A TC4 titanium alloy powder for EBSM and its preparation method and molding method

Abstract

The invention relates to a preparation method of TC4 titanium alloy powder for EBSM, comprising the following steps: S1, pulverizing a TC4 titanium alloy bar material by using a plasma rotating electrode pulverizing device to obtain a first pass powder and a slug; S2, sieving the first pass powder to obtain X powder; S3, friction welding and splicing the slug obtained in S1 to obtain a spliced ​​bar material, and pulverizing the spliced ​​bar material by using an electrode induction melting gas atomization device to obtain a second pass powder; S4, sieving the second pass powder to obtain Y powder; S5, mixing the X powder and the Y powder in a mass ratio of 2:1 to 4:1 to obtain TC4 titanium alloy powder. After the TC4 titanium alloy powder prepared by the invention is formed by an EBSM process, the obtained product has high density, low surface roughness, and significantly improved strength and plasticity.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy powder metallurgy, and in particular to TC4 titanium alloy powder for EBSM (Electron Beam Selective Melting) and a preparation method and a molding method thereof. Background Art

[0002] Metal 3D printing is widely used in aerospace, biomedicine, and other fields. TC4 titanium alloy powder, a commonly used raw material for 3D printing, is crucial for its quality and formability. TC4 titanium alloy powder is typically prepared using the PREP (Plasma Rotating Electrode Process) method or the EIGA (Electrode Induction Melting Gas Atomization) method, and is typically formed using the EBSM method.

[0003] The principle of the EBSM process is: first spread a layer of powder on the base plate, and the electron beam selectively melts according to the information of the cross-sectional profile under the control of the computer. The metal powder is melted together under the bombardment of the electron beam and adheres to the formed part below, stacking layer by layer until the entire part is formed. The EBSM process has high energy density and high energy absorption rate. It can use coarse powder for printing and has high forming efficiency, which is about 2 to 3 times that of the SLM (Selective Laser Melting) method; the forming temperature is high, the thermal stress is small, and the material plasticity is good; the high vacuum environment has low impurity contamination and almost no oxygen addition. However, since this process uses coarse-grained powder for forming, the surface accuracy is low; elements with high vapor pressure (such as Al) are easily volatilized and lost in a vacuum and high-temperature environment, resulting in insufficient strength of TC4 titanium alloy; the deposited metallurgical quality is poor, and the parts have microcracks or pore defects.

[0004] The PREP process works by placing one end of a high-speed rotating metal rod against a high-temperature plasma heat source, where it melts into a liquid state. Centrifugal force shatters the liquid film into droplets, which are then ejected. The tiny droplets solidify in the inert gas flow and, under surface tension, spheroidize into a powder. Advantages of PREP powder in EBSM molding include high sphericity and uniform powder spreading; no hollow powder and no inherited porosity defects in the deposited state; high purity, and minimal impurity element addition. Disadvantages of PREP powder in EBSM molding include poor powder flowability, which can cause the powder bed to collapse due to electron beam impact.

[0005] The EIGA process works by using a high-speed inert gas flow to pulverize the liquid metal stream generated by the bottom of the induction coil into small droplets, which are then rapidly cooled and condensed to form spherical metal powder. The advantages of EIGA powder in EBSM molding include high purity, minimal impurity element increments, low bar size requirements, and low production costs. The presence of a small amount of satellite powder on the particle surface ensures a high powder bed hardness after preheating, resists collapse, and minimizes spatter. However, the disadvantages of EIGA powder in EBSM molding include the high number of hollow powder defects in coarse powder (particle size ≥ 75μm), the presence of inherited porosity in the deposited state, and low density. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the present invention proposes a preparation method of TC4 titanium alloy powder for EBSM and a molding method thereof. The TC4 titanium alloy powder has high strength, excellent surface accuracy, is not easy to collapse, and has high density while ensuring low cost, good powder spreading uniformity, high purity, high molding efficiency and good plasticity.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for preparing TC4 titanium alloy powder for EBSM, comprising the following steps:

[0009] S1. Pulverizing TC4 titanium alloy rods using a plasma rotating electrode pulverizing device to obtain first-pass powder and slugs;

[0010] S2, sieving the first powder to obtain X powder;

[0011] S3, friction welding the material heads obtained in S1 to obtain spliced ​​bars, and using electrode induction melting gas atomization equipment to grind the spliced ​​bars into powder to obtain a second pass of powder;

[0012] S4, sieving the second powder to obtain Y powder;

[0013] S5. Mix the X powder and the Y powder in a mass ratio of 2:1 to 4:1 to obtain TC4 titanium alloy powder.

