372 results about "Hardenability" patented technology

The invention relates to the technical field of metal forge piece machining, in particular to an irregular metal forge piece heat treatment method and system.The irregular metal forge piece heat treatment method comprises the steps that firstly, temperature compensation partitions are divided according to geometrical characteristics, and stepped preheating is implemented to establish a uniform basic temperature field; then, the heat preservation time of each subarea is independently regulated and controlled in the austenitizing stage, and sufficient transformation of a thick-wall area structure and control over the grain size of a thin-wall area are both considered; in the quenching process, partition strength adjustment is carried out based on a preset cooling map, and cooling parameters are dynamically optimized through real-time feedback; and finally, according to the residual stress distribution, carrying out partition stepped tempering. The heating and cooling uniformity is remarkably improved through partition dynamic temperature management, and the structure difference and thermal stress concentration caused by section sudden change are effectively inhibited; the microstructure is ensured to be uniform and stable through austenitizing control; the hardenability and the deformation resistance are balanced through a differential cooling strategy; and directional reduction of residual stress is achieved through an intelligent tempering mechanism, and the cracking risk is greatly reduced while the comprehensive mechanical property is improved.

The invention discloses a 8.8-grade large-specification cold heading steel wire rod with excellent hardenability and a production method thereof, and belongs to the technical field of steel products. The steel wire rod is prepared from the following chemical components in percentage by mass: 0.35 percent to 0.39 percent of C, less than or equal to 0.10 percent of Si, 0.60 percent to 0.85 percent of Mn, 0.20 percent to 0.40 percent of Cr, 0.15 percent to 0.25 percent of Mo, 0.05 percent to 0.10 percent of Ni, 0.020 percent to 0.040 percent of Al, 0.0040 percent to 0.0080 percent of Ca, 0.0010 percent to 0.0030 percent of Ce, less than or equal to 0.0050 percent of N and the balance of Fe and inevitable impurities. The process route comprises the steps of molten iron pretreatment, converter smelting, LF refining, continuous casting, continuous rolling, billet cleaning, heating, rolling and controlled cooling. The produced # imgabs0 cold heading steel wire rod is good in cold heading performance, the hardness of the cross section of the wire rod is larger than 45 HRC after quenching, and the cold heading steel wire rod can be used for producing 8.8-grade high-strength bolts, nuts, screws and other hexagonal flange standard parts.

The invention relates to a high-strength complex-phase hot-rolled wire rod for a 2200MPa-grade stranded wire and a manufacturing method of the high-strength complex-phase hot-rolled wire rod, and the manufacturing method comprises the following steps: rolling and spinning to form a wire rod by adopting a high-hardenability component design, and then carrying out online molten salt mixed phase region quenching isothermal treatment, so that the wire rod is firstly subjected to front-section molten salt treatment and enters a bainite and pearlite phase region from an austenite state; the method comprises the following steps: carrying out high-temperature treatment on austenite to promote part of austenite to be converted into bainite and sorbite, carrying out later-section molten salt treatment, increasing the molten salt temperature, reducing the molten salt circulation amount, promoting unconverted retained austenite to be decomposed and converted into bainite and sorbite, carrying out isothermal tempering, and finally carrying out slow cooling through a roller way, the hot-rolled wire rod with a microscopic structure comprising a complex phase structure composed of tempered bainite and tempered sorbite is prepared, the material cost can be reduced, the complex phase structure and the structure toughness can be regulated and controlled on line, the tensile strength is 1505-1555 MPa, the percentage reduction of area is 32%-37%, efficiency and energy consumption are both considered, off-line heat treatment is avoided, and high-efficiency production of stranded wires is promoted.

