775 results about "Martensite" patented technology

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 discloses a manganese-copper alloy with high damping performance and a preparation method and application thereof. The preparation method comprises the steps that manganese-copper alloy powder is subjected to laser layer-by-layer scanning printing through a laser powder bed melting technology, and then the printed manganese-copper alloy is subjected to direct aging treatment. Obtaining a result parallel to the construction direction by regulating and controlling printing processes such as a laser scanning strategy, a layer thickness, a scanning interval and a substrate temperature; 001gt, 001gt; and the manganese-copper alloy is manufactured through strong texture additive manufacturing. Owing to lt; 001gt, 001gt; the oriented grains have more twin-crystal martensite variants, and twin-crystal martensite is easier to move under the action of external stress, so that the manganese-copper alloy has higher damping performance. The vibration reduction component is prepared by utilizing the special advantages of forming hollow, hollow-out, thin-wall and other complex structures of laser additive manufacturing, combination of manganese-copper damping alloy material vibration reduction and structure vibration reduction can be effectively achieved, and the manganese-copper damping alloy material can be widely applied to the field of vibration reduction and noise reduction of satellites, ships, rail transit, high-precision machine tools and other high-end equipment.

The application discloses a kind of martensitic age steel of additive manufacturing and preparation method thereof, the martensitic age steel, according to mass percentage, its composition is as follows: Ni 16~22%, Co0-5%, Mo 2~6%, Ti 0.2~2.5%, Al 0~1.5%, Re 0~0.3%, wherein Re is selected from at least one of Y or La, the balance is Fe and inevitable impurities.In the application, by reducing Co element, adjusting the ratio of Ni, Ti and Mo in the alloy, while adding a small amount of rare earth (Y and La) element, the alloy has higher M s Under the premise, the raw material cost of alloy powder and the preparation cost of alloy are greatly reduced, and the fine equiaxed grains and high-density nano precipitates formed after aging are formed by combining with the process parameter control of additive manufacturing, so that the mechanical properties of the martensitic age steel are greatly better than those of the traditional casting process.

The application discloses a kind of thick gauge 430 ferritic stainless steel laser weld low-temperature rollability processing method, comprising: using-1~‑2mm negative defocusing+8~10kW low-power laser welding, the grain of heat-affected zone is refined;NiCr-3 welding wire is preheated to 300~400℃ and carried out hot wire laser welding, reduces cooling rate;Weld is implemented 700 DEG C / 10-12 seconds short time induction annealing, decomposes martensite and releases residual stress;Weld is inducted to ≥50 DEG C before rolling and restores plasticity;Optimize five rack continuous rolling parameter, and the reduction of first rack is reduced to 15%-20%.The application is by welding-heat treatment-rolling whole process synergic control, makes weld low-temperature cracking rate from 2.6 times / month reduce to 1 times below, and-10 DEG C impact toughness is promoted to 22J, cup convexity qualification rate reaches 95%, and annual economic benefit is greatly improved, applicable to the thickness 3.0~8.0mm 430 stainless steel cold rolling production, solves the technical problem that thick gauge 430 stainless steel weld is easy to crack under low-temperature environment.

The invention belongs to the technical field of TC4 alloy additive manufacturing, and discloses an electron beam melting TC4 alloy isotropic optimization method based on staged temperature control HIP, which comprises the following steps of: depositing TC4 alloy powder along the normal direction of a substrate, and printing a part through an electron beam powder bed melting additive manufacturing technology; and then, staged temperature control hot isostatic pressing treatment is carried out on the printed part, and defects generated by printing are closed. According to the method, the hot isostatic pressing (HIP) technology is adopted, under the synergistic effect of the high temperature of 920 DEG C and the high pressure (Ar protection) of 150 MPa, the defects of air holes, incomplete fusion and the like in the TC4 alloy formed through EBM are eliminated through a plastic deformation and diffusion creep mechanism, and the density is remarkably improved. Meanwhile, a metastable martensite alpha'phase is promoted to be decomposed into an equilibrium-state alpha + beta double-phase structure in a high-temperature environment, and alpha-phase grains are moderately coarsened (the average size is increased to 3.12 microns from 1.71 microns).

