206 results about "Cryogenic treatment" patented technology

The invention discloses a method for refining grains of a titanium alloy. According to the method, an original low-oxygen-content titanium alloy plate is subjected to cryogenic pretreatment, the temperature of the core of the original low-oxygen-content titanium alloy plate is reduced to a certain temperature, then the cryogenic low-oxygen-content titanium alloy plate is fed into a rolling mill, the single-pass reduction rate is controlled, cryogenic rolling is completed, high refinement and uniform distribution of crystal grains are achieved, and the low-oxygen-content titanium alloy plate is obtained. And the rolled titanium alloy plate is subjected to subzero treatment again, and the titanium alloy plate of the complex twin crystal structure formed by intersection of {11-22} and {10-11} twin crystals is obtained. The method has the beneficial effects that under the synergistic effect of low oxygen and deep cooling, even under the extremely small deformation amount, the cross effect of various twin crystal systems can be efficiently activated, a high-density and complex twin crystal structure is formed, high refinement and uniform distribution of crystal grains are achieved, then the mechanical strength and low-temperature toughness of the material are remarkably improved, and the service life of the material is prolonged. And the application requirements in a severe low-temperature service environment are met.

The invention discloses an ejector pin anti-fatigue strengthening method based on multi-section variable-temperature treatment, and relates to the technical field of ejector pin anti-fatigue strengthening, and the ejector pin anti-fatigue strengthening method comprises the following steps: austenitizing high-temperature quenching: heating an ejector pin to an austenitizing temperature, and then carrying out zoned cooling on the ejector pin; medium-temperature tempering and thermal-state mechanical strengthening are conducted, specifically, the ejector pin is tempered at the medium-temperature tempering temperature, and thermal-state shot blasting or laser shock is conducted on the ejector pin in the heat preservation period or after heat preservation is completed; intermediate low-temperature plasma nitriding: carrying out plasma nitriding in a nitrogen-hydrogen gas environment; subzero treatment: placing the ejector pin in liquid nitrogen; and finally, low-temperature tempering and cold-state mechanical strengthening are conducted. Through multi-section temperature gradient treatment, phase change distribution control over different temperature sections is achieved, too high internal stress and brittleness generated by one-time quenching are avoided, sudden size change and hot cracks induced by phase change are prevented, a controllable surface-core hardness and toughness gradient is formed, the surface crack initiation tendency is reduced, and the surface quality is improved. And the consistency and controllability of anti-fatigue basic conditions are improved.

The invention relates to the technical field of metal heat treatment, in particular to a silicon alloy steel bearing ring high-temperature salt bath quenching process for a high-temperature load environment, which comprises the following steps: S1, carrying out surface sand blasting treatment on a silicon alloy steel bearing ring; s2, stepped heating-heat preservation-cooling treatment is carried out, and the uniformly austenitized ferrule is obtained; s3, the uniformly austenitized ferrule is immersed in a composite salt bath; s4, staged cooling treatment of an air cooling stage and an oil cooling stage is conducted in sequence; s5, the martensite matrix ferrule is subjected to subzero treatment and staged heating; and S6, multi-stage tempering treatment with different temperature gradients is conducted, and the final high-temperature bearing ring is obtained. Through the combined process of stepped austenitizing, composite salt bath ultrasonic quenching, graded cooling, deep cooling and multi-stage tempering, homogenization and stabilization of the structure of the bearing ring are achieved, and the dimensional stability and the tempering resistance of the bearing ring in the high-temperature load environment are improved.

The invention discloses high-toughness low-carbon bainite steel and a preparation method and application thereof, and belongs to the technical field of metal heat treatment, and the high-toughness low-carbon bainite steel comprises the following chemical components: 0.2-0.3% of C, 1.50-1.70% of Si, 0.3-0.6% of Al, 0.1-0.3% of Mo, 1.80-2.1% of Mn, 0.75-0.95% of Cr, 0.01-0.03% of Ni and inevitable impurities. The preparation method comprises the following steps that steel is subjected to heat preservation heat treatment and then sequentially subjected to two-stage isothermal quenching heat treatment, two times of subzero treatment and tempering treatment, and the high-toughness low-carbon bainite steel is obtained. According to the preparation method disclosed by the invention, the low-carbon bainite steel is ensured to have good comprehensive mechanical properties on the basis of a preparation process combined with structure regulation and optimization. And in addition, a complex process is avoided, the production efficiency is improved, and rapid and large-batch production of the low-carbon bainite steel is facilitated.