The invention relates to the technical field of low-temperature studs and bolts, and discloses a low-temperature stud steel hardenability optimization treatment method which comprises the steps of S1, a pretreatment method, S2, quenching method optimization, S3, tempering method optimization, S4, a post-treatment method and S5, a performance verification method. According to the method, the low-temperature impact stability is remarkably improved, the low-temperature impact energy of the material at about-100 DEG C can stably reach 35 J or above by accurately controlling the proportion of alloy elements and optimizing the heat treatment process (for example, the tempering temperature is increased to 640 DEG C or above and the heat preservation time is prolonged), the low-temperature impact energy is improved by about 20%-30% compared with a traditional process, and the problem that the low-temperature impact performance of the wire rod fluctuates is thoroughly solved; and the service safety in a low-temperature environment is ensured.

The invention relates to a high-hardenability gear steel bar for a new energy automobile and a manufacturing method of the high-hardenability gear steel bar. The high-hardenability gear steel bar comprises the following chemical components in percentage by mass: 0.17-0.25% of C, less than or equal to 0.37% of Si, 0.50-0.90% of Mn, 0.85-1.25% of Cr, less than or equal to 0.025% of P, less than or equal to 0.030% of S, less than or equal to 0.30% of Cu, 0.02-0.06% of Ti, 0.02-0.05% of Al, less than or equal to 0.30% of Ni, 0.15-0.45% of Mo, 0.0005-0.0020% of B, 0.020-0.080% of Nb, less than or equal to 0.0030% of Ca, 0.0090-0.0150% of N, less than or equal to The production and manufacturing process comprises the steps of converter treatment, external refining, vacuum degassing, continuous casting, continuous rolling, shearing or saw cutting, stack cooling and finishing flaw detection. According to the invention, fine Nb (C, N) and (Nb, Ti) (C, N) particles are precipitated by microalloying Nb and Ti, the growth of crystal grains is effectively inhibited, and meanwhile, the hardenability of the material is improved by adding a proper amount of B element. According to the invention, Nb, Ti and B are adopted for composite microalloying at the same time, so that the fine-grain and high-hardenability gear steel material is obtained.

The invention discloses a dual-motor dual-rotor flywheel energy storage device which comprises a shell which is arranged in a sealed mode. The flywheel is connected with a motor and arranged on the inner wall of the shell, and the flywheel is arranged to be in a split type; the first wheel body is arranged right above the second wheel body, so that the axial thickness of the flywheel is increased, the energy storage capacity of the whole device is improved, meanwhile, the problem of insufficient quenching depth caused by a flywheel with a large axial size can be solved, and the flywheel is arranged into a split type, so that the axial thickness of a forge piece can be reduced, and the hardenability is improved. The two groups of motors are respectively connected with the first wheel body and the second wheel body, so that the heat dissipation areas of the stators and the rotors in the motors are increased, and the problem of heat dissipation caused by the increase of the structural sizes of the stators and the rotors of the motors due to higher motor power is solved.

The invention relates to the field of ferrous metallurgy and forge piece manufacturing, in particular to high-toughness, ultra-pure and large-quenching-depth 40CrNiMoRE rare earth special steel for a large ring piece and a preparation method of the high-toughness, ultra-pure and large-quenching-depth 40CrNiMoRE rare earth special steel. The invention relates to a high-temperature-resistant steel material, which comprises the following chemical components in percentage by weight: 0.3 to 0.5 percent of C, 0.1 to 0.5 percent of Si, 0.4 to 0.8 percent of Mn, 0.5 to 1.5 percent of Cr, 0.5 to 1.5 percent of Ni, 0.1 to 0.5 percent of Mo, 0.05 to 0.30 percent of V, 0.0005 to 0.0030 percent of B, 0.005 to 0.030 percent of RE and the balance of Fe and inevitable impurities. Through V, B and RE comprehensive microalloying, molten steel purification, inclusion modification and grain refinement, the hardenability is improved, and the surface quenching layer depth, hardness uniformity and impact toughness are ensured. And moreover, the high-toughness, ultra-pure and large-quenching-depth large ring piece is obtained through preparation technologies such as pure smelting, airtight protection pouring and uniform deformation, and the technical problems that an existing large ring piece is low in purity, poor in toughness, insufficient in hardenability, cracked in surface quenching and the like can be effectively solved.

