CN114192782B - Difficult-to-machine material part and forming method thereof - Google Patents
Difficult-to-machine material part and forming method thereof Download PDFInfo
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- CN114192782B CN114192782B CN202111406794.8A CN202111406794A CN114192782B CN 114192782 B CN114192782 B CN 114192782B CN 202111406794 A CN202111406794 A CN 202111406794A CN 114192782 B CN114192782 B CN 114192782B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/12—Both compacting and sintering
- B22F3/14—Both compacting and sintering simultaneously
- B22F3/15—Hot isostatic pressing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
- B22D17/007—Semi-solid pressure die casting
Abstract
The invention belongs to the field of advanced machining, and particularly discloses a part made of a difficult-to-machine material and a forming method thereof, wherein the forming method comprises the following steps: preparing a material to be formed which is difficult to process into a block-shaped part blank with uniform grain size, assembling the part blank in a sheath with a controlled die, and sealing the sheath; and (3) placing the sheath sealed with the part blank into a hot isostatic pressing device, heating to the forming temperature of the material to be formed, loading the pressure to 50-200 MPa at the speed of 0.6-0.8 MPa/min to enable the part blank to generate superplastic forming, and filling the superplastic forming into a controlled mold to obtain the formed part. The forming method can realize the forming of parts with high quality, high speed and low cost, and is particularly suitable for forming large-size nickel-based high-temperature alloy, titanium-aluminum alloy, ceramic material and other materials which are difficult to process.
Description
Technical Field
The invention belongs to the field of advanced machining, and particularly relates to a part made of a difficult-to-machine material and a forming method thereof.
Background
The superplastic forming method of difficult-to-process material which has been proposed generally means that alloy or ceramic blank is treated to obtain uniform fine crystalline structure under the condition of a certain temperature range (not less than 0.5T, T is thermodynamic temperature of material melting point) and low strain rate (10) -4 ～10 -2 s -1 ) The superplastic forming technology is realized. Superplastic forming techniques have been increasingly used in aerospace, military, communications, transportation, and other fields.
However, the method requires a special superplastic forming hydraulic machine to generate high-temperature high-pressure and high-vacuum environment for a long time to form the part, and a high-temperature resistant mold is required. Particularly for forming large-size materials which are difficult to process, such as nickel-based high-temperature alloy, titanium-aluminum alloy, ceramic materials and the like, the forming temperature exceeds 1100 ℃, the forming pressure exceeds 50MPa, and the cost of a large-tonnage superplastic forming hydraulic press and a large-tonnage die is high, which becomes a bottleneck of the application of the technology.
Disclosure of Invention
In view of the above drawbacks or needs for improvement in the prior art, the present invention provides a part made of a material difficult to machine and a forming method thereof, and aims to achieve superplastic forming of the part made of the material difficult to machine, to improve forming speed and quality, and to reduce production cost.
To achieve the above object, according to an aspect of the present invention, there is provided a method for forming a part made of a difficult-to-machine material, comprising the steps of:
preparing a material to be formed which is difficult to process into a block-shaped part blank with uniform grain size, assembling the part blank in a sheath with a controlled die, and sealing the sheath; and (3) placing the sheath sealed with the part blank into a hot isostatic pressing device, heating to the forming temperature of the material to be formed, loading the pressure to 50-200 MPa at the speed of 0.6-0.8 MPa/min to enable the part blank to generate superplastic forming, and filling the superplastic forming into a controlled mold to obtain the formed part.
More preferably, the molding temperature is 0.7 to 0.9 times the melting point of the material to be molded.
Preferably, after the loading pressure is 50MPa to 200MPa, the temperature and pressure are kept for 0.5 to 5 hours, and then after the sheath is cooled, the sheath and the mold control are removed to obtain the formed part.
More preferably, the part blank has a microscopic grain size of 3 to 150 μm.
Preferably, the control mold is prepared according to the structure and the shape of the part, the control mold is of a split structure, and the flow of the part blank to the cavity of the control mold is realized through subsequent assembly.
Further preferably, the material of the controlled mold is ceramic, graphite or a combination of the two.
Preferably, the sheath material is metal, quartz or ceramic, and the thickness is 2 mm-7 mm; isolation layers are arranged among the sheath, the control mold and the part blank.
As further preferred, after the part blank is assembled in a sheath with a controlled mold, the sheath is subjected to a temperature of 400 ℃ to 1000 ℃ and a pressure of 10 -3 Pa～10 -1 And (5) purifying under Pa, and then sealing the sheath.
As a further preference, the part blank is prepared by forging, hot isostatic pressing, extrusion, sintering processes or a combination thereof.
According to another aspect of the present invention, there is provided a difficult-to-machine material part prepared by the above forming method.
Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
1. according to the invention, the inert high-temperature gas in the hot isostatic pressing process is used for generating isostatic pressure in each direction, the sheath provides a vacuum environment, and the accurate regulation and control of temperature and pressure can be realized by controlling the heating unit and the pressure transmission medium; and then the hot isostatic pressing process can be used for obtaining the ultralow strain rate, so that the block blank with uniform grain size can realize superplastic deformation, and the block blank with uniform grains has better superplastic deformation capability due to inconsistent grain uniformity of the powder material. In addition, the hot isostatic pressing does not need a complex die, so that the problems that the existing superplastic deformation needs large hydraulic equipment, the processing of the complex high-temperature die is high, and the cost is high are solved. The invention can obtain the forming of metal, nonmetal and intermetallic compound parts with high quality, high speed and low cost, and is particularly suitable for forming large-size titanium-based and nickel-based high-temperature alloys and other difficult-to-process materials.
2. The invention adopts a method of firstly heating and then boosting pressure, firstly heating to a melting point 0.7-0.9 times of that of a material to be formed, reducing the deformation resistance of the forming material, then loading the pressure to 50-200 MPa at a speed of 0.6-0.8 MPa/min, and enabling the plastic strain rate to be 0.001s -1 Keeping the temperature and the pressure for 0.5 to 5 hours to ensure that the forming material has high temperature and ultralow strain rateViscous or semi-viscous flow is realized under the condition until the cavity of the die is completely filled, so that the superplastic forming of the part blank is realized.
3. The blank adopted by the invention has a uniform and fine microstructure, the size of the microscopic crystal grain of the blank is 3-150 mu m, the size of the microscopic crystal grain of the blank is beneficial to generating a large amount of grain boundary sliding in deformation, and the plastic deformation stability of the material is improved, thereby achieving the superplastic forming of the forming material.
Drawings
FIG. 1 is a flow chart of a method for forming a part made of a difficult-to-machine material according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a starting part blank structure according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of the assembly of a blank, a controlled mold and a jacket according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a vacuum purged enclosure of an embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating part formation using a hot isostatic pressing process according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of a final molded part according to an embodiment of the present invention.
The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein: 1-part blank, 2-air extraction opening, 3-control mold and 4-sheath.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The forming method of the part made of the difficult-to-machine material, which is provided by the embodiment of the invention, as shown in figure 1, comprises the following steps:
(1) Preparing a corresponding block-shaped part blank 1 according to the part structure, wherein the size of the part blank 1 is determined according to the size and the volume of a part to be formed.
Specifically, a material to be formed which is difficult to machine is formed into a part blank through forging, hot isostatic pressing, extrusion and sintering processes or a composite process of the forging, the hot isostatic pressing, the extrusion and the sintering processes, wherein the part blank has a uniform and fine microstructure, and the size of a microscopic crystal grain of the blank is 3-150 μm, and is more preferably 3-70 μm.
(2) According to the part structure and shape characteristics of the region to be formed, a corresponding shape control die 3 is manufactured, and in order to improve the fluidity of the alloy in the cavity, a shunting hole is arranged on the shape control die 3.
Specifically, for different materials to be formed, controlled molds made of different materials are adopted, and ceramic, graphite or a combination of the ceramic and the graphite is preferably selected as the controlled mold material.
(3) Assembling the shape control die 3 and placing the part blank 1 in a sheath 4, and sealing the sheath 4 after high-temperature vacuum purification treatment.
Specifically, the sheath material is made of metal, quartz or ceramic, and the thickness is 2 mm-7 mm; if the sheath material reacts with the control mould or the forming part material in the forming process, an isolation layer is required to be arranged between the sheath material and the control mould or the forming part material; after the formed blank, the controlled mold and the sheath are assembled, the sheath is sheathed at the temperature of 400-1000 ℃ and 10 DEG C -3 Pa～10 -1 And (4) purifying under Pa, and sealing the air exhaust port 2 after the sheath is subjected to purification.
(4) And (3) adopting a hot isostatic pressing process of firstly heating and then boosting, heating a hot isostatic pressing furnace to the forming temperature of the material to be formed, then loading pressure, and forming the blank under the action of a sheath and a controlled mold after heat preservation and pressure maintaining.
Specifically, the forming temperature is 0.7-0.9 times of the melting point of the material to be formed, then the pressure is loaded to 50-200 MPa at the speed of 0.6-0.8 MPa/min, so that the part blank is subjected to superplastic forming, and the temperature and pressure are maintained for 0.5-5 hours.
(5) And removing the sheath and the controlled mold to obtain the required part.
