CN112974820A

CN112974820A - Preparation method of metal powder, 3D printing method and 3D printed part

Info

Publication number: CN112974820A
Application number: CN202110195360.1A
Authority: CN
Inventors: 吴欢欢; 樊恩想; 廖文俊; 付超; 苏青; 刘小欣
Original assignee: Shanghai Electric Group Corp
Current assignee: Shanghai Electric Group Corp
Priority date: 2021-02-19
Filing date: 2021-02-19
Publication date: 2021-06-18
Anticipated expiration: 2041-02-19
Also published as: CN112974820B

Abstract

The application relates to a preparation method of metal powder, a 3D printing method and a 3D printed piece. The preparation method of the metal powder adopts a gas atomization method to prepare the metal powder, and comprises the following steps: smelting the raw materials for 14-16min at a first power, and then continuing to smelt at a second power until the temperature reaches a first temperature; then atomizing under the first power, the first temperature and the pressure of 3-7 MPa; the first power is 13-14KW, the second power is 28-29KW, and the first temperature is 1500-1700 ℃. The method can remarkably improve the yield of the powder with the particle size of less than 75 mu m by the specific process, and the yield is more than 96%. By adopting a specific printing process, metal powder with the density of less than 75 microns can be effectively utilized to obtain a metal piece with the density of 99%, the particle size section of the powder for 3D printing is enlarged, and the utilization rate of the metal powder is improved.

Description

Preparation method of metal powder, 3D printing method and 3D printed part

Technical Field

The application relates to the field of 3D printing, in particular to a preparation method of metal powder, a 3D printing method and a 3D printed piece.

Background

The spherical metal powder is a core material for 3D printing of metal, is the most important link in a 3D printing industrial chain, and is closely related to the development of a 3D printing technology. The current state of the art for milling includes vacuum atomization. The working principle of vacuum gas atomization is that metal and metal alloy are smelted by using a crucible under the condition of gas protection in a vacuum state, and when the smelting is finished, a ceramic stopper rod at the bottom is pulled out, so that molten liquid flows downwards through a liquid guide pipe, and the metal liquid is atomized and crushed into a large number of fine liquid drops by high-pressure gas flow through a nozzle. The fine liquid drops are solidified into spherical and sub-spherical particles in flight, and then the metal powder with various particle sizes is prepared by screening and separating.

At present, the particle size section of powder for 3D printing is mainly 15-53 mu m, the yield of metal powder prepared by a vacuum atomization method below 53 mu m is generally 40%, the yield of metal powder below 75 mu m is generally 50-60%, on one hand, the yield is low, on the other hand, the metal powder with the particle size of 53-75 mu m is difficult to be utilized due to difficult printing, and finally the cost of the metal powder is high.

Disclosure of Invention

The application aims to provide a preparation method of metal powder, a 3D printing method and a 3D printing piece, so that the effects of improving the yield of the metal powder and expanding the particle size section of powder for 3D printing are achieved.

In order to achieve the above purpose of the present application, the following technical solutions are adopted:

in a first aspect, the present application provides a method for preparing metal powder by gas atomization, comprising the following steps:

smelting the raw materials for 14-16min at a first power, and then continuing to smelt at a second power until the temperature reaches a first temperature;

then atomizing under the first power, the first temperature and the pressure of 3-7 MPa;

the first power is 13-14KW, the second power is 28-29KW, and the first temperature is 1500-1700 ℃.

As a further preferred technical solution, the first power is 13.5-14KW, preferably 13.6 KW; the time for smelting at the first power is 14.5-15.5min, preferably 15 min.

As a further preferable technical scheme, the second power is 28.2-28.7KW, preferably 28.5 KW; the first temperature is 1550-; the pressure during atomization is 4-6MPa, preferably 4.5 MPa.

As a further preferred technical scheme, a tightly coupled gas atomization nozzle is adopted during atomization, and the spray angle of the nozzle is 52-76 degrees.

