CN114260330B - Accurate preparation method of superfine crystal tissue thin-wall conical part - Google Patents
Accurate preparation method of superfine crystal tissue thin-wall conical part Download PDFInfo
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Abstract
The application provides a precise preparation method of an ultrafine grain tissue thin-wall conical part, which sequentially carries out multi-pass cold extrusion forming, cold-hot synergistic surface grain refining and precise shaping; the multi-pass cold extrusion forming is to place the blank under the action of three-way compressive stress to carry out multi-pass extrusion deformation; the cold and hot synergistic surface grain refining is laser surface treatment, and adopts liquid nitrogen atomized gas to perform oxidation protection and rapid cooling; the precise shaping is to perform multipass shaping under the three-way compressive stress. The application ensures that the grain structure on the inner surface of the prepared thin-wall conical part is ultrafine and crystallized, and has high dimensional accuracy and good geometric symmetry. The superfine crystal gradient structure distributed along the thickness direction of the member is obtained by the method, and the structure is uniformly distributed along the direction of the bus, so that the comprehensive use performance of the thin-wall conical member is provided.
Description
Technical Field
The application relates to the technical field of metal plastic forming, in particular to a precise preparation method of an ultrafine grain tissue thin-wall conical part.
Background
Energy-accumulating jet, explosion-formed pellets require high penetration damage performance, and jet penetration capability is positively correlated with continuous jet length, while the internal quality of the material is one of the key factors of continuous jet and penetration performance. In particular, the grain structure of the metallic material, such as grain size, grain orientation, and other intrinsic performance parameters, has a significant impact on penetration efficiency.
The thin-wall conical part has great processing difficulty due to the structural characteristics of thin wall and conical shape, the conventional large plastic deformation technology mainly comprises conventional extrusion or forging, reversing rolling and equal channel extrusion methods, and the processes have various defects when processing the thin-wall conical part: (1) The grain size is uneven, and mixed crystal structures exist in a deformation weak area or a severe deformation area; (2) the anisotropy of the rolled plate is large; (3) The yield of the equal channel extrusion material is low, and the performance consistency is poor; (4) The fine grain organization preparation process is long, complex and difficult by a single process; (5) The inner surface layer of the thin-wall conical part can form a main body of effective jet flow, which accounts for about 20 percent of the total weight, and the whole preparation cost is high by adopting a large-size ultrafine crystal material.
Disclosure of Invention
The application solves the technical problem of providing a precise preparation method of a thin-wall conical part, wherein the prepared product has an ultrafine grain structure, and the whole components such as a deformation weak area, a severe deformation area and the like of the thin-wall conical part have uniform ultrafine grains.
The application is realized by the following technical scheme:
the precise preparation process of superfine crystal structure thin-wall conic part includes cold extrusion forming, surface grain refining and precise shaping; the multi-pass cold extrusion forming is to place the blank under the action of three-way compressive stress to carry out multi-pass extrusion deformation; the cold and hot synergistic surface grain refining is laser surface treatment, and adopts liquid nitrogen atomized gas to perform oxidation protection and rapid cooling; the precise shaping is to perform multipass shaping under the three-way compressive stress.
Preferably, the deformation rate of the multi-pass cold extrusion forming is 5-10 mm/s, and the deformation amount of each pass is 5-60% after the extrusion deformation of 5-10 passes. The extrusion deformation of 5-10 passes designs the procedures of required deformation passes, deformation quantity and the like according to the shape and structure characteristics of the caliber size, the inner cone angle, the inner cone depth, the wall thickness and the like of the conical member, the extrusion deformation passes of small-size and simple-shape parts are few, and the deformation passes of the conical member with the same caliber in a single cone angle structure are fewer than those of the conical member with the same caliber in a double cone angle structure. The deformation amount is 5-60%, the deformation amount of each pass is reasonably distributed according to the deformation pass and the structural characteristics of the part, the deformation amount of the corresponding pass is reduced along with the increase of the deformation pass, and the plastic forming of the conical member is controlled through the step deformation amount.
