330 results about "Equiaxed crystals" patented technology

The invention belongs to the technical field of laser processing, and particularly relates to a method for manufacturing a titanium alloy through wire powder coordinated multi-mode laser coupling additive manufacturing, and the method comprises the steps of base material pretreatment, multi-mode coupling laser construction, additive manufacturing, surface strengthening and the like. According to the titanium alloy part manufacturing device and method, material conveying is conducted in the mode that wire feeding and powder feeding are combined, structures with large areas in parts are rapidly manufactured through wire feeding, fine structures are manufactured through powder, and the titanium alloy parts can be efficiently manufactured in a high-precision mode. In the additive manufacturing step, multi-mode coupling annular laser is adopted, annular flat-topped pulse laser can accelerate flowing of a liquid phase before solidification, so that dendritic crystal arms formed through solidification in advance are broken to form new crystal nucleuses, then an equiaxed crystal structure is formed, and the strength and plasticity of the titanium alloy are improved. The annular flat-topped pulse laser can accelerate stirring of the molten pool, the heat mass conveying rate in the molten pool is increased, the element segregation phenomenon is relieved, and finally a uniform and stable titanium alloy structure is obtained.

The invention discloses a method for preparing a congruent-axis structure refractory medium-entropy alloy by regulating and controlling a liquid bridge transition mode in a double-wire additive manufacturing process and an application of the congruent-axis structure refractory medium-entropy alloy. The invention belongs to the technical field of additive manufacturing. The invention aims to solve the technical problems that liquid bridge transition in the whole process cannot be realized and columnar crystals are extremely easy to form in the process of preparing the refractory medium / high-entropy alloy by adopting an electron beam double-wire additive manufacturing process at present. The method comprises the following steps: firstly, carrying out three-dimensional modeling on a target component, and carrying out slicing treatment; then liquid bridge transition is controlled by regulating and controlling a double-wire feeding strategy; and finally carrying out 3D printing. A double-wire deposition strategy and a control method thereof are adopted, the relative position of the wire and the electron beam, the relative position between the double wires and the relative position of the melting position of the double wires and the melting pool are adjusted, heat input is controlled, stable liquid bridge transition of the double wires under the condition of the constant speed or the non-constant speed is guaranteed, and the welding quality is improved. And thus, the stability of the deposition process and the congruent-equiaxed crystal structure and excellent mechanical property of a deposited part are improved.

The invention relates to a non-equimolar-ratio high-entropy thermoelectric ceramic and a preparation method thereof. The chemical formula of the non-equimolar-ratio high-entropy thermoelectric ceramic is (Ca1 / 3Sr1 / 3Ba1 / 3) 1-xLaxTiO3 (x = 0.1-0.4). Through presintering, spark plasma sintering and reduction annealing processes, a single-phase perovskite structure composed of phases of the A-site high-entropy perovskite thermoelectric ceramic is obtained, equiaxed crystal grains are arranged in the ceramic, and the morphology of the equiaxed crystal grains is matched with that of cubic perovskite structure crystal grains. Elements Ca, Sr, Ba, La, Ti and O in the ceramic are uniformly distributed in the ceramic, and no agglomeration phenomenon exists. The A-bit non-equimolar-ratio high-entropy perovskite thermoelectric ceramic (Ca1 / 3Sr1 / 3Ba1 / 3) 1-xLaxTiO3 obtained by the invention has low thermal conductivity, high conductivity and Seebeck coefficient, further shows a high thermoelectric ZT figure of merit, is simple to operate and short in time period, and provides an effective path for preparing high-temperature thermoelectric materials.