As a further preferred technical solution, before melting the raw material at the first power, the method further comprises the step of grinding the stopper rod, wherein the stopper rod is ground by using the following grinding device:

the polishing device comprises a clamp, a percussion drill and a bead rounding device, the bead rounding device is arranged above the percussion drill, the percussion drill is connected with the clamp, and the clamp is used for fixing the percussion drill;

the burnishing stopper rod includes: and placing the plug rod in the bead rounding device, and grinding for 30-60 s.

As a further preferable technical scheme, the method further comprises a screening step after the atomization, wherein an ultrasonic vibration screen is adopted during screening, the amplitude is 0-3mm, 0 is not included, and the vibration frequency is 1400-1500 r/min.

In a second aspect, the application provides a 3D printing method, and the metal powder prepared by the above preparation method of the metal powder is used for 3D printing.

As a further preferable technical scheme, the laser power during 3D printing is 180-480W, the laser scanning speed is 600-2000mm/s, the printing layer thickness is 20-60 μm, the laser track pitch is 0.06-0.18mm, and the powder spreading speed is 10-50 mm/s.

As a further preferable technical scheme, the laser power during 3D printing is 200-400W, the laser scanning speed is 800-1500mm/s, the printing layer thickness is 30-50 μm, the laser track pitch is 0.08-0.15mm, and the powder spreading speed is 10-40 mm/s.

In a third aspect, the application provides a 3D printed product obtained by the above 3D printing method.

Compared with the prior art, the beneficial effect of this application is:

according to the preparation method of the metal powder, firstly, smelting is carried out for a specific time at a first power, then, smelting is continued at a second power until a first temperature is reached, and then, smelting is finished; then atomizing under the first power, the first temperature and the specific pressure, and by the specific process, the yield of the powder with the particle size of less than 75 microns can be obviously improved, and the yield is more than 96%.

According to the 3D printing method provided by the application, the prepared metal powder is adopted for 3D printing, a specific printing process is adopted, the metal powder with the density of less than 75 microns can be effectively utilized, the metal piece with the density of 99% is obtained, the particle size section of the powder for 3D printing is enlarged, and the utilization rate of the metal powder is improved.

Drawings

FIG. 1 is a schematic cross-sectional view of a close-coupled gas atomizing nozzle in accordance with an embodiment of the present application;

FIG. 2 is a schematic view of a sanding block of an abrading device according to one embodiment of the present application;

FIG. 3 is a graph showing a particle size distribution of a metal powder obtained by the method of example 8;

FIG. 4 is a graph showing the distribution of the particle size of the metal powder obtained by the method of example 8 after sieving through a 1000-mesh sieve;

figure 5 is a schematic cross-sectional view of a 3D print obtained using the method of example 11.

Icon: 1-nozzle backflow pipe; 2-gas cavity; 3-spraying a pipe; 4-a stopper rod; 5-bead rounding device; 6-impact drilling; 7-clamping.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: in the present application, all embodiments and preferred methods mentioned herein can be combined with each other to form new solutions, if not specifically stated. In the present application, all the technical features mentioned herein as well as preferred features may be combined with each other to form new technical solutions, if not specifically stated. In the present application, percentages (%) or parts refer to percent by weight or parts by weight relative to the composition, unless otherwise specified. In the present application, the components referred to or the preferred components thereof may be combined with each other to form new embodiments, if not specifically stated. In this application, unless otherwise stated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "6 to 22" means that all real numbers between "6 to 22" have been listed herein, and "6 to 22" is simply a shorthand representation of the combination of these values. The "ranges" disclosed herein may be in the form of lower limits and upper limits, and may be one or more lower limits and one or more upper limits, respectively. In the present application, the individual reactions or process steps may be performed sequentially or in sequence, unless otherwise indicated. Preferably, the reaction processes herein are carried out sequentially.

