CN116855810A - Additive manufacturing method of high specific gravity tungsten alloy complex structure - Google Patents
Additive manufacturing method of high specific gravity tungsten alloy complex structure Download PDFInfo
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- 229910001080 W alloy Inorganic materials 0.000 title claims abstract description 96
- 230000005484 gravity Effects 0.000 title claims abstract description 93
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 45
- 239000000654 additive Substances 0.000 title claims abstract description 38
- 230000000996 additive effect Effects 0.000 title claims abstract description 38
- 239000000843 powder Substances 0.000 claims abstract description 83
- 239000010410 layer Substances 0.000 claims abstract description 23
- 238000000465 moulding Methods 0.000 claims abstract description 22
- 238000010438 heat treatment Methods 0.000 claims abstract description 21
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000001257 hydrogen Substances 0.000 claims abstract description 20
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 19
- 238000005507 spraying Methods 0.000 claims abstract description 6
- 239000012790 adhesive layer Substances 0.000 claims abstract description 4
- 238000005245 sintering Methods 0.000 claims description 28
- 239000002245 particle Substances 0.000 claims description 27
- 239000000853 adhesive Substances 0.000 claims description 20
- 230000001070 adhesive effect Effects 0.000 claims description 20
- 238000007639 printing Methods 0.000 claims description 18
- 238000001035 drying Methods 0.000 claims description 9
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 7
- 229910052721 tungsten Inorganic materials 0.000 claims description 6
- 239000010937 tungsten Substances 0.000 claims description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 5
- 238000004140 cleaning Methods 0.000 claims description 5
- 238000011049 filling Methods 0.000 claims description 3
- 230000008901 benefit Effects 0.000 abstract description 7
- 239000002994 raw material Substances 0.000 abstract description 5
- 238000007602 hot air drying Methods 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 15
- 238000005516 engineering process Methods 0.000 description 11
- 229910045601 alloy Inorganic materials 0.000 description 10
- 239000000956 alloy Substances 0.000 description 10
- 239000007791 liquid phase Substances 0.000 description 9
- 238000004663 powder metallurgy Methods 0.000 description 8
- 238000005238 degreasing Methods 0.000 description 7
- 230000008569 process Effects 0.000 description 6
- 238000005336 cracking Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000002844 melting Methods 0.000 description 5
- 230000008018 melting Effects 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 238000003754 machining Methods 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000007123 defense Effects 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 238000010146 3D printing Methods 0.000 description 2
- 230000001186 cumulative effect Effects 0.000 description 2
- 238000000280 densification Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000003892 spreading Methods 0.000 description 2
- 230000007480 spreading Effects 0.000 description 2
- 206010063385 Intellectualisation Diseases 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000000861 blow drying Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000000713 high-energy ball milling Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
- C22C27/04—Alloys based on tungsten or molybdenum
-
- 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
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/10—Formation of a green body
- B22F10/14—Formation of a green body by jetting of binder onto a bed of metal powder
-
- 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
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/20—Direct sintering or melting
- B22F10/28—Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y10/00—Processes of additive manufacturing
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- Powder Metallurgy (AREA)
Abstract
The application relates to an additive manufacturing method of a high specific gravity tungsten alloy complex structure. The additive manufacturing method comprises the following steps: laying high specific gravity tungsten alloy powder in a powder disc to obtain a powder bed; spraying the water-based adhesive layer by layer on a powder bed according to the molding model to obtain a molded blank; carrying out hot air drying on the formed blank; heating the molded green body in a vacuum environment for the first time until the surface temperature of the molded green body is raised to 150-200 ℃ and preserving heat; heating the molded blank in the vacuum environment for the second time until the surface temperature of the molded blank is raised to 400-600 ℃ and preserving heat; heating the formed blank in the hydrogen environment for the third time until the surface temperature of the formed blank is raised to 1450-1510 ℃, and preserving heat to obtain a high specific gravity tungsten alloy complex structure; the high specific gravity tungsten alloy complex structure is cooled to room temperature. The additive manufacturing method has the advantages of high molding efficiency, low raw material cost, good structural and dimensional adaptability and excellent performance and precision of molded parts.