The present application relates to a kind of Nb-Ti microalloying Cr-Mn gear steel and its preparation method, the chemical composition of the Nb-Ti microalloying Cr-Mn gear steel, by mass percentage, including: C:0.15~0.25%, Si≤0.20, Mn:0.8~1.60%, P:≤0.025%, S:0.010~0.035%, Cr:1.00%~1.80%, Ni:≤0.25%, Cu:≤0.20%, Ti:0.01~0.03%, Nb:0.02~0.07%, B≤0.0005%, Al:0.01~0.04%, [O]:≤12×10 ‑4 %, [N]:0.005~0.010%, [H]:≤1.5×10 ‑4 %, the rest is Fe and inevitable impurities.The Nb-Ti microalloying Cr-Mn gear steel prepared by the application has good hardenability, end hardenability J9=40~45HRc, J15=35~40HRc, which is greatly improved compared with 20CrMnTiH;The gear grain is refined, and the grain size reaches more than 7 levels after carburizing at 960~980 ℃ for 8~10 h, and the strength and toughness and fatigue performance of the gear are significantly improved.

The invention belongs to the technical field of metallurgy, and particularly relates to a production method of fine grains of steel for high-carbon grinding balls, which comprises the following steps: 1) controlling part of chemical components in the steel: controlling the content of Al to be 0.025-0.040%, the content of Mn to be 0.65-0.80% and the content of Cr to be 0.60-0.90% in percentage by weight; (2) the binary alkalinity of LF refining slag is controlled to be 4.5-6.0, the nitrogen content of molten steel after RH refining is 26-38 ppm, and (3) the final rolling temperature of continuous rolling is controlled to be 950-1000 DEG C. According to the method, the technical requirements of steel for large-specification high-carbon steel wear-resistant steel balls are met, the requirement for fine grains of the grinding ball steel at the grade of 7 or above is met, and meanwhile the requirement for high hardenability of the grinding ball steel and the requirement for low-grade inclusions are also met.

The invention discloses steel for a wind power main shaft bearing ring and a production method of the steel, the steel comprises the following chemical components in percentage by mass: 0.46 to 0.53 percent of C, 0.15 to 0.35 percent of Si, 0.70 to 1.00 percent of Mn, 1.10 to 1.30 percent of Cr, 0.40 to 0.70 percent of Ni, 0.25 to 0.35 percent of Mo, 0.020 to 0.050 percent of Al, 0.05 to 0.10 percent of V and 0.005 to 0.012 percent of N. The steel for the soft-belt-free quenched wind power main shaft bearing ring with high hardenability, high hardenability and high low-temperature impact toughness is produced by proportioning the C, the Si, the Mn, the Cr, the Ni, the Mo and the V; after hardening and tempering, good strength, plasticity and low-temperature impact toughness can be obtained, high hardness and deep quenching hardness layer depth can be obtained through soft-belt-free medium-frequency quenching, and the use requirement of the wind power main shaft bearing ring is met.

The invention discloses ultra-high-strength spring steel with the tensile strength larger than or equal to 2100 MPa for a large-specification spring of engineering machinery and a preparation method of the ultra-high-strength spring steel, and relates to the technical field of steel production. 1.50% to 2.00% of Si; 0.80% to 1.50% of Mn; 0.90% to 1.50% of Cr; 0.10% to 0.40% of Mo; 0.40% to 0.80% of Ni; 0.10% to 0.40% of W; 0.08% to 0.15% of V; ti: 0.015% to 0.035%; b: 0.0008% to 0.0035% of the total weight of the P: less than or equal to 0.012%; s: < = 0.006%; o < = 0.0015%; and the balance of Fe and inevitable impurities. The prepared ultrahigh-strength spring steel has the advantages of being excellent in hardenability, high in strength, good in plasticity and toughness and the like.