Preferably, the cold and hot synergistic surface is fine crystallized, the laser power is 50-200W, and the laser power input size is determined according to the depth of a heat treatment layer of 0.01-0.8 mm and the diameter of a light spot of 0.1-5 mm; the scanning line speed of the light beam is 1-5 m/min, and the scanning line speed of the light beam is determined according to the laser power; the liquid nitrogen atomizing gas is converted into gas by adopting a liquid nitrogen atomizing device and is sprayed around the laser light spots, so that the rapid cooling effect is achieved, and the flow rate of the nitrogen is 120-300 ml/min.
Preferably, the precise shaping deformation rate is 2-5 mm/s, and the shaping is carried out for 2-6 times; and (3) shaping for 2-6 times, and determining shaping times according to the shape, caliber and other parameters of the conical member.
The surface of the blank and the inner surface of the die cavity are coated with lubricant in multi-pass cold extrusion forming, the lubricant comprises one or more of common lubricants such as tea oil, fine blanking oil, castor oil and rapeseed oil, and the lubricant is coated on the surfaces of the blank and the die cavity in each pass of forming process, so that friction force between the contact surface of the blank and the die is reduced, metal fluidity in the forming process is improved, and surface quality of a formed member is improved.
Preferably, the precise preparation method of the superfine crystal tissue thin-wall conical part further comprises the steps of preparing a blank before multi-pass cold extrusion forming, placing the blank into a vacuum heat treatment furnace for high-temperature stress relief treatment, cooling the blank with the furnace to below 100 ℃ for 1-4 hours at the temperature of 450-650 ℃ and discharging the blank from the furnace, wherein the vacuum degree is more than or equal to 3 multiplied by 10 -3 Pa。
Preferably, the precise preparation method of the superfine crystal tissue thin-wall conical part comprises the steps of carrying out complete stress relief heat treatment after cold and hot synergistic surface grain refining and before precise shaping, wherein the heat treatment temperature is 200-300 ℃, the heat treatment time is 4-12 h, and the vacuum degree is more than or equal to 3 multiplied by 10 -3 Pa。
The precise preparation method of the superfine crystal tissue thin-wall conical part is realized through the following process steps:
(1) Preparing a blank: calculating the volume of a material according to a structure diagram of the thin-wall conical part, selecting proper blank size according to a plastic forming method and a near-uniform plastic deformation principle, and cutting the length of a corresponding bar according to the plastic forming volume unchanged principle, wherein the diameter phi of the bar is 30-120 mm, and the brand of the material can be Ta, taW2.5, TU1 and other materials; placing the blank into a vacuum heat treatment furnace for high-temperature stress relief treatment, wherein the heat treatment temperature is 450-650 ℃, the heat treatment time is 1-4 hours, then cooling the blank with the furnace to below 100 ℃ and discharging the blank, and the vacuum degree is more than or equal to 3 multiplied by 10 -3 Pa, the hardness of the raw material is reduced, the uneven stress distribution is improved, and the plastic deformation performance is improved.
(2) Multi-pass cold extrusion forming: placing the blank obtained in the step (1) into an extrusion die cavity, under the action of three-way compressive stress, the deformation rate is 5-10 mm/s, the deformation amount of each pass is 5-60% through extrusion deformation of 5-10 passes, a layer of lubricant is coated on the surface of the blank and the inner surface of the die cavity in the forming process, and a conical member with uniform deformation is obtained through multi-pass extrusion forming, wherein the circumferential wall thickness difference is less than or equal to 0.2mm.
(3) Cold and hot synergistic surface grain refining: cleaning the surface of the conical member obtained in the step (2), carrying out laser surface treatment, wherein the laser power is 50-200W, the light spot diameter is 0.1-5 mm, the light beam scanning linear speed is 0.05-0.5 m/min, adopting liquid nitrogen atomized gas to carry out oxidation protection and rapid cooling (the nitrogen flow is 120-300 ml/min), the depth of a heat treatment layer is 0.05-0.5 mm, carrying out static recrystallization treatment through cold and hot cooperative input, eliminating the fibrous tissue deformed by extrusion, and the average grain size is 0.2-1 mu m.