Description
Technical Field
The application relates to the technical field of 3D printing, in particular to an additive manufacturing method of a high specific gravity tungsten alloy complex structure.
Background
The high specific gravity tungsten alloy is an alloy which takes W as a main phase and is composed of trace Ni, fe, cu, co, mn and other elements, has the advantages of high density, high strength, good toughness and the like, and has wide application in national defense science and technology industry, such as armor piercing bullet cores, missile damage units, radioactive shielding materials and the like.
High specific gravity tungsten alloy parts are typically formed by means of "powder metallurgy liquid phase sintering + machining". Because the sintering process needs to manufacture a die in advance to mould the powder, and the machining difficulty of the tungsten alloy with high hardness and high strength is high, the characteristics determine that the method cannot be used for efficiently forming complex components.
The additive manufacturing technology (also called 3D printing technology) is a technology for realizing molding by gradually accumulating materials based on a discrete/stacking principle, and has the remarkable characteristics of digitalization, intellectualization, flexible manufacturing and the like. Compared with the traditional equal material-material reduction manufacturing technology, the material addition manufacturing technology has stronger adaptability to materials and structures, can realize near net forming of a design structure, does not need a die in the manufacturing process, can realize multi-station simplified fusion, greatly shortens the development period and reduces the development cost. Based on the advantages, how to solve the problem of high-efficiency and high-performance molding of the complex structure of the high-specific gravity tungsten alloy by using the additive manufacturing technology becomes the focus of attention of researchers at home and abroad.
The article "Dens identification, microstructure and propert ies of W-7Ni-3Fe fabricated by selective laser melting" proposes a method for forming a 90W-7Ni-3Fe alloy directly by using a laser selective melting technique. The density of the formed piece obtained by fusion bonding of the alloy powder under the action of high-energy laser reaches more than 99%, and the strength reaches 1121MPa. However, due to small laser spots, powder in different areas of the manufacturing and molding process is not uniformly melted, more defects exist in the internal tissues of the molded part, and the elongation is lower than 1%.
Articles Binder jet print ing of tungsten heavy al loy and Manufacturing process and mechanical properties of BJ3DP tungsten heavy al loy components propose a method for preparing a high specific gravity tungsten alloy by degreasing and sintering a preformed blank by using a techniqueIs a method of (2). The former uses 91W alloy powder of common ball milling as raw material to prepare the alloy powder with the density of 17.24g/cm 3 The hardness value of the test bar is 27.3HRc, the tensile strength is 770MPa, the fracture elongation is 8.6 percent, and the mechanical property is lower than that of a test bar prepared by powder metallurgy liquid phase sintering. The latter takes 93W alloy powder after plasma densification as raw material to obtain the alloy powder with the density higher than 17.8g/cm 3 The tensile strength is greater than 950MPa, the elongation at break is greater than 20%, the mechanical properties are equivalent to those of the test sample prepared by powder metallurgy liquid phase sintering, but the powder preparation cost is high.
In summary, the problems of low mechanical property, high cost, complex process and the like still exist in the current additive manufacturing of high-specific gravity tungsten alloy parts.
Disclosure of Invention
Based on the above, it is necessary to provide an additive manufacturing method of a high specific gravity tungsten alloy complex structure which has the advantages of low processing cost, good compactness and mechanical properties and high molding precision.