[0014] Preferably, in S1, the chemical composition of the TC4 titanium alloy bar is as follows by mass percentage: Al: 6.45-6.75%, V: 3.50%-4.50%, Fe: 0.15-0.25%, C: ≤0.08%, N: ≤0.03%, H: ≤0.012%, O: 0.09-0.12%, and Ti as the remainder.

[0015] Preferably, when the first powder is prepared by the plasma rotating electrode powder making equipment, the rotation speed is 28000-32000 rpm, the feed speed is 20-50 mm / min, the power is 100-150 kW, and the oxygen content is ≤1 ppm.

[0016] Preferably, in S2, an ultrasonic vibration screening machine is used to screen the first powder according to the particle size distribution of D10=58±5μm, D50=80±5μm, and D90=101±5μm, and the mesh size of the ultrasonic vibration screening machine is 270 mesh and 140 mesh.

[0017] Preferably, the particle size of the X powder is 53 to 106 μm, the sphericity is ≥97%, and the hollow powder rate is ≤0.03%.

[0018] Preferably, the specifications of TC4 titanium alloy rods are: diameter 55-60 mm, length 700 mm, straightness ≤ 0.05 mm, surface roughness ≤ 3.2 μm; the specifications of spliced ​​rods are: diameter 55-60 mm, length 200-500 mm, straightness ≤ 1 mm.

[0019] Preferably, when the second powder is prepared by electrode induction melting gas atomization equipment, the atomization pressure is 3.0-5.0 MPa, the feed speed is 20-70 mm / min, the power is 30-60 kW, and the oxygen content is ≤1 ppm.

[0020] Preferably, an air flow classification device and an ultrasonic vibration screening machine are successively used to perform air flow classification and vibration screening on the second pass powder according to the particle size distribution D10 = 50 ± 5 μm, D50 = 60 ± 5 μm, and D90 = 70 ± 5 μm. The mesh numbers of the ultrasonic vibration screening machine are 325 mesh and 200 mesh, the particle size of the Y powder is 45 to 75 μm, the sphericity is ≥94%, and the hollow powder rate is ≤0.30%.

[0021] The present invention also provides TC4 titanium alloy powder prepared by the above preparation method.

[0022] The present invention also provides a molding method for the TC4 titanium alloy powder prepared by the above preparation method, wherein the TC4 titanium alloy powder is put into the EBSM equipment, and the powder layer thickness is 0.09-0.11 mm, the preheating temperature is 500-750 ° C, and the energy density is 3.0-4.5 J / mm 2 , the molding is carried out with the parameters of scanning spacing of 0.08 to 0.12 mm and scanning speed of 1.0 to 3.0 m / s.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention utilizes the characteristics of high reduction degree of raw material components in the two powder making processes when preparing alloy powder, and selects the chemical composition of the powdered TC4 titanium alloy rod as follows: Al: 6.45-6.75%, V: 3.50%-4.50%, Fe: 0.15-0.25%, C: ≤0.08%, N: ≤0.03%, H: ≤0.012%, O: 0.09-0.12%, Ti balance; the mass percentage of Al in the TC4 titanium alloy rod is 6.45-6.75%, so that the prepared TC4 titanium alloy powder has a high The high Al content ensures that the Al content of the parts after EBSM forming is ≥6.0%, reducing the impact of insufficient strength caused by the reduction of α-phase content due to the volatilization of the Al element during EBSM forming. The mass percentage of Fe in TC4 titanium alloy bars is 0.15-0.25%, which can improve the strength of the alloy to a certain extent without causing a decrease in the toughness of the alloy. The mass percentage of O in TC4 titanium alloy bars is 0.09-0.12%, which avoids the problem of insufficient strength of the formed parts caused by low O content and circumvents the risk of reduced toughness and plasticity of the alloy caused by high O content.