The invention discloses a method for rapidly optimizing components and heat treatment of super martensitic stainless steel, and relates to the technical field of material research methods.The method comprises the steps that firstly, a wide component FCC phase region of a stainless steel system is determined according to a phase diagram calculation result, end component components are determined, and then two end components are obtained through smelting and linear cutting in sequence; and fixing the two end components together, annealing and carrying out subzero treatment to obtain a super martensitic stainless steel diffusion couple, and finally carrying out component gradient analysis and hardness and Young modulus test on the diffusion couple to obtain the corresponding relationship among the components, hardness and Young modulus of the stainless steel under different heat treatments. Therefore, the composition of the high-hardness super martensite and corresponding heat treatment parameters are determined. A large amount of approximately continuous phase composition-component-heat treatment-hardness-Young modulus corresponding experimental data information can be obtained in a short time, and the high-performance martensitic stainless steel and heat treatment parameters thereof can be quickly optimized.

The invention discloses a preparation method of a copper alloy crystallizer, and belongs to the technical field of copper alloy forming machining. According to the method, a copper alloy raw material serves as a basis, a cast ingot is prepared through burdening and vacuum melting casting in sequence, hot forging reaming operation is conducted on the cast ingot to form an alloy pipe blank, then the alloy pipe blank is machined into an intermediate pipe fitting through a spinning procedure, finally, aging treatment and subzero treatment are conducted on the intermediate pipe fitting in a combined mode, and the copper alloy crystallizer is finally prepared. According to the preparation method, the uniformity of alloy components is guaranteed through vacuum melting, precise plastic processing of the crystallizer is achieved by means of hot forging reaming and spinning forming, the alloy structure performance is optimized in cooperation with aging-cryogenic composite heat treatment, and the prepared crystallizer has excellent mechanical performance and service stability and is suitable for industrial large-scale production.

The application belongs to the technical field of mechanical property strengthening of metal materials, and particularly relates to a composite strengthening method for improving the strength and plasticity of metal alloys. The method comprises the following steps: (1) performing surface pretreatment on a metal alloy sample; (2) performing ion implantation processing on the pretreated metal alloy sample; (3) coating a layer of nanoparticles on the surface of the metal alloy sample after ion implantation processing; (4) performing cryogenic treatment on the metal alloy sample with the surface coated with the nanoparticles; (5) performing electric pulse treatment on the metal alloy sample after the cryogenic treatment; and (6) performing cryogenic holding treatment on the metal alloy sample after the electric pulse treatment. The application can effectively improve the strength and plasticity of the metal alloy.

The invention discloses a cryogenic heat treatment method for reducing elastic hysteresis of 40CrNiMo alloy, which comprises the following steps of: (1) quenching the 40CrNiMo alloy at the quenching temperature of 850 DEG C, preserving heat for 1 hour, and cooling to room temperature by adopting a 10% PAG solution; (2) the quenched 40CrNiMo alloy is subjected to tempering treatment, the tempering temperature ranges from 400 DEG C to 600 DEG C, heat preservation is conducted for 3 h, and after heat preservation is completed, air cooling is conducted to the room temperature; and (3) the tempered 40CrNiMo alloy is subjected to subzero treatment, the subzero temperature ranges from-180 DEG C to-196 DEG C, the heat preservation time ranges from 12 h to 24 h, and then the temperature is naturally increased to the room temperature. According to the method, conventional quenching and tempering processes are combined with subzero treatment, so that the elastic lag of the 40CrNiMo alloy steel is effectively reduced.

