1593 results about "Austenite" 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 relates to a hot-rolled wire rod for a 2230 MPa grade stranded wire and a manufacturing method of the hot-rolled wire rod, after a Cr-Nb-Al high-carbon component design is rolled and spun into a wire rod, the wire rod is subjected to online molten salt isothermal toughening treatment, so that the wire rod is firstly subjected to front-section molten salt treatment and enters a sorbite phase region from an austenite state to form a structure taking a sorbite structure as a main structure; and then carrying out rear-section molten salt treatment, reducing the circulation volume of molten salt, promoting the unconverted retained austenite to be continuously converted into sorbite, carrying out isothermal tempering, promoting fusing of a part of sorbite lamellar layers, and finally carrying out slow cooling through a roller way, so as to prepare the hot-rolled wire rod of which the microscopic structure comprises a mixed structure consisting of tempered sorbite, ferrite and fused sorbite, the material cost can be controlled, the tensile strength is 1513-1563 MPa, the percentage reduction of area is 31%-36%, and the structure uniformity and the production efficiency are both considered, so that off-line heat treatment is avoided during stranded wire manufacturing, and the drawing pass and the cracking risk are reduced.

The invention relates to a hot-rolled wire rod for a 2060MPa-grade stranded wire and a manufacturing method of the hot-rolled wire rod. Mn-Cr high-carbon chemical component design and rolling spinning are performed to form a wire rod, then online molten salt isothermal phase change treatment is performed, the wire rod is firstly subjected to front-section molten salt treatment and enters a sorbite phase region from an austenite state to form a structure taking a sorbite structure as a main structure, and then the wire rod is subjected to rear-section molten salt treatment, so that the hot-rolled wire rod is obtained. The method comprises the following steps of: firstly, carrying out heat treatment on the residual austenite, promoting the unconverted residual austenite to be converted into a sorbite structure, simultaneously promoting isothermal tempering of the structure and fusing of a part of sorbite lamellas, and finally, slowly cooling through a roller way to prepare a hot-rolled wire rod of which a microscopic structure comprises a mixed structure consisting of tempered sorbite, tempered ferrite and fused sorbite, so that the material cost can be controlled; the high-strength and high-plasticity performance matching of the wire rod is improved, the tensile strength is 1370-1420 MPa, the percentage reduction of area is 35%-40%, and the mechanical property fluctuation is reduced, so that the wire breaking risk in stranded wire production is reduced, and efficient and stable production is promoted.

The invention relates to a hot-rolled wire rod for a 2260MPa-grade stranded wire and a manufacturing method of the hot-rolled wire rod, after the high-carbon component design of C-Si-Mn-Cr-Mo-Nb-Al is adopted for rolling and spinning to form the wire rod, online molten salt isothermal toughening treatment is carried out, so that the wire rod is firstly subjected to front-section molten salt treatment and is rapidly cooled, and enters a sorbite phase region from an austenite state to form a structure taking a sorbite structure as a main structure; and then carrying out rear-section molten salt treatment, reducing the circulation volume of molten salt, promoting the unconverted retained austenite to be continuously converted into sorbite, carrying out isothermal tempering, promoting fusing of a part of sorbite lamellar layers, and finally carrying out slow cooling through a roller way, so as to prepare the hot-rolled wire rod of which the microscopic structure comprises a mixed structure consisting of tempered sorbite, ferrite and fused sorbite, the tensile strength can reach 1534-1584 MPa, the percentage reduction of area can reach 33%-38%, and the alloy can be used in the application fields of manufacturing 2260 MPa grade stranded wires and the like without additional heat treatment procedures.

The invention relates to a hot-rolled wire rod for a 2100MPa-grade stranded wire and a manufacturing method thereof, after a high-carbon and high-silicon component system is rolled and spun into a wire rod, the wire rod is cooled at a cooling speed of more than or equal to 31 DEG C / s through online molten salt sorbite regulation and control treatment, and enters a sorbite phase region from an austenite state; the method comprises the following steps of: forming a structure mainly comprising a sorbite structure, performing isothermal tempering, promoting fusing of a part of sorbite lamellas, and finally performing roller way cover opening and slow cooling to prepare the hot-rolled wire rod of which the microscopic structure comprises a mixed structure consisting of tempered sorbite, tempered ferrite and fused sorbite, so that alloy components can be simplified, and the strong plasticity matching and the structure uniformity of the wire rod can be improved; the tensile strength is 1420-1470 MPa, the percentage reduction of area is 36%-41%, the composite material is used for the application field of manufacturing 2100 MPa grade stranded wires and the like, off-line heat treatment can be avoided, and the risk of wire breakage during downstream drawing and twisting is reduced.

