Method for manufacturing titanium powder / titanium alloy powder for 3D printing through hydrogen heat treatment and jet milling

Abstract

The invention discloses a method for manufacturing titanium powder / titanium alloy powder for 3D printing through hydrogen heat treatment and jet milling. The method comprises the steps that hydrogen heat treatment is conducted, and prefabricated particles with grain boundary cracks are generated on a titanium or titanium alloy material through hydrogen absorption and dehydrogenation; coarse crushing: crushing the prefabricated particles subjected to hydrogen heat treatment into coarse powder of 10-20 meshes; crushing and shaping by a jet mill: crushing the coarse powder by the jet mill, crushing the powder in a milling chamber by collision, and shaping by rotary motion. The hydrogen heat treatment production process is fully sealed, and no contact component pollution exists in the whole process; in the whole link, inert gas is used for protecting sealing without oxidation, so that the powder activity is ensured; the sphericity degree of the obtained powder is larger than or equal to 70%, and the yield of the powder is larger than or equal to 95% when the particle size of the powder is 10-50 microns; the percent of pass of the titanium and titanium alloy powder for 3D printing reaches up to 95%.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium powder for 3D laser printing, and relates to a method for manufacturing titanium powder / titanium alloy powder for 3D printing by utilizing hydrogen heat treatment and air flow milling. Background Art

[0002] At present, the main methods for preparing titanium or titanium alloy powder for 3D printing are gas atomization, plasma rotating electrode method (PREP), and plasma atomization method (PA); the core technologies and equipment of PREP and PA are mainly mastered in Russia, Canada, and Sweden. At present, there is still a big gap in the equipment developed and introduced in China. These methods require melting raw materials and high energy consumption when preparing powder materials for 3D printing. The yield of 0-50μm powder by PREP method is less than 20%. The PA method requires its raw materials to be pre-formed into wires, and it is difficult to prepare raw materials from titanium or titanium alloys; and the PA method has more satellite powders, a high hollow rate of 45μm particle size, no shaping, and poor sphericity.

[0003] The high cost of titanium powder is caused by various reasons. The high price of powder slows down the market application of titanium or titanium alloy 3D printing products. Currently, it is only used in military industry and high-end civilian markets such as Apple and Huawei. At present, my country has invested more in 3D printing research, but less in the research of powder preparation equipment and low-cost process technology. Summary of the invention

[0004] The purpose of the present invention is to provide a method for manufacturing titanium powder for 3D printing by hydrogen heat treatment and air flow milling, which can significantly reduce costs and promote the industrial development of the 3D printing industry chain.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for manufacturing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling, comprising the following operations:

[0007] 1) Hydrogen heat treatment:

[0008] A titanium or titanium alloy material with an oxygen content of less than 1000 PPm and a carbon content of less than 500 PPm is introduced with hydrogen gas to a hydrogen pressure of 0.06-0.1 MPa under vacuum conditions, and heated to 200-300°C to absorb hydrogen; after the hydrogen absorption is completed, the hydrogen gas is discharged, and then the material is heated to 400-600°C under vacuum conditions to dehydrogenate;

[0009] Prefabricated particles in which grain boundary cracks are generated in titanium or titanium alloy material through hydrogen absorption and dehydrogenation;

[0010] 2) Coarse crushing:

[0011] Crushing the prefabricated particles after hydrogen heat treatment into coarse powder of 10 to 20 mesh;

[0012] 3) Jet mill crushing and shaping:

[0013] The coarse powder is crushed by air jet mill, the powder collides and breaks in the grinding chamber, and is shaped by the rotating motion.

[0014] When the titanium or titanium alloy material absorbs hydrogen, the heating is stopped 10 to 30 minutes after the start of hydrogen absorption, and hydrogen is supplemented to maintain the hydrogen pressure at 0.06 to 0.1 MPa. The total hydrogen absorption time is calculated as 30 to 50 minutes / 100 kg;

[0015] During the vacuum dehydrogenation, the vacuum degree is maintained at ≤1 Pa, and the dehydrogenation time is 3 to 6 hours.