The invention provides 980 MPa-grade galvanized dual-phase steel and a preparation method thereof, and the 980 MPa-grade galvanized dual-phase steel is composed of the following components in percentage by mass: 0.06%-0.09% of C, 0.20%-0.30% of Si, 2.2%-2.8% of Mn, 0.10%-0.22% of Al, 0.015%-0.04% of Nb, 0.25%-0.40% of Cr, 0.070%-0.140% of Mo, less than or equal to 0.015% of P, less than or equal to 0.015% of S, less than or equal to 0.007% of N and the balance of Fe and inevitable impurities. On the basis that low-carbon components are adopted and low-cost alloys such as Si and Mn are added, a small amount of Al, Nb, Cr and Mo alloys are added, and the product performance and the process feasibility are guaranteed. By reasonably selecting chemical element components and contents, especially by controlling the reasonable contents of C, Si, Mn, Cr, Al, Mo and Nb, the hardenability of austenite during annealing in a critical zone is improved, the martensite content in the structure is ensured, S and N are controlled to be extremely low, it is ensured that the galvanized steel plate has good mechanical properties and formability, a component system is adopted, and the production cost is reduced. And the 980MPa-grade galvanized dual-phase steel with different yield strength grades can be produced by one steelmaking component.

The invention discloses a process for producing a tire bead wire by using a 70 # steel wire rod, the 70 # steel wire rod is used as a raw material, and the 70 # steel wire rod comprises the following components in percentage by mass: 0.70-0.72% of C, 0.20-0.22% of Si, 0.50-0.55% of Mn, less than or equal to 0.015% of P, less than or equal to 0.015% of S, less than or equal to 0.03% of Cr, less than or equal to 0.03% of Ni, less than or equal to 0.04% of Cu and the balance of Fe and inevitable impurities. The 70 # steel wire rod is used for replacing commonly-used 77A and C72DA tire bead grade wire rods, the application grade and cost of wire rod raw materials are reduced, the content of manganese and silicon elements is increased, the hardness and hardenability of the steel wire are enhanced, and the hot working performance of the steel wire is improved; meanwhile, the organization structure of the steel wire material is innovatively improved through the tempering process, it is guaranteed that the steel wire rod with the low application grade obtains high strength and toughness, and the key indexes such as the breaking force, the yield ratio and torsion of the steel wire rod are improved. While the strength requirement of the automobile tire is met, the process difficulty of raw material production is reduced, the energy consumption is saved from the source, and the emission of three wastes is reduced.

The invention relates to a high-speed rail gear steel bar produced through a continuous casting and rolling process and a manufacturing method of the high-speed rail gear steel bar, and belongs to the technical field of metallurgy. The steel comprises the following chemical components in percentage by mass: 0.15 to 0.20 percent of C, less than or equal to 0.40 percent of Si, 0.50 to 0.90 percent of Mn, 1.50 to 1.80 percent of Cr, less than or equal to 0.025 percent of P, less than or equal to 0.025 percent of S, less than or equal to 0.30 percent of Cu, less than or equal to 0.005 percent of Ti, 0.02 to 0.05 percent of Al, 1.40 to 1.70 percent of Ni, 0.25 to 0.35 percent of Mo, 0.015 to 0.035 percent of Nb, less than or equal to 0.0030 percent of Ca, 0.0090 to 0.0150 percent of N, less than or equal to 0.0012 percent of [O], less than or equal to 0.0001 percent of [H] and the balance of Fe and inevitable impurity elements. A narrow hardenability bandwidth control technology is realized by establishing a hardenability prediction model, accurately controlling smelting components and uniformly controlling solidification components, and the hardenability bandwidth of the material is less than or equal to 4 HRC; the gear steel is subjected to high-temperature carburization at 980 DEG C for 4 h, and the grain size reaches the level 5 or above.

