CN114260330A - Accurate preparation method of ultrafine-grained tissue thin-wall conical part - Google Patents
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Abstract
The invention provides an accurate preparation method of an ultrafine-grained tissue thin-wall conical part, which comprises the steps of carrying out multi-pass cold extrusion forming, cold-hot synergistic surface grain refining and accurate shaping in sequence; the multi-pass cold extrusion forming is to place the blank under the action of three-dimensional compressive stress to carry out multi-pass extrusion deformation; the cold and hot cooperative surface grain refining is laser surface treatment and adopts liquid nitrogen atomizing gas to perform anti-oxidation protection and rapid cooling; the precise shaping is to carry out multi-pass shaping on the three-way compressive stress. The invention leads the grain structure of the inner surface of the prepared thin-wall conical piece to be ultra-fine grained, and has high dimensional precision and good geometric symmetry. The ultrafine grain gradient structure distributed along the thickness direction of the member is obtained by the method, and the structure is uniformly distributed along the bus direction, so that the comprehensive use performance of the thin-wall conical member is provided.
Description
Technical Field
The invention relates to the technical field of metal plastic forming, in particular to an accurate preparation method of an ultra-fine grain tissue thin-wall conical piece.
Background
Energy-gathering jet flow and explosive forming of the shot need high penetration and damage efficiency, the penetration capability of the jet flow is positively correlated with the length of the continuous jet flow, and the internal quality of the material is one of the key factors of the continuous jet flow and the penetration efficiency. 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 performance.
The thin-wall conical part has the structural characteristics of thin wall and conical shape, the processing difficulty is high, the conventional large plastic deformation technology is mainly based on the conventional extrusion or forging, reversing rolling, equal channel extrusion methods, and the processes have a plurality of defects when the thin-wall conical part is processed: (1) the grain size is not uniform, and mixed crystal structure exists in a weak deformation area or a severe deformation area; (2) the anisotropy of the rolled plate is large; (3) the equal channel extrusion material has low yield and poor performance consistency; (4) the fine grain structure preparation process is long, complex and difficult through a single process; (5) the inner surface layer of the thin-wall conical part can form a main body of effective jet flow, the main body accounts for about 20% of the total weight, and the whole preparation cost is high by adopting large-size ultrafine crystal materials.
Disclosure of Invention
The technical problem to be solved by the invention is to provide an accurate preparation method of a thin-wall conical part, wherein the prepared product has an ultrafine grain structure, and the whole components of a deformation weak area, a severe deformation area and the like of the thin-wall conical part have uniform ultrafine grains.
The invention is realized by the following technical scheme:
an accurate preparation method of an ultra-fine grain structure thin-wall conical part sequentially carries out multi-pass cold extrusion forming, cold-hot synergistic surface grain refining and accurate shaping; the multi-pass cold extrusion forming is to place the blank under the action of three-dimensional compressive stress to carry out multi-pass extrusion deformation; the cold and hot cooperative surface grain refining is laser surface treatment and adopts liquid nitrogen atomizing gas to perform anti-oxidation protection and rapid cooling; the precise shaping is to carry out multi-pass shaping on 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 5-10 passes of extrusion deformation. The 5-10-pass extrusion deformation is characterized in that required deformation passes, deformation amount and other procedures are designed according to the shape structure characteristics of the conical component such as the caliber size, the inner cone angle, the inner cone depth and the wall thickness, the extrusion deformation passes of parts with small size and simple shape are few, and the deformation passes of a single-cone-angle structure with the same caliber conical component internal shape are less than those of a double-cone-angle structure. The deformation is 5-60%, the deformation of each pass is reasonably distributed according to the deformation passes and the structural characteristics of the part, the pass deformation corresponding to the increase of the deformation passes is reduced, and the plastic forming of the conical component is controlled through the stepped deformation.
Preferably, the cold and hot cooperative surface is subjected to grain refining, 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 linear speed of the light beam scanning is 1-5 m/min, and the linear speed of the light beam scanning is determined according to the power of the laser; and (3) atomizing the liquid nitrogen into gas by adopting a liquid nitrogen atomizing device, and spraying the gas around the laser spot to play a role in quickly cooling, wherein the flow rate of the nitrogen is 120-300 ml/min.