The application discloses a process method for improving the hardness of 5A06 aluminum magnesium alloy, and comprises the following steps: step 1, cutting processing is performed on the 5A06 aluminum alloy rod to form a plurality of cylindrical short samples; step 2, the sample is subjected to deformation treatment: the sample is compressed once, and the deformation amount is 16%-32%; step 3, the sample subjected to the deformation treatment is directly immersed in liquid nitrogen for cryogenic treatment, is placed in air to be warmed to room temperature, and the hardness of the sample is measured. The application solves the problems that it is difficult to improve the hardness of the aluminum magnesium alloy and difficult to prolong the service life at present, the cryogenic treatment time has a significant influence on the structure of the 5A06 aluminum alloy, the number of Al3Mg2 phases in the structure is obviously increased with the prolonging of the cryogenic treatment time, the hardness of the alloy can be further improved by adopting the process of deformation superposition and cryogenic treatment, so that the wear resistance is improved, and the service life of the alloy is prolonged.

The invention relates to the technical field of metal material surface chemical heat treatment, in particular to W-containing ultrahigh-strength steel, a preparation method thereof and a surface carbon-nitrogen composite strengthening process. The preparation method comprises the following steps of smelting preparation of steel, forging cogging forming, annealing heat treatment after forging of a bar, carburization, subzero treatment and surface pressurization nitriding. The ultrahigh strength steel comprises the following chemical components: 0.27-0.34 wt.% of C; 0.4 to 1.4 wt.% of Cr; 9 to 10 wt.% of Ni; 6 to 8 wt.% of Co; 1.5 to 2.5 wt.% of Mo; 1.1 to 1.6 wt.% of W; and the balance of Fe and impurity elements. The highest hardness of the carbonitriding layer of the W-containing ultrahigh-strength steel is not lower than 900 HV, the tensile strength of the steel is not lower than 2000 MPa, the yield strength is not lower than 1700 MPa, the impact absorption capacity is not lower than 60 J, and the service condition requirements of gears for aero-engines are met.

This invention provides a high-strength, high-toughness martensitic precipitation hardening stainless steel fastener and its preparation method, belonging to the field of metallurgical technology. The fastener is made of X5CrNiCuMo15-06 steel, and its chemical composition, by mass percentage, includes: C: ≤0.05%, Cr: 14-16%, Ni: 6.0-7.0%, Cu: 1.25-1.75%, Mo: 0.5-1.0%, Mn: ≤1.0%, Si: ≤1.0%, P: ≤0.008%, S: ≤0.005%, V: ≥8%C, with the balance being Fe and unavoidable impurities. This invention utilizes an ultra-low C+V microalloying composition design, a dual high-purity smelting process of vacuum induction and protective atmosphere electroslag remelting, combined with an integrated heat treatment system of solution treatment, deep cryogenic treatment, and aging treatment. This allows the material to maintain high strength while achieving excellent room temperature and ultra-low temperature toughness. The fasteners prepared can meet the high load-bearing and long-term service requirements of high-end equipment.

The application relates to the technical field of alloy steel, in particular to a rare earth-containing high-strength corrosion-resistant cutter alloy steel and a preparation method thereof. Fe is used as a matrix, and the alloy steel contains C, Si, Mn, Cr, Mo, V, Nb, N, composite rare earth and TiB2, the contents of P and S are controlled in an extremely low range; the composite rare earth is a mixture of La and Ce, the content and form of inevitable impurities are strictly controlled, there is no coarse Al2O3 inclusion, and the non-metallic inclusions are spherical or spheroidal and small in size; the preparation method comprises raw material pretreatment, electric arc furnace smelting, AOD refining, electroslag remelting, homogenization annealing and hot forging, hot rolling, cold rolling and cryogenic treatment, tempering and post-treatment. The alloy component and the preparation process are optimized, the organization is refined, the inclusion form is improved, the matrix density and dislocation density are improved, the mechanical properties, corrosion resistance and wear resistance of the alloy are far superior to those of the prior art, and the balance between strength, toughness and corrosion resistance is achieved.