Unless otherwise defined, technical and scientific terms used herein have the same meaning as is familiar to those skilled in the art. In addition, any methods or materials similar or equivalent to those described herein can also be used in the present application.

According to one aspect of the present application, there is provided a method for preparing metal powder by gas atomization, comprising the steps of:

The gas atomization method refers to a method of producing metal powder by breaking up a continuous thin stream of molten metal using a gas as an atomization medium.

The first power is, for example, 13KW, 13.1KW, 13.2KW, 13.3KW, 13.4KW, 13.5KW, 13.6KW, 13.7KW, 13.8KW, 13.9KW, or 14 KW. The time for melting at the first power is, for example, 14min, 14.2min, 14.4min, 14.6min, 14.8min, 15min, 15.2min, 15.4min, 15.6min, 15.8min, or 16 min.

The second power is, for example, 28KW, 28.1KW, 28.2KW, 28.3KW, 28.4KW, 28.5KW, 28.6KW, 28.7KW, 28.8KW, 28.9KW or 29 KW. The first temperature is, for example, 1500 deg.C, 1520 deg.C, 1540 deg.C, 1560 deg.C, 1580 deg.C, 1600 deg.C, 1620 deg.C, 1640 deg.C, 1660 deg.C, 1680 deg.C or 1700 deg.C. The atomization pressure is, for example, 3MPa, 3.2MPa, 3.4MPa, 3.6MPa, 3.8MPa, 4MPa, 4.2MPa, 4.4MPa, 4.6MPa, 4.8MPa, 5MPa, 5.2MPa, 5.4MPa, 5.6MPa, 5.8MPa, 6MPa, 6.2MPa, 6.4MPa, 6.6MPa, 6.8MPa or 7 MPa.

The preparation method of the metal powder comprises the steps of firstly smelting for a specific time at a first power, then continuously smelting at a second power until a first temperature is reached, and at the moment, finishing the smelting; then atomizing under the first power, the first temperature and the specific pressure, and by the specific process, the yield of the powder with the particle size of less than 75 microns can be obviously improved, and the yield is more than 96%.

The above yield is a percentage of the weight of the metal powder of the target particle size to the total weight of the metal powders of all particle sizes.

In a preferred embodiment, the first power is between 13.5 and 14KW, preferably 13.6 KW; the time for smelting at the first power is 14.5-15.5min, preferably 15 min.

In a preferred embodiment, the second power is between 28.2 and 28.7KW, preferably 28.5 KW; the first temperature is 1550-; the pressure during atomization is 4-6MPa, preferably 4.5 MPa.

The above preferred embodiment can further improve the yield of the metal powder having a desired particle diameter by further optimizing the above parameters.

In a preferred embodiment, a close-coupled gas atomization nozzle is used for atomization, the spray angle of the nozzle being 52 ° to 76 °. The above-mentioned injection angle is, for example, 52 °, 53 °, 54 °, 55 °, 56 °, 57 °, 58 °, 59 °, 60 °, 61 °, 62 °, 63 °, 64 °, 65 °, 66 °, 67 °, 68 °, 69 °, 70 °, 71 °, 72 °, 73 °, 74 °, 75 °, or 76 °. The tightly coupled gas atomizing nozzle is a laval nozzle with a retractable gas outflow channel, and the gas flow reaches the maximum speed and the gas flow is the minimum at the outlet of the nozzle. The close coupling gas atomization nozzle can adopt any one of the prior arts (for example, the nozzle shown in fig. 1, which comprises a nozzle backflow pipe 1, a gas cavity 2 and a nozzle pipe 3, can be adopted), and the spraying angle of the close coupling gas atomization nozzle is preferably 52-76 degrees, so that the condition can be better matched with melting parameters and atomization parameters, and the efficiency and the effect of powder preparation can be improved.