Preferably, the precise shaping deformation rate is 2-5 mm/s, and shaping is performed for 2-6 times; and the 2-6-pass shaping is carried out, and the shaping times are determined according to parameters such as the shape and the caliber of the conical component.
The lubricant is mixed with one or more of common lubricants such as tea oil, refined oil, castor oil, rapeseed oil and the like, and is coated on the surfaces of the blank and the die cavity in each forming process, so that the friction force between the blank and the die contact surface is reduced, the metal fluidity in the forming process is improved, and the surface quality of a formed component is improved.
Preferably, the accurate preparation method of the ultrafine grained tissue thin-wall conical piece further comprises the step of preparing a blank before multi-pass cold extrusion forming, wherein the blank is placed into a vacuum heat treatment furnace for high-temperature stress relief treatment, the heat treatment temperature is 450-650 ℃, the heat treatment time is 1-4 hours, the blank is cooled to be below 100 ℃ along with the furnace and is discharged, and the vacuum degree is more than or equal to 3 x 10-3Pa。
Preferably, in the accurate preparation method of the ultrafine-grained tissue thin-wall conical part, after cold and hot cooperative surface grain refining, complete stress relief heat treatment is carried out before accurate shaping, 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 10-3Pa。
An accurate preparation method of an ultra-fine grain tissue thin-wall conical part is realized by the following process steps:
(1) preparing a blank: calculating the material volume according to the structure diagram of the thin-wall conical part, selecting a proper blank size according to a plastic processing forming method and a nearly uniform plastic deformation principle, and cutting the corresponding length of a bar material according to the plastic forming volume invariant principle, wherein the diameter of the bar material is phi 30-120 mm, and the material brand can be Ta, TaW2.5, TU1 and other materials; putting the blank into a vacuum heat treatment furnace for high-temperature stress relief treatment at the temperature of 450-650 ℃ for 1-4 h, cooling the blank to the temperature below 100 ℃ along with the furnace, discharging the blank from the furnace, wherein the vacuum degree is more than or equal to 3 multiplied by 10-3Pa, reducing the hardness of raw materials, improving uneven stress distribution and improving plastic deformation performance.
(2) Multi-pass cold extrusion forming: putting the blank obtained in the step (1) into an extrusion die cavity, under the action of three-dimensional compressive stress, enabling the deformation rate to be 5-10 mm/s, performing extrusion deformation for 5-10 passes, enabling the deformation amount of each pass to be 5-60%, coating a layer of lubricant on the surface of the blank and the inner surface of the die cavity in the forming process, and performing multi-pass extrusion forming to obtain a conical component with uniform deformation, wherein the thickness difference of the circumferential wall is less than or equal to 0.2 mm.
(3) Cold and hot cooperated with 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 spot diameter is 0.1-5 mm, the beam scanning linear velocity is 0.05-0.5 m/min, performing anti-oxidation protection and rapid cooling (nitrogen flow is 120-300 ml/min) by using liquid nitrogen atomizing gas, the depth of a heat treatment layer is 0.05-0.5 mm, performing static recrystallization treatment by using cold and heat synergistic input, eliminating an extrusion deformation fibrous tissue, and the average grain size is 0.2-1 mu m.
(4) And (3) complete stress relief 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 10-3Pa。
(5) And (3) precise shaping: and (3) placing the conical component 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 component 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 method mainly comprises the steps of multi-pass cold extrusion forming, laser cold and hot cooperative surface quenching treatment grain refining, stress relief heat treatment, precise shaping and the like (figure 1), so that the uniform deformation controllability of the internal structure of the conical component is realized, and the obtained geometric dimension meets the requirements of the formed component; the grain structure of the inner surface is fine and uniform; realizing the surface brightness and the size precision of the inner cone of the component. The invention leads the grain structure of the inner surface of the prepared thin-wall conical piece to be ultra-fine grained, and has high dimensional precision and good geometric symmetry. The ultrafine grain gradient structure distributed along the thickness direction of the member is obtained by the method, and the structure is uniformly distributed along the bus direction, so that the comprehensive use performance of the thin-wall conical member is provided.
2. According to the invention, based on the relationship between the continuous jet length and the penetration efficiency and the theory of the metal material grain boundary, the thin-wall conical piece has smaller and uniform crystal grains, the isotropy, the yield ratio and the ductility can be obviously improved, and the damage power of a warhead is further improved. According to the velocity gradient effect of the energy-gathered jet flow of the thin-wall conical piece, the application provides an accurate preparation method of the ultra-fine grain tissue thin-wall conical piece.