[0025] (2) The present invention uses the PREP method and the EIGA method in series, which not only fully utilizes the waste material to save costs, but also achieves the goal of consistent powder composition in different processes and eliminates the difference in composition of raw material batches;

[0026] (3) The present invention processes the powder through two processes, vibratory screening and airflow classification, to achieve the effect of limiting the powder particle size and improving the particle sphericity; it obtains both coarse-grained PREP powder with no hollow powder and high sphericity, and fine-grained EIGA powder with a small amount of hollow powder and satellite powder;

[0027] (4) By mixing coarse-grained PREP powder and fine-grained EIGA powder in a certain proportion and introducing a small amount of satellite powder, the problem of easy collapse of PREP powder molding is solved, and the stability of the molding process is guaranteed; the advantage of almost no hollow powder is also brought into play, and the problem of many metallurgical defects in EIGA powder molding is solved, which significantly improves the density of the deposited state; at the same time, the powder particle size is reduced by mixing the powder, thereby reducing the surface roughness of the molded part and improving the surface quality;

[0028] (5) The present invention provides a better raw material of TC4 alloy powder for EBSM and develops its forming supporting process parameters. The surface roughness of the obtained parts is ≤20μm, the density is ≥99.5%, the room temperature tensile strength is ≥1020MPa, the yield strength is ≥950MPa, the elongation after fracture is ≥14%, the cross-sectional shrinkage is ≥40%, the bending strength is ≥2000Mpa, and the fracture toughness is ≥90Mpa·m 1 / 2 , fatigue strength ≥500Mpa, with excellent comprehensive mechanical properties, which is higher than the existing technical level. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 (a) is the SEM image of X powder in Example 1 of the present invention, Figure 1 (b) is the SEM image of Y powder in Example 1 of the present invention, Figure 1 (c) is a SEM image of the TC4 titanium alloy powder in Example 1 of the present invention;

[0030] Figure 2 This is a photo of EBSM molding of TC4 titanium alloy powder in Example 1 of the present invention;

[0031] Figure 3 This is a metallographic photograph of the TC4 titanium alloy powder in the EBSM formed deposition state in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] Example 1

[0034] A molding method of TC4 titanium alloy powder for EBSM, comprising: feeding the TC4 titanium alloy powder into an EBSM device, and performing the molding process according to the conditions of a powder layer thickness of 0.11 mm, a preheating temperature of 750° C., and an energy density of 4.5 J / mm 2 , the molding was performed with the parameters of scanning spacing 0.12 mm and scanning speed 3.0 m / s;

[0035] The preparation method of TC4 titanium alloy powder in this embodiment includes the following steps:

[0036] S1. Powdering TC4 titanium alloy rods by plasma rotating electrode powder making equipment to obtain first-pass powder and slug; wherein the chemical composition of TC4 titanium alloy rods is as follows by mass percentage: Al: 6.75%, V: 4%, Fe: 0.25%, C: 0.01%, N: 0.01%, H: 0.005%, O: 0.09%, Ti balance, and the specifications of TC4 titanium alloy rods are The straightness is ≤0.05mm and the surface roughness is ≤3.2μm. During the first pass of powder preparation, the key parameters are set as rotation speed 32000rpm, feed speed 50mm / min, power 150kw, and oxygen content ≤1ppm.

[0037] S2. Using an ultrasonic vibration screening machine, the first powder was sieved according to the particle size distribution of D10 = 58 ± 5 μm, D50 = 80 ± 5 μm, and D90 = 101 ± 5 μm to obtain X powder with a particle size of 53 to 106 μm, a sphericity of 97.5%, and a hollow powder rate of 0.02%; wherein the mesh size of the ultrasonic vibration screening machine is 270 mesh and 140 mesh;