An additive manufacturing method of a high specific gravity tungsten alloy complex structure comprises the following steps:
obtaining a molding model of a high specific gravity tungsten alloy complex structure;
laying high specific gravity tungsten alloy powder in a powder tray to obtain a powder bed; the mass percentage content of tungsten in the high-specific-gravity tungsten alloy powder is 85 to 98 percent;
spraying a water-based adhesive layer by layer on the powder bed according to the molding model to obtain a molded blank;
drying the formed green body by using hot air at 140-170 ℃ for a first preset time period;
placing the molded green body into a high-temperature sintering furnace, and vacuumizing the high-temperature sintering furnace to enable the molded green body to be in a vacuum environment;
heating the molded blank body for the first time in a vacuum environment until the surface temperature of the molded blank body is raised to 150-200 ℃, and preserving heat for a second preset time period;
heating the molded blank body in a vacuum environment for the second time until the surface temperature of the molded blank body is raised to 400-600 ℃, and preserving heat for a third preset time period;
filling hydrogen into the high-temperature sintering furnace to make the formed blank body in a hydrogen environment;
heating the molded blank in a hydrogen environment for the third time until the surface temperature of the molded blank is raised to 1450-1510 ℃ and preserving heat for a fourth preset time period to obtain a high specific gravity tungsten alloy complex structure;
and cooling the high specific gravity tungsten alloy complex structure to room temperature.
In one embodiment, the powder particle size of the high specific gravity tungsten alloy powder is 2-20 μm; d, d 10 The particle size of the powder is 2-4 mu m, d 50 The particle size of the powder is 7-10 mu m, d 90 The powder particle size of (2) is 17-20 mu m; the bulk density of the high specific gravity tungsten alloy powder is 7.5g/cm 3 ～9.5g/cm 3 The Hall flow rate (50 g) is 25 s-30 s.
In one embodiment, the water-based adhesive has a viscosity of 9cP to 15cP, a surface tension of 28mN/m to 35mN/m, and a cracked carbon residue fraction of less than 1% at 1000 ℃.
In one embodiment, the layer-by-layer spray of the water-based adhesive is performed at a printing speed of 9 to 13 seconds per layer with a printing layer thickness of 30 to 60 μm.
In one embodiment, the first preset time period is 1 h-2 h.
In one embodiment, the second preset time period is 1h±15min, and the third preset time period and the fourth preset time period are both 2h±30min.
In one embodiment, the rate of temperature rise at the first heating is 5+ -1deg.C/min and the rate of temperature rise at the second heating is 3+ -1deg.C/min.
In one embodiment, the rate of temperature rise upon the third heating is 10.+ -. 2 ℃ per minute.
In one embodiment, the step of cooling the high specific gravity tungsten alloy complex structure to room temperature is: and cooling the high specific gravity tungsten alloy complex structure along with the furnace and taking out.
In one embodiment, before the step of placing the shaped green body into the high temperature sintering furnace, the method further comprises the steps of: and cleaning the dried molded green body to remove residual powder on the surface of the molded green body.
The additive manufacturing method of the high specific gravity tungsten alloy complex structure can mold complex structures such as grooves in walls, non-circular sections, variable wall thicknesses and the like which are difficult to machine, and the molding precision is as high as 0.1mm, and compared with the traditional preparation mode of powder metallurgy liquid phase sintering and mechanical processing of the high specific gravity tungsten alloy parts, the additive manufacturing method of the high specific gravity tungsten alloy complex structure has better adaptability to the structure and lower cost.
The high specific gravity tungsten alloy complex structure obtained by the additive manufacturing method of the high specific gravity tungsten alloy complex structure is subjected to hot air drying, vacuum degreasing and high-temperature sintering, so that the density of the high specific gravity tungsten alloy complex structure is not lower than 99%, the tensile strength is 900-1000 MPa, the elongation is 15-24%, and the molding precision is less than 0.1mm. Therefore, compared with the traditional high specific gravity tungsten alloy additive manufacturing technologies such as laser selective melting forming, droplet injection forming and the like, the high specific gravity tungsten alloy complex structure obtained by the additive manufacturing method of the high specific gravity tungsten alloy complex structure has better density and mechanical property, and meets the mechanical requirement of powder metallurgy liquid phase sintered parts.
Therefore, the additive manufacturing method of the high specific gravity tungsten alloy complex structure has the advantages of high forming efficiency, low raw material cost, good structural and dimensional adaptability, and excellent performance and precision of formed parts, and can be used for forming the high specific gravity tungsten alloy complex structure in national defense science and technology industry.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the accompanying drawings. In the drawings:
FIG. 1 is a flow chart of an additive manufacturing method of a complex structure of a high specific gravity tungsten alloy according to a preferred embodiment of the application.