The following are specific examples:
example 1
Referring to fig. 2 for a blank of an initial part and fig. 6 for a final part, a material to be formed was SUS316L, and a method of forming a part included the steps of:
step S1: obtaining a blank for forming (see fig. 2) having a uniform and fine microstructure through forging, hot isostatic pressing, extrusion, and sintering processes or a composite process thereof, the blank having an average grain size of 15.9 μm;
step S2: and low-carbon steel or stainless steel is adopted as a jacket material. The controlled mould is made of ceramic material. The part blank is arranged in a sheath and a controlled mould (see figure 3), and an air exhaust port is reserved in the sheath;
and step S3: assembling the formed blank, the controlled mold and the sheath, and then performing high-temperature vacuum air exhaust purification treatment. The coating is at 400-600 ℃ and 10 DEG C -3 Pa～10 -1 And (5) purifying under Pa.
And step S4: and (5) sealing after the sheath is purified. After the envelope is sealed (see fig. 4), the blank and the controlled mold are positioned 10 in the envelope -3 Pa～10 -1 Pa, in a vacuum.
Step S5: the capsule is placed in a hot isostatic pressing furnace and hot isostatic pressed (see fig. 5). The hot isostatic pressing process adopts a mode of first heating and then boosting, the temperature is first raised to 1050 ℃, the pressure loading rate is 0.7MPa/min, and the plastic strain rate is 0.001s -1 And (5) loading the pressure to 50MPa, stopping loading, and keeping the temperature and the pressure for 3h. The sheath is in isostatic pressing action of inert high-temperature high-pressure gas in a hot isostatic pressing furnace and deforms under the restraint of the controlled mold, the sheath deformation area drives the blank to generate plastic deformation, and finally the blank is filled into a mold cavity of the controlled mold so as to obtain a formed part. And finally, covering the sleeve, cooling along with the furnace, and discharging from the furnace.
Step S6: the sheath and the controlled mold are removed and the part is finished or heat treated to obtain the final part (see fig. 6).
Wherein, after the part is obtained by forming, the method also comprises the step of carrying out finish machining or heat treatment on the part.
Example 2
The initial part blank is shown in figure 2, the final part is shown in figure 6, the material is nickel-base superalloy GH4169, and the superplastic forming method of the part comprises the following steps:
step S1: obtaining a blank for forming through forging, hot isostatic pressing, extruding and sintering processes or a composite process of the forging, the hot isostatic pressing, the extruding and the sintering processes, wherein the blank has a uniform and fine microstructure, and the average grain size of the blank is 13.3 mu m;
step S2: and low-carbon steel or stainless steel is adopted as a jacket material. The control mold is made of ceramic materials. The part blank is arranged in a sheath and a controlled mold, and an air exhaust port is reserved in the sheath;
and step S3: assembling the formed blank, the controlled mold and the sheath, and then performing high-temperature vacuum air exhaust purification treatment. The coating is at 400-600 ℃ and 10 DEG C -3 Pa～10 -1 And (5) purifying under Pa.
And step S4: and (5) sealing after the sheath is purified. After the covering is sealed, the blank and the control mold are positioned in the covering at 10 - 3 Pa～10 -1 Pa, in a vacuum.
Step S5: and (4) placing the sheath into a hot isostatic pressing furnace for hot isostatic pressing treatment. The hot isostatic pressing process adopts a mode of first heating and then boosting, the temperature is firstly raised to 1150 ℃, the pressure loading rate is 0.8MPa/min, and the plastic strain rate is 0.001s -1 And (5) loading the pressure to 200MPa, stopping loading, and keeping the temperature and the pressure for 4 hours. The sheath is in isostatic pressing action of inert high-temperature high-pressure gas in a hot isostatic pressing furnace and deforms under the restraint of the controlled mold, the sheath deformation area drives the blank to generate plastic deformation, and finally the blank is filled into a mold cavity of the controlled mold so as to obtain a formed part. And finally, covering the sleeve, cooling along with the furnace, and discharging from the furnace.
Step S6: and removing the sheath and the controlled mold, and performing finish machining or heat treatment on the part to obtain the final part.
Example 3
The initial part blank is shown in figure 2, the final part is shown in figure 6, the material is gamma-TiAl, and the superplastic forming method of the part comprises the following steps:
step S1: obtaining a blank for forming through forging, hot isostatic pressing, extruding and sintering processes or a composite process of the forging, the hot isostatic pressing, the extruding and the sintering processes, wherein the blank has a uniform and fine microstructure, and the average grain size of the blank is 11.2 mu m;
step S2: and low-carbon steel or stainless steel is adopted as a jacket material. The control mold is made of ceramic materials. The part blank is arranged in a sheath and a controlled mold, an air suction opening is reserved in the sheath, and an isolation layer is required to be arranged between the sheath, the blank and a mold core;
and step S3: assembling the formed blank, the controlled mold and the sheath, and then performing high-temperature vacuum air exhaust purification treatment. The coating is at 400-600 ℃ and 10 DEG C -3 Pa～10 -1 And (5) purifying under Pa.