The invention belongs to the technical field of research and development of fast neutron reactor jackets and structural materials, and particularly relates to a high-temperature-lead-bismuth-corrosion-resistant high-silicon-content ferrite / martensite steel ladle tube and a preparation method thereof. According to the mass percentage, the composition mainly comprises the following components: 0.16-0.24% of C; 0.4 to 0.8 percent of Mn; cr: 11.6% to 12.4%; 1.2 to 1.8 percent of W; 0.1 to 0.4 percent of Ta; 0.2 to 0.4 percent of V; 1.0%-1.8% of Si and Fe. The preparation method comprises the steps of vacuum induction and vacuum arc remelting. Carrying out homogenization treatment and forging; extruding and annealing; cold rolling and annealing; and performing normalizing and tempering treatment. Through an efficient short-flow process route and reasonable smelting, pipe machining deformation and heat treatment processes, the microscopic structure of the material is remarkably improved, then the mechanical property and high-temperature lead and bismuth corrosion resistance of the finished pipe are improved, and the use requirement of the lead and bismuth cooling fast reactor fuel assembly cladding material under the high-temperature working condition is met.

According to the low-strength high-formability austenitic stainless steel and the manufacturing method thereof, C + N is controlled to be smaller than or equal to 0.035%, the manganese content is controlled to be within 1.5%, the tin content is limited to be 0.01%-0.30%, the copper content is limited to be 2.4%-4.5%, and the tin-copper ratio is that (Sn / Cu) * 1000 is larger than or equal to 5 and smaller than or equal to 50, so that it is guaranteed that tin exerts the beneficial effects such as the corrosion resistance is improved, and the harm of tin segregation can be controlled to be at the low level; according to the finally obtained austenitic stainless steel, the yield strength is smaller than or equal to 160 Mpa, the tensile strength is smaller than or equal to 500 Mpa, the ductility is larger than or equal to 55%, the grain size grade is 6-8, edge cracks cannot occur during hot rolling, the martensite content of a cup drawing deformation part is 0.05% or below during large deformation machining, in other words, the austenite phase is still stable under the complex deformation condition, deformation cracks are avoided, and the service life of the austenitic stainless steel is prolonged. The comprehensive effects of high corrosion resistance, low strength and high forming machinability of the material are achieved.

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.

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.

The invention discloses an ultrahigh-strength maraging steel wire as well as a preparation method and application thereof, and belongs to the field of steel product manufacturing. The steel wire alloy comprises the following components in percentage by weight: 0.02%-0.05% of C, 0.10%-0.35% of Si, 0.20%-0.60% of Mn, 0.60%-2.50% of Cr, 18.5%-22.0% of Ni, 8.0%-13.0% of Co, 1.2%-2.0% of Ti, 3.0%-5.5% of Mo, 0.10%-0.50% of Al, less than or equal to 1.50% of Cu, less than or equal to 1.50% of Nb, less than or equal to 0.05% of V, less than or equal to 0.04% of N, less than or equal to 0.02% of La + Ce and the balance of Fe and inevitable impurity elements. And the equivalence ratio Nieq / Creq of nickel to chromium is greater than or equal to 1.80. The steel wire provided by the invention has ultrahigh strength, excellent toughness and plasticity, wear resistance, heat resistance, drawing performance and bending and twisting performance.