The invention overcomes the technical problems of mixed crystal in the component, poor consistency of crystal grain appearance, poor size precision 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 performance is good. The structure density is high, the average grain size is not more than 2 μm, and the stability and the ductility of the jet flow of the conical member under the action of high temperature and high pressure are better.
(2) The product size consistency is good. The deviation of the taper angle is less than or equal to 2', the thickness difference of the circumferential wall is less than or equal to 0.1mm, and the surface roughness reaches Ra0.1 mu m.
(3) The utilization rate of the product material is high. The outer surface of the conical component only has a machining allowance of 0.4-1 mm, and the inner surface of the conical component is not machined at all, so that the material utilization rate can be obviously improved.
(4) The product quality is high-efficient controllable. The required structure performance and geometric structure are obtained by controlling technological parameters such as deformation pass, deformation, temperature, time and the like through narrow specifications, and the high-efficiency controllability of the product quality is realized.
Drawings
FIG. 1 flow chart of a process for preparing a conical member
FIG. 2 is a process diagram of multi-pass extrusion of a conical member
FIG. 3 microstructure after multi-pass extrusion deformation
FIG. 4 morphology after cold-hot synergistic surface treatment
FIG. 5 fine crystal structure
FIG. 6 metallographic microscope method sample sampling position for testing grain structure sample
FIG. 7 shows the grain structure of different parts of the metallographic microscope method
FIG. 8 is a typical portion grain structure
Detailed Description
The present invention is further illustrated by the following specific examples.
Example 1
An accurate preparation method of an ultra-fine grain tissue thin-wall conical part comprises the following steps:
(1) preparing a blank: taking a variable-wall-thickness member with an inner cavity of a double-cone structure as an example, the diameter size is phi 200mm, the height is 280mm, the inner cone depth is 240mm, the wall thickness is 4.5-6.5 mm, the top part of the member has a small cone angle of 30 degrees and a large cone angle of 70 degrees, and a transition circular arc between the large cone angle and the small cone angle is R250 mm; according to the plastic processing forming theory and the nearly uniform plastic deformation principle, a machining allowance of 0.8mm is reserved on the outer surface of the conical component, and a forming process handle with the diameter of 35mm is designed on the conical top of the component; UG and DEFORM software is adopted to carry out simulation analysis and optimization on the forming process, the volume of the blank is calculated, an extruded TU1 copper bar with the diameter of 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.
The blank is put into an VQG-2500 type intelligent temperature-control vacuum heat treatment furnace for heat preservation for 1.5h at the temperature of 550 +/-5 ℃ and the vacuum degree of 1.5 multiplied by 10-3Pa, cooling the blank to 80 ℃ along with the furnace after heat preservation and heat treatment, and discharging the blank to obtain a blank with uniform tissue and hardness distribution, wherein the hardness is HB 35-38 through testing.
(2) Multi-pass cold extrusion forming: and (2) putting the blank obtained in the step (1) into a die cavity of an extrusion die, and performing 9-pass extrusion deformation under the action of three-way compressive stress and a certain deformation rate to obtain the 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 equipment is a 20MN cold extrusion machine, the deformation rate is 5-10 mm/s, the female die system of the extrusion die is arranged on a working table surface 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 extrusion male die is driven to apply extrusion forming force through the working slide block of the press, and the extrusion male die is matched with the extrusion female die to enable a blank to be in a three-way pressure stress state. The 1 st pass is the forward extrusion large deformation of the blank to obtain a conical blank; the subsequent 2-9-pass forming is reaming extrusion forming (the deformation is not more than 40%), so that the wall 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; and the final forming is performed in the last 1 pass, so that the dimensional accuracy and dimensional stability of the formed part 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 thickness difference of the circumferential wall is 0.05-0.2 mm.
(3) Cold and hot cooperated with 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 linear speed of light beam scanning is 0.3 m/min; the liquid nitrogen is formed into gas by the aid of the atomization device and sprayed to the periphery of a laser spot to achieve the effects of rapid cooling and oxidation resistance, the nitrogen flow is 200ml/min, the depth of a heat treatment layer is 0.15mm, and the fibrous structure of extrusion deformation is eliminated by means of static recrystallization.