The invention relates to a hot-rolled wire rod for a 2200MPa-grade stranded wire and a manufacturing method of the hot-rolled wire rod, after Nb-Al high-carbon component is rolled and spun into a wire rod, the wire rod is subjected to online molten salt strong isothermal treatment, so that the wire rod is firstly subjected to front-section molten salt treatment and enters a sorbite phase region from an austenite state to form a structure taking a sorbite structure as a main structure, and then is subjected to rear-section molten salt treatment to form the hot-rolled wire rod for the 2200MPa-grade stranded wire. The molten salt temperature is increased, the molten salt circulation amount is reduced, unconverted retained austenite is promoted to be continuously converted into sorbite, isothermal tempering is carried out, part of sorbite lamellas are promoted to be fused, and finally slow cooling is carried out through a roller way, so that the hot-rolled wire rod with the microscopic structure comprising a mixed structure composed of tempered sorbite, ferrite and fused sorbite is prepared. According to the method, abnormal structures can be inhibited, the strength of a hot-rolled wire rod can be improved, plasticity and production efficiency are both considered, the tensile strength is 1490-1540 MPa, the percentage reduction of area is 34%-39%, downstream users can avoid off-line heat treatment, and stable production of stranded wires is promoted.

The invention relates to a hot-rolled wire rod for a 1960MPa-grade stranded wire and a manufacturing method of the hot-rolled wire rod, after high-carbon components of C-Si-Mn-Cr-B are rolled and spun into a wire rod, the wire rod is subjected to rapid online molten salt isothermal treatment, and the wire rod is subjected to front-section molten salt treatment, so that the wire rod is cooled at the cooling speed of more than or equal to 32 DEG C / s and enters a sorbite phase region from an austenite state; the steel wire rod is subjected to rear-section molten salt treatment, the molten salt temperature is reduced, unconverted retained austenite is promoted to be converted into the sorbite structure, meanwhile, isothermal tempering of the structure and fusing of a part of sorbite lamellas are promoted, and finally slow cooling is conducted through a roller way; the microstructure of the hot-rolled wire rod comprises a mixed structure composed of tempered sorbite, ferrite and fused sorbite, the tensile strength is 1305-1355 MPa, the percentage reduction of area is 37%-42%, and the hot-rolled wire rod is used for being used as base metal to manufacture high-strength stranded wires and other application fields and is beneficial to reducing the risk of wire breakage.

The invention relates to the field of additive manufacturing, and discloses a dynamic phase change control additive ultrahigh-strength steel strengthening and toughening process which comprises the following steps: S1, constructing a phase change structure design target which comprises retained austenite distribution, a structure space structure and mechanical property requirements; s2, based on the phase change structure design target, establishing a free energy model taking a phase field variable as a core for representing a phase change driving behavior between austenite and martensite; s3, on the basis of the free energy model, constructing a multi-field partial differential control model coupling phase field evolution, element diffusion and heat conduction; and S4, in combination with the multi-field partial differential control model, determining an interface adsorption parameter, a diffusion coefficient and a thermophysical parameter based on experimental characterization data. According to the method, path parameters are optimized through a multi-field partial differential control model and tissue deviation feedback, and accurate control of the phase change tissue and dynamic closed-loop adjustment of the machining process are achieved.

The invention belongs to the field of metal materials, and provides a hard alloy wear-resistant steel ball suitable for mine ore grinding and a preparation method thereof.The hard alloy wear-resistant steel ball is prepared from waste steel pig iron as a basic raw material and chemical components including 2.1%-2.2% of C, 9.8%-10.0% of Cr, 0.10%-0.20% of V and 0.03%-0.06% of Ti; a core-shell precipitated phase microstructure design with MN / MCN as a hard core and chromium carbonitride as a gradient self-passivation shell layer is formed through medium-frequency induction furnace smelting, controlled nitrogen introduction establishment of a V-Ti-C-N microalloy system, bottom pouring solidification and austenitizing quenching and tempering heat treatment processes, and the performance indexes that the surface hardness is HRC60-63 and the core hardness is HRC54-58 are achieved; the average particle size of a core-shell precipitated phase is in dispersed distribution of 20-200nm, the shell thickness is 5-50nm, and the alloy steel ball has excellent wear resistance and corrosion resistance under the high-impact and high-wear working conditions of wet ore grinding, solves the problem of insufficient wear resistance and corrosion resistance of a traditional alloy steel ball, and has wide mine ore grinding application value.