(4) And (3) completely stress-relieving heat treatment: carrying out complete stress relief heat treatment on the conical member obtained in the step (3) in a vacuum heat treatment furnace, wherein the heat treatment temperature is 200-300 ℃, the heat treatment time is 4-12 h, and the vacuum degree is more than or equal to 3 multiplied by 10 -3 Pa。
(5) And (3) precise shaping: and (3) placing the conical member obtained in the step (4) into a die cavity of an extrusion die, and shaping for 2-6 times under the action of three-dimensional compressive stress and deformation rate of 2-5 mm/s, wherein the deformation of each time is less than or equal to 2%, so that the inner cone angle deviation of the conical member is less than or equal to 2', the circumferential wall thickness difference is less than or equal to 0.1mm, and the surface roughness reaches Ra0.1 mu m.
Advantageous effects
1. The application mainly comprises the steps of multipass cold extrusion forming, laser cold and hot cooperated surface quenching treatment grain refining, stress relief heat treatment, precise shaping and the like (figure 1), realizes uniform deformation controllability of the internal tissues of the conical member, and obtains the geometric dimension to meet the requirements of the formed member; realizing tiny homogenization of the grain structure on the inner surface; the brightening and the dimensional accuracy of the inner cone surface of the component are realized. The application ensures that the grain structure on the inner surface of the prepared thin-wall conical part is ultrafine and crystallized, and has high dimensional accuracy and good geometric symmetry. The superfine crystal gradient structure distributed along the thickness direction of the member is obtained by the method, and the structure is uniformly distributed along the direction of the bus, so that the comprehensive use performance of the thin-wall conical member is provided.
2. According to the application, from the relation between the continuous jet length and penetration efficiency and from the theory of metal material grain boundary, the thinner and uniform crystal grains of the thin-wall conical part can obviously improve isotropy, yield ratio and ductility, and further improve the damage power of the warhead. According to the velocity gradient effect of the energy-gathering jet flow of the thin-wall conical part, the application provides a precise preparation method of the ultrafine grain tissue thin-wall conical part.
The application solves the technical problems of mixed crystal inside the component, poor uniformity of crystal grain morphology, poor dimensional accuracy and the like obtained by the conventional preparation method, and has the advantages of high production efficiency, good process stability, environmental protection, easy realization of industrial production and the like.
(1) The product has good performance. The structure density is high, the average grain size is not more than 2 mu m, and the stability and the ductility of the conical member jet flow under the action of high temperature and high pressure are better.
(2) The product size consistency is good. The cone angle deviation is less than or equal to 2', the circumferential wall thickness difference is less than or equal to 0.1mm, and the surface roughness reaches Ra0.1μm.
(3) The utilization rate of the product materials is high. The outer surface of the conical member only leaves 0.4-1 mm of machining allowance, and the inner surface is not machined at all, so that the material utilization rate can be remarkably improved.
(4) The product quality is high-efficient and controllable. The required tissue performance and geometric structure are obtained by controlling the technological parameters such as deformation pass, deformation, temperature, time and the like in a narrow specification, and the high-efficiency and controllable product quality is realized.
Drawings
FIG. 1 is a flow chart of a process for preparing a conical member
FIG. 2 is a multi-pass extrusion process diagram of a tapered member
FIG. 3 microstructure after multipass extrusion deformation
FIG. 4 morphology after cold and hot synergistic surface treatment
FIG. 5 fine grain structure
FIG. 6 metallographic microscope method for testing sampling position of grain structure sample
FIG. 7 metallographic microscope method for grain structure of different parts
FIG. 8 is a typical site grain structure
Detailed Description
The application is further illustrated below with reference to specific examples.
Example 1
The precise preparation method of the superfine crystal tissue thin-wall conical part comprises the following steps:
(1) Preparation of a blank: taking a wall thickness-variable component with a double-cone structure as an example, wherein the caliber size is phi 200mm, the height is 280mm, the depth of an inner cone is 240mm, the wall thickness is 4.5-6.5 mm, the small cone angle is 30 degrees, the large cone angle is 70 degrees, and the transitional circular arc between the large cone angle and the small cone angle is R250mm at the top of the component; according to the plastic forming theory and the near-uniform plastic deformation theory, reserving a machining allowance of 0.8mm on the outer surface of the conical member, and designing a forming process handle with the diameter of 35mm on the conical top of the member; simulation analysis and optimization are carried out on the forming process by adopting UG and DEFORM software, the volume of a blank is calculated, an extruded TU1 copper rod with phi 90mm is selected as a raw material (R state), and the blank with the diameter of 88mm and the height of 76mm is manufactured by blanking and turning the outer surface.