Detailed Description
In order that the application may be readily understood, a more complete description of the application will be rendered by reference to the appended drawings. Preferred embodiments of the present application are shown in the drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
When an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present unless otherwise specified. It will also be understood that when an element is referred to as being "between" two elements, it can be the only one between the two elements or one or more intervening elements may also be present.
Where the terms "comprising," "having," and "including" are used herein, another component may also be added unless explicitly defined as such, e.g., "consisting of … …," etc. Unless mentioned to the contrary, singular terms may include plural and are not to be construed as being one in number.
Referring to fig. 1, an additive manufacturing method for forming a complex structure of a high specific gravity tungsten alloy according to a preferred embodiment of the present application includes steps S100 to 1001.
Step S100, a molding model of the high specific gravity tungsten alloy complex structure is obtained.
The molding model is a three-dimensional model built according to a high specific gravity tungsten alloy complex structure to be molded, so that subsequent additive manufacturing work is facilitated.
Step S200, laying up high specific gravity tungsten alloy powder in a powder pan to obtain a powder bed. The mass percentage content of tungsten in the high specific gravity tungsten alloy powder is 85% -98%.
Specifically, a high specific gravity tungsten alloy powder was uniformly laid in a powder pan of a 3DP printing apparatus to obtain a powder bed.
Specifically, before step S200, the method further includes: uniformly mixing tungsten powder, iron powder and nickel powder in a mechanical mixing mode to obtain high-specific gravity tungsten alloy powder. More specifically, tungsten powder, iron powder and nickel powder are uniformly mixed by a high-energy ball milling method. The high specific gravity tungsten alloy mainly comprises tungsten, nickel and iron.
Step S300, spraying the water-based adhesive layer by layer on the powder bed according to the molding model to obtain a molded green body.
Specifically, step S300 includes the steps of: setting printing parameters and printing tracks according to the molding model; and spraying the water-based bonding layer-by-layer agent on the powder bed according to the printing parameters and the printing track to obtain the molded green body.
Step S400, drying the formed blank body by using hot air at 140-170 ℃ for a first preset time period.
Specifically, the shaped green body is transferred to a blow drying oven at 140 ℃ to 170 ℃ for a first preset period of time. More specifically, the powder disk is transferred to a blast drying oven at 140-170 ℃ together with the molded green body on the powder disk for a first preset period of time. The first preset time period can be set according to the structure, the size and the like of the formed blank.
Specifically, the blank is dried and molded for 1 to 2 hours by hot air at 140 to 170 ℃.
And S500, placing the molded blank into a high-temperature sintering furnace, and vacuumizing the high-temperature sintering furnace to enable the molded blank to be in a vacuum environment. Thus, the molded blank is ensured to be in a vacuum environment with extremely low oxygen content when the step S600 and the step S700 are executed, and the influence of oxygen in the air on the drying and degreasing treatment of the molded blank is reduced.
And S600, heating the molded blank in the vacuum environment for the first time, and preserving heat for a second preset time period when the surface temperature of the molded blank is raised to 150-200 ℃. By executing step S600, the drying process is performed on the molded green body in the vacuum environment, so that the drying effect on the molded green body is ensured and the drying effect can be reduced.
Specifically, the molded blank in the vacuum environment is heated for the first time until the surface temperature of the molded blank is raised to 150-200 ℃, and the temperature is kept for 1 h+/-15 min.
And step S700, performing secondary heating on the molded blank in the vacuum environment until the surface temperature of the molded blank is raised to 400-600 ℃, and preserving heat for a third preset time period.