In a preferred embodiment, before melting the feedstock at the first power, there is further included the step of grinding the stopper rod, as shown in fig. 2, the stopper rod 4 being ground using the following grinding device:

the polishing device comprises a clamp 7, a percussion drill 6 and a bead rounding device 5, wherein the bead rounding device 5 is arranged above the percussion drill 6, the percussion drill 6 is connected with the clamp 7, and the clamp 7 is used for fixing the percussion drill 6;

the burnishing stopper rod includes: the plug rod 4 is placed in the bead rounding device 5 and is polished for 30-60 s.

The plug rod can be a ceramic plug rod.

The stopper rod can be polished to avoid leakage between the catheter and the stopper rod, and the stopper rod is polished for tens of minutes in the prior art, so that the efficiency is low. In the preferred embodiment, the plug rod is polished by using a specific polishing device, so that the polishing effect is good, the efficiency is extremely high, and only 30-60s of polishing is needed. The sanding time is for example 30s, 35s, 40s, 45s, 50s or 60 s.

Preferably, the diameter of the sand beads in the bead rounder is 15-18 mm.

In a preferred embodiment, after the atomization, the method further comprises a step of sieving, wherein an ultrasonic vibration sieve is adopted during sieving, the amplitude is 0-3mm, 0 is not included, and the vibration frequency is 1400-1500 r/min. The amplitude is, for example, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm or 3 mm. The vibration frequency is 1400r/min, 1410r/min, 1420r/min, 1430r/min, 1440r/min, 1450r/min, 1460r/min, 1470r/min, 1480r/min, 1490r/min or 1500r/min, for example. By adopting the screening method, the metal powder with the particle size of less than 75 mu m can be quickly obtained, and the metal powder with the particle size of less than 75 mu m accounts for 96 percent of the weight of all the metal powder.

By the same screening method, the mesh number of the screen is changed to remove metal powder with a particle size of 15-75 μm, and the yield of the metal powder with the particle size range is about 92%.

Optionally, a drying step is included after sieving, for example at a temperature of 75-85 ℃ for a period of time of, for example, 3-5 h.

Optionally, before the raw material is smelted at the first power, the step of winding a ring of asbestos fibers on the inner periphery of the outer crucible is further included, and the asbestos fibers are used as a buffer layer, so that the inner crucible can be prevented from cracking due to expansion.

The steps and parameters not mentioned in the present application may be any ones that can be implemented in the art, and the present application is not particularly limited thereto.

According to another aspect of the application, a 3D printing method is provided, and 3D printing is performed by using the metal powder prepared by the preparation method of the metal powder. According to the 3D printing method, the prepared metal powder is adopted for 3D printing, a specific printing process is adopted, the metal powder with the density of less than 75 microns can be effectively utilized, a metal piece with the density of 99% is obtained, the particle size section of the powder for 3D printing is enlarged, and the utilization rate of the metal powder is improved.

In a preferred embodiment, the laser power during 3D printing is 180-480W, the laser scanning speed is 600-2000mm/s, the printing layer thickness is 20-60 μm, the laser track pitch is 0.06-0.18mm, and the powder spreading speed is 10-50 mm/s.

The laser power is, for example, 180W, 200W, 220W, 240W, 260W, 280W, 300W, 320W, 340W, 360W, 380W, 400W, 420W, 440W, 460W or 480W. The above laser scanning speed is, for example, 600mm/s, 700mm/s, 800mm/s, 900mm/s, 1000mm/s, 1100mm/s, 1200mm/s, 1300mm/s, 1400mm/s, 1500mm/s, 1600mm/s, 1700mm/s, 1800mm/s, 1900mm/s or 2000 mm/s. The print layer has a thickness of, for example, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm or 60 μm. The above-mentioned laser track pitch is, for example, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.10mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm or 0.18 mm. The above-mentioned powder-laying speed is, for example, 10mm/s, 15mm/s, 20mm/s, 25mm/s, 30mm/s, 35mm/s, 40mm/s, 45mm/s or 50 mm/s.