Preserving the blank in a VQG-2500 intelligent temperature-controlled vacuum heat treatment furnace at 550+ -5deg.C for 1.5 hr with vacuum degree of 1.5X10 -3 Pa, carrying out heat preservation and heat treatment, cooling to 80 ℃ along with a furnace, and discharging to obtain a blank with uniform structure and hardness distribution, wherein the hardness is HB 35-38 through test.
(2) Multi-pass cold extrusion forming: and (3) placing the blank obtained in the step (1) into a die cavity of an extrusion die, performing 9-pass extrusion deformation under the action of three-way compressive stress and a certain deformation rate to obtain a thin-wall conical member, wherein the forming process is shown in figure 2, and the deformation distribution of each pass is shown in table 1. The multi-pass extrusion forming die comprises a female die system, a male die system and an ejection system, wherein the multi-pass extrusion forming device is a cold extruder with 20MN, the deformation rate is 5-10 mm/s, the female die system of the extrusion die is arranged on the working table of the press, the ejection system is connected with an ejection mechanism of the press, the male die system is connected with a working slide block of the press, the working slide block of the press drives an extrusion male die to apply extrusion forming force, and the extrusion male die is matched with the extrusion female die to enable a blank to be in a three-way compressive stress state. The first pass is the forward extrusion large deformation of the blank, and a conical blank is obtained; the subsequent 2-9 times of forming is reaming extrusion forming (the deformation is not more than 40%), so that the wall part of the component is gradually thinned, the work hardening effect is enhanced along with the increase of the extrusion pass, and the deformation is gradually reduced; the final forming is carried out in the last 1 pass, so that the dimensional accuracy and dimensional stability of the formed piece are improved, and the deformation is generally less than 10%.
TABLE 1 deformation process parameters etc
After multi-pass extrusion deformation, the geometric dimension of the component meets the design requirement, and the circumferential wall thickness difference is 0.05-0.2 mm.
(3) Cold and hot synergistic surface grain refining: cleaning the surface of the conical member obtained in the step (2), and then carrying out laser surface treatment, wherein the laser power is 120W, the spot diameter is 0.2mm, and the beam scanning linear speed is 0.3m/min; the synergistic atomizing device sprays liquid nitrogen to form gas around the laser light spots, so that the rapid cooling and oxidation preventing effects are achieved, the nitrogen flow is 200ml/min, the depth of a heat treatment layer is 0.15mm, and the extrusion deformation fibrous tissue is eliminated through static recrystallization.
(4) And (3) completely stress-relieving heat treatment: carrying out complete stress relief heat treatment on the conical member obtained in the step (3) in a vacuum heat treatment furnace, wherein the heat treatment temperature is 280 ℃, the heat treatment time is 2h, and the vacuum degree is more than or equal to 3 multiplied by 10 -3 Pa。
(5) And (3) precise shaping: and (3) placing the conical member obtained in the step (4) into a die cavity of an extrusion die, shaping for 4 times under the action of three-dimensional compressive stress and deformation rate of 5mm/s, wherein the deformation of each time is less than or equal to 2%, the internal cone angle deviation of the obtained conical member is-0.9 'to 1.5', the circumferential wall thickness difference is 0.02 to 0.08mm, and the surface roughness is 0.02 to 0.07 mu m.
The prepared product has the following properties:
1. the grain structure is tested along the wall thickness direction and the bus direction of the component by adopting a metallographic microscope method (3 layers of samples, namely, tip, middle and port positions are taken on a bus, 4 samples are taken on each layer, and 12 samples are taken in total, as shown in figure 6), the samples are subjected to rough grinding, fine grinding and polishing treatment, finally, the samples are corroded by adopting nitric acid aqueous solution, the samples are amplified by 500 times under the metallographic microscope, and the average grain size of the component in the wall thickness direction is 0.5-1 mu m and the average grain size of the component in the bus direction is 0.5-1.2 mu m (figure 7) by adopting an area method or a sectional line method (3 positions are counted for each sample).