The invention belongs to the field of material processing and manufacturing, and particularly relates to a preparation method and application of a surface-strengthened anti-corrosion steel mold. One purpose of the invention is to provide a material for a surface-strengthened anti-corrosion steel mold. The material comprises the following chemical components in percentage by weight: 75 to 80 percent of Fe, 11 to 13 percent of Cr, 0.5 to 2.5 percent of Ni, 1 to 5 percent of Mo, 2 to 5 percent of Co, 0.3 to 0.6 percent of Cu, 0.1 to 0.2 percent of C, 0 to 2 percent of W, 0.3 to 0.6 percent of Cu, 0.1 to 0.2 percent of C, 0 to 0.3 percent of V, 0 to 0.1 percent of Nb and 0 to 0.005 percent of La. The invention provides the preparation method of the steel mold for compression molding of the PBX raw material, which is simple and convenient to operate and can be industrially applied. Through combination of alloy matrix design, high-temperature and high-pressure nitriding and subzero treatment, collaborative optimization of corrosion resistance and mechanical properties of the steel die is achieved, and it is guaranteed that the surface of the steel die has long service life and high stability in the complex forming environment where the surface makes contact with PBX raw materials.

The invention belongs to the technical field of aluminum alloy material processing, and discloses a cryogenic treatment process of a 7xxx series high-strength aluminum alloy pipe, the process sequentially comprises three core steps of solution treatment, cryogenic treatment and aging treatment, and the 7xxx series high-strength aluminum alloy pipe is obtained by accurately controlling key parameters of each step. The technical problems that in a traditional T6 heat treatment process, a 7xxx series aluminum alloy pipe is uneven in precipitated phase distribution, grain refinement is insufficient, the strength and plasticity are difficult to consider, and internal stress is large are solved. After being treated by the process, the tensile strength of the pipe is improved to 705MPa, the yield strength is improved to 678MPa, the ductility is improved to 11.8%, the size of a precipitated phase in a microstructure is smaller, distribution is more uniform, the internal stress is remarkably reduced, the size stability is greatly improved, industrial batch production can be realized, and the requirements of the fields of aerospace, rail transit and the like on the high-performance aluminum alloy pipe are met.

The invention discloses a laser welding method for an ultra-high-strength stainless steel welding part and the ultra-high-strength stainless steel welding part, and particularly provides two stainless steel blank workpieces to form an assembly, and the blank assembly is melted to form a laser welding joint under the action of a laser heat source. And the welded joint is placed in a low-temperature environment at the temperature T for a period of time to be subjected to subzero treatment, and then the welded joint with the excellent joint performance within the wide temperature range is obtained. The welding joint has ultrahigh strength, and the strength of the welding joint can reach 90% or above of the strength of a base material in typical low-temperature (-196 DEG C), room-temperature and high-temperature (100 DEG C) environments; and the application in environments with different assembly gaps can be met.

This invention discloses a multi-process synergistic method for strengthening and toughening titanium alloys. The method includes: firstly, pre-treating the titanium alloy surface with sandblasting; then, subjecting the pre-treated titanium alloy to solid embedding carburizing treatment; subsequently, under inert atmosphere protection, sequentially subjecting the carburized titanium alloy to solution treatment, rapid cryogenic treatment, and aging treatment; and finally, shot peening the surface of the heat-treated titanium alloy. This invention solves the problem in existing technologies where a single process is insufficient to synergistically improve the strength and toughness of titanium alloys, achieving a synergistic match between high strength and high hardness on the surface of the titanium alloy material and high toughness in the matrix.

The invention relates to the technical field of hard alloy for synthesis of superhard materials, and particularly discloses a hard alloy holding-up hammer for synthesis of high-purity large single crystal diamond and a preparation method of the hard alloy holding-up hammer. The holding-up hammer material is composed of the following components in percentage by weight: 80%-88% of WC, 4%-8% of Co, 2%-5% of TaC, 3%-7% of TiC and 0.5%-2% of Cr3C. Wherein WC serves as a hard phase, Co serves as a binding phase, TaC inhibits grain growth, TiC nanoparticles are dispersed and distributed to form a pinning effect, and Cr3C2 improves the wettability of the binding phase and improves the oxidation resistance. The preparation method comprises the steps of raw material selection and ball-milling mixing, vacuum drying and sieving, cold pressing and cold isostatic pressing forming, gradient sintering and grinding and subzero treatment.