The invention discloses a manufacturing method of a silicon steel continuous casting billet, which comprises the following steps: the thickness of a liquid slag layer of adopted casting powder is within 10-18mm, the viscosity of the casting powder is within 0.20-0.29 Pa.S, and the melting point is within 1000-1110 DEG C; the liquid level fluctuation of the molten steel is kept within + / -3mm; and the secondary cooling area is cooled by adopting a process system that the cooling water amount is sequentially reduced in the casting blank drawing direction. According to the method, parameters such as the thickness of a casting powder liquid slag layer, the viscosity of the casting powder, the melting point, the superheat degree of tundish molten steel, stirring current and the like are controlled, and a secondary cooling area is divided into a high-temperature strong cooling process system and a low-temperature weak cooling process system in the throwing direction for cooling. And silicon steel production has the characteristics of high pulling speed, few defects, high equiaxed crystal rate, high casting blank temperature and the like.

The invention relates to the technical field of metal materials, and particularly provides a rare earth modified in-situ reinforced particle reinforced aluminum-based composite material and a preparation method thereof.The preparation method of the rare earth modified in-situ reinforced particle reinforced aluminum-based composite material comprises the steps that reactants and rare earth oxide are mixed, pressed into blocks and dried, and reactant blocks are obtained; the reactant blocks are added into the aluminum alloy melt for a high-temperature self-propagating reaction, in-situ reinforced particles are generated, and particle reinforced aluminum matrix composite melt is obtained; and degassing the particle reinforced aluminum matrix composite melt, and preparing the rare earth modified in-situ reinforced particle reinforced aluminum matrix composite by adopting a near liquidus casting method. According to the preparation method, micron-sized reinforced phase particles are generated in situ under the conventional casting condition by utilizing the high-temperature self-propagating reaction of a reaction system and the activity effect of rare earth elements, and the aluminum-based composite material with the fine equiaxed crystal structure is prepared.

The invention relates to an aluminum alloy strengthening method for high-frequency pulse nanosecond laser surface remelting after low-temperature rolling, which comprises the following steps: firstly, carrying out low-temperature rolling deformation treatment on an aluminum alloy plate to obtain an aluminum alloy material with a high dislocation density fiber structure and realize deformation strengthening; afterwards, the surface of the aluminum alloy plate is subjected to high-frequency pulse nanosecond laser remelting treatment, the aluminum alloy plate is rapidly melted by means of the characteristics of high instantaneous energy density, short acting time and the like of high-frequency pulse nanosecond laser, a small molten pool is obtained, the small molten pool has the great supercooling degree, the driving force of crystallization is increased, and ultra-rapid solidification is achieved; and submicron equiaxed crystals with the grain size ranging from 0.55 micrometer to 0.7 micrometer are obtained on the surface of the aluminum alloy, and fine grain strengthening of the surface is achieved. Through the low-temperature rolling and laser remelting processes, the aluminum alloy material with the special structure is prepared, the interior of the aluminum alloy material is of a hardened state high dislocation density structure, and the surface layer of the aluminum alloy material is of a submicron equiaxed structure.

The invention relates to a method for controlling the internal quality of a medium-carbon alloy steel continuous casting large round billet, which comprises the following steps of: 1) casting: casting by adopting a tundish integral crystallizer four-hole water gap with a downward water gap outlet angle of 15 degrees through tundish heat preservation and whole-course protection casting, immersing the water gap into a depth of 110-130mm below a meniscus of the crystallizer, and controlling the degree of superheat of a continuous casting tundish; 2) primary cooling: controlling the total water quantity of a crystallizer to be 4800-5300L / min, and controlling the water inlet and outlet temperature difference to be 3-7 DEG C; (3) secondary cooling is conducted, specifically, the secondary cooling specific water flow is controlled to range from 0.15 L / kg to 0.2 L / kg; 4) electromagnetic stirring of a crystallizer; (5) carrying out tail end electromagnetic stirring; (6) controlling the soft reduction of the fan-shaped section; and (7) slowly cooling the cast blank in a burial pit for more than 36 hours after the cast blank is poured, wherein the temperature in the burial pit is higher than 600 DEG C, and the temperature out of the burial pit is lower than 200 DEG C. The method has the advantages that central cracks and shrinkage cavities disappear, and the proportion of an equiaxed crystal area is increased.