2. The grain structure of the tip portion (severe deformation region) and the mouth portion (weak deformation region) of the tapered member was studied by using the EBSD analysis method (FIG. 8), and the grain size of the severe deformation region of the tip portion was 0.01 to 0.1 μm and the grain size of the weak deformation region of the mouth portion was 0.1 to 1 μm by automatic statistical calculation.
3. By adopting a mechanical property test, the room temperature tensile strength is 240-270 MPa, the elongation after breaking is 54-60 percent (compared with the elongation after breaking of the initial material is less than 50 percent, the elongation after breaking is improved by 10-20 percent), and the impact absorption energy is 160-180J under the quasi-static tensile test condition; at a strain rate of 10 4 Under the condition, the impact deformation reaches more than 95%, and the surface of the sample has no defects such as cracks and the like.
4. The comprehensive use performance assessment is adopted, firstly, a pulse X-ray photographic test is carried out, and the effective jet length, head speed, collimation and the like of the component under the detonation action of the explosive are obtained, wherein the effective jet length is increased by more than 30% compared with the traditional product; and secondly, a static nail breaking test is carried out on a certain reference test device, and compared with the traditional product, the static nail breaking depth is improved by more than 12%.
Example 2
The precise preparation method of the superfine crystal tissue thin-wall conical part comprises the following steps:
(1) Preparation of a blank: taking an equal wall thickness component with a single cone structure as an example, wherein the caliber size is phi 150mm, the height is 175mm, the depth of an inner cone is 148mm, the maximum wall thickness is 3.2mm, the inner cone angle is 60 degrees, the processing allowance of 0.5mm is reserved on the outer surface of a multipass extrusion forming piece according to the plastic processing forming theory and the near uniform plastic deformation principle, and a forming process handle of phi 25mm is designed on the top of the forming piece; simulating the forming process by adopting UG and DEFORM software, calculating the volume of the blank, selecting a drawing Ta copper rod with phi 70mm as a raw material (R state), blanking and turning the outer surface to prepare the blank with the diameter of 68mm and the height of 56 mm.
Preserving the blank in a VQG-2500 intelligent temperature-controlled vacuum heat treatment furnace at 480+ -5deg.C for 2h with a vacuum degree of 1.5X10 -3 Pa, carrying out heat preservation and heat treatment, cooling to 80 ℃ along with a furnace, and discharging to obtain a blank with uniform components and tissues, wherein the hardness is HB 32-40 after test.
(2) Multi-pass cold extrusion forming: and (3) placing the blank obtained in the step (1) into a die cavity of an extrusion die, and performing 8-pass extrusion deformation under the action of three-way compressive stress and a certain deformation rate, wherein the deformation amount distribution of each pass is shown in table 2. The multi-pass extrusion forming die comprises a female die system, a male die system and an ejection system, wherein the multi-pass extrusion forming device is a cold extruder with 20MN, the deformation rate of a press is 5-10 mm/s, the female die system of the extrusion die is arranged on a working table of the press, the ejection system is connected with an ejection mechanism of the press, the male die system is connected with a working slide block of the press, the working slide block of the press drives an extrusion male die to apply extrusion forming force, and the extrusion male die is matched with the extrusion female die to enable blanks to be in a three-dimensional stress state. The first pass is the forward extrusion large deformation of the blank, and a conical blank is obtained; the subsequent 2-8 times of forming is reaming extrusion forming (the deformation is less than 40%), so that the wall part of the conical member is gradually thinned, the work hardening effect is enhanced along with the increase of the extrusion pass, and the deformation is gradually reduced; the final forming is carried out in the last 1 pass, so that the dimensional accuracy and dimensional stability of the formed piece are improved, and the deformation is generally less than 10%. After multiple times of extrusion deformation, the conical component with the required shape, size, surface quality and certain mechanical property is obtained.
TABLE 2 deformation process parameters and the like
After multi-pass extrusion deformation, the geometric dimension of the conical member meets the design requirement, and the circumferential wall thickness difference is 0.03-0.15 mm.