[0038] S3, friction welding the material heads obtained in S1 to obtain spliced ​​bars, and using electrode induction melting gas atomization equipment to grind the spliced ​​bars into powder to obtain the second pass powder, wherein the specifications of the spliced ​​bars are Straightness ≤1mm; when preparing the second pass powder, the key parameters are atomization pressure 5.0Mpa, feed speed 70mm / min, power 60kw, and oxygen content ≤1ppm;

[0039] S4. The second powder was subjected to airflow classification and vibration screening in succession using an airflow classification device and an ultrasonic vibration screening machine according to a particle size distribution of D10 = 50 ± 5 μm, D50 = 60 ± 5 μm, and D90 = 70 ± 5 μm to obtain Y powder with a particle size of 45 to 75 μm, a sphericity of 94.5%, and a hollow powder rate of 0.20%; the key parameters for airflow classification were set as a feed frequency of 20 Hz, a classification frequency of 20 Hz, an air supply pressure of 0.5 MPa, and an oxygen content of ≤ 50 ppm; the mesh sizes of the ultrasonic vibration screening machine during vibration screening were 325 mesh and 200 mesh;

[0040] S5. Using a conical mixer, mix powder X and powder Y in a mass ratio of 2:1 to obtain TC4 titanium alloy powder having a particle size distribution of D10 = 53 ± 5 μm, D50 = 75 ± 5 μm, D90 = 95 ± 5 μm, a sphericity of 96.5%, and a hollow powder rate of 0.08%. During the mixing process of powder X and powder Y, the single mixing weight is 500 kg, the rotation speed is 15 rpm, and the mixing time is 5 h.

[0041] refer to Figure 1 It can be seen that the X powder prepared by the PREP process of the present invention has a coarse particle size, extremely high sphericity, a smooth surface, and no satellite powder and hollow powder; the Y powder prepared by the EIGA process has a fine particle size, with a small amount of satellite powder and hollow powder; and the morphology of the mixed powder TC4 titanium alloy powder inherits the characteristics of the powders of the two powder making processes, with no hollow powder, high sphericity, and a high content of powder particles. A small amount of fine-grained powder can improve the filling property during powder spreading, and the introduced satellite powder can increase the hardness of the powder bed.

[0042] Example 2

[0043] A molding method of TC4 titanium alloy powder for EBSM, comprising: feeding the TC4 titanium alloy powder into an EBSM device, and performing the following steps according to the conditions: a powder layer thickness of 0.09 mm, a preheating temperature of 500° C., and an energy density of 3.0 J / mm 2 , the molding was performed with the parameters of scanning spacing 0.08 mm and scanning speed 1.0 m / s;

[0044] The preparation method of TC4 titanium alloy powder in this embodiment includes the following steps:

[0045] S1. Powdering TC4 titanium alloy rods by plasma rotating electrode powder making equipment to obtain first-pass powder and slug; wherein the chemical composition of TC4 titanium alloy rods is as follows by mass percentage: Al: 6.45%, V: 4.50%, Fe: 0.15%, C: 0.01%, N: 0.01%, H: 0.005%, O: 0.10%, Ti balance, and the specifications of TC4 titanium alloy rods are Straightness ≤ 0.05mm, surface roughness ≤ 3.2μm; during the first pass of powder preparation, the key parameters are set as rotation speed 28000rpm, feed speed 20mm / min, power 100kw, and oxygen content ≤ 1ppm;

[0046] S2. Using an ultrasonic vibration screening machine, the first powder was sieved according to the particle size distribution of D10 = 58 ± 5 μm, D50 = 80 ± 5 μm, and D90 = 101 ± 5 μm to obtain X powder with a particle size of 53 to 106 μm, a sphericity of 97.3%, and a hollow powder rate of 0.01%; wherein the mesh size of the ultrasonic vibration screening machine is 270 mesh and 140 mesh;

[0047] S3, friction welding the material heads obtained in S1 to obtain spliced ​​bars, and using electrode induction melting gas atomization equipment to grind the spliced ​​bars into powder to obtain the second pass powder; wherein, the spliced ​​bars are of the following specifications: Straightness ≤1mm; when preparing the second pass powder, the key parameters are atomization pressure 3.0Mpa, feed speed 20mm / min, power 30kw, and oxygen content ≤1ppm;