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 discloses a preparation process of a high-strength corrosion-resistant stainless steel fastener. The preparation process comprises the steps of material modification, warm upsetting forming, stabilizing treatment, cryogenic strengthening, gradient aging, surface treatment, post-treatment and the like. According to the process, the alloy component proportion is optimized, a thermal mechanical treatment technology of warm upsetting forming, subzero treatment and gradient aging is combined, a nano-composite coating and micro-arc oxidation sealing process is innovatively introduced, and the process comprises vacuum melting and controlled rolling of customized high-nitrogen stainless steel wires, deformation-induced martensite regulation in warm upsetting forming, low-temperature hot rolling, high-temperature hot rolling, high-temperature hot rolling, high-temperature hot rolling, high-temperature hot rolling and high-temperature hot rolling. The tensile strength and the salt spray corrosion resistance of the fastener are remarkably improved through deep cooling-medium temperature aging synergistic strengthening, double-layer nano TiN / CrN composite coating deposition and micro-arc oxidation micropore sealing treatment, the problem that a traditional stainless steel fastener is insufficient in strength and low in stress corrosion sensitivity is solved through the technology, and the technology is particularly suitable for the extreme environments such as aerospace and ocean engineering.

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 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 relates to a clamping system, in particular to a low-stress flexible clamping system for an aluminum-based silicon carbide ultrathin reflector, which comprises an air floatation supporting part, a clamping part and a clamping part, the air floatation supporting part comprises an air bag, the air bag is arranged above a bottom plate, the air bag is U-shaped, and two U-shaped supporting sheets at the upper end of the air bag are opened after the air bag is inflated; the self-adaptive clamp is also in a U shape, when the air bag is opened, the self-adaptive clamp is pulled to be opened outwards, and when the high-temperature reflecting mirror is clamped, the self-adaptive clamp recovers to the original shape, and the reflecting mirror is clamped; after the air bag is inflated, the two U-shaped supporting sheets at the upper end of the air bag are opened, and the opening tension is enough to pull open the self-adaptive clamp in a martensite phase, so that the reflecting mirror can be conveniently placed in the clamping system; when the reflector is clamped, the micro-displacement compensation block begins to extend under the inverse piezoelectric effect, the thickness of the micro-displacement compensation block is reduced, the counter-acting force on the reflector is reduced, flexible clamping is achieved, the assembling stress of the reflector is reduced, surface precision loss is prevented, and therefore the flatness of the surface of the reflector is improved.

The present invention relates to a high-strength and high-plastic quenching-partitioning steel based on Mn chemical inhomogeneity and a preparation method thereof, which belongs to the field of third-generation advanced high-strength steel; its chemical composition mass percentage is: C: 0.2-0.4%, Mn: 2-5%, Si: 1-3%, P: ≤ 0.005%, S: ≤ 0.005%, and the balance is Fe and unavoidable impurities. By optimizing process parameters such as critical annealing temperature and time, it is ensured that a reasonable volume fraction of poor / rich Mn zone and Mn content are obtained; and by utilizing rapid heating and extremely short austenitization and heat preservation, the diffusion of Mn element is suppressed, the uneven distribution of Mn is retained, and a high-temperature austenite consisting of polygonal Mn-poor austenite and polygonal Mn-rich austenite is formed. Due to the uneven distribution of Mn elements, the martensitic phase transformation temperature range is increased, and martensitic lath refinement is achieved using a lower quenching temperature. The present invention achieves martensitic lath refinement while retaining more residual austenite, and the yield strength of the material is significantly improved.

The invention discloses a controlled cooling method of a steel wire rod 87Mn for a bridge cable. The rolling temperature, the spinning temperature and the roller way speed are accurately controlled, the Stelmor air cooling control cooling technology is adopted, it is ensured that the temperature of a wire rod is evenly distributed in the cooling process, and too fast or too slow local cooling is avoided. A sectional controlled cooling process is adopted, network cementite is prevented from being generated through first-section rapid cooling, uniform transformation of the structure is ensured through second-section slow cooling, the structure is stabilized through third-section natural cooling, the process design is reasonable, and operation is easy and convenient. The finally obtained 87Mn hot-rolled wire rod is free of martensite and network cementite in the core, the sorbite rate is larger than or equal to 93%, and the 87Mn hot-rolled wire rod has high strength, high plasticity and good drawing performance and is suitable for the high-requirement field such as bridge cables.