The present application relates to a kind of electromagnetic coupling cryogenic treatment method for improving the shear strength of dissimilar material brazing interface. Mainly solve the technical problems of poor comprehensive performance and short service life of brazing interface existing in existing single cryogenic treatment or magnetic field processing. The technical scheme used in the present application is: the electromagnetic coupling cryogenic treatment method, first, the brazing composite material sample of low alloy steel / copper-zinc alloy / tungsten-cobalt hard alloy is prepared, then the sample is subjected to electromagnetic coupling cryogenic treatment, finally, the treated sample is put into a heating furnace, low-temperature tempering treatment is carried out first, and then medium-temperature tempering treatment is carried out. The two processes of magnetic field and cryogenic treatment used in the present application have the advantages of green environmental protection and high efficiency and energy saving, etc. In the case of not affecting the structural deformation, the overall strengthening from inside to outside can be achieved, which can be applied to various fields.

The invention discloses a high-speed steel heat treatment machining method for a precise valve needle, and relates to the field of high-speed steel heat treatment. High-speed steel continuous resistance furnace heat treatment processing; high-speed steel is straightened, straightened and cut off on line; and performing subzero treatment on the high-speed steel straight rod. According to the SKH51 high-speed steel treated through the method, internal carbide distribution is more uniform and fine, a quenched martensite structure and a part of retained austenite structure are fully tempered and converted into tempered martensite, and the content of a small amount of retained austenite is accurately controlled, so that the high hardness is guaranteed, and meanwhile, the service life of the SKH51 high-speed steel is prolonged. The toughness, the fatigue resistance and the dimensional stability of the material are greatly improved; the high-end precision valve needle processed by the high-speed steel has the advantages that the wear resistance is obviously enhanced, the fatigue resistance is outstanding, and the service life is prolonged.

The application discloses a heat treatment method for improving mechanical properties of an additive manufacturing GH4169 high-temperature alloy part, and belongs to the technical field of heat treatment, which comprises the following steps: S1, placing the additive manufacturing GH4169 high-temperature alloy part into a hot isostatic pressing device for heat preservation and pressure preservation treatment; S2, placing the additive manufacturing GH4169 high-temperature alloy part obtained in the step S1 into a vacuum heat treatment furnace for aging treatment; S3, placing the additive manufacturing GH4169 high-temperature alloy part obtained in the step S2 into a deep cooling control box for deep cooling treatment; S4, placing the additive manufacturing GH4169 high-temperature alloy part obtained in the step S3 after the cooling treatment into the vacuum heat treatment furnace for heating treatment; S5, placing the additive manufacturing GH4169 high-temperature alloy part obtained in the step S4 after the aging treatment into the deep cooling control box for deep cooling treatment; and S6, placing the additive manufacturing GH4169 high-temperature alloy part obtained in the step S5 after the cooling treatment into the vacuum heat treatment furnace for heating treatment. The application has the advantages of reducing heat treatment procedures and reducing working hours.

The invention discloses a medium-power turboprop engine transmission gear machining method which comprises gear rough machining and subsequent gear finish machining, and deformation restraining treatment is connected between the gear finish machining and the gear rough machining. The deformation inhibition treatment comprises subsection carburization, isothermal quenching and subzero treatment; the subsection carburizing is divided into a strong carburizing stage, a diffusion stage and a soaking stage; the isothermal quenching adopts a nitrate bath; the temperature of the subzero treatment is-70 DEG C to-90 DEG C. The problem that in the prior art, after gear machining is completed, operation of a turboprop engine is easily affected after storage and transportation links are conducted and then the gear is applied to the turboprop engine is solved.

