellent cold workability. The steel sheet disclosed herein has the following composition by mass %: C: 0.15~0.50%, Si: 0.01~0.50%, Mn: 0.20~1.30%, P: less than 0.100%, S: less than 0.100%, Al: less than 0.100%, Cr: 0.01~1.20%, N: less than 0.0150%, and the balance being Fe and impurities. The total surface area of ​​ferrite and cementite particles is 95% or more, the average grain size of ferrite is 5.0~20.0 μm, and the Cr concentration in the cementite particles is [Cr]. θ and Mo concentration [Mo] θ To satisfy equation (1), the average particle size of the cementite particles is less than 1.50 μm, the sphericity of the cementite particles is greater than 85%, and the dispersion DI of the number of cementite particles in a small square partition with a side length of 10 μm, as defined by equation (2), is less than 45%. 2[Cr] θ +3[Mo] θ ≤3 / √C (1) DI=σ θ / N θ ×100 (2)

This application relates to an 1180MPa grade ultra-high strength steel and its preparation method, belonging to the field of steel manufacturing technology. The chemical composition of the ultra-high strength steel, by mass fraction, is: C: 0.04%~0.25%, Si: 0.60%~1.80%, Mn: 1.20%~3.00%, Al: 0.02%~0.10%, P≤0.005%, S≤0.002%, Ti: 0.010%~0.040%, Cr: 0.10%~0.80%, N≤0.004%, B: 0.0010%~0.0030%, with the remainder being Fe and unavoidable impurities. The microstructure of the ultra-high strength steel includes ferrite and martensite. A breakthrough in the performance of ultra-high strength steel is achieved by employing a C-Si-Mn-Cr-B composition system and a segmented cooling process. After finishing rolling, the slab is air-cooled under a temperature-controlled insulation hood, allowing it to enter the water-cooling stage within the phase transformation temperature range and complete the martensitic phase transformation at an ultra-high cooling rate. The resulting ultra-high-strength steel possesses both ultra-high strength and good ductility, while its elongation, cold bending performance, and sheet shape quality are all comprehensively improved. This method effectively overcomes the sheet shape defects, performance fluctuations, and weld softening problems of traditional methods, and is suitable for the industrial production of ultra-thin ultra-high-strength steel.

The invention discloses economical high-strength and high-hardenability round steel for a wind power ground anchor bolt and a production method of the economical high-strength and high-hardenability round steel, and the economical high-strength and high-hardenability round steel for the wind power ground anchor bolt comprises the following chemical components in percentage by weight: 0.36-0.42% of C, 0.20-0.40% of Si, 1.60-1.70% of Mn, less than or equal to 0.020% of P, less than or equal to 0.015% of S, 0.40-0.60% of Cr, less than or equal to 0.20% of Cu, 0.015-0.030% of Ti, 0.020-0.040% of Al, 0.002-0.005% of B and the balance of Fe and inevitable impurities. The round steel for the wind power ground anchor bolt can meet the performance of a 10.9-grade high-strength bolt, and compared with large-specification wind power bolt materials produced by 42CrMoA, B7 and 40CrNiMoA, the cost is greatly reduced.

The steel for the gas cylinder pipe comprises the following components in percentage by weight: 0.30 to 0.37 percent of C, 0.15 to 0.35 percent of Si, 0.60 to 0.90 percent of Mn, not more than 0.015 percent of P, not more than 0.008 percent of S, not more than 0.02 percent of P + S, not more than 0.15 percent of Cu, 0.1 to 0.3 percent of Ni, 0.9 to 1.2 percent of Cr, 0.1 to 0.3 percent of Mo, not more than 0.02 percent of Nb, not more than 0.05 percent of V, 0.01 to 0.025 percent of Ti, 0.01 to 0.04 percent of Alt, 0.001 to 0.002 percent of B, not more than 0.0025 percent of O, 0.001 to 0.006 percent of N, not more than 0.0002 percent of H, 0.001 to 0.004 percent of Ca and the balance of Fe and inevitable impurities. The ratio of (Mo + Cr + 5C) / 0.33 Ni is equal to 30-70; alt: N > = 2; [B] * [N] < = 1 * 10-5.

The invention discloses a manufacturing method for improving mechanical property uniformity of high-chromium steel and a product thereof, and relates to the technical field of manufacturing of weathering resistant steel for railway vehicles, photovoltaics and the like. According to the method, after a rough rolling procedure is finished, an intermediate billet is subjected to heat compensation; the heat compensation process comprises the step of heating the two side parts of the intermediate billet in the width direction by adopting medium-frequency induction heating to prevent the temperature drop of the two sides from being too fast; wherein the heat compensation range is within the range of 28-32 mm of the two side parts, the heat compensation temperature is 50 DEG C * K, and K is a hardenability coefficient and is dimensionless; k = [14 * omega (Cr) + 5.5 * omega (Ni) + 16 * omega (Mn)] / 100. According to the high-chromium steel product disclosed by the invention, good structure homogeneity and excellent mechanical property uniformity are obtained from key component design, rolling and cooling process design and the like.

The application relates to a torsion beam steel and a preparation method thereof, and the chemical components of the torsion beam steel include the following contents: the content of C is 0.05-0.08%, the content of Si is <=0.15%, the content of Mn is 1.2-1.7%, the content of P is <=0.015%, the content of S is <=0.003%, the content of Nb is 0.01-0.05%, the content of Ti is 0.03-0.08%, the content of Cr is 0.1%-0.4%, the content of Mo is 0.1-0.25%, the content of V is 0.01-0.04%, and the content of Ca is 0.0005-0.005%; and the following conditions are met: [Ti] / [Mo] <=0.6, and [Cr]+[Mo] = 0.2-0.5%; the microstructure of the torsion beam steel includes ferrite and bainite. The torsion beam steel has the advantages that the tensile strength is >=650 MPa, the hole expansion rate lambda is >=85%, and the elongation A80 is >=24%.

This invention relates to a method for preparing a metal crusher guard plate, comprising a substrate and a wear-resistant plate layer; the wear-resistant plate layer is attached to one side of the substrate, and the substrate and the wear-resistant plate are metallurgically bonded; the composition of the substrate by weight percentage is: C: 0.40~0.45%, Si: 0.15~0.30%, Mn: 0.60~0.75%, Cr: 0.20~0.45%, Mo: 0.10~0.25%, Cu: 0.15~0.25%, with the balance being Fe; the composition of the wear-resistant plate layer by weight percentage is: C: 3.5~4.5%, Si: 1.8~2.2%. The composition of the wear-resistant plate is as follows: Mn: 0.4~0.5%, Mo: 0.15~0.35%, Cr: 0.25~0.50%, Cu: 0.12~0.20%, Mg: 0.02~0.1%, W: 0.02~0.1%, N: 0.005~0.02%, WC: 0.5~0.1%, with the balance being Fe. The preparation process of the wear-resistant plate includes the manufacturing of sand cores and sand molds, the preparation of molten steel for the base material and molten iron for the wear-resistant plate layer, casting and molding, and heat treatment. The wear-resistant plate layer has high hardness and wear resistance, and contains hard particles of tungsten carbide, thereby improving the wear resistance of the wear-resistant plate and extending its service life.