A titanium alloy part with harmonic heterostructure and a preparation method and application thereof

Abstract

The application belongs to the technical field of metal processing and manufacturing, and relates to a titanium alloy workpiece with a harmonic heterogeneous structure and a preparation method and application thereof. The method comprises the following steps: step 1, two titanium alloy raw material powders with different particle size distributions and grinding balls are ball-mixed according to a set mass ratio, and after ball-mixing, the grinding balls are separated through a screen to obtain titanium alloy mixed powders with different particle sizes; step 2, the titanium alloy mixed powders are loaded into a can, and after the titanium alloy mixed powders are filled and vibrated, the can is heated and vacuumized, and after the vacuum degree is less than 1.0*10 ‑3 Pa, the can is sealed and welded; step 3, the sealed and welded can is subjected to hot isostatic pressing treatment in a mode of first increasing pressure and then increasing temperature to obtain a hot isostatic pressing blank; and step 4, the hot isostatic pressing blank is subjected to heat treatment, and the surface of the heat-treated blank is machined to remove the can and surface grinding, so that the preparation of the titanium alloy workpiece with the harmonic heterogeneous structure is completed.

Description

Technical Field

[0001] This invention belongs to the field of metal processing and manufacturing technology, and relates to the processing of titanium alloy materials, specifically to a titanium alloy part with a harmonic heterostructure, its preparation method and application. Background Technology

[0002] Titanium alloys, as important metallic structural materials, possess unique advantages such as high strength, high specific strength, low density, and excellent corrosion resistance, demonstrating broad application potential in many key fields such as national defense, aviation, aerospace, high-end automobiles, and submarines. However, titanium alloys are not without their flaws. Similar to traditional homogeneous structural materials, increasing the strength of titanium alloys often leads to a decrease in ductility and toughness, making it difficult to achieve a balance between high strength and high ductility.

[0003] In recent years, with the continuous development of materials science, heterogeneous materials, especially those with harmonic structures, have gradually become a research hotspot. Harmonic structures, characterized by specific periodic variations in the distribution of elements and microstructure within a material, have been proven to significantly enhance its strength and toughness. Therefore, it is crucial to successfully prepare harmonic titanium alloys with superior properties using advanced fabrication processes, thereby solving the challenges of titanium alloys in specific applications. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a titanium alloy part with a harmonic heterostructure, its preparation method and application, aiming to achieve a comprehensive improvement in the performance of titanium alloys by optimizing powder distribution and hot isostatic pressing process.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a titanium alloy part with a harmonic heterostructure, specifically including the following steps:

[0007] Step 1: Mix two titanium alloy raw material powders with different particle size distributions with grinding balls in a set mass ratio. After ball milling and mixing, separate the grinding balls through a sieve to obtain titanium alloy mixed powder with different particle sizes.

[0008] Step 2: Load the titanium alloy powder mixture into the packaging sleeve. After the sleeve is fully filled and compacted, heat and evacuate it until the vacuum level is less than 1.0 × 10⁻⁶. -3 After Pa, the sleeve is sealed by welding;

[0009] Step 3: After sealing, the sheath is subjected to hot isostatic pressing by first increasing the pressure and then increasing the temperature to obtain a hot isostatic pressing billet.

[0010] Step 4: Heat-treat the hot isostatic pressed billet, and then machine the surface of the heat-treated billet to remove the cladding and grind the surface to complete the preparation of the titanium alloy part with harmonic heterostructure.

[0011] Specifically, in step 1, the titanium alloy raw material powder is prepared using a plasma rotating electrode method; wherein, the titanium alloy raw material powder includes fine powder and coarse powder, and the mass ratio of the fine powder to the coarse powder is 1:(0.5~2); the particle size D of the fine powder is... 50 =40μm~53μm, the particle size D of the coarse powder 50 =150μm~170μm.

[0012] Specifically, in step 1, the mass ratio of the grinding ball to the titanium alloy raw material powder is 3:1 to 10:1.

[0013] Specifically, the grinding balls are composed of stainless steel balls with particle sizes of 3mm-5mm, 5mm-8mm, and 8mm-10mm in a mass ratio of (4-5):(1-2):(1-2).

[0014] Specifically, in step 1, the rotation speed of the ball mill used for ball milling is 100 r / min to 300 r / min.

[0015] Specifically, in step 2, the cladding is sealed using an electron beam sealing process; in the electron beam sealing process, the welding current is 50mA to 100mA, the welding speed is 120° / min to 300° / min, and the number of welding passes is 2 to 4.

[0016] Specifically, in step 3, the hot isostatic pressing process is as follows:

[0017] First, the pressure is increased to 80MPa to 100MPa within 30 to 45 minutes and then held at that pressure. At the same time, the temperature is increased to 700℃ to 800℃ at a rate of 9℃ / min to 11℃ / min and then held at that temperature for 30 to 60 minutes.

[0018] Then, the pressure is increased to 150MPa to 180MPa within 10 to 15 minutes and held. Then, the temperature is increased to 900℃ to 1000℃ at a rate of 11℃ / min to 15℃ / min and held for 1 hour to 6 hours.