The invention provides a round billet continuous casting machine and multi-stage multi-mode electromagnetic stirring device matching method, and belongs to the technical field of metallurgy continuous casting, and the method comprises the steps that an electromagnetic stirrer in a crystallizer area applies a rotating magnetic field in the initial solidification stage, and the forming quality of an initial solidification shell is optimized; an electromagnetic stirrer in the secondary cooling area utilizes a traveling wave magnetic field to continuously regulate and control the solidification process of the core part of the casting blank; the feeding effect of a final solidification section is remarkably improved through the action of a high-intensity magnetic field by an electromagnetic stirrer in a solidification tail end area, and multiple matching modes are produced to be matched with existing continuous casting processes of different steel grades according to the characteristics of the steel grades, the throwing direction of each area and the type of the electromagnetic stirrer. And then through linkage of the multi-stage multi-mode electromagnetic stirring device and cooperative control over continuous casting process parameters, the equiaxed crystal area of the casting blank is enlarged, segregation is reduced, the internal quality of the casting blank is improved, and the density, uniformity and mechanical performance of the casting blank are improved.

The application provides a superplastic forming process for preparing a large-size titanium alloy component, and belongs to the field of welding, heat treatment and superplastic forming of metal materials. The process is characterized in that: two or more titanium alloy plates are spliced together by using a friction stir welding technology under low heat input, fine equiaxed crystal organization is obtained at the welding core, and then the large-size titanium alloy plate after splicing is subjected to heat treatment to further control the microstructure. By using the principle that the coarse rate of the fine organization is greater than that of the coarse organization during the heat treatment, the holding temperature and the holding time are adjusted, and finally the microstructure of the base material and the welding core is uniform. Then, under a specific process, the large-size titanium alloy plate with the weld is subjected to overall superplastic forming, synchronous superplastic deformation of the weld and the base material is realized, and a high-performance large-size titanium alloy integral component is prepared.

The invention belongs to the field of ferrous metallurgy, and particularly relates to a method for improving the quality of a continuous casting billet through ultrasonic waves. According to the method, a multi-directional focused ultrasonic field and solidification front edge dynamic regulation and control combined mode is adopted, and electromagnetic stirring phase difference control and cooperative control of a secondary cooling section (fan-shaped section) auxiliary ultrasonic vibrator are combined at the same time. Wherein the composite action mode of the longitudinal standing wave field and the transverse traveling wave field of the multidirectional focused ultrasonic wave field and the solidification front edge dynamic regulation and control mode act on the casting blank, so that the equiaxed crystal rate can be remarkably increased, and the combination of ultrasonic waves and electromagnetic stirring is beneficial to reducing the segregation degree of the casting blank; and the addition of nano aluminum oxide and magnesium oxide mixed particles in the casting powder is beneficial to improving sound wave conduction so as to reduce subcutaneous bubbles. The isometric crystal rate of the finally obtained continuous casting billet is increased to 30%-55%; the center segregation index of the finally obtained continuous casting billet is reduced to 1.05 or below; and the number of subcutaneous bubbles per square meter is less than 0.5.

The invention belongs to the technical field of nickel-based alloy material processing and forming, and particularly relates to a preparation method and application of a powder metallurgy and isothermal forging In738 disc shaft ring piece. The hot isostatic pressing technology is adopted for preforming the blank, internal gaps and cracks of the material are eliminated, the structure is homogenized, element segregation is improved, the fatigue life is prolonged, and a plastic blank is provided for subsequent isothermal forging. Furthermore, the temperature difference between the blank and the mold is reduced through preheating treatment, deformation resistance sudden change caused by local chilling is avoided, and microcrack initiation is inhibited. In addition, dynamic recrystallization is promoted through isothermal forging, a fine equiaxed crystal structure is obtained, and the high-temperature strength is improved; and through solution treatment, grain coarsening is inhibited, a supersaturated solid solution is reserved, and driving force is provided for aging precipitation. And then a dual-mode gamma'phase strengthening system is formed through a two-stage aging process, and the endurance life is optimized. Therefore, the high-temperature comprehensive mechanical property of the In738 nickel-based alloy is improved, and the use requirement of the In738 nickel-based alloy at high temperature is met.