The invention belongs to the technical field of metal composite materials and hydrogen storage and transportation materials, and particularly relates to a high-strength hydrogen-embrittlement-resistant layered metal composite material for hydrogen storage and a preparation method and application of the high-strength hydrogen-embrittlement-resistant layered metal composite material. According to the preparation method, the nickel-saving austenitic stainless steel (NEASS) and the 30CrMo steel are alternately overlapped in a multi-layer mode, and the processes of vacuum electron beam welding, high-temperature hot rolling, accumulative ply rolling, multi-stage heat treatment and the like are combined, so that the composite board with the layer number reaching hundreds of layers, firm interface bonding, excellent mechanical performance and good hydrogen embrittlement resistance is prepared; the technical problem that strength, toughness and hydrogen brittleness resistance of an existing metal material in a high-pressure hydrogen environment are difficult to consider at the same time is solved. The obtained composite material has high strength, high plasticity and excellent hydrogen embrittlement resistance, and is suitable for structural materials of high-pressure hydrogen storage tanks, hydrogen conveying pipelines and other key hydrogen energy equipment.

The present application relates to the field of additive manufacturing, and discloses a simulation method for determining a laser powder bed fusion printing process for single-crystal austenitic stainless steel. The simulation method comprises the following steps: S1, establishing a three-dimensional polycrystalline powder bed microstructure model; S2, establishing a three-dimensional temperature field prediction model on the basis of a finite element method; S3, establishing a three-dimensional polycrystalline microstructure evolution model by using a phase-field method; and, S4, coupling the models from steps S1, S2 and S3, and simulating a multi-layer, multi-pass laser powder bed fusion process by using different process parameters, so as to determine appropriate single-crystal process parameters. The present invention replaces conventional trial-and-error experimental methods with numerical simulation methods to determine single-crystal process parameters, thereby greatly reducing the time and economic costs of process exploration, and assisting experiments in revealing the microstructure evolution mechanism of single crystal preparation via laser powder bed fusion additive manufacturing.

The invention relates to the technical field of medium manganese steel, in particular to high-strength and high-toughness medium manganese steel and a preparation method thereof.The preparation method is characterized by comprising the steps that S1, smelting is conducted through an electric furnace according to the chemical component ratio of the medium manganese steel, then refining is conducted through a ladle refining furnace, then vacuum degassing treatment is conducted through a vacuum circulation degassing method, and then continuous casting is conducted to form a plate blank with the thickness being 200-300 mm; s2, the plate blank is heated to 1150-1250 DEG C in a walking beam furnace, heat preservation is conducted for 2-4 hours, and then a controlled rolling technology is adopted to machine the plate blank into a steel plate within the range of 4-20 mm; s3, after rolling is completed, the steel plate is treated through a composite cooling technology of ultra-fast cooling and laminar cooling; s4, the cooled steel plate is heated to 750-850 DEG C, heat preservation is conducted for 10-60 minutes, and a ferrite and austenite double-phase structure is formed; the comprehensive performance is greatly improved, and excellent strength, plasticity, low-temperature toughness and welding adaptability are shown.

The invention discloses a hydrogen embrittlement-resistant welding wire for tailor welding of ultrahigh-strength aluminum-silicon coating hot-formed steel and a welding method, and belongs to the technical field of metal materials. 5.0%-7.0% of Ni; 0.3%-0.6% of Mo; 0.08% to 0.12% of Nb; mo, Nb and C react to form Mo2C / NbC nanophase fixed free hydrogen; 0.05%-0.1% of V: carrying out a reaction to form VC nanophase fixed free hydrogen; 0.5% to 0.8% of La; 0.3%-0.5% of Ce; 0.1%-0.5% of Ti; according to the invention, hydrogen atoms diffused in the welding process can be captured, the hydrogen content in a welding seam is obviously reduced, and the diffusible hydrogen amount is reduced by more than 40% under the hydrogen capturing effect of retained austenite, so that the hydrogen-induced crack sensitivity is reduced by 70%.