[0016] Further, the hydrogen heat treatment includes the following operations:

[0017] Put titanium or titanium alloy into a reactor and evacuate it; introduce hydrogen into the reactor until the hydrogen pressure is 0.06-0.1 MPa, and heat the reactor to 200-300°C until the titanium or titanium alloy begins to absorb hydrogen;

[0018] 10 to 30 minutes after the start of hydrogen absorption, stop heating and add hydrogen to a pressure of 0.06 to 0.1 MPa; the total hydrogen absorption time is calculated as 30 to 50 minutes / 100 kg;

[0019] The reactor after hydrogen absorption is evacuated, and when the vacuum degree reaches 0.1-1Pa, it is heated to 400-600°C; the dehydrogenation time is 3-6h, and the vacuum degree is ensured to be ≤1Pa at the end of dehydrogenation.

[0020] The coarse crushing is to mix the prefabricated particles with the antioxidant, and then ball-mill and screen out qualified coarse particles under protective gas; the crushing time is 50 to 60 minutes.

[0021] Further, the coarse crushing includes the following operations:

[0022] The hydrogen content of the prefabricated particles is ≤500PPm; an antioxidant is added at a mass ratio of 0.1% to 0.25% and the materials are fully mixed;

[0023] Then, the pre-crushing is carried out in a belt-screen ball mill: vacuum is drawn, and the vacuum degree is ≤10Pa; then protective gas is filled in until the pressure is 0.03-0.08MPa; the prefabricated particles are sent into the belt-screen ball mill, and the pre-crushing is started, while grinding and screening, and the crushing time is 50-60min; and the coarse powder is collected.

[0024] The jet mill crushing and shaping is to further crush the coarse powder in the jet mill to a particle size of 10-50 μm, and the shaping sphericity is ≥70%.

[0025] Furthermore, the jet mill crushing and shaping includes the following operations:

[0026] When the oxygen content in the jet mill is ≤200PPm, the separation motor is turned on at a preset speed, and the working gas is charged to stabilize the working gas pressure between 0.5 and 0.7MPa, and then the coarse powder is added into the grinding chamber;

[0027] After the grinding chamber starts to discharge, To adjust the speed n of the sorting motor, m is the preset speed, d is the target powder particle size, d is 10~50μm, d 0 The particle size of the powder to be discharged.

[0028] Furthermore, the nozzle air velocity of the jet mill is set to 1 to 3 Mach, and the angles between the nozzles converge into a circle in the mill chamber, with an angle of 10 to 30 degrees.

[0029] The hydrogen heat treatment production process is fully sealed, and the coarse crushing and air flow mill crushing are sealed with inert gas protection.

[0030] Compared with the prior art, the present invention has the following beneficial technical effects:

[0031] Based on the crystallographic analysis of titanium or titanium alloy, the present invention proposes that hydrogen heat treatment of titanium or titanium alloy material changes the crystal structure of the material, lattice dislocation occurs, tensile strength decreases and plasticity deteriorates, and micro cracks are prefabricated in titanium and alloy particles to facilitate subsequent coarse crushing and air flow mill crushing. The present invention uses a ball mill with a screen to perform coarse crushing, and then uses an air flow mill to crush and shape the powder, with high crushing efficiency.

[0032] The present invention establishes a preparation method for titanium or titanium alloy powder through hydrogen heat treatment, coarse crushing and air flow mill crushing. The hydrogen heat treatment production process is fully sealed and there is no contact component pollution in the whole process. In addition, the whole process uses inert gas protection and sealing to prevent oxidation, thereby ensuring the activity of the powder. This solves the problem that only 10%-30% of the traditional titanium powder or titanium alloy powder can be used for 3D printing, resulting in a low yield rate.

[0033] The advantages of the present invention are that the pressure and temperature of the hydrogen absorption process are relatively low, the pressure is 0.06-0.1 MPa, and the temperature is 200-300° C. Moreover, the temperature of the dehydrogenation process is relatively low, the temperature is 400-600° C.