The invention discloses a solidification melting zone thermal compensation repairing device and method for adjusting a heat source mode, and belongs to the technical field of metal part repairing. In the traditional Gaussian laser single crystal repairing process, columnar crystal orientation isometric crystal transformation can be induced due to the violent heat dissipation effect on the top of a molten pool and the component supercooling effect of the solidification front edge, new crystal grains preferentially nucleate and grow on the top of the molten pool, and the mixed crystal defect on the top of a repairing layer is caused. The scheme that annular laser is adopted as main laser, a thermal compensation auxiliary laser beam and a zoom laser beam expander are added for cooperative regulation and control is provided, the temperature gradient and the cooling speed of a molten pool are controlled by accurately adjusting a heat source energy distribution mode, the tendency of columnar crystal orientation isometric crystal transformation is restrained, and the quality of the molten pool is improved. And mixed crystal defects at the top of the repair layer are eliminated. Compared with an existing method, the method is large in process window and good in parameter adaptability; the material application range is wide, and the repairing requirements of different alloy systems can be met; equipment adjustment is simple, and industrial application is easy to achieve.

The invention belongs to the related technical field of additive manufacturing, and discloses an electron beam melting wire liquid nitrogen copious cooling additive manufacturing method and system.The method comprises the steps that in the electron beam melting printing forming process, liquid nitrogen is sprayed to a molten printing wire under electron beam irradiation, and the liquid nitrogen is sprayed to the molten printing wire; the molten printing wires are subjected to nitridation reaction under the action of electron beams while being subjected to liquid nitrogen cryogenic cooling, so that the crystal structure of a formed part is regulated and controlled, and the mechanical performance is enhanced; and / or liquid nitrogen is sprayed to the printing wire material which begins to be solidified, so that the printing wire material is subjected to liquid nitrogen deep cooling, and the crystal structure of the formed part is regulated and controlled to achieve mechanical property enhancement. Liquid nitrogen is introduced into the electron beam additive manufacturing device for deep cooling, the extruded printing wire is solidified at an extremely high cooling speed after being melted, a large number of homogeneous nucleation sites are formed in a melting area due to the high supercooling degree, the solidification speed is high, a microstructure is customized into uniform and fine equiaxed crystals, the strength and toughness of the material are improved, and the production cost is reduced. The mechanical property is improved.

The invention relates to a preparation method of a high-strength and high-conductivity copper alloy wire, which comprises the following steps of: performing gradient extrusion and extrusion under a high-temperature condition to obtain a copper rod with a uniform and fine equiaxed crystal structure; performing large-deformation extrusion under medium and low temperature conditions to obtain a copper rod with a streamline fibrous structure; and carrying out multi-pass drawing treatment to obtain the copper alloy wire which is in a long and thin fiber structure along the radial direction. The copper alloy wire has high tensile strength and high conductivity, and the contradiction that in the prior art, a copper alloy wire cannot meet high strength and high conductivity at the same time is solved.

The invention belongs to the technical field of alloys, and provides a lightweight refractory multi-principal-element alloy with excellent high-temperature creep property, and a preparation method and application thereof. The general formula of the light refractory multi-principal-element alloy with the excellent high-temperature creep property is TiaVbAlcCrdMoe, wherein 43% < = a < = 48%, 43% < = b < = 48%, 2% < = c < = 8%, 2% < = d < = 8% and 1% < = e < = 5%, a + b + c + d + e = 100%, and a, b, c, d and e are mole percentages. The alloy presents an isometric crystal structure in a complete recrystallization state in a thermal mechanical treatment state, the phase structure is a single-phase body-centered cubic BCC structure, the alloy has low density and shows excellent creep property at 650 DEG C / 100 MPa, the creep time exceeds 90 h, and the creep elongation is lower than 10%.