The invention discloses a method for improving the interlayer performance uniformity of a large-size high-toughness 7xxx aluminum alloy pre-stretched super-thick plate, and relates to the field of improvement of interlayer performance differences of high-strength aluminum alloy pre-stretched super-thick plates. The method aims at solving the problems that in the subsequent part machining and application process of the 7xxx alloy super-thick pre-stretched thick plate, the performance difference of a plate thickness layer is large, the damage resistance of the position where the performance of the plate is weak is reduced, the part loses efficacy, and the model safety is reduced. The method comprises the steps of controlling the uniformity of cross-section structure components of a large-size cast ingot, performing strong rolling deformation of plate interlayer performance uniformity, and performing strong quenching for improving the hardenability of the plate. According to the plate prepared through the method, the bottleneck that the comprehensive performance of the plate is synergistically improved is broken through, the overall performance of the thick plate is improved, the service life of parts is prolonged, the structural safety is enhanced, and the market competitiveness of products is improved. The method disclosed by the invention is used for controlling the interlayer performance uniformity of the 7xxx large-specification, super-thick and ultrahigh-strength aluminum alloy pre-stretched thick plate.

The invention relates to a method for predicting the hardenability of an 8620H steel and iron material, and belongs to the technical field of steel and iron material quality control methods. According to the technical scheme, on the basis of a 8620H steel and iron material hardenability data set, more than one machine learning algorithm is applied to perform model training, 8620H steel and iron material hardenability prediction models of the algorithms are constructed respectively, and key hardenability indexes J7.9 and J12.7 of steel are predicted; and a ten-fold cross validation method is adopted to evaluate the training model, evaluation indexes are used to measure the accuracy and reliability of each model, and an optimal hardenability prediction model is determined according to the accuracy and reliability. The method has the beneficial effects that the high-precision hardenability prediction model is constructed, the hardenability of the 8620H steel and iron material to be tested can be accurately predicted, and the method has the advantages of high precision, low cost and rapid implementation of material hardenability performance evaluation.

The invention relates to the technical field of steel production, in particular to a production process of 40CrH steel smelted by an electric furnace and used for automobile steering knuckles, and the steel comprises the following chemical components in percentage by weight: 0.385%-0.410% of C, 0.20%-0.32% of Si, 0.73%-0.77% of Mn, less than or equal to 0.022% of P, less than or equal to 0.020% of S, 1.02%-1.06% of Cr, 0.020%-0.040% of Alt, less than or equal to 0.04% of Mo, less than or equal to 0.0004% of B, less than or equal to 0.08% of Cu and the balance of Fe and impurities. The production process route comprises ecological electric furnace smelting, LF refining, RH vacuum degassing, continuous casting, heating and rolling. According to the method, the finished steel has narrow hardenability and good comprehensive performance by accurately controlling the chemical components of the steel and combining the technological means of electric furnace end point control, crystallizer and solidification end electromagnetic stirring, rolling temperature optimization and the like.

The invention provides hot-rolled round steel for forging bucket teeth, a production method of the hot-rolled round steel, the bucket teeth and the production method of the bucket teeth. The hot-rolled round steel comprises the following components: 0.28%-0.36% of C, 1.10%-1.35% of Si, 1.60%-1.90% of Cr, 1.20%-1.60% of Mn, 0.10%-0.40% of Mo, 0.06%-0.15% of V, 0.04%-0.10% of Ti, 0.018%-0.030% of Al, less than or equal to 0.020% of P, less than or equal to 0.020% of S and the balance of Fe and inevitable impurities. Compared with the prior art, the components of the bucket tooth steel are controlled, so that the steel has better hardenability and hardenability, and the bucket tooth can obtain ideal strength, hardness and impact toughness through heat treatment.