[0034] The present invention obtains a powder sphericity of ≥70%, and when the powder particle size is narrow as a whole of 10-50 μm, the powder finished product rate is ≥95%; the present invention achieves a qualified rate of up to 95% for titanium powder for 3D printing. Compared with the current methods of preparing titanium powder by spraying, etc., which have a qualified rate of only 10%-30%, the present method is at the international leading level. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a process flow chart of the present invention;

[0036] Figure 2 This is a schematic diagram of the hydrogen crushing principle of the present invention;

[0037] Figure 3 It is a schematic diagram of the airflow angle of the jet mill chamber nozzle;

[0038] Figure 4 The titanium powder for 3D printing prepared by the present invention. DETAILED DESCRIPTION

[0039] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] The present invention provides a method for manufacturing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling, comprising the following operations:

[0041] 1) Hydrogen heat treatment:

[0042] A titanium or titanium alloy material with an oxygen content of less than 1000 PPm and a carbon content of less than 500 PPm is introduced with hydrogen gas to a hydrogen pressure of 0.06-0.1 MPa under vacuum conditions, and heated to 200-300°C to absorb hydrogen; after the hydrogen absorption is completed, the hydrogen gas is discharged, and then the material is heated to 400-600°C under vacuum conditions to dehydrogenate;

[0043] Prefabricated particles in which grain boundary cracks are generated in titanium or titanium alloy material through hydrogen absorption and dehydrogenation;

[0044] 2) Coarse crushing:

[0045] Crushing the prefabricated particles after hydrogen heat treatment into coarse powder of 10 to 20 mesh;

[0046] 3) Jet mill crushing and shaping:

[0047] The coarse powder is crushed by air jet mill, the powder collides and breaks in the grinding chamber, and is shaped by the rotating motion.

[0048] Among them, hydrogen heat treatment produces grain boundary cracks at the grain boundaries of the material, which improves the crushability of the material;

[0049] Coarse crushing is to crush the prefabricated particles with cracks into particles of 10-20 meshes, so as to improve the efficiency of the air jet mill;

[0050] Titanium or titanium alloy still has higher plasticity and strength than general hard and brittle materials after absorbing and dehydrogenating hydrogen. In order to crush titanium or titanium alloy particles containing microcracks, higher energy is required. At the same time, most of the crushed powder particles are non-spherical. Therefore, air flow mill is used for further crushing; the powder has both high-speed collision and crushing action in the grinding chamber, and a shaping process of mutually chasing rotating grinding motion, so as to achieve the crushing and sphericity requirements of the powder.

[0051] Specific examples are given below.

[0052] Example 1

[0053] like Figure 1 As shown, a method for manufacturing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling includes the following operations:

[0054] Step 1: The raw materials are blocks or particles of titanium or titanium alloy, the oxygen content of which should be less than 1000 PPm, and the carbon content should be less than 500 PPm. The raw materials are measured using an oxygen, nitrogen, and hydrogen tester and a carbon and sulfur analyzer;

[0055] Step 2: Vacuum hydrogen absorption:

[0056] Step 2.1, put titanium or titanium alloy particles with qualified oxygen and carbon content into a reaction kettle, evacuate the reactor, and the vacuum degree in the reactor is required to reach 0.1-1Pa;

[0057] Step 2.2, hydrogen is introduced into the reactor at a pressure of 0.06 to 0.1 MPa, and the reactor is heated to 200 to 300° C., and the titanium or titanium alloy in the reactor begins to absorb hydrogen;

[0058] Step 2.3: The hydrogen absorption process is an exothermic reaction. 10 to 30 minutes after the start of hydrogen absorption, the heating is stopped and hydrogen is supplemented to ensure that the hydrogen pressure in the reactor is 0.06 to 0.1 MPa. The total hydrogen absorption time is calculated as 30 to 50 min / 100 kg.

[0059] Step 2.4, after the hydrogen absorption is completed, the excess hydrogen in the reactor is discharged, and argon (argon purity ≥ 99.99%) is introduced into the reactor at a pressure of 0.06-0.1 MPa for gas replacement, and dehydrogenation is performed after the argon is discharged.

[0060] Step 3, vacuum dehydrogenation:

[0061] Step 3.1, evacuate the reactor after hydrogen absorption, and when the vacuum reaches 0.1-1Pa, start heating at a temperature of 400-600°C and a dehydrogenation time of 3-6h, ensuring that the vacuum is ≤1Pa at the end of dehydrogenation.