When the surface temperature of the molded green body is raised to 400-600 ℃, the water-based adhesive in the molded green body is cracked, so that degreasing of the molded green body is realized. The cracking temperature of the water-based adhesive is generally related to the type of the water-based adhesive, and the cracking temperature of different water-based adhesives may be different, so that the surface temperature of the molded blank may be raised to different temperatures in the range of 400 ℃ to 600 ℃ according to the type of the water-based adhesive when the step S700 is performed. By executing step S700, the molded green body may be subjected to degreasing treatment.
Specifically, the molded blank in the vacuum environment is heated for the second time until the surface temperature of the molded blank is raised to the cracking temperature of the water-based adhesive, and the temperature is kept for 2 h+/-30 min.
And step S800, carrying out hydrogen filling treatment in the high-temperature sintering furnace to enable the formed blank body to be in a hydrogen environment. In this way, it is ensured that the molded body is always in a hydrogen atmosphere while the step S900 is performed, and hydrogen is used as an inert gas, so that the oxygen content in the high-temperature sintering atmosphere can be further reduced, and the influence of oxygen on the high-temperature sintering process can be reduced.
And step S900, heating the molded blank in the hydrogen environment for the third time until the surface temperature of the molded blank is raised to 1450-1510 ℃ and preserving heat for a fourth preset time period, so as to obtain the high-specific gravity tungsten alloy complex structure. Thus, the step S900 is performed to sinter the molded green body.
Specifically, the molded blank in the hydrogen environment is heated for the third time until the surface temperature of the molded blank is raised to 1450-1510 ℃, and the temperature is kept for 2 h+/-30 min, so as to obtain the high specific gravity tungsten alloy complex structure
In step S1001, the high specific gravity tungsten alloy complex structure is cooled to room temperature.
By performing the steps S100 to S300, a shaped blank having the same or similar shape, size, or the like as the complex structure of the high specific gravity tungsten alloy can be obtained, and by performing the steps S400 to S1001, after post-processing the shaped blank, the complex structure of the high specific gravity tungsten alloy can be obtained. Therefore, by executing steps S100 to S1001, it is possible to form a complex structure in which machining is difficult, such as a groove in a wall, a non-circular cross section, a variable wall thickness, etc., and compared with the conventional preparation method of a high specific gravity tungsten alloy part by powder metallurgy liquid phase sintering+machining, the additive manufacturing method of the complex structure of the high specific gravity tungsten alloy has better adaptability to the structure and lower cost.
Through executing the steps from S400 to S1001, the formed blank body can be subjected to hot air drying, vacuum degreasing and high-temperature sintering under a hydrogen environment, so that a high-specific gravity tungsten alloy complex structure with high density, high tensile strength and high elongation is obtained.
In order to make the performance of the high specific gravity tungsten alloy complex structure prepared by the additive manufacturing method of the high specific gravity tungsten alloy complex structure more intuitively understood, the performance test results of several embodiments are listed below.
Example 1 the high specific gravity tungsten alloy powder in step S200 and step S300 was 90W-7.1Ni-2.9Fe alloy powder; step S400, drying and forming a blank body for 2h by using hot air at 170 ℃; step S900 is to heat the molded blank in the hydrogen environment for the third time until the surface temperature of the molded blank is raised to 1450 ℃ and keep the temperature for a fourth preset time period.
Example 2 the high specific gravity tungsten alloy powder in step S200 and step S300 was 93W-4Ni-3Fe alloy powder; step S900 is to heat the molded blank in the hydrogen environment for the third time until the surface temperature of the molded blank is raised to 1480 ℃ and keep the temperature for the fourth preset time period.
Example 3 the high specific gravity tungsten alloy powder in step S200 and step S300 was 95W-3Ni-2Fe alloy powder; step S900 is to heat the molded blank in the hydrogen environment for the third time until the surface temperature of the molded blank is raised to 1510 ℃ and keep the temperature for a fourth preset time period.
The tensile properties of examples 1-3 were tested with reference to the requirements of GB/T228.1 and the dimensional accuracy of examples 1-3 was measured using a altimeter. The overall test results are shown in table 1.