The invention discloses a preparation method of a high-bearing wear-resistant antifriction integrated functional layer on the surface layer of a shaft gear part. The preparation method comprises the following stages of a vacuum variable pulse carbon-nitrogen composite strengthening process, cryogenic treatment, low-temperature tempering and magnetron sputtering coating. A carbon-nitrogen composite strengthening layer is formed on the surface of the shaft gear part through the vacuum variable pulse carbon-nitrogen composite strengthening process to serve as a bearing layer; martensite transformation is promoted through subzero treatment, and the surface hardness is improved; the performance of the carbon-nitrogen composite strengthened layer is stabilized through low-temperature tempering; a high-wear-resistant film is formed by magnetron sputtering coating, and the high-wear-resistant film and the bearing layer jointly form an integrated functional layer. The wear rate can be greatly reduced, the limitation of a single carburizing and coating technology is broken through, the development trend and service requirements of heavy-duty gears and high-performance bearings of large equipment are met, the process integration degree is high, and important engineering application value is achieved.

The invention relates to the technical field of hard alloy, in particular to an intelligent machining system for a double-spiral-hole hard alloy bar, which comprises a machining parameter construction module, a mixing module, an extrusion forming control module, a dewaxing pre-sintering control module, a subzero treatment control module, an acquisition module, a calculation module, an analysis module and a control module, corresponding machining parameters are extracted through the machining parameter construction module, machining is conducted, the analysis module accurately judges the machining state through key data such as the alloy bar blank density, and the relevant machining parameters are corrected according to the machining state to form an intelligent regulation and control closed loop. According to the method, the problem of quality fluctuation caused by the fact that parameters are fixed and cannot be adjusted in real time in traditional machining is effectively solved, the machining precision and quality stability of the double-spiral-hole hard alloy bar are remarkably improved, and powerful guarantee is provided for machining of the double-spiral-hole hard alloy bar.

This invention discloses a multi-station hot forming and quenching process for aluminum plates. After solution treatment, the billet is hot-pressed, with changes in pressure and temperature. The temperature changes integrate quenching and cryogenic treatment to improve product performance and microstructure. A second cryogenic treatment followed by short-term aging eliminates stress and further enhances product performance. The resulting product exhibits significantly increased strength, stable dimensions, and no springback, making it particularly suitable for forming parts with negative angles. The process integrates hot forming, punching, and shaping processes, saving turnaround time between subsequent processes, improving production efficiency, and helping to reduce costs.

The invention discloses a high-wear-resistance steel ball manufacturing method and belongs to the field of wear-resistant materials. Molten medium-carbon steel and molten high-carbon steel are smelted, the molten medium-carbon steel is formed by smelting 81.6%-82.3% of 45 # steel cuttings, 9.5%-9.8% of nitrided ferromanganese, 8.0%-8.5% of ferrotitanium and 0.13%-0.16% of metal aluminum, and the molten high-carbon steel is prepared from 1.92%-2.07% of C, 2.44%-2.75% of Cr, 1.13%-1.36% of Si, 0.55%-0.74% of Mn, 0.16%-0.23% of B and 0.02%-0.06% of Al < lt >; 0.050% P, lt; 0.045% of S, and the balance Fe and inevitable impurities. The two kinds of molten steel are evenly mixed, subjected to external treatment, cast into a steel bar and then forged into a steel ball, and the steel ball has high hardness and excellent wear resistance after being subjected to quenching, subzero treatment and low-temperature tempering and has an excellent use effect when applied to a large mill.

The utility model discloses heat treatment equipment for cryogenic aging strengthening of an aluminum alloy sheet. The heat treatment equipment for cryogenic aging strengthening of the aluminum alloy sheet comprises a support, a cryogenic treatment box body is installed at the top of the support, a supporting frame is installed in the cryogenic treatment box body, rotating shafts are installed on the two sides of the supporting frame and connected with the cryogenic treatment box body, and a driving mechanism is installed on the side face of the cryogenic treatment box body. The driving mechanism is connected with the rotating shaft, and a sealing door is installed on one side of the subzero treatment box body. According to the heat treatment equipment for cryogenic aging strengthening of the aluminum alloy thin plate, the rotatable supporting frame is installed in the cryogenic treatment box body, when the aluminum alloy thin plate is taken and placed, by adjusting the inclination angle of the supporting frame, the aluminum alloy thin plate can be taken and placed in a more labor-saving mode, use is more convenient, and labor intensity is reduced.