[0062] Step 3.2: After dehydrogenation is completed, turn off the heating device and the vacuum unit;

[0063] Step 3.3, after the reactor is air-cooled for 30 to 60 minutes, water is poured into the reactor to cool for 60 to 180 minutes, and the material is discharged.

[0064] Step 4: Discharge inspection and mixing

[0065] Step 4.1. After cooling, connect the powder storage tank to the glove box at the reactor outlet, introduce nitrogen into the glove box to exhaust oxygen. When the oxygen content in the glove box is ≤200 PPM, open the end cover of the reactor outlet, take out 10-50 g of sample and seal it separately in a sealed bag.

[0066] Step 4.2, measure the hydrogen content of the titanium or titanium alloy in the sealed bag with an oxygen, nitrogen and hydrogen measuring instrument, and the hydrogen content must be ≤500PPm; if it is unqualified, close the end cover of the reactor outlet and re-dehydrogenate; if the hydrogen content of the powder is qualified, rotate the reactor, let the dehydrogenated titanium or titanium alloy flow out of the reactor, and load it into a sealed powder storage tank through a glove box.

[0067] Step 4.3, adding an antioxidant (commonly used antioxidants in the art) to the powder storage tank in a weight ratio of 0.1% to 0.25%;

[0068] Step 4.4, put the powder storage tank into the three-dimensional horizontal mixer and mix for 1 to 3 hours to fully disperse the antioxidant;

[0069] Step 5: Coarse crushing with a sieve ball mill to make the particle size of the material uniform and relatively consistent before entering the jet mill. The specific steps are as follows:

[0070] Step 5.1, connect the powder storage tank to the feed port of the ball mill with screen, connect a powder storage tank to the discharge port of the ball mill with screen, start the vacuum pump to evacuate, when the vacuum degree is ≤10Pa, close the exhaust valve and stop the vacuum pump. Fill the ball mill with argon gas, the pressure is 0.03~0.08MPa.

[0071] Step 5.2, open the powder storage tank butterfly valve and the manual valve of the feeding port of the ball mill with screen, start the feeding motor of the ball mill with screen, and feed the dehydrogenated titanium or titanium alloy material into the ball mill with screen through the screw feeder. After adding 60-80 kg of material, close the manual valve of the feeding port and the butterfly valve of the powder storage tank.

[0072] Step 5.3, open the manual valve of the ball mill with screen, start the rotating motor of the ball with screen, start coarse crushing, grind and screen at the same time, and the particles that can pass the screen are screened out; the crushing time is 50 to 60 minutes.

[0073] Step 5.4: After the first crushing is completed, repeatedly add grinding materials until the materials in the powder storage tank are ground up and the coarse crushed particles are collected.

[0074] Step 6: Grinding with a jet mill. The coarse powder after coarse crushing is further crushed in a jet mill to a particle size of 10-50 μm, and the sphericity of the powder is ≥ 70%. The specific steps are as follows:

[0075] Step 6.1, connect the powder storage tank filled with coarse powder to the feed port of the jet mill, and connect the empty powder storage tank to be filled with fine powder to the powder outlet of the jet mill;

[0076] Step 6.2, introduce nitrogen into the air flow mill to remove oxygen. When the oxygen content is ≤200PPm, turn on the sorting motor, preset the motor speed to 1250 rpm, turn on the nitrogen compressor, add nitrogen to the system, stabilize the working gas pressure between 0.5 and 0.7 MPa, and turn on the feeding motor to feed the mill chamber.

[0077] Step 6.3: When the grinding chamber starts to discharge, take a powder sample from the sampling port and use a laser particle size measuring instrument to test the particle size to obtain the powder particle size d 0 ;

[0078] According to the formula To adjust the speed n of the sorting motor, m is the preset speed, d is the target powder particle size, d is 10~50μm, d 0 The particle size of the powder to be discharged; in this embodiment, the preset speed is 1250 rpm;

[0079] Step 6.4, take samples to test the oxygen, carbon and hydrogen content of the powder. Use an oxygen-nitrogen-hydrogen tester to measure the oxygen content and hydrogen content, and use a carbon-sulfur detector to measure the carbon content. After passing the test, package it.