The invention relates to a hot-rolled wire rod for a 2160MPa-grade stranded wire and a manufacturing method of the hot-rolled wire rod, after a high-carbon component system containing trace Nb is rolled and spun into a wire rod, the wire rod is subjected to online molten salt sorbite regulation and control treatment, so that the wire rod is firstly subjected to front-section molten salt treatment and quickly enters a sorbite phase region from an austenite state to form a structure taking a sorbite structure as a main structure; the method comprises the following steps: firstly, carrying out hot rolling on unconverted retained austenite, then carrying out rear-section molten salt treatment, increasing the molten salt temperature, reducing the molten salt circulation amount, promoting the unconverted retained austenite to be continuously converted into sorbite, carrying out isothermal tempering, and finally, carrying out roller way slow cooling to prepare a hot-rolled wire rod of which the microscopic structure comprises a mixed structure consisting of tempered sorbite, ferrite and fused sorbite, so that the deterioration of the structure can be inhibited, and the service life of the hot-rolled wire rod is prolonged. The tensile strength of the hot-rolled wire rod is 1461-1496 MPa, the percentage reduction of area is 33%-38%, the difference of the same circle of mechanical properties is smaller than or equal to 42 MPa, meanwhile, the production energy consumption is reduced, and efficient and stable production of the hot-rolled wire rod and the stranded wire is facilitated.

The invention provides corrosion-fatigue-resistant ultrahigh-strength maritime work steel and a preparation method thereof, and relates to the technical field of maritime work steel manufacturing. The maritime work steel comprises the following components in percentage by mass: 0.04 to 0.07 percent of C, 0.20 to 0.26 percent of Si, 1.45 to 1.60 percent of Mn, less than or equal to 0.01 percent of P, less than or equal to 0.015 percent of S, 1.44 to 1.52 percent of Cr, 1.44 to 1.52 percent of Ni, 0.88 to 0.96 percent of Cu, 0.08 to 0.12 percent of Nb, 0.08 to 0.12 percent of Sb and the balance of Fe and inevitable impurities. The corrosion-fatigue-resistant ultrahigh-strength maritime work steel is prepared through raw material smelting and casting, austenitizing heat treatment, multi-pass hot rolling and cooling and temperature control. The corrosion resistance, the fatigue resistance and the corrosion fatigue resistance of the ultrahigh-strength maritime work steel are remarkably improved while the mechanical property of the ultrahigh-strength maritime work steel is improved, and the ultrahigh-strength maritime work steel has great significance in guaranteeing safe and stable operation of ocean engineering.

The application discloses a super-soft austenitic stainless steel and a preparation method thereof. The super-soft austenitic stainless steel is composed of carbon C, nitrogen N, silicon Si, manganese Mn, chromium Cr, nickel Ni, copper Cu and iron Fe. The mass percentage of each component in the super-soft austenitic stainless steel is as follows: C: 0.005%-0.02%, N: 0.05%-0.2%, Si: 0.01%-0.1%, Mn: 1.5%-6.5%, Cr: 15.5%-19.6%, Ni: 7.5%-13.5%, Cu: 1.8%-5.3%, and the balance is iron. The super-soft austenitic stainless steel has the characteristics of low tensile strength and hardness, low strain-induced martensite in the bending process, low crack initiation rate and low failure fracture.

This invention provides a high-strength, high-ductility austenitic stainless steel and its production method. The composition is: C 0.045%-0.085%, N 0.10%-0.40%, Si 0.90%-1.55%, Cr 16%-20.1%, Ni 7.5%-12.5%, Mn 1.5%-3.5%, Mo 1.5%-3.0%, Nb 0.08%-0.22%, Ti 0.015-0.065%, O≤0.005%, P≤0.003%, S≤0.003%, with the remainder being Fe and unavoidable impurities. Compared with existing technologies, this invention obtains a reasonable grain size and second-phase particles through nitrogen, titanium, and niobium alloying, combined with low-temperature rolling and appropriate annealing and aging heat treatment, thus developing an austenitic stainless steel with excellent mechanical properties. It achieves excellent ductility at a high strength level, with a strength-ductility product as high as 60 GPa·s.

