CN115502415B - A method for nano-graphene reinforced metal powder 3D printing additive manufacturing mixing head - Google Patents

Abstract

The invention discloses a method for 3D printing additive manufacturing of a mixing head using nano-graphene reinforced metal powder. Metal powder and nano-graphene sheets are used as raw materials, and a shell laminated braided structure is used as a bionic design structure object to construct a mixing head model. The mixing head is prepared through 3D printing; nano-graphene reinforced metal powder is used, and combined with 3D printing, bionic shell lamination strengthening structure technology, deep supercooling impact strengthening processing technology and external electromagnetic field composite technology innovations are applied to the processing and manufacturing of the mixing head, which is different. Based on traditional metal materials and processing and manufacturing methods, it realizes the rapid processing and manufacturing of mixing heads of special metal materials, refractory and difficult-to-process high-performance metal materials, and realizes the rapid design and processing of mixing heads with high performance, complex structures and surface shapes. Manufacturing, realizing the processing and manufacturing of low-cost, high-temperature and wear-resistant, batch mixing heads, greatly improving the comprehensive performance of ordinary metal mixing heads.

Description

A method for nano-graphene reinforced metal powder 3D printing additive manufacturing mixing head

Technical field

The invention relates to the field of friction stir welding technology and additive manufacturing, and specifically relates to a method for 3D printing additive manufacturing stirring heads of electric nanographene-reinforced tool and die steel metal powder.

Background technique

The stir head is a key component of friction stir welding technology. As the core component of friction stir welding, the design, materials and manufacturing of the stir head are crucial to obtaining high-quality friction stir welding joints. At the same time, the stir head can also affect the friction stir welding process. The effective application range of technology in metal materials and structures. Friction stir welding technology is a solid-state welding technology that uses a stirring head to weld two metal structures together. Friction heat is generated between the rotating stirring needle and the metal structure, which softens the metal in the welding area to achieve high-quality connections. It has many melting welding technology advantages. It has special advantages and is especially suitable for welding low melting point non-ferrous metals and their structures. For high melting point metals and their structures, friction stir welding technology has great limitations. The main reason why friction stir welding technology is still limited to low melting point metals and their structures is the lack of high-performance stir heads suitable for mass production, low cost, and resistant to high temperature and wear. As the core of the friction stir welding process, the stir head is the decisive factor in friction stir welding. An important factor in whether quality is reliable. When friction stir welding of low-melting-point metals (such as Lu alloy), it can be easily achieved by using low-cost metal materials such as tool steel and mold steel and using traditional processing methods to manufacture the stirring head. However, when welding high-melting-point metals such as steel and titanium alloy with a mixing head made of ordinary materials, the mixing head will also soften in the high-temperature welding area where the high-melting-point metal is softened, causing the mixing head made of ordinary materials to wear out quickly, and finally due to stirring The head is seriously worn and fails and cannot be used; although stirring heads using high-performance materials such as ceramics, PCBN, and tungsten-rhenium alloys have been developed, the shape characteristics and surface modeling of the stirring needle have a great impact on the flow of metal materials and the performance of the joints. impact, making the processing of these special materials very difficult. Therefore, the mixing heads made of these special materials have high raw material costs and long processing and manufacturing cycles, resulting in very high cost and short lifespan of the mixing heads. They are not suitable for mass production, which limits the wide application of friction stir welding technology in high melting point metals. . During the friction stir welding process of high melting point materials, the stir head has to withstand greater mechanical force, frictional heat, and suffers serious wear and tear. The stir head material is generally made of refractory metal alloys or structural ceramics. However, it is difficult to manufacture and process the stir head using these materials. All are relatively large. At present, the materials of high melting point alloy mixing heads mainly use tungsten-based alloy (W-25Re) and polycrystalline cubic boron nitride (PCBN), and nickel-based alloys, cemented carbide and cermets are used as manufacturing materials. The processing and manufacturing of traditional mixing heads Costs remain higher. The stirring needle is processed into threads and shoulder characteristic shapes to adapt to friction stir welding under different materials and conditions. These surface shapes and complex structure processing can increase the generation of heat by increasing the friction between the stirring head and the workpiece, resulting in more heat. The heat makes the metal easy to thermoplasticize, and at the same time enhances the material flow and affects the axial and lateral forces to form a high-quality joint. Therefore, the complex structure and surface shape of the stirring needle have an important impact on the performance of the joint.