[0080] Step 7: vacuum packaging the powder.

[0081] Further, in the method of Example 1:

[0082] The detection in step 1 is to control the carbon and oxygen content in the raw materials. Raw materials with too much oxygen and carbon content cannot undergo hydrogen absorption and dehydrogenation operations. This is because the introduced hydrogen will preferentially undergo redox reactions with the oxygen and carbon in the material, rather than entering the grain boundaries of the material to produce grain boundary cracks, making subsequent work impossible to complete.

[0083] Step 2 is to use the principle that titanium or titanium alloy can absorb hydrogen. By placing titanium or titanium alloy in a hydrogen environment, hydrogen slowly penetrates into the grain boundaries of titanium or titanium alloy. The purpose of maintaining a certain pressure of 0.06-0.1MPa and raising the temperature to 200-300°C is to heat the material and increase the activity of the material, so that the material can absorb hydrogen rapidly under positive pressure. The entry of hydrogen causes grain boundary cracks to form at the grain boundaries of the material (such as Figure 2 shown).

[0084] Step 3 is to use titanium or titanium alloy under vacuum at a temperature of 400-600°C, the hydrogen inside it can be released quickly, and the hydrogen will expand the internal cracks (such as Figure 2 As shown), the crushability of the material is improved.

[0085] The coarse crushing in step 5 is to crush the block or granular titanium or titanium alloy material with cracks after hydrogen absorption and dehydrogenation into uniform 10-20 mesh particles with steel balls; the ball mill with screen is a drum with steel balls and titanium or titanium alloy rotating together, and the steel balls fall down from a high place to crush the titanium or titanium alloy material; the outer side of the drum is wrapped with a 10-20 mesh stainless steel screen to screen out the crushed fine particles, and the coarse particles continue to be crushed until all are crushed and screened out, so as to improve the efficiency of the air flow mill.

[0086] Step 6 is to crush the 10-20 mesh titanium or titanium alloy particles into powders of 10-50 μm in a jet mill. Titanium or titanium alloys still have higher plasticity and strength than general hard and brittle materials after hydrogen absorption and dehydrogenation. In order to crush titanium or titanium alloy particles containing microcracks, higher energy is required. At the same time, most of the crushed powder particles are non-spherical. Therefore, a jet mill is used for further crushing, and the jet mill nozzle air velocity is set to 1-3 Mach. The angle between the nozzles converges into a circle in the grinding chamber, and the angle is 10-30 degrees (such as Figure 3 The airflow angle of the jet mill nozzle is shown in the figure); in this way, the powder has both high-speed collision and crushing action in the mill chamber and a shaping process of mutual chasing and rotating grinding motion, thereby achieving the crushing and sphericity requirements of the powder.

[0087] Example 2

[0088] A method for manufacturing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling, comprising the following operations:

[0089] 1) Purchase raw material sponge titanium blocks with a purity of 99.8%, an oxygen content of 350ppm, and a carbon content of 420ppm;

[0090] 2) Hydrogen absorption: Load 100kg of hydrogen into the furnace, evacuate to 0.6Pa, introduce pure hydrogen, the pressure is 0.08MPa, heat to 220℃, keep warm for 25min, the hydrogen pressure starts to drop, and the hydrogen absorption reaction begins. Turn off the heating, continue to introduce hydrogen into the reactor, ensure that the hydrogen pressure in the reactor is 0.06-0.08MPa, the reaction lasts for 50min, stop supplying hydrogen to the reactor, when the pressure in the reactor no longer drops, or the pressure drop rate is less than 0.01MPa in 5min, the hydrogen absorption ends.

[0091] 3) Dehydrogenation: Fill the reactor with argon to 0.1MPa, and after discharging, start the vacuum unit to evacuate. When the vacuum degree is ≤1Pa, start heating and heat up to 550℃, keep warm for 3.5h, and continue to evacuate during the process. After the insulation is completed, air cool for 30min and water cool for 3h before discharging into the powder storage tank; the hydrogen content of the powder is tested to be 450ppm.