(3) Cold and hot synergistic surface grain refining: cleaning the surface of the conical member obtained in the step (2), and then carrying out laser surface treatment, wherein the laser power is 75W, the spot diameter is 0.1mm, and the beam scanning linear speed is 0.18m/min; the synergistic atomizing device sprays liquid nitrogen to form gas around the laser light spots, so that the rapid cooling and oxidation preventing effects are achieved, the nitrogen flow is 300ml/min, the depth of a heat treatment layer is 0.2mm, and the extrusion deformation fibrous tissue is eliminated through static recrystallization.
(4) And (3) completely stress-relieving heat treatment: the conical component obtained in the step (3) is in truePerforming complete stress relief heat treatment in an air heat treatment furnace at 260 ℃ for 2h with vacuum degree not less than 3 multiplied by 10 -3 Pa。
(5) And (3) precise shaping: and (3) placing the conical member obtained in the step (4) into a die cavity of an extrusion die, shaping for 3 times under the action of three-way compressive stress and deformation rate of 5mm/s, wherein the deformation of each time is less than or equal to 2%, the inner cone angle deviation of the conical member is-0.6 '-1.8', the circumferential wall thickness difference is 0.02-0.08 mm, and the surface roughness reaches 0.01-0.05 mu m.
The prepared product has the following properties:
1. the grain structure is tested along the wall thickness direction and the bus direction of the component by adopting a metallographic microscope method (3 layers of samples, namely, tip, middle and port positions are taken on a bus, 4 samples are taken on each layer, and 12 samples are taken in total, as shown in figure 6), the samples are subjected to rough grinding, fine grinding and polishing treatment, finally, the samples are corroded by adopting nitric acid aqueous solution, the samples are amplified by 500 times under the metallographic microscope, and the average grain size of the component in the wall thickness direction is 0.8-1.7 mu m and the average grain size of the component in the bus direction is 0.9-1.5 mu m (figure 7) by adopting an area method or a sectional line method (3 positions are counted for each sample).
2. The grain structure of the tip portion (severe deformation region) and the mouth portion (weak deformation region) of the conical member was studied by using an EBSD analysis method (FIG. 8), and the grain size of the severe deformation region of the tip portion was 0.02 to 0.11 μm and the grain size of the weak deformation region of the mouth portion was 0.2 to 1.5 μm by automatic statistical calculation.
3. By adopting a mechanical property test, under the quasi-static tensile test condition, the room temperature tensile strength is 230-265 MPa, the elongation after breaking is 53-61 percent (compared with the elongation after breaking of the initial material is less than 50 percent, the impact absorption energy is improved by about 15J) and the impact absorption energy is 140-175J; at a strain rate of 10 4 Under the condition, the impact deformation reaches more than 95%, and the surface of the sample has no defects such as cracks and the like.
4. The comprehensive use performance assessment is adopted, firstly, a pulse X-ray photographic test is carried out, and the effective jet length, head speed, collimation and the like of the component under the detonation action of the explosive are obtained, wherein the effective jet length is increased by more than 30% compared with the traditional product; and secondly, a static nail breaking test is carried out on a certain reference test device, and compared with the traditional product, the static nail breaking depth is improved by more than 15%.
The results show that:
the accumulated large plastic deformation is adopted, so that the uniform deformation of the internal tissues of the conical member is realized, the geometric dimension is obtained, and the requirement of the shape element of the formed member is met; the inner surface of the component is refined and quantitatively heat-treated for refining by the cold and hot cooperated with surface refining, so that fine and uniform grain structure of the inner surface is realized; and the precise cold extrusion shaping technology is applied to realize the brightening and the dimensional refinement of the inner cone surface of the component. The method has the advantages that the circumferential wall thickness difference of the member is 0.01-0.08 mm, the inner surface roughness Ra0.01-0.1 mu m and the cone angle deviation less than or equal to 2', the internal tissue structure has superfine crystallization, the physical characteristics of fine crystal materials are fully utilized, the cohesiveness and the stability of jet flow can be obviously improved, and the damage efficiency is increased.