Therefore, a new stirrer head manufacturing method is needed that can overcome the problems existing in the stirrer head material, complex shape design and processing and manufacturing in the existing friction stir welding technology.

Contents of the invention

In view of this, the purpose of the present invention is to overcome the problems existing in the stir head material, complex shape design and processing and manufacturing in the existing friction stir welding technology, and provide a device with high performance, complex structure, suitable for mass production, low cost, The high-temperature wear-resistant mixing head manufacturing method can effectively enhance the performance of ordinary metal materials, conveniently and quickly design the complex structure and surface shape of the mixing head, rapidly additively manufacture the mixing head of refractory and difficult-to-process metal, and improve the performance, life and quality of the mixing head. Value for money.

The present invention's method for additively manufacturing a mixing head by 3D printing of nanographene-enhanced metal powder uses metal powder and nanographene sheets as raw materials, and uses a shell laminated braided structure as a bionic design structure object to construct a mixing head model, and through 3D printing Prepare the mixing head;

Further, include the following steps:

S ₁ , preparation of spheroidized powder: mix metal powder and nanographene sheets and spheroidize;

S ₂ , bionic model construction: using the shell laminated braided structure as the bionic design structure object, design and optimize the 3D printing additive manufacturing unsupported structural model of the mixing head, design and optimize the bionic modeling of the mixing needle and shaft shoulder surface;

S ₃ , 3D printing: using laser selective melting or electron beam melting;

Further, in step _S1 , the content of the nanographene sheets is 0.1-5wt% of the mixed powder, and the diameter of the powder after spheroidization is 1-50um;

Further, in step _S3 , the laser selective melting molding uses 99.99% argon as a protective gas, and controls the oxygen content to be less than 0.15%, the power is 100W~800W, the laser focusing diameter is 50um~200um, and the scanning speed is 400mm /s～2000mm/s, scanning spacing is 20um～100um, layer thickness is 10um～50um;

Further, in step _S3 , the stirring head is 3D printed and additively manufactured on the substrate of the same material or low alloy steel or low carbon steel. The preheating temperature is 200~1400°C. During the printing process, a variety of glyph mixed weaving methods are used for scanning. After each layer of metal printing is completed, the laser scanning direction is rotated 60 to 70°, and then the next layer of mixing head metal is 3D printed. The glyphs include regular Z-shape, L-shape, V-shape, N-shape, W-shape, and S-shape. ,X shape;

Further, in step _S3 , the output power of the electron beam melting molding is 200W~3000W, the scanning speed is 500mm/s~3000mm/s, the linear energy density is 0.2J/mm~1.2J/mm, the spot diameter is 80um~400um, and the layer The thickness is 20um ~ 100um, and the vacuum degree is 1×10 ^-2 ~ 1×10 ^-3 Pa; the stirring head is 3D printed and additively manufactured on the substrate of the same material or low alloy steel or low carbon steel, and the preheating temperature is 200 ~ 1400℃;

Further, for non-ferromagnetic materials, an external electric field or external magnetic field is set outside the 3D printing area, and the external electric field or external magnetic field is parallel or perpendicular to the center line of the molten pool;

Further, the intensity of the external electric field is 50V/cm-500V/cm; the magnetic field intensity of the external magnetic field is 5-800mT.

Furthermore, during the 3D printing process, one of low-temperature liquid nitrogen, low-temperature liquid CO ₂ , and low-temperature liquid ammonia media is used for deep supercooling treatment, and high-intensity ultrasonic impact methods, laser shot blasting methods, and mechanical methods are simultaneously used under low temperature conditions. One of the shot peening methods is to subject the printed mixing head to deep supercooling and high-intensity impact treatment. The processing time is 0.5h to 24h, and then the shape, geometric dimensions and surface quality of the mixing head are refined at room temperature.