[0092] 4) Mix the powder and antioxidant in a three-dimensional horizontal mixer for 120 minutes

[0093] 5) Coarse crushing: Connect the powder tank to a ball mill with a sieve, evacuate to 0.6Pa, fill with argon to 0.05MPa, and carry out the ball milling with a sieve for 110min. When the discharge is completed, collect the coarsely crushed particles.

[0094] 6) Jet mill: Connect the powder storage tank with coarse powder to the feed port of the jet mill, introduce nitrogen to stabilize the working gas pressure between 0.5 and 0.7 MPa; add materials into the mill chamber, the speed of the sorting motor is 1350 rpm, the working gas pressure is 0.6 MPa, the test powder particle size D50 = 12 μm, sphericity = 71%, powder D100 = 45 μm, and the qualified rate is 97%; the powder morphology is as follows Figure 4 As shown;

[0095] Powder oxygen, carbon and hydrogen measurement results: oxygen content 950ppm, carbon content 552ppm, hydrogen content 456ppm.

[0096] 7) Carry out vacuum packaging of powder.

[0097] The above embodiments are preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential additions and substitutions made by those skilled in the art based on the technical features of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for producing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling, characterized in that: The following operations are included: 1) Hydrogen heat treatment: A titanium or titanium alloy material with an oxygen content of less than 1000 PPm and a carbon content of less than 500 PPm is introduced with hydrogen gas to a hydrogen pressure of 0.06-0.1 MPa under vacuum conditions, and heated to 200-300°C to absorb hydrogen; after the hydrogen absorption is completed, the hydrogen gas is discharged, and then the material is heated to 400-600°C under vacuum conditions to dehydrogenate; Prefabricated particles in which grain boundary cracks are generated in titanium or titanium alloy material through hydrogen absorption and dehydrogenation; 2) Coarse crushing: Crushing the prefabricated particles after hydrogen heat treatment into coarse powder of 10 to 20 mesh; 3) Jet mill crushing and shaping: The coarse powder is crushed by air jet mill, the powder collides and breaks in the grinding chamber, and is shaped by the rotating motion.

2. The method for producing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling as claimed in claim 1, characterized in that: When the titanium or titanium alloy material absorbs hydrogen, the heating is stopped 10 to 30 minutes after the start of hydrogen absorption, and hydrogen is supplemented to maintain the hydrogen pressure at 0.06 to 0.1 MPa. The total hydrogen absorption time is calculated as 30 to 50 minutes / 100 kg; During the vacuum dehydrogenation, the vacuum degree is maintained at ≤1 Pa, and the dehydrogenation time is 3 to 6 hours.

3. The method for producing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling as claimed in claim 1, characterized in that: The hydrogen heat treatment comprises the following operations: Put titanium or titanium alloy into a reactor and evacuate it; introduce hydrogen into the reactor until the hydrogen pressure is 0.06-0.1 MPa, and heat the reactor to 200-300°C until the titanium or titanium alloy begins to absorb hydrogen; 10 to 30 minutes after the start of hydrogen absorption, stop heating and add hydrogen to a pressure of 0.06 to 0.1 MPa; the total hydrogen absorption time is calculated as 30 to 50 minutes / 100 kg; The reactor after hydrogen absorption is evacuated, and when the vacuum degree reaches 0.1-1Pa, it is heated to 400-600°C; the dehydrogenation time is 3-6h, and the vacuum degree is ensured to be ≤1Pa at the end of dehydrogenation.

4. The method for producing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling as claimed in claim 1, characterized in that: The coarse crushing is to mix the prefabricated particles with the antioxidant, and then ball-mill and screen out qualified coarse particles under protective gas; the crushing time is 50 to 60 minutes.