The invention belongs to the field of engineering materials, and discloses an ultrahigh-strength steel plate with yield strength of 1500 MPa for engineering machinery and a manufacturing method of the ultrahigh-strength steel plate. Through reasonable component design and combination with proper rolling reduction, finish rolling temperature and quenching temperature, the microalloying effect of Nb, V and Ti is fully utilized, ultra-fine grain martensite is obtained, the effects of fine grain strengthening, precipitation strengthening and dislocation strengthening are fully exerted, the effects of C and alloy are exerted, and the Q1500 steel plate with the low carbon equivalent CEV is obtained. By means of the process, the high-strength steel plate which is good in production performance, easy to weld, 5-20 mm thick, 1500 MPa in yield strength and used for engineering machinery can be stably produced, and the high-strength steel plate is widely applied to large engineering machinery equipment such as crawler cranes and wheeled cranes.

The invention relates to the technical field of machine manufacturing, and provides a stainless steel rocket storage tank barrel section forming method, device, equipment and medium, the method comprises the steps that an X-ray diffraction test is conducted on a sample, and the martensite volume fraction and dislocation density are obtained based on an obtained diffraction curve; constructing a first function based on the martensite volume fraction, the corresponding environmental parameters and the deformation amount of the deformed sample; obtaining yield strength according to the dislocation density, and constructing a quantitative model according to the yield strength and a first function; and actual operation parameters are obtained and input into the quantitative model, corresponding optimal operation parameters are obtained, and the rocket tank cylinder section is manufactured. According to the method, the base metal and the welding seam are deformed at the same time by adopting the obtained optimal operation parameters such as low-temperature parameters to conduct a low-temperature deformation method, so that the base metal and the welding seam are both subjected to deformation strengthening, the joint strength coefficient of the cylinder section welding seam is improved, the integrity and reliability of the component structure are improved, resource waste is reduced, and the production efficiency is remarkably improved; and the comprehensive performance of the rocket tank is improved.

The invention discloses a high-toughness anti-fatigue high-pressure-resistant seamless steel tube and a gradient preparation method thereof, and relates to the technical field of metal material processing. The seamless steel tube forms a performance gradient from the inner wall to the outer wall in the wall thickness direction; the seamless steel pipe sequentially comprises a ferrite-pearlite structure layer, a transition structure layer and a tempered martensite structure layer from the inner wall to the outer wall, a Fe4N nitride layer and a Ni-Ti alloy layer are arranged on the inner wall, and a reinforced surface layer is formed on the outer wall through ceramic coating treatment. According to the seamless steel pipe, the performance gradient is formed along the wall thickness, the inner wall has high toughness and corrosion resistance, and the outer wall has high strength and fatigue resistance and adapts to complex working conditions; the gradient preparation method solves the problems that a traditional technology is large in heating temperature difference, uneven in rolling deformation, asynchronous in heat treatment phase change and the like, the comprehensive performance is improved, the technology is based on the prior art, the improvement cost is low, and industrial production is facilitated.

The invention discloses a laser powder bed molten high-strength, high-plasticity and high-work-hardening titanium alloy and a preparation method and application thereof.The preparation method comprises the steps that two kinds of titanium alloy powder with different Mo equivalents are mixed according to a certain mass ratio to form mixed powder, and the mixed powder is put into laser powder bed melting equipment; the titanium alloy is finally obtained through layer-by-layer forming by laser powder bed melting equipment according to a slicing path and process parameters of a three-dimensional model, the microstructure of the prepared titanium alloy comprises hexagonal martensite alpha 'and orthorhombic martensite alpha', and in a preferable scheme, under the condition that heat treatment is not needed, the yield strength of the titanium alloy is larger than or equal to 950 MPa, the tensile strength is larger than or equal to 1250 MPa, and the tensile strength is larger than or equal to 1250 MPa. The alloy has the advantages of high strength, high plasticity and excellent work hardening capacity, can meet the requirements of forming and high mechanical properties of titanium alloy components in complex shapes, and is especially suitable for the fields of aerospace, automobiles, weapon armors, ships, oceans and the like, and the ductility is greater than or equal to 14%, and the work hardening capacity is greater than or equal to 250 MPa.