The invention discloses a method for preparing fine-grain copper and copper alloy through pulsed magnetic field and rare earth adding composite regulation and control, and belongs to the technical field of copper and copper alloy material preparation. Graphite mold casting is adopted in the method, and the method comprises the specific steps that electrolytic copper with the purity larger than or equal to 99.95 wt% or a copper alloy with specific components is prepared as a matrix raw material; after smelting, adding pure lanthanum blocks and uniformly stirring; after the melt is poured into a preheating mold, a pulsed magnetic field is applied immediately for treatment, and the parameters of the magnetic field are as follows: the pulse voltage is 180-250 V, the frequency is 4.5-6.5 Hz, and the duration time is 15-20 minutes. According to the method, the heterogeneous nucleation effect of rare earth lanthanum is combined with the melt forced convection and dendritic crystal crushing effect caused by the pulsed magnetic field to synergistically refine a solidification structure and promote columnar crystal orientation equiaxed crystal transformation, so that a cast ingot with fine crystal grains is directly obtained in the casting stage, and the possibility is provided for simplifying the subsequent processing technology.

The invention relates to the technical field of heat treatment of steel for high-performance heading machine tools, and discloses an ultra-fine grain solid-phase regulation and control process for improving the structure uniformity of alloy steel, which comprises the following steps: collecting electrical parameters of an induction loop and identifying sudden change of parameters of a phase change point to determine a phase change leading edge position; triggering pulse disturbance heating at a preset depth to generate transient volume dislocation stress, breaking core carbide segregation and driving stress extreme values to gather towards the center; controlling the temperature rise rate to make the nucleation rate higher than the diffusion rate so as to form a dispersed crystal nucleus; according to the method, the phase change transient volume dislocation strain field is used for blocking the continuity of the net-shaped hard and brittle phase, the structure heredity of the large-scale section steel is eliminated, the total cross-section structure is highly homogenized, equiaxed crystals are ultra-refined, and the intergranular fracture resistance of the material in the service environment is enhanced.

The utility model discloses a large-scale tin bronze pressure disc centrifugal casting mold, which belongs to the technical field of centrifugal casting, and comprises a mold assembly, a suspension plate, a pouring assembly and a guide pipe, the mold assembly is assembled on a vertical centrifugal casting machine, the suspension plate is suspended above the mold assembly, the pouring assembly is assembled on the lower surface of the suspension plate, and the guide pipe is arranged on the suspension plate. The cooling pipes are evenly arranged in the annular cavity of the outer mold, the total length of each set of cooling pipes is short, cooling capacity can be effectively provided to promote cooling of castings, the segregation phenomenon is effectively reduced, meanwhile, isometric crystals can be formed easily, the casting quality is improved, the casting quality is improved, and the casting quality is improved. In addition, by means of the designed pouring assembly and the designed guide pipe, molten metal can be shunted, even pouring can be achieved in the cavity, the flow speed of the molten metal is increased, the centrifugal rotating speed is matched, the retention time of the molten metal in the cavity is shortened, the lead phase sedimentation window is reduced, and the product quality is improved.

The present invention relates to the technical field of continuous casting electromagnetic stirrers, and specifically discloses a special-shaped iron core type high-energy continuous casting traveling wave linear electromagnetic stirrer, which includes a yoke, a special-shaped iron core, and an induction coil. The yoke is of a cylindrical structure; a plurality of special-shaped iron cores are welded to the inner side of the yoke. The special-shaped iron cores are arranged in layers along the axis direction of the yoke, and each layer of special-shaped iron cores is evenly distributed along the circumference of the yoke. A core ring is sleeved on the special-shaped iron core; the induction coil is horizontally wound between adjacent layers of special-shaped iron cores. Thus, it can improve the utilization efficiency of the electromagnetic field, reduce the heat generation of the electromagnetic stirrer, increase the electromagnetic density of the working surface, improve the stirring force intensity on the molten metal, thereby expanding the equiaxed crystal zone of the billet, reducing segregation, and improving the internal quality of the billet.