(4) And (3) complete stress relief heat treatment: carrying out complete stress relief heat treatment on the conical component obtained in the step (3) in a vacuum heat treatment furnace, wherein the heat treatment temperature is 280 ℃, the heat treatment time is 2 hours, and the vacuum degree is more than or equal to 3 multiplied by 10-3Pa。
(5) And (3) precise shaping: and (3) placing the conical component obtained in the step (4) into a die cavity of an extrusion die, and shaping for 4 times under the action of three-way compressive stress and a 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 component is-0.9 '-1.5', the circumferential wall thickness difference is 0.02-0.08 mm, and the surface roughness reaches 0.02-0.07 mu m.
The performance of the prepared product is as follows:
1. the method comprises the steps of testing a grain structure along the wall thickness direction and the bus direction of a component by adopting a metallographic microscope method (taking 3 layers of samples, namely a tip part, a middle part and a mouth part, taking 4 samples in each layer, and taking 12 samples in total as shown in figure 6), carrying out coarse grinding, fine grinding and polishing on the samples, finally corroding by adopting a nitric acid aqueous solution, amplifying by 500 times under the metallographic microscope, and obtaining the average grain size of 0.5-1 mu m in the wall thickness direction and the average grain size of 0.5-1.2 mu m in the bus direction by adopting an area method or a line cutting method (counting 3 positions in each sample) (figure 7).
2. By adopting an EBSD analysis method, the grain structures (figure 8) of the tip (severe deformation zone) and the mouth (weak deformation zone) of the conical member are researched, and the grain size of the severe deformation zone of the tip is 0.01-0.1 mu m and the grain size of the weak deformation zone of the mouth is 0.1-1 mu m through automatic statistical calculation.
3. Adopting a mechanical property test, under the condition of a quasi-static tensile test, the tensile strength at room temperature is 240-270 MPa, the elongation after fracture is 54-60% (compared with the elongation after fracture of the initial material which is less than 50%, the elongation after fracture is improved by 10-20%), and the impact absorption energy is 160-180J; at a strain rate of 104Under the condition, the impact deformation reaches more than 95 percent, and the surface of the sample has no defects such as cracks and the like.
4. Comprehensive performance evaluation is adopted, firstly, a pulse X-ray photo test is carried out, the jet flow length, the head speed, the collimation and the like of the member under the explosive detonation effect are obtained, and compared with the traditional product, the effective jet flow length is increased by more than 30%; and secondly, a static nail penetration test is carried out on a certain reference test device, and compared with the traditional product, the static nail penetration depth is improved by more than 12%.
Example 2
An accurate preparation method of an ultra-fine grain tissue thin-wall conical part comprises the following steps:
(1) preparing a blank: taking an equal-wall-thickness component with an inner cavity of a single-cone structure as an example, the caliber size is phi 150mm, the height is 175mm, the inner cone depth is 148mm, the maximum wall thickness is 3.2mm, the inner cone angle is 60 degrees, according to the plastic processing forming theory and the nearly uniform plastic deformation principle, the processing allowance of 0.5mm is reserved on the outer surface of a multi-pass extrusion forming piece, and a forming process handle with the phi 25mm is designed at the top of the forming piece; and (3) simulating the forming process by adopting UG and DEFORM software, calculating the volume of the blank, selecting a drawing Ta copper rod with the diameter of 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.
The blank is put into an VQG-2500 type intelligent temperature-control vacuum heat treatment furnace, and the temperature is kept for 2 hours at 480 +/-5 ℃ with the vacuum degree of 1.5 multiplied by 10-3Pa, cooling the blank to 80 ℃ along with the furnace after heat preservation and heat treatment, and discharging the blank to obtain a blank with uniform components and tissues, wherein the hardness is HB 32-40 through tests.