The beneficial effects of the present invention are: the nanographene-reinforced metal powder 3D printing method for additive manufacturing of a mixing head disclosed by the present invention uses nanographene-reinforced metal powder, combined with 3D printing, bionic shell lamination reinforced structure technology, deep processing Cold impact strengthening treatment technology and external electromagnetic field composite technology are innovatively applied to the processing and manufacturing of mixing heads. Different from traditional metal materials and processing and manufacturing methods, it realizes the rapid processing of mixing heads of special metal materials and refractory and difficult-to-process high-performance metal materials. Manufacturing, realizing the rapid design and manufacturing of high-performance, complex structure and surface modeling mixing heads, realizing the processing and manufacturing of low-cost, high-temperature wear-resistant, batch mixing heads, greatly improving the comprehensive performance of ordinary metal mixing heads performance, achieving high-efficiency processing of special metal material mixing heads, using simple and effective means to effectively control the mixing head processing and manufacturing process, greatly reducing the porosity and number of pores in 3D printed metal load-bearing structural parts, and improving the internal microstructure size and crystal structure. The growth direction of the grains enhances the performance and life of the special mixing head under harsh environments and conditions.

Detailed ways

Embodiment 1

This embodiment uses nanographene-enhanced 5Cr15MoV high-carbon martensitic stainless steel metal powder to 3D print the additive manufacturing method of a mixing head. The average diameter of the 5Cr15MoV high-carbon martensitic stainless steel metal powder is 50um. The number of layers is 10 and the plane size is For graphene flakes of 1 to 6um, mix 0.25% (wt.%) graphene flakes and 5Cr15MoV high-carbon martensitic stainless steel metal powder using a planetary ball milling method, and use a 250-mesh sieve to screen out the powder that is severely deformed after ball milling. , the screened graphene + 5Cr15MoV high carbon martensitic stainless steel metal powder with an average diameter of 45um is dried in a vacuum drying oven for 2 hours; the SLM 3D printing additive manufacturing process is used, and the reasonable and optimized SLM parameters are power 120W, laser diameter 60um, scanning speed 600mm/s, scanning spacing 50um, layer thickness 20um, the mixing head is prepared according to the imitation conch shell additive manufacturing design structure, and a zigzag scanning strategy is used during the printing process. After each layer of metal printing is completed, the laser The scanning direction is rotated 66.7° before printing the next layer of metal parts. 99.99% industrial pure argon is used as a protective gas in the forming chamber of the SLM printer, and the oxygen content is controlled below 0.15%. All samples were formed on a 304 stainless steel substrate, and the substrate temperature was 60°C. During the printing process, the forming direction of the sample and the dust purification wind direction were set to an angle of 50°, so that the spatter would be blown away from the part of the workpiece being printed by the dust purification gas. Surface, the applied transverse electric field strength is 100V/cm; after SLM printing is completed, place the mixing head in a -196°C liquid nitrogen environment, and use mechanical shot blasting with a load capacity of 1 to 60Kg and a time of 1 to 20 minutes to blast the mixing head. Deep supercooling impact treatment is used to further improve the surface quality and comprehensive mechanical properties of the 3D printed mixing head. The wear resistance of the mixing head manufactured by this method is increased by 18 to 32%.

Embodiment 2

This embodiment uses nanographene-enhanced 5Cr15MoV high-carbon martensitic stainless steel metal powder to 3D print the additive manufacturing method of a mixing head. The average diameter of the 5Cr15MoV high-carbon martensitic stainless steel metal powder is 50um. The number of layers is 10 and the plane size is For graphene flakes of 1 to 6um, mix 0.25% (wt.%) graphene flakes and 5Cr15MoV high-carbon martensitic stainless steel metal powder using a planetary ball milling method, and use a 100-mesh sieve to screen out the powder that is severely deformed after ball milling. , the screened graphene + 5Cr15MoV high-carbon martensitic stainless steel metal powder with an average diameter of 10um is dried for 2 hours in a vacuum drying oven; the SLM 3D printing additive manufacturing process is used, and the reasonable and optimized SLM parameters are power 180W, laser diameter 100um, scanning speed 900mm/s, scanning spacing 70um, layer thickness 30um, the mixing head is prepared according to the imitation conch shell additive manufacturing design structure, and a zigzag scanning strategy is used during the printing process. After each layer of metal printing is completed, the laser The scanning direction is rotated 66.7° before printing the next layer of metal parts. 99.99% industrial pure argon is used as a protective gas in the forming chamber of the SLM printer, and the oxygen content is controlled below 0.15%. All samples were formed on a 304 stainless steel substrate, and the substrate temperature was 90°C. During the printing process, the forming direction of the sample and the dust purification wind direction were set to an angle of 70°, so that the spatter was blown away from the workpiece being printed by the dust purification gas. On the surface, the applied transverse electric field strength is 250V/cm; after SLM printing is completed, place the mixing head in a -196°C liquid nitrogen environment, and use mechanical shot blasting with a load capacity of 1 to 60Kg and a time of 1 to 20 minutes to blast the mixing head. Deep supercooling impact treatment is used to further improve the surface quality and comprehensive mechanical properties of the 3D printed mixing head. The wear resistance of the mixing head manufactured by this method is increased by 18 to 32%.