The above print layer thickness means the thickness of each print layer.

The laser track interval refers to the interval between the centers of two adjacent lasers.

The powder spreading speed refers to the speed of spreading powder on the molded substrate by the scraper.

In a preferred embodiment, the laser power during 3D printing is 200-400W, the laser scanning speed is 800-1500mm/s, the printing layer thickness is 30-50 μm, the laser track pitch is 0.08-0.15mm, and the powder spreading speed is 10-40 mm/s. By optimizing the parameters, the density and the mechanical property of the printed product can be further improved.

Optionally, the scanning policy is a checkerboard or a partition.

Optionally, the method comprises forming and heat treatment, wherein the forming is performed by using the above parameters, the heat treatment is performed after the forming, and the heat treatment process can be realized in the field. For example, the inside of the heat treatment furnace is evacuated to below 0.05MPa by a mechanical pump, then pure nitrogen is filled to the standard atmospheric pressure, the inside is evacuated to below 0.05MPa by the mechanical pump, the process is repeated at least three times, and finally the heat treatment is carried out under the nitrogen protection environment. The heat treatment process comprises the steps of heating to the temperature of between 20 and 50 minutes and 700 ℃ for 1 to 3 hours, and cooling to the room temperature in a furnace.

According to another aspect of the application, a 3D printed product obtained by the 3D printing method is provided. The 3D printed product obtained by the method has the advantages of high density and good mechanical property.

The application has the following advantages:

1. the close coupling type atomizing nozzle is matched with a corresponding smelting process, so that the yield of the gas atomized metal powder can be improved.

2. The asbestos fiber is used as a buffer layer, and can prevent the inner crucible from cracking due to expansion.

3. The ceramic stopper rod polishing device can greatly improve the safety performance and save time of experiment and production, and improve the efficiency.

4. And part of the finest powder particles and the coarse powder particles are removed, the printable metal powder particle size range is found, the metal powder particle size range is enlarged to the maximum extent, and the powder utilization rate is improved.

5. The powder with the particle size of 0-75 mu m can be successfully printed by using a flexible plastic soft scraper and matching with a lower powder spreading speed and matched printing process parameters.

The present application will be described in further detail with reference to examples and comparative examples.

Example 1

A preparation method of metal powder adopts a gas atomization method to prepare the metal powder, and comprises the following steps:

(1) and a circle of asbestos fiber is surrounded inside the outer crucible, the inner crucible is placed into the outer crucible, and the gap is filled with coarse magnesia, wherein the asbestos fiber is used for preventing the inner crucible from cracking due to thermal expansion. The cement plate is mounted and serves to prevent the molten steel from flowing out and to protect the underlying atomising nozzle (as in CN 107377984). The crucible is placed on a cement plate and positioned and fixed.

(2) The ceramic stopper rod is used for concentric finding, the top of the ceramic stopper rod is hemispherical, a fine sand bead rounding device with the diameter of 15-18mm needs to be used for smooth polishing, and after the ceramic stopper rod is polished by the bead rounding device, liquid can not leak from the positions of the liquid guide tube and the ceramic stopper rod. The mixture of fine magnesia and glass water fills the gap between the liquid guide pipe and the crucible. The mixture of the coarse magnesia and the glass water is put into an inner crucible and is crushed flat, and is dried by a hot air blower at 150 ℃ for 15 min. And (4) determining that the flow channel of the catheter is unobstructed, compacting the plug rod, and discharging. The vacuum is pumped by a mechanical pump and a Roots pump, and if high vacuum is required, the molecular pump can be started. And (5) after the vacuum pumping is finished, closing the vacuum pump, and filling argon to the micro positive pressure.

(3) Smelting the raw materials for 16min under 13KW, and then continuing smelting under 28KW until the temperature reaches 1500 ℃; then atomized at 28KW, 1500 ℃ and 3 MPa.