[0048] S4. The second powder was subjected to airflow classification and vibration screening in succession according to the particle size distribution of D10 = 50 ± 5 μm, D50 = 60 ± 5 μm, and D90 = 70 ± 5 μm, to obtain Y powder with a particle size of 45 to 75 μm, a sphericity of 94.2%, and a hollow powder rate of 0.25%; the key parameters for airflow classification were set as feeding frequency 10 Hz, classification frequency 10 Hz, air supply pressure 0.5 MPa, and oxygen content ≤ 50 ppm; the mesh sizes of the ultrasonic vibration screening machine during vibration screening were 325 mesh and 200 mesh;

[0049] S5. Using a conical mixer, mix powder X and powder Y in a mass ratio of 2:1 to obtain TC4 titanium alloy powder having a particle size distribution of D10 = 53 ± 5 μm, D50 = 75 ± 5 μm, D90 = 95 ± 5 μm, a sphericity of 96.5%, and a hollow powder rate of 0.07%. During the mixing process of powder X and powder Y, a single mixing weight of 50 kg, a rotation speed of 5 rpm, and a mixing time of 1 hour were used.

[0050] Example 3

[0051] A molding method of TC4 titanium alloy powder for EBSM, comprising: feeding the TC4 titanium alloy powder into an EBSM device, and performing the molding process according to the conditions of a powder layer thickness of 0.10 mm, a preheating temperature of 625° C., and an energy density of 3.7 J / mm 2 , the molding was performed with the parameters of scanning spacing 0.10 mm and scanning speed 2.0 m / s;

[0052] The preparation method of TC4 titanium alloy powder in this embodiment includes the following steps:

[0053] S1. Powdering TC4 titanium alloy rods by plasma rotating electrode powder making equipment to obtain first-pass powder and slug; wherein the chemical composition of TC4 titanium alloy rods is as follows by mass percentage: Al: 6.60%, V: 3.5%, Fe: 0.20%, C: 0.01%, N: 0.01%, H: 0.005%, O: 0.12%, Ti balance, and the specifications of TC4 titanium alloy rods are The straightness is ≤0.05mm and the surface roughness is ≤3.2μm. During the first pass of powder preparation, the key parameters are set as rotation speed 30,000rpm, feed speed 35mm / min, power 125kw, and oxygen content ≤1ppm.

[0054] S2. Using an ultrasonic vibration screening machine, the first powder was screened according to the particle size distribution of D10 = 58 ± 5 μm, D50 = 80 ± 5 μm, and D90 = 101 ± 5 μm to obtain X powder with a particle size of 53 to 106 μm, a sphericity of 97.4%, and a hollow powder rate of 0.02%; wherein the mesh size of the ultrasonic vibration screening machine is 270 mesh and 140 mesh;

[0055] S3, friction welding the material heads obtained in S1 to obtain spliced ​​bars, and using electrode induction melting gas atomization equipment to grind the spliced ​​bars into powder to obtain the second pass powder; wherein, the spliced ​​bars are of the following specifications: Straightness ≤1mm; when preparing the second pass powder, the key parameters are atomization pressure 4.0Mpa, feed speed 45mm / min, power 45kw, and oxygen content ≤1ppm;

[0056] S4. The second powder was subjected to airflow classification and vibration screening in succession according to the particle size distribution of D10 = 50 ± 5 μm, D50 = 60 ± 5 μm, and D90 = 70 ± 5 μm, to obtain Y powder with a particle size of 45 to 75 μm, a sphericity of 94.1%, and a hollow powder rate of 0.22%. The key parameters for airflow classification were set as a feed frequency of 15 Hz, a classification frequency of 15 Hz, an air supply pressure of 0.7 MPa, and an oxygen content of ≤ 50 ppm. The mesh sizes of the ultrasonic vibration screening machine during vibration screening were 325 mesh and 200 mesh.

[0057] S5. Using a conical mixer, mix powder X and powder Y in a mass ratio of 4:1 to obtain TC4 titanium alloy powder having a particle size distribution of D10 = 53 ± 5 μm, D50 = 75 ± 5 μm, D90 = 95 ± 5 μm, a sphericity of 96.7%, and a hollow powder rate of 0.06%. During the mixing process of powder X and powder Y, the single mixing weight is 250 kg, the speed is 10 rpm, and the mixing time is 3 h.