Claims (3)
1. The precise preparation method of the superfine crystal tissue thin-wall conical part sequentially comprises the steps of blank preparation, multi-pass cold extrusion forming, cold-hot synergistic surface grain refining, complete stress-relief heat treatment and precise shaping;
the blank is prepared by placing the blank into a vacuum heat treatment furnace for high-temperature stress relief treatment, wherein the heat treatment temperature is 450-650 ℃, the heat treatment time is 1-4 hours, and then cooling the blank with the furnace to below 100 ℃ and discharging the blank, and the vacuum degree is more than or equal to 3 multiplied by 10 -3 Pa；
The multi-pass cold extrusion forming is to place the blank under the action of three-way compressive stress to carry out multi-pass extrusion deformation; the deformation rate of the multi-pass cold extrusion forming is 5-10 mm/s, and the deformation amount of each pass is 5-60% after the extrusion deformation of 5-10 passes;
the cold and hot synergistic surface grain refining is laser surface treatment, and adopts liquid nitrogen atomized gas to perform oxidation protection and rapid cooling; the laser power of the laser surface treatment is 50-200W, the diameter of a light spot is 0.1-5 mm, the scanning linear speed of a light beam is 0.05-0.5 m/min, the depth of a heat treatment layer is 0.05-0.5 mm, and the flow rate of nitrogen is 120-300 ml/min;
the fully destressing heat treatment: subjecting the component to a fully destressing heat treatment in a vacuum heat treatment furnace, whereThe treatment temperature is 200-300 ℃, the heat treatment time is 4-12 h, and the vacuum degree is more than or equal to 3 multiplied by 10 -3 Pa；
The precise shaping is to perform multipass shaping under the three-way compressive stress; the precise shaping deformation rate is 2-5 mm/s, and the shaping is carried out for 2-6 times.
2. The precise preparation method of the superfine crystal tissue thin-wall conical part according to claim 1, wherein the surface of a blank and the inner surface of a die cavity in multi-pass cold extrusion forming are coated with a lubricant, and the lubricant comprises one or more of tea oil, fine blanking oil, castor oil and common rapeseed oil lubricants.
3. The precise preparation method of the superfine crystal tissue thin-wall conical piece according to claim 1 or 2, comprising the following steps:
(1) Preparing a blank: selecting a bar material, wherein the diameter phi of the bar material is 30-120 mm, and the material mark is Ta, taW2.5 or TU 1; placing the blank into a vacuum heat treatment furnace for high-temperature stress relief treatment, wherein the heat treatment temperature is 450-650 ℃, the heat treatment time is 1-4 hours, then cooling the blank with the furnace to below 100 ℃ and discharging the blank, and the vacuum degree is more than or equal to 3 multiplied by 10 -3 Pa；
(2) Multi-pass cold extrusion forming: placing the blank obtained in the step (1) into an extrusion die cavity, under the action of three-way compressive stress, enabling the deformation rate to be 5-10 mm/s, performing extrusion deformation for 5-10 times, enabling the deformation of each pass to be 5-60%, and coating lubricant on the surface of the blank and the inner surface of the die cavity in the forming process;
(3) Cold and hot synergistic surface grain refining: cleaning the surface of the conical member obtained in the step (2), performing laser surface treatment, wherein the laser power is 50-200W, the light spot diameter is 0.1-5 mm, the light beam scanning line speed is 0.05-0.5 m/min, performing anti-oxidation protection and rapid cooling by adopting liquid nitrogen atomized gas, the nitrogen flow is 120-300 ml/min, and the heat treatment layer depth is 0.05-0.5 mm;
(4) And (3) completely stress-relieving heat treatment: carrying out complete stress relief heat treatment on the conical member obtained in the step (3) in a vacuum heat treatment furnace, wherein the heat treatment temperature is 200-300 ℃, the heat treatment time is 4-12 h,vacuum degree is more than or equal to 3 multiplied by 10 -3 Pa；
(5) And (3) precise shaping: and (3) placing the conical member obtained in the step (4) into a die cavity of an extrusion die, and shaping for 2-6 times under the action of three-dimensional compressive stress and deformation rate of 2-5 mm/s, wherein the deformation of each time is less than or equal to 2%, so that the inner cone angle deviation of the conical member is less than or equal to 2', the circumferential wall thickness difference is less than or equal to 0.1mm, and the surface roughness reaches Ra0.1 mu m.
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