(4) And after the atomization is finished, the power supply is turned off, the draught fan is turned off, and the air blowing gas at the bent pipe is opened to collect the powder.

(5) Sieving with ultrasonic vibration sieve with amplitude of 4mm, vibration frequency of 1300r/min and mesh number of 200 meshes (aperture of 75 μm).

(6) Drying, drying the obtained metal powder at 80 ℃ for 3 h.

Example 2

Unlike example 1, a method for producing a metal powder according to the present example includes the following steps (3): smelting the raw materials for 14min under 14KW, and then continuing smelting under 29KW until the temperature reaches 1700 ℃; then atomized at 29KW, 1700 ℃ and 7 MPa. The remaining steps were the same as in example 1.

Example 3

Unlike example 1, a method for producing a metal powder according to the present example includes the following steps (3): smelting the raw materials for 15min under 13.6KW, and then continuing smelting under 29KW until the temperature reaches 1700 ℃; then atomized at 29KW, 1700 ℃ and 7 MPa. The remaining steps were the same as in example 1.

In the present embodiment, the power and time for starting smelting of the raw material in the step (3) are both within the preferable range of the present application.

Example 4

Unlike example 1, a method for producing a metal powder according to the present example includes the following steps (3): smelting the raw materials for 15min under 13.6KW, and then continuing smelting under 28.5KW until the temperature reaches 1600 ℃; then atomized at 28.5KW, 1600 ℃ and 4.5 MPa. The remaining steps were the same as in example 1.

All parameters in step (3) of this example are within the preferred ranges of the present application.

Example 5

Unlike example 4, the atomizing nozzle used in this example was a close-coupled gas atomizing nozzle having a spray angle of 60 °. The remaining steps were the same as in example 4.

The nozzle in this embodiment is the preferred nozzle in this application.

Example 6

Unlike example 5, in the present example, step (2) was performed by using the following polishing apparatus in polishing a stopper rod: the polishing device comprises a clamp, a percussion drill and a bead rounding device, the bead rounding device is arranged above the percussion drill, the percussion drill is connected with the clamp, and the clamp is used for fixing the percussion drill; the burnishing stopper rod includes: and placing the plug rod in the bead rounding device, and grinding for 30-60 s. The remaining steps were the same as in example 5.

The preferred device and process of this application are used to polish the stopper rod in this embodiment.

Example 7

A method for producing a metal powder, which is different from example 6, in this example, the step (5) had an amplitude of 3mm at the time of sieving and a vibration frequency of 1400 r/min. The remaining steps were the same as in example 6.

Example 8

A method for producing a metal powder, which is different from example 6 in that in the present example, the amplitude of the step (5) during sieving was 1mm and the vibration frequency was 1440 r/min. The remaining steps were the same as in example 6.

The sizing process in examples 7 and 8 are within the preferred range of the present application.

After sieving by the method of example 8, the metal powder D10 ═ 8.62 μm, D50 ═ 27.0 μm, and D90 ═ 63.8 μm (see fig. 3), and further sieving was carried out for 30 minutes by using a 1000-mesh sieve (pore size: 15 μm), the metal powder D10 ═ 10.1 μm, D50 ═ 32.3 μm, and D90 ═ 71.3 μm (see fig. 4).

Example 9

A 3D printing method using the metal powder prepared in example 8 for 3D printing, comprising the steps of:

installation 3D printer base plate, the base plate is 304 stainless steel, installation and regulation flexible plastic scraper, and flexible plastic scraper material is imported pure natural rubber to flexible plastic scraper surface scribbles the little graphite particle coating of carbon of frictional force, makes flexible plastic scraper can be more smooth when spreading metal powder, and is more wear-resisting, increase of service life. After the scraper is adjusted, the machine cabin door is closed, the substrate is opened for heating, the heating temperature is set to be 90 ℃, pure argon is introduced, the oxygen content in the printing cavity is enabled to be lower than 1000ppm, and technological parameters are set. The laser power is 180W, the laser scanning speed is 600mm/s, the printing layer thickness is 20 microns, the laser track pitch is 0.06mm, the scanning strategy is chessboard or subarea, and the powder spreading speed on the molding substrate is 10 mm/s.