TABLE 1 results of Performance test of examples 1-3
Practical tests prove that the density of the high specific gravity tungsten alloy complex structure obtained by the additive manufacturing method of the high specific gravity tungsten alloy complex structure is not lower than 99%, the tensile strength is 900-1000 MPa, the elongation is 15-24%, and the molding accuracy is less than 0.1mm. Therefore, compared with the traditional high specific gravity tungsten alloy additive manufacturing technologies such as laser selective melting forming, droplet injection forming and the like, the high specific gravity tungsten alloy complex structure obtained by the additive manufacturing method of the high specific gravity tungsten alloy complex structure has better density and mechanical property, and meets the mechanical requirement of powder metallurgy liquid phase sintered parts.
Therefore, the additive manufacturing method of the high-specific gravity tungsten alloy complex structure is simple and convenient to operate, high in forming efficiency, low in raw material cost, good in structural and dimensional adaptability, excellent in forming part performance and precision, and can be used for forming the high-specific gravity tungsten alloy complex structure in national defense science and technology industry.
In some embodiments, the high gravity tungsten alloy powder has a powder particle size of 2 μm to 20 μm; d, d 10 The particle size of the powder is 2-4 mu m, d 50 The particle size of the powder is 7-10 mu m, d 90 Is of the powder particle size of17-20 μm; the bulk density of the high specific gravity tungsten alloy powder is 7.5g/cm 3 ～9.5g/cm 3 The Hall flow rate (50 g) is 25 s-30 s.
D is the same as 10 Is as follows: accumulating one sample (adding the percentages of all the particle sizes in the front or the back) and obtaining the particle size corresponding to the particle size distribution number reaching 10%; d, d 50 Is as follows: particle size corresponding to a cumulative particle size distribution percentage of one sample reaching 50%; d, d 90 Is as follows: the particle size corresponding to the number of cumulative particle size distributions of one sample reaches 90%.
When the steps S100 to S300 are executed, if the powder is too thin, the powder has poor fluidity, so that the problems of uneven powder spreading, peeling after the adhesive is sprayed and the like are easily caused, and the molding efficiency and the molding precision are affected; and when the steps S400 to S1001 are performed, if the powder is too coarse, the sintering activity is also low, so that the density of the prepared component is poor and the mechanical properties cannot meet the requirements.
Based on the above, the high specific gravity tungsten alloy powder with the powder particle size of 2-20 μm is selected in the step S200 and the step S300, the particles with the particle size of less than or equal to 2-4 μm only account for 10% of all the high specific gravity tungsten alloy powder, the median particle size or median particle size of less than or equal to 7-10 μm account for 50% of all the high specific gravity tungsten alloy powder, and the particles with the particle size of less than or equal to 17-20 μm account for 90% of all the high specific gravity tungsten alloy powder, so the high specific gravity tungsten alloy powder has small and uniform particle size, is easier to be molded when the step S100-S300 is executed, is beneficial to improving the molding efficiency and the molding precision, and can ensure that the density of the prepared high specific gravity tungsten alloy complex structure is not lower than 99%, the tensile strength reaches 900-1000 MPa, the elongation percentage is 15-24%, and the molding precision is less than 0.1mm.
In some embodiments, the water-based adhesive has a viscosity of 9cP to 15cP, a surface tension of 28mN/m to 35mN/m, and a cracked carbon residue fraction of less than 1% at 1000 ℃.
The high specific gravity tungsten alloy powder needs to be bonded and molded by the adhesive, the viscosity and the surface tension of the adhesive are too large, the wetting effect on the powder is poorer, the peeling of the surface layer of the powder is easy to cause, the bonding of the powder at the lower layer is loose, and the strength and the dimensional accuracy of a blank are poorer; however, if the viscosity and the surface tension of the adhesive are too small, the adhesive has weak bonding effect on the lower powder and is easy to permeate into the lower layer of the powder bed, so that the powder spreading is difficult, and the green body strength and the dimensional accuracy are poor; in addition, the cracking residual carbon content of the adhesive is related to the density and impurity related content of the sintered blank, and the mechanical property of the part is directly affected.