5. The method for producing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling as claimed in claim 1, characterized in that: The coarse crushing includes the following operations: The hydrogen content of the prefabricated particles is ≤500PPm; an antioxidant is added at a mass ratio of 0.1% to 0.25% and the materials are fully mixed; Then, the pre-crushing is carried out in a belt-screen ball mill: vacuum is drawn, and the vacuum degree is ≤10Pa; then protective gas is filled in until the pressure is 0.03-0.08MPa; the prefabricated particles are sent into the belt-screen ball mill, and the pre-crushing is started, while grinding and screening, and the crushing time is 50-60min; and the coarse powder is collected.

6. The method for producing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling as claimed in claim 1, characterized in that: The jet mill crushing and shaping is to further crush the coarse powder in the jet mill to a particle size of 10-50 μm, and the shaping sphericity is ≥70%.

7. The method for producing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling as claimed in claim 1, characterized in that: Jet mill crushing and shaping includes the following operations: When the oxygen content in the jet mill is ≤200PPm, the separation motor is turned on at a preset speed, and the working gas is charged to stabilize the working gas pressure between 0.5 and 0.7MPa, and then the coarse powder is added into the grinding chamber; After the grinding chamber starts to discharge, To adjust the speed n of the sorting motor, where m is the preset speed, d is the target powder particle size, d is 10-50μm, and d0 is the powder particle size of the discharge.

8. The method for manufacturing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling as claimed in claim 1, wherein the nozzle air flow velocity of the air flow mill is set to 1 to 3 Mach, and the angle between the nozzles converges into a circle in the grinding chamber, and the angle is 10 to 30 degrees.

9. The method for producing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling as claimed in claim 1, characterized in that: The following operations are included: 1) The raw materials are blocks or particles of titanium or titanium alloy. The oxygen content of the raw materials should be less than 1000PPm and the carbon content should be less than 500PPm when measured by oxygen, nitrogen and hydrogen tester and carbon and sulfur analyzer. 2) Hydrogen absorption: Put titanium or titanium alloy materials into hydrogen cracking furnace, evacuate, introduce hydrogen to the pressure of 0.06-0.1MPa, heat to 200-300℃; after keeping warm for 20-30min, the hydrogen pressure begins to drop and hydrogen absorption begins; Turn off the heating and continue to introduce hydrogen to ensure that the hydrogen pressure is between 0.06 and 0.08 MPa. The reaction continues for a period of time, and then the hydrogen supply is stopped. When the hydrogen pressure no longer decreases, or the pressure drop rate is less than 0.01 MPa / 5 min, the hydrogen absorption is completed. 3) Dehydrogenation: Inert gas is introduced into the reactor to replace hydrogen, and then vacuum is evacuated to a vacuum degree of ≤1Pa; heated to 400-600°C, kept warm for 3-6 hours, and vacuum is continuously evacuated during the process; After the insulation is completed, the dehydrogenation is completed, and the reaction kettle is discharged to the powder storage tank to obtain prefabricated particles; 4) adding an antioxidant to the prefabricated particles at a mass ratio of 0.1% to 0.25%, and mixing the materials so that the antioxidant is fully dispersed; 5) Connect the powder storage tank to the feed port of the ball mill with screen; when the ball mill with screen is vacuumed to ≤10Pa, close the exhaust valve and stop the vacuum pump; fill the ball mill with screen with protective gas until the pressure is 0.03-0.08MPa; The prefabricated particles are fed into the ball mill with screen through the feeder, and the rotating motor of the ball with screen is started to start coarse crushing, grinding and screening at the same time, until the materials in the powder storage tank are ground and the coarse powder is collected; 6) Connect the powder storage tank filled with coarse powder to the feed port of the jet mill. When the oxygen content in the jet mill is ≤200PPm, start the sorting motor at a preset speed and fill it with working gas to stabilize the working gas pressure between 0.5 and 0.7MPa, and then add coarse powder into the mill chamber; After the grinding chamber starts to discharge, To adjust the speed n of the sorting motor, where m is the preset speed, d is the target powder particle size, d is 10-50μm, and d0 is the powder particle size of the discharge.

10. The method for producing titanium powder / titanium alloy powder for 3D printing by hydrogen heat treatment and air flow milling according to claim 1 or 9, characterized in that: The hydrogen heat treatment production process is fully sealed, and the coarse crushing and air flow mill crushing use inert gas protection seal.

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