The invention relates to a 1400 MPa-grade high-strength tool steel wire rod and a manufacturing method thereof.The method comprises the steps that after a Cr-V chemical component design is adopted for rolling and spinning to form a wire rod, online fused salt mixing quenching isothermal treatment is conducted, the wire rod is controlled to enter a sorbite phase region from a high-temperature austenite state at the cooling speed larger than or equal to 32 DEG C / s, part of austenite is promoted to be converted into a sorbite structure, and then the steel wire rod is rolled and spun; the method comprises the following steps: quenching austenite to form a quenching structure mainly comprising the retained austenite, carrying out isothermal tempering on the quenching structure to convert the retained austenite into martensite, toughening and destressing, and carrying out roller way slow cooling to prepare the steel wire rod with a microscopic structure comprising isothermal sorbite, tempered martensite and ferrite, so that the material cost can be properly controlled; the cold machining performance and the high-strength characteristic of the wire rod are considered, the tensile strength of a product is 1370-1420 MPa, and the percentage reduction of area is 35-40%, so that the heat treatment procedure after cold machining of the tool steel is omitted, the production energy consumption and cost of the tool steel are reduced, and the production efficiency is improved.

The present application relates to the manufacture of high-strength steel coated plate welded parts, in particular to a welding material, a high-strength steel workpiece, a laser welded joint and a manufacturing method thereof. The composition of the welding material satisfies the following conditions in terms of percentage by weight: C is greater than or equal to 0.5%, trace alloying elements are 0-0.36%, the content of Mn and Si is less than or equal to 2%, 6% is greater than or equal to 5C+Mn and is greater than or equal to 2.5%, and the rest is Fe and inevitable other elements; the trace alloying elements are at least one of Nb, V and Ti elements, and the content of Nb, V and Ti elements is less than or equal to 0.12%. The method does not need to remove the aluminum coating, utilizes the solid solution strengthening effect of C, and makes the volume fraction of lath martensite in the final weld after quenching greater than or equal to 90%. This scheme reduces the addition of alloying elements, reduces the cost and process control difficulty, avoids the formation of coarse carbides, improves the mechanical properties and stability of the joint, has high fracture strength and elongation, and realizes the double improvement of the strength and toughness and economy of the joint.

A transducer for determining a pressure of a hydrogen-containing fluid medium confined in a first space includes a pressure side end configured to be disposed facing the fluid medium. The transducer includes a housing, which defines a second space, and a measuring arrangement disposed in the second space. The pressure side end includes a diaphragm configured and disposed for hermetically separating the first space from the second space. The diaphragm includes a metallic material that is made of a high-alloy martensite.

The invention discloses a preparation method of a heterostructure high-performance metastable beta titanium alloy capable of inducing a deformation mechanism in a multilevel and sequential mode, and belongs to the technical field of metal materials. The method comprises the following steps: firstly, carrying out hot rolling in a beta single-phase region to prepare a blank and crushing coarse grains; substructures such as twin crystals and martensite are introduced through cold rolling; and through short-time annealing in a beta single-phase region, a multi-stage heterogeneous lamellar structure composed of thick equiaxed crystal grains, deformation recovery crystal grains and fine recrystallized crystal grains in an alternating manner is successfully constructed. The characteristic that twin crystals and martensite induce different stresses under different grain sizes is utilized, during deformation, thick equiaxed grains firstly start a deformation mechanism, and then fine recrystallized grains are activated; and in the later period of plastic deformation, the interior of the primary deformation strip further triggers a secondary deformation mechanism. The unique behavior of'grading-time sequence 'activation of a multi-deformation mechanism along with the increase of the dependent variable enables the metastable beta titanium alloy to keep excellent plasticity, and meanwhile, the work hardening rate is remarkably improved.