Based on the above, in the step S300, the water-based adhesive with the viscosity of 9 cP-15 cP, the surface tension of 28 mN/m-35 mN/m and the cracking carbon residue at 1000 ℃ of less than 1% is selected, so that the molded blank with larger blank strength and higher dimensional accuracy can be obtained after the steps S100-S300 are executed, the molded blank with larger density and mechanical property reaching the performance requirement of the powder metallurgy liquid phase sintered part can be obtained after the steps S400-S1001 are executed, and the product quality of the complex structure of the high-specific gravity tungsten alloy is ensured to be higher.
In some embodiments, the printing layer is 30 μm to 60 μm thick and the printing speed is 9 seconds/layer to 13 seconds/layer when step S300 is performed.
The design of the droplet spraying process parameters is matched with the characteristics of the water-based adhesive, the printing layer is too thin or the printing speed is too slow, the processing efficiency of the complex structure of the liquid-phase high-specific gravity tungsten alloy can be realized, the printing layer is too thick or the printing speed is too fast, and the water-based adhesive cannot completely infiltrate the single-layer powder. Therefore, when step S200 and step S300 are performed, the printing layer thickness is set to 30 μm to 60 μm, the printing speed is set to 9 seconds/layer to 13 seconds/layer, and the mechanical properties and the product quality of the high specific gravity tungsten alloy complex structure are ensured while the large forming speed is ensured.
In some embodiments, the rate of temperature rise upon the first heating is 5.+ -. 1 ℃ per minute and the rate of temperature rise upon the second heating is 3.+ -. 1 ℃ per minute. From this, it is understood that the rate of temperature rise is low when both step S600 and step S700 are performed.
The degreasing sintering is a key process for endowing the tungsten alloy with high specific gravity with complex structural performance, and the premise of high performance is that the component has high density, less impurity phase and fine grains. In the additive manufacturing method of the high-specific gravity tungsten alloy complex structure, the step S600 and the step S700 are executed to dry and degrease the formed blank, and the step S600 and the step S700 are designed with a slower temperature rise speed and a vacuum environment in a high-temperature sintering furnace so as to ensure that moisture and organic matters are completely removed in a low-temperature area, thereby being beneficial to improving the performance of the high-specific gravity tungsten alloy complex structure.
In some embodiments, the rate of temperature rise upon the third heating is 10±2 ℃/min. In this way, the rate of temperature rise at the time of executing step S900 is high.
In the additive manufacturing method of the high specific gravity tungsten alloy complex structure, the step S800 and the step S900 are executed to perform high-temperature sintering on the formed blank under the hydrogen environment, so that the faster temperature rise speed and the hydrogen environment in the high-temperature sintering furnace are designed in the step S900. So as to avoid the strength reduction caused by oxidation reaction, grain coarsening and other reactions on the premise of ensuring the sintering densification of the high-specific gravity tungsten alloy, and is beneficial to the improvement of the mechanical properties of the high-specific gravity tungsten alloy complex mechanism.
In some embodiments, step S1001 is: and cooling the high specific gravity tungsten alloy complex structure along with the furnace and taking out.
And as follows, the high specific gravity tungsten alloy complex structure is naturally cooled to room temperature or close to room temperature in a hydrogen environment, so that the probability of oxidization caused by contact of the high specific gravity tungsten alloy complex structure with air at a high temperature is avoided, and further improvement of product quality is facilitated.
In some embodiments, before step S500, the method further comprises the step of: and cleaning the dried molded green body to remove residual powder on the surface of the molded green body.
The steps are added between step S400 and step S500: and cleaning the dried molded green body to remove residual powder on the surface of the molded green body. When step S300 is performed, some powder is inevitably adhered to the surface of the molded blank, and after step S400 is performed, the residual powder is cleaned to ensure the cleaning of the surface of the molded blank, so as to avoid the formation of the surface of the complex structure of the high-specific gravity tungsten alloy after the melting of the residual powder occurs when step S500 to step S900 are performed subsequently
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.