[0058] Comparative Example 1

[0059] A molding method for TC4 titanium alloy powder comprises the following steps: placing the TC4 titanium alloy powder into an EBSM device and molding the powder according to parameters such as a powder layer thickness of 0.12 mm, a preheating temperature of 800° C., an energy density of 2.8 J / mm2, a scanning interval of 0.07 mm, and a scanning speed of 0.9 m / s.

[0060] In this embodiment, the preparation method of TC4 titanium alloy powder includes the following steps:

[0061] S1: PREP powder making: TC4 titanium alloy rods are powdered using ultra-high speed plasma rotating electrode powder making equipment. The chemical composition of the TC4 titanium alloy rods is as follows by mass percentage: Al: 5.95%, V: 4.00%, Fe: 0.10%, C: 0.01%, N: 0.01%, H: 0.005%, O: 0.06%, and Ti as the balance; the specifications of the TC4 titanium alloy rods are Straightness ≤ 0.05mm, surface roughness ≤ 3.2μm; key parameters for preparing masa flour are: rotation speed 30000rpm, feed speed 35mm / min, power 125kw, oxygen content ≤ 1ppm;

[0062] S2: Using an ultrasonic vibration screening machine, the powder obtained in S1 was sieved according to the particle size distribution of D10 = 58 ± 5 μm, D50 = 80 ± 5 μm, and D90 = 101 ± 5 μm to obtain TC4 titanium alloy powder with a particle size of 53 to 106 μm, a sphericity of 97.4%, and a hollow powder rate of 0.02%; the mesh sizes of the ultrasonic vibration screening machine are 270 mesh and 140 mesh.

[0063] Comparative Example 2

[0064] A molding method for TC4 titanium alloy powder comprises the following steps: placing the TC4 titanium alloy powder into an EBSM device and molding the powder according to parameters such as a powder layer thickness of 0.08 mm, a preheating temperature of 450° C., an energy density of 4.6 J / mm2, a scanning interval of 0.13 mm, and a scanning speed of 3.2 m / s.

[0065] In this embodiment, the preparation method of TC4 titanium alloy powder includes the following steps:

[0066] S1: EIGA powder making: TC4 titanium alloy rods are powdered using electrode induction melting gas atomization equipment to obtain pure powder; the chemical composition of the TC4 titanium alloy rods is as follows by mass percentage: Al: 6.25%, V: 4.00%, Fe: 0.30%, C: 0.01%, N: 0.01%, H: 0.005%, O: 0.14%, Ti balance; the specifications of the TC4 titanium alloy rods are Straightness ≤1mm; when preparing cornmeal, the key parameters are atomization pressure 5.5Mpa, feed speed 45mm / min, power 45kw, and oxygen content ≤1ppm;

[0067] S2: An airflow classification device and an ultrasonic vibration screening machine were used successively to perform airflow classification and vibration screening on the powder obtained in S1 according to the particle size distribution of D10 = 53 ± 5 μm, D50 = 75 ± 5 μm, and D90 = 95 ± 5 μm, to obtain TC4 titanium alloy powder with a particle size of 53 to 106 μm, a sphericity of 93.5%, and a hollow powder rate of 0.35%; the key parameters of the airflow classification were a feed frequency of 15 Hz, a classification frequency of 15 Hz, an air supply pressure of 0.8 MPa, and an oxygen content of ≤50 ppm; the mesh sizes of the ultrasonic vibration screening machine were 270 mesh and 140 mesh.