The invention discloses a method for predicting the grain morphology of a titanium alloy cast ingot. The method comprises the steps that S1, longitudinal cutting structures of the titanium alloy cast ingot under different processes are collected, and an equiaxed crystal zone and a columnar crystal zone are distinguished; s2, establishing a titanium alloy ingot numerical model through software; s3, actual smelting parameters are input into the titanium alloy ingot numerical model, and solidification dynamic information is output; s4, a CET marking program is used for making the longitudinally-cut tissue correspond to the solidification dynamic information in the spatial position; s5, drawing a G-R macroscopic structure map; s6, the critical temperature gradient G * and the critical solidification rate R * are obtained according to the macroscopic structure atlas, and titanium alloy as-cast structure prediction is achieved. According to the prediction method for the grain morphology of the titanium alloy cast ingot, temperature field and flow field information corresponding to the cast ingot under different smelting parameters is obtained through numerical simulation, a certain relation is established between solidification dynamic information in the cells and an actual solidification structure, and the macrostructure morphology of the titanium alloy cast ingot is predicted more rapidly and accurately.

The invention discloses a method for constructing a periodic directional solidification structure based on modulated ultrasound, and relates to the technical field of metal material preparation. The method comprises the following steps: smelting a metal raw material to obtain a metal melt; the metal melt is subjected to directional solidification, and periodic modulation ultrasound is applied to the front edge of a liquid-solid interface of the metal melt in the directional solidification process; and after periodical modulation ultrasound is applied, a periodical directional solidification structure with the grain size controllable and columnar / equiaxed crystals alternately appearing is obtained. According to the method, the sound field characteristics at the front edge of the liquid-solid interface in the directional solidification process can be detected in real time, feedback adjustment is conducted, and it is guaranteed that multi-mode ultrasonic treatment is efficient, stable, accurate and controllable.

The invention discloses a continuous casting production method of a medium carbon steel large round billet, which is characterized in that electromagnetic stirring is carried out in the following three solidification stages in the continuous casting process of the large round billet: (1) electromagnetic stirring is carried out at the middle lower part of a crystallizer, and the value range of magnetic field intensity distribution along the center line of the crystallizer is 0-10mT; (2) electromagnetic stirring is conducted at the position where the solidification rate of the casting blank ranges from 65% to 75%, and the value range of magnetic field intensity distribution ranges from 7 mT to 16 mT; and (3) electromagnetic stirring is conducted at the position where the solidification rate of the casting blank is 85%-90%, and the value range of magnetic field intensity distribution is 10-25 mT. The method acts on the casting blank in the appropriate solidification process, appropriate electromagnetic stirring force is applied, and macrosegregation of the large round blank is improved; the electromagnetic field is used for acting on three casting blanks in different solidification stages, on one hand, the flow field in the crystallizer can be improved, and the impact depth is reduced; and on the other hand, electromagnetic stirring is used in a casting flow area to reduce positive segregation of a CET area, the grain size of an equiaxed crystal area is refined, then the macrosegregation degree of a casting blank is reduced, and the carbon range is reduced.

The invention belongs to the technical field of electron beam high-temperature alloy preparation, and particularly relates to a high-temperature alloy thin-wall component additive manufacturing device and method. The device comprises a vacuum cavity, a powder feeding mechanism, a two-dimensional translation driving mechanism, a forming cylinder, a lifting platform, a horizontal moving platform, an electronic gun, a lifting mechanism, a pressure plate and an electromagnetic stirrer, wherein the lifting platform is arranged in the forming cylinder; the powder feeding mechanism is used for pushing high-temperature alloy powder; the horizontal moving platform is arranged on the two-dimensional translation driving mechanism, the electron gun is arranged on the horizontal moving platform, and the pressure plate is connected below the horizontal moving platform through the lifting mechanism; an electromagnetic stirrer is arranged on the pressure plate; and electron beams emitted by the electron gun irradiate the high-temperature alloy powder to form a molten pool, the electromagnetic stirrer conducts electromagnetic stirring on the molten pool, and the high-temperature alloy thin-wall component is manufactured through additive manufacturing. In the additive manufacturing process, a stirring magnetic field is provided, grains are refined, equiaxed crystals are achieved, meanwhile, the cooling gradient is slowed down, and solidification stress concentration and generation of micro cracks are eliminated.