Claims (10)
1. The additive manufacturing method of the high specific gravity tungsten alloy complex structure is characterized by comprising the following steps of:
obtaining a molding model of a high specific gravity tungsten alloy complex structure;
laying high specific gravity tungsten alloy powder in a powder tray to obtain a powder bed; the mass percentage content of tungsten in the high-specific-gravity tungsten alloy powder is 85 to 98 percent;
spraying a water-based adhesive layer by layer on the powder bed according to the molding model to obtain a molded blank;
drying the formed green body by using hot air at 140-170 ℃ for a first preset time period;
placing the molded green body into a high-temperature sintering furnace, and vacuumizing the high-temperature sintering furnace to enable the molded green body to be in a vacuum environment;
heating the molded blank body for the first time in a vacuum environment until the surface temperature of the molded blank body is raised to 150-200 ℃, and preserving heat for a second preset time period;
heating the molded blank body in a vacuum environment for the second time until the surface temperature of the molded blank body is raised to 400-600 ℃, and preserving heat for a third preset time period;
filling hydrogen into the high-temperature sintering furnace to make the formed blank body in a hydrogen environment;
heating the molded blank in a hydrogen environment for the third time until the surface temperature of the molded blank is raised to 1450-1510 ℃ and preserving heat for a fourth preset time period to obtain a high specific gravity tungsten alloy complex structure;
and cooling the high specific gravity tungsten alloy complex structure to room temperature.
2. Additive manufacturing method according to claim 1, characterized in that the powder particle size of the high specific gravity tungsten alloy powder is 2-20 μm; d, d 10 The particle size of the powder is 2-4 mu m, d 50 The particle size of the powder is 7-10 mu m, d 90 The powder particle size of (2) is 17-20 mu m; the bulk density of the high specific gravity tungsten alloy powder is 7.5g/cm 3 ～9.5g/cm 3 The Hall flow rate (50 g) is 25 s-30 s.
3. Additive manufacturing method according to claim 1, characterized in that the water-based adhesive has a viscosity of 9 cP-15 cP, a surface tension of 28 mN/m-35 mN/m and a cracked carbon residue fraction of less than 1% at 1000 ℃.
4. Additive manufacturing method according to claim 1, characterized in that the printing layer thickness is 30 μm to 60 μm and the printing speed is 9 seconds/layer to 13 seconds/layer when the water-based adhesive is sprayed layer by layer.
5. An additive manufacturing method according to claim 1, wherein the first preset time period is 1-2 h.
6. An additive manufacturing method according to claim 1, wherein the second preset time period is 1h±15min, and the third preset time period and the fourth preset time period are each 2h±30min.
7. An additive manufacturing method according to claim 1, wherein the rate of temperature rise at the first heating is 5±1 ℃/min and the rate of temperature rise at the second heating is 3±1 ℃/min.
8. Additive manufacturing method according to claim 1, characterized in that the rate of temperature rise upon the third heating is 10±2 ℃/min.
9. An additive manufacturing method according to claim 1, wherein the step of cooling the high specific gravity tungsten alloy complex structure to room temperature is: and cooling the high specific gravity tungsten alloy complex structure along with the furnace and taking out.
10. An additive manufacturing method according to claim 1, further comprising, before the step of placing the shaped blank into the high temperature sintering furnace, the step of: and cleaning the dried molded green body to remove residual powder on the surface of the molded green body.
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| CN117600494A (en) * | 2024-01-24 | 2024-02-27 | 安庆瑞迈特科技有限公司 | Printing method for improving corrosion resistance and strength of 3D printing collimator |
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| CN117600494A (en) * | 2024-01-24 | 2024-02-27 | 安庆瑞迈特科技有限公司 | Printing method for improving corrosion resistance and strength of 3D printing collimator |
| CN117600494B (en) * | 2024-01-24 | 2024-04-02 | 安庆瑞迈特科技有限公司 | Printing method for improving corrosion resistance and strength of 3D printing collimator |
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