Embodiment 3

This embodiment uses nanographene-enhanced 5Cr15MoV high-carbon martensitic stainless steel metal powder to 3D print the additive manufacturing method of a mixing head. The average diameter of the 5Cr15MoV high-carbon martensitic stainless steel metal powder is 50um. The number of layers is 10 and the plane size is For graphene flakes of 1 to 6um, mix 0.25% (wt.%) graphene flakes and 5Cr15MoV high-carbon martensitic stainless steel metal powder using a planetary ball milling method, and use a 200-mesh sieve to screen out the powder that is severely deformed after ball milling. , the screened graphene + 5Cr15MoV high-carbon martensitic stainless steel metal powder with an average diameter of 40um is dried for 2 hours in a vacuum drying oven; the SLM 3D printing additive manufacturing process is used, and the reasonable and optimized SLM parameters are power 150W, laser diameter 150um, scanning speed 750mm/s, scanning spacing 60um, layer thickness 25um, the mixing head is prepared according to the imitation conch shell additive manufacturing design structure, and a zigzag scanning strategy is used during the printing process. After each layer of metal printing is completed, the laser The scanning direction is rotated 66.7° before printing the next layer of metal parts. 99.99% industrial pure argon is used as a protective gas in the forming chamber of the SLM printer, and the oxygen content is controlled below 0.15%. All samples were formed on a 304 stainless steel substrate, and the substrate temperature was 75°C. During the printing process, the forming direction of the sample and the dust purification wind direction were set to an angle of 60°, so that the spatter would be blown away from the surface of the workpiece being printed by the dust purification gas. On the surface, the applied transverse electric field intensity is 50V/cm; after SLM printing is completed, place the mixing head in a -196°C liquid nitrogen environment, and use mechanical shot blasting with a load capacity of 1 to 60Kg and a time of 1 to 20 minutes to blast the mixing head. Deep supercooling impact treatment is used to further improve the surface quality and comprehensive mechanical properties of the 3D printed mixing head. The wear resistance of the mixing head manufactured by this method is increased by 18 to 32%.

Embodiment 4

Nanographene-enhanced high-temperature alloy K418 metal powder 3D printing additive manufacturing method of stirring head, high-temperature alloy K418 metal powder with an average diameter of 80um, graphene flakes with a layer number of 12 to 15 layers and a plane size of 1 to 10um, will 2% (wt.%) graphene flakes and high-temperature alloy K418 metal powder were mixed using planetary ball milling. Use a 300-mesh sieve to screen out the powder that was severely deformed after ball milling. The graphene + high-temperature alloy with an average diameter of 50um after screening was K418 metal powder is dried in a 150°C vacuum drying oven for 2 hours; the EBM 3D printing additive manufacturing process is used. The reasonable and optimized EBM parameters are power 140W, scanning speed 600mm/s, scanning spacing 60um, and layer thickness 30um. The mixing head is prepared according to the design structure of the additive manufacturing of imitation river mussel shells. An N-shaped scanning strategy is used during the printing process. After each layer of metal is printed, the electron beam scanning direction is rotated 64.5° before printing the next layer of metal parts. EBM printer The vacuum degree is 1×10 ^-2 . All samples are formed on a 316 stainless steel substrate. The substrate temperature is 150°C. During the printing process, the external longitudinal magnetic field strength is 100mT. After the EBM printing is completed, the stirring head is placed at -33°C. In a liquid ammonia environment, a low-temperature laser shot blasting strengthening method with a power density of 2.2GW/cm ² , a spot diameter of 2mm, and an overlap rate of 40% was used to perform deep supercooling impact treatment on the mixing head to further improve the surface of the 3D printed mixing head In terms of quality and comprehensive mechanical properties, the comprehensive performance of the mixing head manufactured by this method is improved by more than 20%.