The application belongs to the technical field of aluminum alloy additive manufacturing, and particularly relates to an in-situ strengthening method for improving the fracture toughness of aluminum alloy in additive manufacturing, which comprises the following steps: (1) preparation before additive manufacturing; drying high-strength aluminum alloy powder and then putting the powder into a powder feeder; (2) setting of a remelting width of a forming path; the remelting width is controlled by a laser scanning interval method or a line energy density method; and (3) additive manufacturing and heat treatment; through the setting of the remelting width, partial grain remelting and re-nucleation and growth are realized, at the bottom of a molten pool, new crystal nuclei form fine equiaxed crystals with Al3(Zr, Er) as the core instead of epitaxial columnar crystals; through the alternate distribution of the columnar crystals and the equiaxed crystals, the crack propagation resistance is increased, and the fracture toughness of the material is significantly improved, while the high-strength characteristics are maintained.

The invention provides a method for improving the hardenability of a gear steel bar and the gear steel bar, and belongs to the technical field of continuous casting process.The method comprises the steps that molten steel with qualified components is cast through a continuous casting machine; in the solidification stage, a reduction process is adopted; after solidification, the hot-state casting blank is rolled; in the continuous casting process, the superheat degree of a tundish is 40-45 DEG C, and the electromagnetic stirring current of a crystallizer is 50-150A; according to the reduction process, the reduction amount is controlled through the change of the center solid fraction of a casting blank, the center solid fraction of a reduction area is 0.05-1.0, and the reduction amount is not smaller than 1 mm and not larger than 3 mm in a continuous casting reduction area corresponding to the center solid fraction smaller than 0.3. And the rolling section compression ratio is not less than 90%. By controlling the degree of superheat, electromagnetic stirring of a crystallizer, a pressing process and a rolling process, an equiaxed crystal area of a casting blank and a bar is reduced, meanwhile, formation of semi-macroscopic point segregation of the equiaxed crystal area is restrained, and an as-cast structure of a bar hardenability detection area is converted into columnar crystals from equiaxed crystals; and the section solute range and standard deviation and dendritic structure solute distribution uniformity are further improved, the A and B surface difference values of J9 and J15 are both smaller than or equal to 1.5 HRC, the hardenability index is qualified, the subsequent gear heat treatment non-uniform distortion is reduced, and the product homogeneity is improved.

The application provides a method for rapidly improving the surface structure and roughness of a cast aluminum alloy part, and relates to the technical field of laser beam processing, and comprises the following steps: fixing the cast aluminum alloy part on a multi-axis movable object platform; using a continuous laser beam to scan the initial surface layer of the cast aluminum alloy part, and controlling the laser power and scanning speed to make adjacent molten pools continuously overlap to form a uniform molten layer; when the thickness of the uniform molten layer reaches a first preset thickness required for surface structure reconstruction, stopping the laser scanning; the uniform molten layer is self-cooled and solidified in a room temperature environment to form a solidified surface layer; wherein the solidified surface layer forms a submicron equiaxed crystal structure, and the roughness of the solidified surface layer is smaller than that of the initial surface layer. The method directly generates a submicron equiaxed crystal structure under the condition of room temperature self-solidification by accurately controlling the molten pool overlap and the cooling rate, and achieves the purpose of rapidly modifying the surface layer of the cast aluminum alloy part.