An austenitic Fe—Ni—Cr alloy has superior oxidation resistance even under extreme high temperatures and includes, in mass %: C: 0.004 to 0.13%, Si: 0.15 to 1.0%, Mn: 0.03 to 2.0%, P:≤0.040%, S:≤0.003%, Ni: 20.0 to 38.0%, Cr: 18.0 to 28.0%, Mo:≤1.0%, Cu:≤1.0%, N:≤0.03%, B:≤0.01%, Al: 0.10 to 1.0%, at least one of Ti: 0.10 to 1.0% and Zr: 0.01 to 0.6%, O: 0.0002 to 0.0030%, Ca:<0.002%, total weight of one or more from La, Ce, and Y: 0.001 to 0.010%, Fe as a remainder and inevitable impurities, and wherein the chemical composition satisfies formulae (1) and (2): 85≥0.3×Si+1.5×Ni+1.3×Cr+5.8×Al+7.7×Zr +2.7×Ti+2173×REM −3582×S ×32.9×Mo -2448×B≥47 . . . (1) 40≥0.6×Si+1.3×Cr +23.53×Al+5.88×Ti+3074×REM −5067×S −0.8×Mn −816×N≥. . . (2), and each element symbols indicates content of each element.

The invention relates to the technical field of stainless steel production and manufacturing, and discloses a high-strength corrosion-resistant duplex stainless steel shaft forging method which comprises the steps of blank preparation, homogenization treatment, preheating treatment, multidirectional forging, interrupted cooling, solution treatment, aging treatment and surface finish machining. Uniformity of components in the blank and consistency of temperature distribution are guaranteed, a uniform microstructure basis is provided for subsequent forging, meanwhile, grains are refined through large deformation and multi-pass deformation in multi-directional forging, the strength and toughness of the shaft are improved, brittle phase formation is avoided, and the mechanical property is optimized; by interrupting cooling and solution treatment, controlling the cooling rate and heating parameters in real time, inhibiting harmful phase precipitation and optimizing the austenite-ferrite phase proportion, the shaft has high corrosion resistance, and by means of aging treatment, through a stable structure, the long-term durability of the shaft in a severe environment is guaranteed, and the corrosion weight loss and pitting corrosion risk are reduced.

The application relates to the technical field of austenitic stainless steel, in particular to high-strength and high-toughness austenitic stainless steel with large expansion and a preparation method thereof, alloy components of which are as follows in percentage by weight: C: 0.45-0.65 wt.%, Mn: 6.0-9.0 wt.%, Ni: 6.5-10.0 wt.%, Cr: 8.0-12.0 wt.%, Mo: 1.5-3.0 wt.%, V: 0.8-2.0 wt.%, Cu: 1.5-4.0 wt.%, Nb: 0.015-0.045 wt.% and Ti: 0.035-0.100 wt.%, and the balance is Fe. The thermal expansion coefficient of the obtained steel is superior to that of the prior art, the yield strength is greater than 950 MPa, the elongation after fracture is greater than 15%, no sensitization characteristics caused by grain boundary Cr carbide are generated, the steel is composed of pure FCC austenite with stable thermal mechanical properties, and no martensite and deformed austenite or austenite with high dislocation density appears.

Provided are a gas-shielded metal arc welded joint of high-Mn steel, which is simple, has high strength and excellent extremely low-temperature toughness, and a method for producing the same. A gas-shielded metal arc-welded joint in which a welding metal is formed from a steel material of a high-Mn-content austenitic steel containing, in mass%, 18.0-30.0% of Mn using a shielding gas and a solid welding wire, the welding metal having a chemical composition containing, in mass%, 0.15-0.80% of C, 0.10-1.00% of Si, 17.0-30.0% of Mn, 0.030% or less of P, 0.030% or less of S, 0.001-0.100% of Al, 0.4-5.5% of Cr, 0.01-3.50% of Mo, 0.01-10.00% of Ni, and 0.0200-0.1500% of N, with the remainder being Fe and unavoidable impurities. Methods of making a gas shielded metal arc welded joint by incorporating a given concentration of nitrogen in a shielding gas, or increasing the N content of a solid wire.

The invention discloses a secondary aging heat treatment method for maraging stainless steel, and belongs to the technical field of stainless steel production. The secondary aging heat treatment method for the maraging stainless steel comprises the following steps that S130 maraging stainless steel is heated to the temperature 5-55 DEG C higher than the austenite transformation temperature for solution treatment, then cooling is conducted, and an intermediate A is obtained; heating the intermediate A to 35-125 DEG C below the dissolution temperature of a precipitated phase, carrying out first aging treatment, and then cooling to obtain an intermediate B; and the intermediate B is heated to 125-175 DEG C below the dissolved temperature of the precipitated phase for secondary aging treatment, then cooling is conducted, and the modified S130 martensitic stainless steel is obtained. The invention aims to solve the problem of toughness and plasticity loss caused by a solid solution and aging process of the traditional S130 maraging stainless steel through modification in the aspect of a heat treatment process, and meanwhile, the yield strength and the tensile strength are improved as much as possible.