Embodiment 5

Nanographene-enhanced high-temperature alloy K418 metal powder 3D printing additive manufacturing method of stirring head, high-temperature alloy K418 metal powder with an average diameter of 80um, graphene flakes with a layer number of 12 to 15 layers and a plane size of 1 to 10um, will 2.4% (wt.%) graphene flakes and high-temperature alloy K418 metal powder are mixed using the planetary ball milling method. Use a 300-mesh sieve to screen out the powder that is severely deformed after ball milling. The average diameter of the screened graphene + high-temperature alloy is 50um. K418 metal powder is dried in a 150°C vacuum drying oven for 2 hours; the EBM 3D printing additive manufacturing process is used. The reasonable and optimized EBM parameters are power 220W, scanning speed 1200mm/s, scanning spacing 80um, and layer thickness 50um. The mixing head is prepared according to the design structure of the additive manufacturing of imitation river mussel shells. An N-shaped scanning strategy is used during the printing process. After each layer of metal is printed, the electron beam scanning direction is rotated 64.5° before printing the next layer of metal parts. EBM printer The vacuum degree is 8×10 ^-2 . All samples are formed on a 316 stainless steel substrate. The substrate temperature is 380°C. During the printing process, the applied longitudinal magnetic field strength is 600mT. After the EBM printing is completed, the stirring head is placed at -33°C. In a liquid ammonia environment, a low-temperature laser shot peening method with a power density of 3.8GW/cm ² , a spot diameter of 2mm, and an overlap rate of 60% was used to perform deep supercooling impact treatment on the mixing head to further improve the surface of the 3D printed mixing head In terms of quality and comprehensive mechanical properties, the comprehensive performance of the mixing head manufactured by this method is improved by more than 20%.

Embodiment 6

Nanographene-enhanced high-temperature alloy K418 metal powder 3D printing additive manufacturing method of stirring head, high-temperature alloy K418 metal powder with an average diameter of 80um, graphene flakes with a layer number of 12 to 15 layers and a plane size of 1 to 10um, will 2% (wt.%) graphene flakes and high-temperature alloy K418 metal powder are mixed using planetary ball milling. Use a 300-mesh sieve to screen out the powder that is severely deformed after ball milling. The average diameter of the screened graphene + high-temperature alloy is 30um. K418 metal powder is dried in a 150°C vacuum drying oven for 2 hours; the EBM 3D printing additive manufacturing process is used. The reasonable and optimized EBM parameters are power 180W, scanning speed 900mm/s, scanning spacing 70um, and layer thickness 40um. The mixing head is prepared according to the design structure of the additive manufacturing of imitation river mussel shells. An N-shaped scanning strategy is used during the printing process. After each layer of metal is printed, the electron beam scanning direction is rotated 64.5° before printing the next layer of metal parts. EBM printer The vacuum degree is 5×10 ^-2 . All samples are formed on a 316 stainless steel substrate. The substrate temperature is 250°C. During the printing process, the external longitudinal magnetic field strength is 300mT. After the EBM printing is completed, the stirring head is placed at -33°C. In a liquid ammonia environment, a low-temperature laser shot blasting strengthening method with a power density of 2.8GW/cm ² , a spot diameter of 2mm, and an overlap rate of 50% was used to perform deep supercooling impact treatment on the mixing head to further improve the surface of the 3D printed mixing head In terms of quality and comprehensive mechanical properties, the comprehensive performance of the mixing head manufactured by this method is improved by more than 20%.