(2) Multi-pass cold extrusion forming: and (2) placing the blank obtained in the step (1) into a die cavity of an extrusion die, and carrying out extrusion deformation for 8 passes under the action of three-way compressive stress and a certain deformation rate, wherein the distribution of the deformation 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 equipment is a 20MN cold extrusion machine, the deformation rate of the press is 5-10 mm/s, the female die system of the extrusion die is arranged on a working table surface 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 extrusion male die is driven to apply extrusion forming force through the working slide block of the press, and the extrusion male die is matched with the extrusion female die to enable a blank to be in a three-dimensional stress state. The 1 st pass is the forward extrusion large deformation of the blank to obtain a conical blank; the subsequent 2-8-pass forming is reaming extrusion forming (the deformation is less than 40%), so that the wall of the conical component is gradually thinned, the work hardening effect is enhanced along with the increase of the extrusion pass, and the deformation is gradually reduced; and the final forming is performed in the last 1 pass, so that the dimensional accuracy and dimensional stability of the formed part are improved, and the deformation is generally less than 10%. After multi-pass extrusion deformation, the conical component with the required shape, size, surface quality and certain mechanical property is obtained.
TABLE 2 deformation Process parameters, etc
After multi-pass extrusion deformation, the geometric dimension of the conical member meets the design requirement, and the thickness difference of the circumferential wall is 0.03-0.15 mm.
(3) Cold and hot cooperated with 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 velocity is 0.18 m/min; the liquid nitrogen is formed into gas by the aid of the synergistic atomization device and sprayed to the periphery of a laser spot to achieve the effects of rapid cooling and oxidation resistance, the nitrogen flow is 300ml/min, the depth of a heat treatment layer is 0.2mm, and the fibrous structure of extrusion deformation is eliminated by means of static recrystallization.
(4) And (3) complete stress relief 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 260 ℃, the heat treatment time is 2 hours, and the vacuum degree is more than or equal to 3 multiplied by 10-3Pa。
(5) And (3) precise shaping: and (3) placing the conical component obtained in the step (4) into a die cavity of an extrusion die, and shaping by 3 times under the action of three-way compressive stress and a deformation rate of 5mm/s, wherein the deformation amount of each time is less than or equal to 2%, the inner cone angle deviation of the conical component 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 performance of the prepared product is as follows:
1. the method comprises the steps of testing a grain structure along the wall thickness direction and the bus direction of a component by adopting a metallographic microscope method (taking 3 layers of samples, namely a tip part, a middle part and a port position, taking 4 samples in each layer, and taking 12 samples in total as shown in figure 6), carrying out coarse grinding, fine grinding and polishing on the samples, finally corroding by adopting a nitric acid aqueous solution, amplifying by 500 times under the metallographic microscope, and obtaining the average grain size of 0.8-1.7 mu m in the wall thickness direction and the average grain size of 0.9-1.5 mu m in the bus direction by adopting an area method or a line cutting method (counting 3 positions in each sample) (figure 7).
2. By adopting an EBSD analysis method, the grain structures (figure 8) of the tip (severe deformation zone) and the mouth (weak deformation zone) of the conical member are researched, and the grain size of the severe deformation zone of the tip is 0.02-0.11 mu m and the grain size of the weak deformation zone of the mouth is 0.2-1.5 mu m through automatic statistical calculation.
3. Adopting mechanical property test, and under the condition of quasi-static tensile test, the room temperature is adoptedThe tensile strength is 230-265 MPa, the elongation after fracture is 53-61% (compared with the elongation after fracture of less than 50% of the initial material, the elongation after fracture is improved by about 15%), and the impact absorption energy is 140-175J; at a strain rate of 104Under the condition, the impact deformation reaches more than 95 percent, and the surface of the sample has no defects such as cracks and the like.
4. Comprehensive performance evaluation is adopted, firstly, a pulse X-ray photo test is carried out, the jet flow length, the head speed, the collimation and the like of the member under the explosive detonation effect are obtained, and compared with the traditional product, the effective jet flow length is increased by more than 30%; and secondly, a static nail penetration test is carried out on a certain reference test device, and compared with the traditional product, the static nail penetration depth is improved by more than 15%.
The results show that:
the accumulated large plastic deformation is adopted to realize the uniform deformation of the internal structure of the conical member, and the geometric dimension is obtained to meet the requirements of the shape elements of the formed member; the inner surface of the component is subjected to fine quantitative heat treatment and fine crystallization through cold and hot cooperative surface fine crystallization, so that fine homogenization of the grain structure of the inner surface is realized; the surface brightness and size precision of the inner cone of the component are realized by applying the precise cold extrusion shaping technology. The circumferential wall thickness difference of the member obtained by the method is 0.01-0.08 mm, the inner surface roughness Ra0.01-0.1 mu m, the cone angle deviation is less than or equal to 2', the internal organization structure has ultra-fine grain, the physical characteristics of fine grain materials are fully utilized, the cohesiveness and the stability of jet flow can be obviously improved, and the damage efficiency is increased.