And after printing is finished, taking out the powder in the part, immediately putting the part into a heat treatment furnace, before heat treatment, vacuumizing the interior of the hot discharge furnace by using a mechanical pump to below 0.05MPa, then filling pure nitrogen to standard atmospheric pressure, vacuumizing by using the mechanical pump to below 0.05MPa, repeating the steps for three times, and finally performing heat treatment in a nitrogen protection environment. The heat treatment process comprises the following steps: heating for 35min to 600 ℃, preserving heat for 2h, and cooling the furnace to room temperature.

Example 10

A3D printing method adopts the metal powder prepared in the embodiment 8 to perform 3D printing, wherein the laser power is 480W, the laser scanning speed is 2000mm/s, the printing layer thickness is 60 microns, the laser track pitch is 0.18mm, and the powder spreading speed is 50 mm/s. The other steps and parameters were the same as in example 9.

Example 11

A3D printing method adopts the metal powder prepared in the embodiment 8 to perform 3D printing, wherein the laser power is 440W, the laser scanning speed is 1500mm/s, the printing layer thickness is 50 microns, the laser track pitch is 0.10mm, and the powder spreading speed is 10 mm/s. The other steps and parameters were the same as in example 9.

A schematic cross-sectional view of a 3D print obtained using this example is shown in fig. 5.

Example 12

A3D printing method adopts the metal powder prepared in the embodiment 8 to perform 3D printing, wherein the laser power is 300W, the laser scanning speed is 1200mm/s, the printing layer thickness is 40 mu m, the laser track pitch is 0.10mm, and the powder spreading speed is 20 mm/s. The other steps and parameters were the same as in example 9.

The above parameters in this example 11-12 are all within the further preferred ranges of the present application.

Example 13

A3D printing method adopts the metal powder prepared in the embodiment 8 to perform 3D printing, wherein the laser power is 150W, the laser scanning speed is 550mm/s, the printing layer thickness is 70 mu m, the laser track pitch is 0.20mm, and the powder spreading speed is 60 mm/s. The other steps and parameters were the same as in example 9.

None of the above parameters in this embodiment are within the preferred ranges of the present application.

Comparative example 1

A method for producing a metal powder, which is different from example 1 in that step (3) in this comparative example is: smelting the raw materials for 10min under 12KW, and then continuing smelting under 25KW until the temperature reaches 1500 ℃; and then atomized at 25KW, 1500 ℃ and a pressure of 3 MPa. The other steps and parameters were the same as in example 1.

The relevant parameters in this comparative example are not within the ranges provided in the present application.

Comparative example 2

A method for producing a metal powder, which is different from example 1 in that step (3) in this comparative example is: smelting the raw materials for 10min under 20KW, and then continuing smelting under 25KW until the temperature reaches 1400 ℃; then atomized at 25KW, 1400 ℃ and 8 MPa. The other steps and parameters were the same as in example 1.

None of the relevant parameters in this comparative example are within the ranges provided in this application.

Comparative example 3

A method for producing a metal powder, which is different from example 1 in that step (3) in this comparative example is: smelting the raw materials under 28KW until the temperature reaches 1500 ℃; then atomized at 28KW, 1500 ℃ and 3 MPa. The other steps and parameters were the same as in example 1.

In the comparative example, the smelting was carried out directly at 28KW, but not at 13 KW.

The yields of metal powders having particle diameters of 75 μm or less obtained by the methods of examples 1 to 8 and comparative examples 1 to 3 were respectively counted, and the results are shown in Table 1. The 3D prints obtained using the methods of examples 9-13 were tested for density, tensile strength and elongation, respectively, and the results are shown in table 2.