The invention relates to a steel wire rod for a non-quenched and tempered fastener, a production method of the steel wire rod and the fastener, and the steel wire rod is characterized in that through component design, an element B is added on the basis of strengthening elements such as carbon, silicon and manganese, so that excellent hardenability and plasticity of steel are guaranteed; the tensile strength of the steel wire rod obtained through the production process of converter smelting, LF refining, bloom continuous casting, cogging, steel wire rod rolling and offline salt bath of the steel wire rod is 1050-1250 MPa, and the percentage reduction of area is 65-70%; the steel wire rod is subjected to drawing and cold heading to produce the fastener, thermal refining can be omitted, the technical requirements of the 12.9-grade fastener can be met, and the production cost and the carbon emission are effectively reduced.

The invention relates to a production method of high-strength, high-toughness and corrosion-resistant ship anchor chain steel. The steel comprises the following chemical components in percentage by mass: 0.25-0.30% of C; si is equal to 0.10% to 0.30%; mn is equal to 0.80%-1.20%; less than or equal to 0.015% of P; less than or equal to 0.015% of S; the content of Cr is 0.80%-1.20%; ni < = 0.40%; al is equal to 0.030% to 0.050%; b is equal to 0.0006 percent to 0.0020 percent; ti is equal to 0.015 to 0.025 percent; v is equal to 0.010 percent to 0.050 percent; n is less than or equal to 0.0040%, and the balance is Fe and inevitable impurities. Mn is replaced by Cr, so that the hardenability, strength and toughness are guaranteed, and meanwhile, the corrosion resistance of the steel is improved; the hardenability is improved by adding B, the nitrogen is fixed by adding Ti, the effect of B is ensured, grains are refined by adding Nb, and the toughness of the anchor chain steel is improved. Through coordination and optimization of a refining process, the purity of molten steel is improved, a continuous casting process is reasonably designed, segregation of a continuous casting billet is controlled, and performance fluctuation caused by segregation is eliminated; and the toughness of the steel is improved through two quenching processes.

The invention discloses a rolling manufacturing method of low-decarburization medium-chromium round steel for a caterpillar track link and a product of the rolling manufacturing method, and belongs to the technical field of alloy steel rolling. The method comprises the following steps: smelting molten steel, wherein the molten steel comprises the following components in percentage by mass: 0.28-0.34% of C, 0.15-0.35% of Si, 0.50-0.85% of Mn, less than or equal to 0.030% of P, less than or equal to 0.030% of S, 0.80-1.10% of Cr, less than or equal to 0.30% of Ni, 0.10-0.30% of Mo, less than or equal to 0.30% of Cu, 0.010-0.060% of Al and the balance of Fe and impurities; lF refining, RH vacuum degassing (the time is longer than or equal to 20 min, and the hydrogen content is smaller than or equal to 1.5 ppm), electromagnetic stirring continuous casting (the superheat degree is 15-25 DEG C), slow cooling (longer than or equal to 12 h), segmented heating (the total time is shorter than or equal to 200 min, and the residual oxygen content is lt, 3%), multi-stage high-pressure water descaling (the pressure before finish rolling is 30-35 MPa) and hot continuous rolling (the compression ratio is larger than or equal to 6) are conducted. The total decarburized layer depth of the obtained round steel is smaller than or equal to 0.30 mm, and the round steel has high hardenability, excellent mechanical property and low surface defect rate and is suitable for heavy-load components such as a hydraulic excavator caterpillar track link.

The invention relates to 1500MPa-grade corrosion-resistant stainless steel for hot stamping forming of automobile parts. The steel comprises the following chemical components in percentage by weight: 0.05%-0.20% of C, 0.05%-0.50% of Si, 0.50%-2.00% of Mn, less than or equal to 0.020% of P, less than or equal to 0.010% of S, 12.0%-15.0% of Cr, 0.05%-0.15% of V, 0.02%-0.10% of Nb, less than or equal to 1.00% of Ni, less than or equal to 0.30% of Cu, less than 0.05% of Al, 0.01%-0.10% of N and the balance of Fe and inevitable impurity elements. According to the hot stamping stainless steel for the automobile structural parts and the welding parts, the tensile strength reaches 1500 MPa or above, the pitting potential is larger than or equal to 0.05 VSCE, and good corrosion resistance is achieved. The novel stainless steel has the advantages of being low in cost, free of plating, environmentally friendly, ultrahigh in strength, good in corrosion resistance, high in hardenability and the like, and can be suitable for industrial large-scale production of rolled hot-rolled plates or cold-rolled plates, and the hot stamping forming technology completely meets the requirements of a current hot forming production line.