Claims (8)
1. An accurate preparation method of an ultra-fine grain structure thin-wall conical part sequentially carries out multi-pass cold extrusion forming, cold-hot synergistic surface grain refining and accurate shaping; the multi-pass cold extrusion forming is to place the blank under the action of three-dimensional compressive stress to carry out multi-pass extrusion deformation; the cold and hot cooperative surface grain refining is laser surface treatment and adopts liquid nitrogen atomizing gas to perform anti-oxidation protection and rapid cooling; the precise shaping is to carry out multi-pass shaping on the three-way compressive stress.
2. The method for precisely preparing the ultrafine grained thin-walled conical part according to claim 1, wherein 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 5-10 passes of extrusion deformation.
3. The method for precisely preparing the ultrafine grained thin-walled conical member as claimed in claim 1 or 2, wherein the laser power for the laser surface treatment is 50 to 200W, the spot diameter is 0.1 to 5mm, the linear velocity of the beam scanning is 0.05 to 0.5m/min, the depth of the heat treatment layer is 0.05 to 0.5mm, and the nitrogen flow rate is 120 to 300 ml/min.
4. The method for precisely fabricating an ultrafine grained thin-walled conical member as claimed in any one of claims 1 to 3, wherein the precise shaping deformation rate is 2 to 5mm/s, and the shaping is performed in 2 to 6 passes.
5. The method for precisely manufacturing the ultrafine grained tissue thin-walled cone as claimed in any one of claims 1 to 4, wherein the lubricant is applied to the surface of the billet and the inner surface of the die cavity in the multi-pass cold extrusion forming, and the lubricant comprises one or more of common lubricants such as tea oil, refined oil, castor oil, rapeseed oil, and the like.
6. The method for precisely preparing an ultrafine grained thin-walled conical member as claimed in any one of claims 1 to 5, further comprising the step of preparing a billet before multi-pass cold extrusion molding, wherein the billet is placed in a vacuum heat treatment furnace for high-temperature stress relief treatment at a temperature of 450 to 650 ℃ for 1 to 4 hours, and then is cooled to a temperature of less than 100 ℃ with the furnace, and then is discharged from the furnace, and the vacuum degree is not less than 3 x 10-3Pa。
7. The method for precisely fabricating an ultrafine grained thin-walled conical member as claimed in any one of claims 1 to 6, wherein the heat treatment temperature is 200 to 300 ℃, the heat treatment time is 4 to 12 hours, and the degree of vacuum is 3 x 10 or more-3Pa。
8. The method for precisely fabricating an ultra-fine grained thin-walled cone as claimed in any one of claims 1 to 7, comprising the steps of:
(1) preparing a blank: selecting a bar material with the diameter phi of 30-120 mm, wherein the material grade can be Ta, TaW2.5, TU1 and the like; putting the blank into a vacuum heat treatment furnace for high-temperature stress relief treatment at the heat treatment temperature of 450-650 ℃ for 1-4 h, cooling the blank to the temperature below 100 ℃ along with the furnace, discharging the blank from the furnace, wherein the vacuum degree is more than or equal to 3 multiplied by 10-3Pa；
(2) Multi-pass cold extrusion forming: placing the blank obtained in the step (1) into a cavity of an extrusion die, under the action of three-dimensional compressive stress, enabling the deformation rate to be 5-10 mm/s, performing extrusion deformation for 5-10 passes, enabling the deformation amount of each pass to be 5-60%, and coating a lubricant on the surface of the blank and the inner surface of the cavity of the die in the forming process;
(3) cold and hot cooperated with surface grain refining: cleaning the surface of the conical member obtained in the step (2), then carrying out laser surface treatment, wherein the laser power is 50-200W, the spot diameter is 0.1-5 mm, the beam scanning linear velocity is 0.05-0.5 m/min, and liquid nitrogen atomizing gas is adopted for carrying out anti-oxidation protection and rapid cooling (the nitrogen flow is 120-300 ml/min), and the depth of a heat treatment layer is 0.05-0.5 mm;
(4) and (3) complete stress relief 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 10-3Pa；
(5) And (3) precise shaping: and (3) placing the conical component 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 component 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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