Embodiment 7

Nano-graphene enhanced H13 mold steel metal powder 3D printing additive manufacturing method of mixing head, H13 mold steel metal powder with an average diameter of 80um, graphene flakes with a layer number of 12 to 15 layers and a plane size of 1 to 10um, will 2~2.4% (wt.%) graphene flakes and H13 mold steel metal powder are mixed using the planetary ball milling method, and a 200-mesh sieve is used to screen out the powder that is severely deformed after ball milling, and the graphene+ with an average diameter of 35um after screening is H13 mold steel metal powder is dried in a 150°C vacuum drying oven for 2 hours; SLM's 3D printing additive manufacturing process is used to manufacture the stirring needle of the mixing head, and EBM's 3D printing additive manufacturing process is used to manufacture the shoulder and shoulder of the mixing head. For the mixing head and its parts, the SLM and EBM process parameters are reasonably set and optimized; after 3D printing is completed, the mixing head is subjected to low-temperature laser or mechanical shot blasting to perform deep supercooling impact treatment on the mixing head to further improve 3D printing. The surface quality and comprehensive mechanical properties of the mixing head are improved by more than 20%.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified. Modifications or equivalent substitutions without departing from the spirit and scope of the technical solution of the present invention shall be included in the scope of the claims of the present invention.

Claims (2)

1. A method for 3D printing additive manufacturing of mixing heads with nano-graphene reinforced metal powder, which is characterized by: using metal powder and nano-graphene sheets as raw materials, and using a shell laminated braided structure as a bionic design structure object to build a mixing head model , prepare the mixing head through 3D printing; including the following steps: S _1. Preparation of spheroidized powder: mix metal powder and nanographene sheets and spheroidize them. The content of the nanographene sheets is 0.1~5wt% of the mixed powder, and the diameter of the powder after spheroidization is 1~50um; S ₂ , bionic model construction: using the shell laminated braided structure as the bionic design structure object, design and optimize the 3D printing additive manufacturing unsupported structural model of the mixing head, design and optimize the bionic modeling of the mixing needle and shaft shoulder surface; S ₃ , 3D printing: using laser selective melting molding or electron beam melting molding. The laser selective melting molding uses 99.99% argon as a protective gas, and controls the oxygen content to be less than 0.15%. The power is 100W~800W, and the laser is focused. The diameter is 50um~200um, the scanning speed is 400mm/s~2000mm/s, the scanning spacing is 20um~100um, and the layer thickness is 10um~50um; the output power of the electron beam melting molding is 200W~3000W, and the scanning speed is 500mm/s~ 3000mm/s, linear energy density 0.2J/mm～1.2J/mm, spot diameter 80um～400um, layer thickness 20um～100um, vacuum degree 1×10 ^-2 ～1×10 ^-3 Pa; the stirring head is at the same time 3D printing additive manufacturing is performed on the material substrate or low alloy steel or low carbon steel, and the preheating temperature is 200~1400°C; the mixing head is 3D printed additively manufactured on the same material substrate or low alloy steel or low carbon steel, and the preheating temperature is 200-1400°C. The thermal temperature is 200 to 1400°C. During the printing process, a variety of glyph mixed weaving methods are used to scan. After each layer of metal printing is completed, the laser scanning direction is rotated 60 to 70°, and then the next layer of stirring head metal is 3D printed. The glyph shapes include regular Z-shaped, L-shaped, V-shaped, N-shaped, W-shaped, S-shaped, and X-shaped; for non-ferromagnetic materials, an external electric field or external magnetic field is set outside the 3D printing area, and the external electric field or external magnetic field is consistent with The center line of the molten pool is parallel or vertical; during the 3D printing process, one of low-temperature liquid nitrogen, low-temperature liquid CO ₂ , and low-temperature liquid ammonia media is used for deep supercooling treatment, and high-intensity ultrasonic impact is used simultaneously under low temperature conditions. The printed mixing head is subjected to deep supercooling and high-intensity impact treatment using one of laser shot blasting or mechanical shot peening methods. The processing time is 0.5h~24h, and then the shape, geometry, and surface of the mixing head are processed at room temperature. Quality refinement. 2. The method for nanographene-enhanced metal powder 3D printing additive manufacturing stirring head according to claim 1, characterized in that: the intensity of the external electric field is 50V/cm~500V/cm; the magnetic field intensity of the external magnetic field is 5~800mT.