And step S4: and (5) sealing after the sheath is purified. After the covering is sealed, the blank and the control mold are positioned in the covering at 10 - 3 Pa～10 -1 Pa in vacuum.
Step S5: and putting the sheath into a hot isostatic pressing furnace for hot isostatic pressing treatment. The hot isostatic pressing process adopts a mode of first heating and then boosting, wherein the temperature is firstly raised to 1250 ℃, the pressure loading rate is 0.6MPa/min, and the plastic strain rate is 0.001s -1 And then, loading the pressure to 120MPa, stopping loading, and keeping the temperature and the pressure for 4 hours. The sheath is under the isostatic pressure action of inert high-temperature high-pressure gas in the hot isostatic pressing furnace and deforms under the restraint of the controlled mold, the sheath deformation area drives the blank to generate plastic deformation, and finally the blank is filled into a mold cavity of the controlled mold so as to obtain a formed part. And finally, covering the sleeve, cooling along with the furnace, and discharging from the furnace.
Step S6: and removing the sheath and the mold, and performing finish machining or heat treatment on the part to obtain the final part.
Wherein, after the part is obtained by forming, the method also comprises the step of carrying out finish machining or heat treatment on the part.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. A forming method of a part made of difficult-to-machine materials is characterized by comprising the following steps:
preparing a material to be formed which is difficult to process into a block-shaped part blank with uniform grain size, assembling the part blank in a sheath with a controlled die, and sealing the sheath; placing the sheath with the part blank in a hot isostatic pressing device, and heating to the forming temperature of the material to be formed, wherein the forming temperature is 0.7-0.9 time of the melting point of the material to be formed; then loading the pressure to 50 MPa-200 MPa at the speed of 0.6 MPa/min-0.8 MPa/min to enable the part blank to generate superplastic forming, wherein the plastic strain rate is 0.001s -1 Then, the molded article was filled in a controlled mold to obtain a molded article.
2. The method for forming a part made of a material difficult to machine as claimed in claim 1, wherein the pressure is applied to 50MPa to 200MPa, the temperature and pressure are maintained for 0.5 to 5 hours, and then the sheath is cooled, and the sheath and the mold are removed to obtain the formed part.
3. The method of forming a difficult-to-machine material part according to claim 1, wherein the microscopic grain size of the part blank is 3 μm to 150 μm.
4. The method for forming a part made of a difficult-to-machine material according to claim 1, wherein the controlled mold is prepared according to the structure and shape of the part, the controlled mold is a split structure, and the flow of the part blank to the cavity of the controlled mold is realized through subsequent assembly.
5. The method for forming a part made of difficult-to-machine material according to claim 1, wherein the material of the controlled mold is ceramic, graphite or a combination of both.
6. The method for forming a member made of a difficult-to-machine material according to claim 1, wherein the sheath material is a metal, quartz or ceramic, and has a thickness of 2mm to 7mm; isolation layers are arranged among the sheath, the control mold and the part blank.
7. The method for forming a part made of a difficult-to-machine material as claimed in claim 1, wherein the blank of the part is assembled in a capsule having a controlled die, and the capsule is then heated at a temperature of 400 ℃ to 1000 ℃ and a pressure of 10 -3 Pa～10 -1 And (5) purifying under Pa, and then sealing the sheath.
8. The method of forming a part of difficult-to-machine material as claimed in any one of claims 1 to 7, characterized in that the part blank is prepared by forging, hot isostatic pressing, extrusion, sintering process or their composite process.
9. A part made of a difficult-to-machine material, characterized by being produced by the forming method according to any one of claims 1 to 8.
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| CN115852282A (en) * | 2022-12-30 | 2023-03-28 | 苏州英忆新材料有限公司 | Heat treatment auxiliary device for preventing nickel-titanium alloy material from being oxidized and using method thereof |
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| CN102941344A (en) * | 2012-12-11 | 2013-02-27 | 胡增荣 | Technology for forming component by virtue of super-plastic hot-pressing and diffusion-bonding for titanium alloy powder |
| CN103302214B (en) * | 2013-06-14 | 2015-05-13 | 北京科技大学 | Difficultly-deformed nickel-based superalloy superplastic forming method |
| CN104148557B (en) * | 2014-06-30 | 2016-05-25 | 贵州安大航空锻造有限责任公司 | The super plastic forming method of GH4169 alloy complex section annular element |
| CN105436505B (en) * | 2015-11-14 | 2017-10-13 | 华中科技大学 | A kind of high temperature insostatic pressing (HIP) manufacturing process for being used to improve surface quality of workpieces |
| CN112281039B (en) * | 2020-11-13 | 2022-03-22 | 西安鑫昌机电设备有限责任公司 | Ta-Hf-Zr-ZrB2Alloy bar and preparation method thereof |
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