Apparatus and methods for regulating cryogenic treatments are disclosed which comprise devices and methods for delivering controlled treatment of a cryoablative agent. In one variation, such devices may generally comprise an elongate probe having a distal tip and a flexible length, at least one infusion lumen positioned through or along the elongate probe, wherein the infusion lumen defines one or more openings along its length, and a liner expandably enclosing the probe. An inflow reservoir or canister valve may be fluidly coupled with a reservoir or canister containing the cryoablative agent and a modulation control unit may also be fluidly coupled with the inflow reservoir or canister valve and in fluid communication with the at least one infusion lumen. Additionally, a warming element may also be thermally coupled with the reservoir or canister.

The application belongs to the technical field of metal materials, and discloses a high-strength and high-toughness medium-manganese steel based on warm rolling and deep cryogenic treatment and a preparation method thereof. The preparation method comprises the following steps: combining a specific warm rolling process (720 DEG C~760 DEG C) with liquid nitrogen deep cryogenic treatment (soaking for 0.3~0.6h) and supplementing low-temperature tempering (180 DEG C~220 DEG C). The process induces deformation through warm rolling, promotes the transformation and refinement of austenite into martensite in combination with deep cryogenic treatment, and then eliminates internal stress and precipitates fine carbides through low-temperature tempering, so as to synergistically control the microstructure. The technical bottleneck that the strength and plasticity of traditional medium-manganese steel are difficult to be compatible is effectively solved, and the organization is super-refined and the stability is improved. The obtained medium-manganese steel has a good match between ultra-high strength and excellent plasticity, the yield strength is greater than 1800MPa, the tensile strength is as high as 2300MPa, the elongation after fracture is more than 17%, and the comprehensive mechanical properties are significantly improved.

The invention discloses a wear-resistant steel-based mold material for plastic magnetic injection molding and a preparation method of the wear-resistant steel-based mold material, and relates to the technical field of mold steel materials. When the steel-based mold material is prepared, metal chromium, titanium powder, ferromolybdenum, graphite, ferroboron, lanthanum iron and electrolytic iron are weighed according to a specific proportion, and a cast ingot is obtained through vacuum induction melting and argon protection pouring; a calcium fluoride-aluminum oxide-calcium oxide mixed slag system serves as a remelting medium, electroslag remelting, homogenization treatment and oil quenching are conducted on the cast ingot, and a steel ingot is obtained; the steel ingot is subjected to multidirectional forging and temperature-controlled cooling, and forged die steel is obtained; and finally, the forging die steel is subjected to gas nitriding subzero treatment and multi-stage tempering, gradient titanium nitride and chromium nitride metal ceramic layers are induced to be formed on the surface, and the wear-resistant steel-based die material for plastic magnetic injection molding is prepared. The prepared steel-based mold material has high hardness, high wear resistance and corrosion resistance.

The invention relates to the field of gate valve casting, in particular to a high-density high-pressure-resistant nodular cast iron gate valve casting technology. The raw materials are selected from 40-60 parts of Q10 high-purity pig iron, 30-40 parts of low-carbon waste steel, 25-35 parts of ductile iron foundry returns, 1.5-2.5 parts of a calcium carbide desulfurizer, 0.5-1 part of cryolite powder, 2-3 parts of magnesium-rare earth-calcium alloy wires, 0.5-1 part of a barium-containing ferrosilicon alloy, 0.3-0.5 part of a strontium-containing ferrosilicon alloy and 0.2-0.4 part of a zirconium-containing ferrosilicon alloy. According to the method, the nano particles are added to enable the graphite nodules to be finer and denser, liquid nitrogen is used for cooling and eliminating internal holes, then pouring is conducted in a vacuum environment to avoid bubbles, then subzero treatment is conducted to enhance the hardness of the material, and finally laser is used for cladding the superhard alloy layer on the sealing face, so that the strength, compactness and temperature resistance limit of the nodular cast iron can be greatly enhanced; and the use function is improved.