The invention relates to a medium-high carbon steel reverse component design method and system based on a conditional generative network. The method comprises the following steps: converting a steel design index into a hardenability curve; inputting the hardenability curve and a preset random latent code into a trained and checked generator; the generator reversely generates steel components and grain size based on the hardenability curve; and the generated grain size and components are adjusted based on the component adjusting module so as to meet the smelting requirement. By adopting the method, a hardenability GAN algorithm can be taken as a core, database input and real hardenability curve input are increased, and a CGAN-based hardenability model is constructed. The model can learn a hardenability data probability distribution dependent on the alloy composition and grain size, and samples extracted from the multi-dimensional distribution will represent the alloy composition and grain size with predictable attributes.

The invention relates to the field of materials and processes for automobile parts, in particular to a homogenization evaluation method for hardenability of Ti-containing carburizing steel and application. According to different specifications and different looseness and segregation levels of the round steel, sampling regulation is carried out on the center part and the center part of the section of the Ti-containing carburizing steel round steel, and the hardenability and the hardenability bandwidth of the carburizing steel can be more truly reflected. When the hardness of the tail end hardenability sample is detected, two surfaces equidistant from the circle center of the section of the round steel are detected, a telecentric surface far away from the circle center of the section of the round steel and a proximal surface close to the circle center of the section of the round steel are detected, and compared with the current national standard, the detection result is more scientific and accurate. The method can be applied to almost all carburized steel bars with large component fluctuation, the uniformity is truly reflected, technicians can select raw materials with proper hardenability bandwidth to be applied to shaft gear parts with different size characteristics and using performance requirements, and the application prospect is very wide.

The present invention provides a Q690D steel plate with high and low temperature impact toughness and a production method thereof. The Q690D steel plate with high and low temperature impact toughness is designed with low-C steel, and Nb, V, and Ti elements are added to improve the strength of the steel plate; Cr and Mo elements improve hardenability, and P, S, N, and impurity elements are strictly controlled. The production method of the Q690D steel plate with high and low temperature impact toughness includes the following technological steps: hot metal pretreatment, converter steelmaking, post-furnace argon blowing, LF steel refining treatment, RH steel refining treatment, slab continuous casting, slab heating, descaling, rough rolling, finish rolling, preliminary straightening, ultra-fast cooling process, straightening, cooling bed, tempering, sampling, steel plate inspection, marking and warehousing. The Q690D steel plate produced by the present invention has high strength, excellent comprehensive properties such as plasticity, toughness, bending, and welding, and meets the use requirements of users.

The invention belongs to the technical field of metallurgy, and particularly relates to steel for grinding balls with low cost and good wear resistance and a production method of the steel, and the steel comprises the following chemical components in percentage by weight: 0.72%-0.80% of C, 0.70%-0.80% of Mn, 0.70%-0.95% of Si, 0.70%-0.90% of Cr, less than or equal to 0.025% of S, less than or equal to 0.030% of P, 0.025%-0.040% of Alt and the balance of Fe and inevitable impurities. According to the method, the influence of carbon and all alloy elements on hardenability, hardenability, thermal conductivity, heat resistance and linear expansion coefficient is comprehensively considered, and through low-cost alloy design and process design, the flaw detection qualification rate of base metal round steel is increased, meanwhile, the surface hardness and the average volume hardness of the grinding balls are increased, hollow grinding balls are reduced, the wear resistance of the grinding balls is improved, and the cost is reduced.