TABLE 1

Group of	Yield of the product
		Example 1	89.3％
Example 2	89.7％
		Example 3	89.9％
Example 4	90.2％
		Example 5	90.6％
Example 6	91.4％
		Example 7	91.9％
Example 8	92.2％
		Comparative example 1	88.4％
Comparative example 2	88.8％
		Comparative example 3	89.1％

As can be seen from Table 1, the yield of the metal powder obtained by the method of examples 1-8 is higher than that of comparative examples 1-3, which shows that the method of the present application has scientific and reasonable process steps and parameters, can effectively improve the yield of the metal powder, and the yield is reduced by changing the process steps or process parameters.

Further, the yield of example 3 is higher than that of examples 1-2, which shows that the yield can be further improved by optimizing the power and time for starting the smelting of the raw materials; the yields of the examples 3 to 7 are sequentially improved, which shows that the yield can be further improved by further optimizing parameters, adopting an optimized nozzle, an optimized grinding device and process and an optimized screening process; the yields of examples 7 and 8 are higher than those of example 6, which shows that the yield can be further improved by using the preferred sieving process.

TABLE 2

Group of	Compactness degree	Tensile strength	Elongation percentage
				Example 9	99.31％	720.1MPa	46.3％
Example 10	99.36％	728.4MPa	47.1％
				Example 11	99.38％	732.5MPa	47.8％
Example 12	99.41％	743.8MPa	50.1％
				Example 13	99.22％	712.5MPa	44.9％

As can be seen from Table 2, the overall performance of examples 9-12 is better than that of example 13, which shows that the density, tensile strength and elongation of the printed product can be higher by adopting the preferred printing process parameters of the application. The overall performance of examples 11-12 is superior to that of examples 9-10, indicating that the density, tensile strength and elongation of the prints can be further improved by further optimizing the printing process parameters.

It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims

1. The preparation method of the metal powder is characterized in that the metal powder is prepared by adopting a gas atomization method, and comprises the following steps:

2. Method for the production of a metal powder according to claim 1, wherein the first power is 13.5-14KW, preferably 13.6 KW; the time for smelting at the first power is 14.5-15.5min, preferably 15 min.

3. Method for the production of a metal powder according to claim 1, wherein the second power is 28.2-28.7KW, preferably 28.5 KW; the first temperature is 1550-; the pressure during atomization is 4-6MPa, preferably 4.5 MPa.

4. The method of claim 1, wherein the atomizing is performed by using a close-coupled gas atomizing nozzle having a spray angle of 52 ° to 76 °.

5. The method of claim 1, further comprising the step of grinding the stopper rod prior to melting the feedstock at the first power, the stopper rod being ground using the following grinding apparatus:

6. The method as claimed in any one of claims 1 to 5, further comprising a step of sieving after the atomization, wherein the sieving is performed by using an ultrasonic vibration sieve, the amplitude is 0-3mm, 0 is excluded, and the vibration frequency is 1400-1500 r/min.

7. A 3D printing method, characterized in that the metal powder produced by the method for producing metal powder according to any one of claims 1 to 6 is subjected to 3D printing.

8. The 3D printing method as claimed in claim 7, wherein the laser power during 3D printing is 180-480W, the laser scanning speed is 600-2000mm/s, the printing layer thickness is 20-60 μm, the laser track pitch is 0.06-0.18mm, and the powder spreading speed is 10-50 mm/s.

9. The 3D printing method as claimed in claim 7 or 8, wherein the laser power during 3D printing is 200-400W, the laser scanning speed is 800-1500mm/s, the printing layer thickness is 30-50 μm, the laser track pitch is 0.08-0.15mm, and the powder spreading speed is 10-40 mm/s.

10. 3D print obtained with the 3D printing method according to any of claims 7 to 9.