A cold rolled and annealed steel sheet, made of a steel having a composition including, by weight percent: C: 0.03-0.18%, Mn: 6.0-11.0%, Al: 0.2-3%, 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%, Ti≤0.050%, Nb≤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 25% to 55% of retained austenite, from 45% to 75% of ferrite, less than 5% of fresh martensite, a carbon [C]A and manganese [Mn]A content in austenite, expressed in weight percent, such that the ratio ([C]A×[Mn]2A) / (C %×Mn %) is from 19.0 to 41.0 wt %, C % and Mn % being the nominal values in carbon and manganese in weight % and a carbides density below 3×106 / mm2 and—an inhomogeneous repartition of manganese characterized by a manganese distribution with a slope above or equal to −30.

The invention discloses a method for producing martensite heat-resistant steel G115 for an ultra-supercritical power station based on electroslag remelting. The method comprises the following steps that S1, an electrode bar is obtained through EAF electric furnace smelting, LF refining, VD vacuum treatment and electrode die casting; s2, the electrode bar is subjected to electroslag remelting to obtain an electroslag ingot, a CaF2-Al2O3-CaO ternary slag system is adopted in the electroslag remelting process, Al powder, Si-Ca powder and B-Fe powder are added into the slag system, and argon protection is adopted in the whole process; and S3, after the electroslag ingot is demolded, annealing treatment is conducted. Smelting is conducted through the EAF electric furnace smelting technology, the LF refining technology, the VD vacuum treatment technology, the electrode die casting technology and the electroslag remelting technology, the problems of precise control over the easily-burnt element B and the gas content N and solidification structure segregation are solved, the product performance is further improved, and the welding process window is improved.

The invention discloses a manufacturing process and equipment of a high-performance long-service-life cold working die. The process comprises the following steps: quenching and tempering a cold-work die steel blank to obtain a tempered martensite structure; plasma nitrocarburizing is carried out to form a reinforced diffusion layer; the micro-pit array is machined through pulse laser, and an annular heat-affected softening zone is formed around the opening of the pit; depositing a hard coating, and forming a cantilever structure on the edge of the micro pit; wherein plasma nitrocarburizing is carried out in a low-pressure plasma atmosphere, laser processing and coating deposition are carried out in a vacuum or protective atmosphere, and transfer among the steps is not exposed to the atmosphere. The invention further provides corresponding manufacturing equipment which comprises a heat treatment cavity, a plasma nitrocarburizing cavity, a surface micro-texture machining cavity, a coating deposition cavity and a vacuum transfer cavity. According to the invention, the hardness mutation between the coating and the matrix is relieved, a hardness gradient transition structure is constructed, the fatigue stripping resistance of the coating is obviously improved, and the service life of a mold is prolonged.

Disclosed is a laser welded joint (2). When two steel plate base materials are butt-jointed for laser welding, a laser welding solder is added to a molten pool, thereby forming an initial weld seam, and the initial weld seam is quenched to form the laser welded joint (2), wherein at least one steel plate is a steel plate having an aluminum coating or an aluminum alloy coating; the volume fraction of lath martensite (21) in the laser welded joint (2) is not less than 90%, the average mass fraction of Mn is not less than 3.2%, the average mass fraction of Al is not higher than 1.4%, and the average mass fraction of C is lower than the C content of the steel plate base materials; and the height h1 of a reinforcement on the front face of a final weld seam formed by the laser welded joint (2) and the height h2 of a reinforcement on the back face of the final weld seam do not exceed 0.4 mm.