The invention discloses a preparation method of a novel low-alloy steel solid welding wire. The preparation method comprises the following steps of S1, raw material smelting, S2, a hot working stage, S3, a cold working stage, S4, surface treatment and S5, quality detection. During raw material selection, C-Mn-Si is adopted as a basic alloy, the content of C is 0.06-0.12%, the content of Mn is 1.2-1.6%, then a Ti-B microalloy is added, the hardenability is improved, the O / N content is limited at the same time, then a two-stage refining process combining vacuum induction melting and electroslag remelting is adopted, the melting temperature, time and refining slag system components are regulated and controlled, and the hardness of the alloy is improved. The method comprises the following steps: preparing a copper plating solution through equipment, deeply removing harmful impurities such as S and P, promoting floating and size refinement of inclusions by applying an electromagnetic stirring technology, remarkably improving the purity of a metal matrix, thereby improving the purity of raw material smelting, proportioning the copper plating solution through the equipment, setting the parameters of the copper plating equipment to be 10-15A / dm in current density and 2-3mu m in plating thickness, and carrying out a copper plating process on a welding wire.

Provided is a steel sheet that has excellent quenching properties and cold-working properties. This steel sheet comprises, by mass%, 0.50%–0.90% of C, 0.01%–0.50% of Si, 0.20%–1.30% of Mn, no more than 0.100% of P, no more than 0.100% of S, no more than 0.100% of Al, 0.01%–1.20% of Cr, and no more than 0.0150% of N, the remainder being Fe and impurities. The total area ratio of ferrite and cementite particles is at least 95%, the average particle diameter of the ferrite is 5.0–20.0 μm, the Cr concentration [Cr]θ in the cementite particles is less than 2.00%, the Mo concentration [Mo]θ in the cementite particles is no more than 1.00%, the average particle diameter of the cementite particles is no more than 1.50 μm, and the spheroidization rate of the cementite particles is at least 85%.

Provided is a steel sheet that has excellent quenching properties and cold-working properties. This steel sheet comprises, by mass%, 0.50%–0.90% of C, 0.01%–0.50% of Si, 0.20%–1.30% of Mn, no more than 0.100% of P, no more than 0.100% of S, no more than 0.100% of Al, 0.01%–1.20% of Cr, and no more than 0.0150% of N, the remainder being Fe and impurities. The total area ratio of ferrite and cementite particles is at least 95%, the average particle diameter of the ferrite is 5.0–20.0 μm, the Cr concentration [Cr]θ in the cementite particles is less than 2.00%, the Mo concentration [Mo]θ in the cementite particles is no more than 1.00%, the average particle diameter of the cementite particles is no more than 1.50 μm, and the spheroidization rate of the cementite particles is 75% or more but less than 85%.

The invention discloses a cold-crack-resistant welding wire for thick-specification ultrahigh-strength steel and a welding method of the cold-crack-resistant welding wire, and belongs to the technical field of welding, a low-cost alloy system with Mn as a leading part and Cr as an auxiliary part is constructed, Mn is used for reducing the Ms point, the hardenability of Cr is improved, and the Ms point of weld metal is regulated and controlled to be in a low-temperature phase change interval of 100-150 DEG C; in the welding process, the inter-pass temperature is controlled to be higher than the Ms point all the time, all layers of welding beads are kept in the austenite state in the filling process, all the welding beads are uniformly cooled, low-temperature martensite phase transformation is synchronously generated, the situation that phase transformation of the welding beads which are firstly welded too early occurs, and consequently pressure stress relaxation is caused is avoided, and part of retained austenite is reserved is avoided. By means of the characteristics of a medium Mn alloy system, the common cold crack risk in thick plate high-restraint welding is effectively avoided, it is ensured that weld metal has the ultrahigh strength, meanwhile, the alloy cost is remarkably reduced, and therefore the technical bottleneck of thick ultrahigh-strength steel in the low-cost and efficient welding application aspect is broken through.