[0068] The EBSM forming properties corresponding to the above-mentioned Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 are shown in Table 1:

[0069] Table 1 TC4 titanium alloy performance test results

[0070] performance Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Surface roughness μm 17 18 19 24 23 Density% 99.5 99.7 99.8 98.5 96.4 Tensile strength MPa 1025 1033 1040 988 956 Yield strength MPa 953 968 970 935 910 Elongation after break % 15.3 15.6 14.3 14.2 13.5 Sectional shrinkage% 44.5 45.1 43.8 39.1 38.3 Bending strength MPa 2041 2032 2020 1980 1965 <![CDATA[Fracture toughness Mpa·m 1 / 2 > 95.4 93.1 91.5 83.3 79.2 Fatigue strength MPa 532 528 512 483 445

[0071] It can be seen from the data in Table 1 that the present invention can significantly improve the density of EBSM-formed TC4 titanium alloy, reduce surface roughness, and significantly improve the strength and plasticity of the material, which has very good promotion value.

[0072] The specific embodiments of the present invention are provided to enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0073] It should be understood that the present invention is not limited to the above description and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing TC4 titanium alloy powder for EBSM, characterized in that: The following steps are involved: S1. Pulverizing a TC4 titanium alloy rod by a plasma rotating electrode pulverizing device to obtain a first pass powder and a slug; the chemical composition of the TC4 titanium alloy rod is as follows by mass percentage: Al: 6.45-6.75%, V: 3.50-4.50%, Fe: 0.15-0.25%, C: ≤0.08%, N: ≤0.03%, H: ≤0.012%, O: 0.09-0.12%, and Ti as the balance; S2, sieving the first powder to obtain X powder; S3, friction welding the material heads obtained in S1 to obtain spliced ​​bars, and using electrode induction melting gas atomization equipment to grind the spliced ​​bars into powder to obtain a second pass of powder; S4. Screening the second powder to obtain Y powder. The specific process is: using an airflow classification device and an ultrasonic vibration screening machine, the second powder is subjected to airflow classification and vibration screening according to the particle size distribution of D10 = 50 ± 5 μm, D50 = 60 ± 5 μm, and D90 = 70 ± 5 μm. The particle size of the Y powder is 45-75 μm, the sphericity is ≥ 94%, and the hollow powder rate is ≤ 0.30%; S5. Mix the X powder and the Y powder in a mass ratio of 2:1 to 4:1 to obtain TC4 titanium alloy powder.

2. The method for preparing TC4 titanium alloy powder for EBSM according to claim 1, wherein: When the first pass powder is prepared by the plasma rotating electrode powder making equipment, the rotation speed is 28000~32000rpm, the feed speed is 20~50mm / min, the power is 100~150kw, and the oxygen content is ≤1ppm.

3. The method for preparing TC4 titanium alloy powder for EBSM according to claim 1, wherein: In S2, an ultrasonic vibration screening machine is used to screen the first powder according to the particle size distribution of D10=58±5μm, D50=80±5μm, and D90=101±5μm.

4. The method for preparing TC4 titanium alloy powder for EBSM according to claim 1, wherein: The particle size of X powder is 53~106μm, the sphericity is ≥97%, and the hollow powder rate is ≤0.03%.

5. The method for preparing TC4 titanium alloy powder for EBSM according to claim 1, wherein: The specifications of TC4 titanium alloy bars are: diameter 55~60mm, length 700mm, straightness ≤0.05mm, surface roughness ≤3.2μm; the specifications of spliced ​​bars are: diameter 55~60mm, length 200~500mm, straightness ≤1mm.

6. The method for preparing TC4 titanium alloy powder for EBSM according to claim 1, characterized in that: When the second pass powder is prepared by electrode induction melting gas atomization equipment, the atomization pressure is 3.0~5.0Mpa, the feed speed is 20~70mm / min, the power is 30~60kw, and the oxygen content is ≤1ppm.

7. A TC4 titanium alloy powder for EBSM, characterized in that: The TC4 titanium alloy powder is prepared by the preparation method according to any one of claims 1 to 6.

8. A method for forming TC4 titanium alloy powder for EBSM, characterized in that: Put TC4 titanium alloy powder into EBSM equipment, according to the powder layer thickness of 0.09~0.11mm, preheating temperature of 500~750℃, energy density of 3.0~4.5J / mm 2 , scanning spacing 0.08~0.12mm, scanning speed 1.0~3.0m / s parameters for molding, the TC4 titanium alloy powder is prepared by the preparation method according to any one of claims 1 to 6.

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