The invention discloses a heat-treatment-free control method for inhibiting hydrogen-induced cracks in ultrahigh-strength steel welding, which belongs to the technical field of welding, and enables weld metal to obtain a low-phase-transition-temperature characteristic and a double-phase structure containing retained austenite under a specific dilution rate window by cooperatively regulating and controlling components of a welding material and welding process parameters. Therefore, preheating-free and post-heat-treatment-free efficient welding of the ultrahigh-strength steel is achieved. According to the method, the volume expansion effect generated by low-temperature martensite phase transformation of weld metal is utilized to actively counteract restrained tensile stress formed by welding cooling shrinkage; on the other hand, the effect of the retained austenite serving as an efficient'hydrogen trap 'is fully played, migration and enrichment of hydrogen to crack sensitive areas such as a heat affected zone or a fusion line are effectively blocked, and finally effective inhibition of hydrogen-induced cracks in ultrahigh-strength steel welding is achieved; the obtained welding joint is free of hydrogen-induced cracks and has the mechanical property level well matched with base metal.

The invention belongs to the technical field of stainless steel, and discloses 4.2 K steel for a nuclear fusion superconducting armor structure with the yield strength of 1500 MPa and a manufacturing method of the 4.2 K steel. The steel comprises the following chemical components: 0.01-0.04% of C, 0.25-0.45% of Si, 5.00-8.00% of Mn, 21-22.5% of Cr, 10-13% of Ni, 2-3% of Mo, 0.35-0.40% of N, 0.10-0.30% of V, 0.05-0.15% of Nb, 0.15-0.25% of Cu, less than or equal to 0.002% of S and less than or equal to 0.02% of P. The top temperature before electroslag billet cogging and upsetting is 1180-1220 DEG C, and the top temperature during drawing is 900-940 DEG C; the top temperature after cogging is 1180-1220 DEG C, the total deformation rate of rough rolling is less than or equal to 60%, the initial rolling temperature of finish rolling is 910-930 DEG C, the total deformation rate of finish rolling is less than or equal to 50%, cooling is performed after rolling, and the re-redness is less than or equal to 400 DEG And the solid solution temperature is 1140-1160 DEG C, and the quenching cooling speed after solid solution is 39.5-40.5 DEG C / s. The yield strength of the 4.2 K steel plate is larger than or equal to 1500 MPa, the ductility is larger than or equal to 30%, the fracture toughness is larger than or equal to 180 MPa.m < 1 / 2 >, and the problems of air holes and edge cracks of high-nitrogen austenitic stainless steel are solved.

The manufacturing method comprises the following steps: rolling and spinning high-carbon and high-silicon components of Nb-Mo to form a wire rod, and then carrying out online molten salt strong isothermal toughening treatment, so that the wire rod is firstly subjected to front-section molten salt treatment and is rapidly cooled, and enters a sorbite phase region from an austenite state to form a structure taking a sorbite structure as a main structure; and then carrying out rear-section molten salt treatment, reducing the circulation volume of molten salt, promoting the unconverted retained austenite to be continuously converted into sorbite, carrying out isothermal tempering, promoting fusing of a part of sorbite lamellar layers, and finally carrying out slow cooling through a roller way, so as to prepare the hot-rolled wire rod of which the microscopic structure comprises a mixed structure consisting of tempered sorbite, ferrite and fused sorbite, according to the invention, abnormal tissues can be inhibited, the tensile strength is 1566-1616 MPa, the percentage reduction of area is 33%-38%, and the production efficiency is considered, so that the ultrahigh-strength stranded wire can be produced without off-line heat treatment, and the risk of wire breakage is reduced.