The application discloses an alloy vacuum self-consumption electric arc smelting magnetic pulse grain refining device, which comprises a vacuum self-consumption electric arc furnace body and a copper crucible, a metal molten pool is arranged in the copper crucible, a plurality of non-contact magnetic pulse coils are wound on the outer wall of the copper crucibble, and a water-cooling interlayer is arranged between the vacuum self-consumption electric arc furnace body and the copper crucible; a screw rod is arranged between the vacuum self-consumption electric arc furnace body and the copper crucible, and the screw rod is connected with a motor. The application further discloses a method for alloy vacuum self-consumption electric arc smelting magnetic pulse grain refining, cooling water is introduced into the water-cooling interlayer, a power supply of the vacuum self-consumption electric arc furnace is turned on for smelting, a pulse power supply is turned on when the height of the metal molten pool formed at the bottom of the copper crucible reaches 50 mm, and the plurality of non-contact magnetic pulse coils are uniformly moved upwards until the process is finished. The metal molten pool is directionally treated by electromagnetic pulse in a moving mode, the columnar crystal-equiaxed crystal transition is realized in the alloy ingot preparation process, the grain is refined, and segregation is reduced, so that the overall organization of the large-size long ingot is refined.

A segmented roller multi-mode electromagnetic stirring flow control device for the secondary cooling zone of continuous casting includes two pairs of electromagnetic stirring rollers arranged in parallel, each pair of electromagnetic stirring rollers includes an electromagnetic stirring upper roller and a lower roller, the slab is located between the two pairs of electromagnetic stirring rollers, and gaps are left between the slab and the upper roller and the lower roller; the electromagnetic stirring upper roller and the electromagnetic stirring lower roller have the same structure, both adopt a segmented roller structure, the roller body has four sections, each roller body includes an iron core and a coil, the coil is coaxially wound on the iron core, an insulating sheet is arranged between adjacent coils, and all coils are equipped with a cooling device. The present invention generates a constant alternating magnetic field by energizing the coil, forms an induced current in the molten steel, and then generates an electromagnetic force, which acts on the molten steel, promotes the fluidity of the molten steel inside the shell, drives heat transfer and solute migration, realizes the expansion of the equiaxed crystal zone, the uniformity of the solute composition, the improvement of the loose shrinkage cavity, the improvement of the solidification hysteresis, and the reduction of the generation of the "white bright band", thereby improving the quality of wide and thick slabs.

The invention relates to a method and a device for regulating and controlling the structure performance of a nickel-based high-temperature alloy in pulse laser-assisted additive manufacturing, and belongs to the technical field of additive manufacturing. The method comprises the following steps: controlling the oxygen content in a sealed forming cabin of an LPBF forming device, and paving nickel-based high-temperature alloy powder on a substrate of the sealed forming cabin; and the pulse laser and the continuous laser are controlled to output laser beams, the pulse laser beams and the continuous laser beams are coupled in a polarization beam combination or wavelength beam combination mode, and after the focal length of the coupled laser beams is adjusted, the nickel-based superalloy powder on the substrate is subjected to fusion forming. According to the method, the pulse laser and the continuous laser are coupled into the coaxial light spots, in-situ synchronous disturbance on the molten pool in the LPBF additive manufacturing process is achieved, the solidification behavior of the nickel-based high-temperature alloy can be accurately regulated and controlled, epitaxial growth of columnar crystals is effectively broken, formation of fine isometric crystals is promoted, and the yield of the nickel-based high-temperature alloy is improved. And the anisotropy and cracking risk of the material can be reduced.

The invention belongs to the technical field of laser welding defect prediction, and discloses an aluminum alloy laser welding seam three-dimensional solidification crack sensitivity prediction method, which comprises the following steps: accurately calculating a lap joint temperature / solid fraction (TB / fB) and a T-fS curve of adjacent dendrites of a polycrystalline structure in a welding seam pasty area through laser welding macro-micro thermal mass coupling simulation; a novel solidification crack sensitivity prediction method fusing microstructure information is provided, accurate prediction of the solidification crack sensitivity of aluminum alloy laser welding is achieved, the solidification crack inhibition mechanism that an ultra-fine equiaxed crystal structure shortens an intergranular liquid phase channel and reduces solute segregation is disclosed, and the stability of the solidification crack sensitivity is improved. The method has very important engineering application significance for realizing solidification crack-free welding of the high-strength aluminum alloy thick-wall component.