The invention provides low-cost low-alloy steel with the fracture toughness higher than 140 MPa.m < 1 / 2 > and the product of strength and elongation higher than 50 GPa% and a manufacturing method. The microstructure of the steel is as follows: 78-88% of martensite matrix, 10-20% of retained austenite, 1-3% of transition carbide and less than 1% of stable nano precipitated carbide. The steel comprises the following element components in percentage by mass: 0.60 to 0.70 percent of C, 1.25 to 1.75 percent of Mn, 1.25 to 1.75 percent of Si, 0.02 to 0.05 percent of Nb + V and the balance of iron. According to the manufacturing process, at least one time of normalizing treatment is carried out, and then a quenching-distribution-tempering (Q-P-T) heat treatment process is carried out. The mechanical property of the low-alloy steel is improved by designing a proper microstructure fraction, optimizing steel components and adjusting a heat treatment process, so that the fracture toughness of the low-alloy steel is higher than 140 MPa.m < 1 / 2 >, and the product of strength and elongation is higher than 50 GPa%.

A cold rolled and double annealed steel sheet, made of a steel having a composition including, by weight percent: C: 0.03-0.18%, Mn: 6.0-11.0%, 0.2≤Al<3%, Mo: 0.05-0.5%, B: 0.0005-0.005%, S≤0.010%, P≤0.020%, N≤0.008%, and including optionally one or more of the following elements. In weight percentage: Si≤1.20%, Nb≤0.050%, Ti≤0.050%, Cr≤0.5%,V≤0.2%, the remainder of the composition being iron and unavoidable impurities resulting from the smelting, the steel sheet having a microstructure including, in surface fraction, from 0% to 45% of ferrite, from 20% to 50% of retained austenite, from 5 to 80% of annealed martensite, less than 5% of fresh martensite, a carbon [C]A and manganese [Mn]A content in austenite, expressed in wt %, such that the ratio ([C]A2×[Mn]A) / (C %2×Mn %) is from 4.5 to 11.0, C % and Mn % being the nominal C and Mn weight percent in the steel and a carbides density below 4×106 / mm2.

The present invention relates to the technical field of hot stamping steel. Disclosed is a soaking-type stamping method and apparatus for hot-formed steel, comprising the following steps: step 1: transporting a prepared blank into a furnace chamber for austenitizing heating, the blank being made of a hot-formed steel material; and step 2: immersing a lower forming punch into a liquid medium within a tank assembly, and placing the heated blank onto a material support frame by means of a loading manipulator, the tank assembly being internally provided with the liquid medium. A soaking-type stamping method is used in the present invention, which, compared to the direct hot-forming method in the prior art, optimizes the structure of a mold, reduces the machining of water channels in hot stamping devices of the prior art, and shortens the processing cycle and reduces costs while broadening the applicable range of materials, solving the issue of oxide scale on uncoated plates and the lime problem of galvanized steel plates, and having low investment costs and being easily controlled for automation.

The application provides a high-strength nano-particle reinforced high-temperature-resistant austenitic stainless steel and a preparation method thereof. The preparation method of the high-strength nano-particle reinforced high-temperature-resistant austenitic stainless steel comprises the following steps: firstly, Ti powder and B4C powder are mixed to obtain mixed powder; then the mixed powder and nickel powder are mixed in four proportions and sequentially placed into a nickel thin tube layer by layer from top to bottom according to a certain mass ratio; laser welding technology is used for welding to obtain a nickel column body with gradient distribution of the mixed powder; nano-particles are introduced into the stainless steel liquid by adding the nickel column body in the melting process of the austenitic stainless steel; and finally, the high-strength nano-particle reinforced high-temperature-resistant austenitic stainless steel is obtained after vacuum casting, high-temperature homogenization and solid solution quenching. The high-strength nano-particle reinforced high-temperature-resistant austenitic stainless steel obtained by the application has a yield strength of greater than or equal to 165 MPa and a tensile strength of greater than or equal to 347 MPa when used at a working temperature of 600 DEG C or above.

This hot-rolled steel sheet has a predetermined chemical composition, in a microstructure at a depth position of 1 / 4 from a surface in a sheet thickness direction, in terms of area %, residual austenite is less than 3.0%, ferrite is 15.0% or more and less than 60.0%, and pearlite is less than 5.0%, an E value is 10.7 or more, an I value is 1.020 or more, a CS value is −8.0×105 to 8.0×105, a standard deviation of Mn concentrations is 0.60 mass % or less, a solute Cr concentration in an outermost layer region is 0.10 mass % or more, a number density of Cr oxides having a sphere equivalent radius of 0.1 μm or more at the surface is 1.0×104 pieces / cm2 or less.