[0019] Specifically, in step 4, the heat treatment process is as follows: first, the hot isostatic pressing blank is kept at a temperature of 900℃~950℃ for 1h~3h, and then air-cooled to room temperature; then, the hot isostatic pressing blank is heated to 500℃~600℃ at a heating rate of 5K / min~9K / min, and kept at that temperature for 3h~6h, and finally air-cooled to room temperature.

[0020] Secondly, the present invention also provides a titanium alloy part prepared by some or all of the preparation methods described above, wherein the titanium alloy part has a harmonic structure in which equiaxed α phase surrounds lamellar α phase, and the prepared titanium alloy has a better strength-toughness match.

[0021] Furthermore, this invention also provides an application of the preparation method described above, in part or all of which is used in the preparation of TC21 titanium alloy parts, resulting in TC21 titanium alloy parts with a tensile strength R. m The fracture toughness is 1186MPa~1294MPa, K IC It is 56.4 MPa·m 1 / 2 ~66.3MPa·m 1 / 2 .

[0022] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0023] 1) Pre-treatment of titanium alloy raw material powder by ball milling, that is, increasing the pre-deformation amount on the surface of titanium alloy raw material powder by ball milling, improving the distortion energy of the titanium alloy raw material powder surface, so that after recrystallization on the surface of titanium alloy mixed powder during hot isostatic pressing deformation, equiaxed α phase with smaller grain size and more uniform distribution is formed.

[0024] 2) By adjusting the mass ratio of fine powder to coarse powder, the tap density of the titanium alloy mixed powder is changed, thereby altering the deformation of the titanium alloy mixed powder particles during hot isostatic pressing, and thus controlling the volume fraction of the equiaxed α phase, thereby achieving the purpose of controlling the mechanical properties of titanium alloy parts.

[0025] 3) Hot isostatic pressing is carried out by "pressurizing first and then heating". "Pressurizing first" is beneficial to improving the shape stability and deformation uniformity of titanium alloy parts and ensuring the consistency of powder deformation in different positions.

[0026] In summary, the preparation method provided by this invention, compared with traditional titanium alloy forging processes, can produce titanium alloy parts with a lamellar α-phase harmonic structure surrounded by equiaxed α-phase. This structure is beneficial for achieving heterogeneous deformation-induced strengthening, improving plasticity, and realizing a synergistic improvement in strength and plasticity. The successful development of the preparation method involved in this invention will provide strong support for the safe service and expanded application of titanium alloys in a wider range of fields, and has significant social and economic value. Attached Figure Description

[0027] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A flowchart illustrating a method for preparing a titanium alloy part with a harmonic heterostructure provided by the present invention;

[0030] Figure 2 The hot isostatic pressing process curve of TC21 titanium alloy with harmonic heterostructure provided in Embodiment 1 of the present invention;

[0031] Figure 3 Micrograph of TC21 titanium alloy with harmonic heterostructure provided in Embodiment 1 of the present invention. Detailed Implementation

[0032] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0033] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] Example 1

[0035] See Figure 1 As shown, this embodiment provides a method for preparing a titanium alloy part with a harmonic heterostructure, specifically including the following steps:

[0036] Step 1: Two titanium alloy raw material powders with different particle size distributions are ball-milled and mixed with grinding balls at a set mass ratio. After ball milling and mixing, the grinding balls are separated through a sieve to obtain titanium alloy mixed powders with different particle sizes. Specifically:

[0037] Step 1.1: Weigh 1500g of stainless steel balls and put them into the ball mill jar, wherein the mass ratio of stainless steel balls with a diameter of 3mm to 5mm, 5mm to 8mm, and 8mm to 10mm is 4:1:1;

[0038] Step 1.2, Weigh D 50 = TC21 powder with a particle size of 40μm to 53μm and D 50 300g of TC21 powder with a particle size of 150μm to 170μm was placed in a ball mill jar, with the mass ratio of fine powder to coarse powder being 1:0.5.

[0039] Step 1.3: Transfer the prepared ball mill jar to a planetary ball mill for ball milling. The ball milling speed is 100 r / min and the ball milling time is 3 h.

[0040] Step 1.4: Pass the ball-milled powder through a 250-mesh sieve to separate the stainless steel balls and obtain titanium alloy mixed powder;

[0041] Step 2: Load the titanium alloy powder mixture from Step 1.4 into the steel liner. After the powder is fully loaded and compacted, heat the liner and evacuate it until the vacuum level is less than 1.0 × 10⁻⁶. -3 After the pa, the cladding is sealed with electron beam welding. The welding current is 50mA to 100mA, the welding speed is 120° / min to 300° / min, and the number of welding times is 2 to 3.

[0042] Step 3: Perform hot isostatic pressing (HIP) on the sealed sleeve to obtain a hot isostatic pressed blank; for details, see [link to relevant documentation]. Figure 2 The hot isostatic pressing process is as follows:

[0043] At the beginning of hot isostatic pressing, the pressure is increased to 80MPa-85MPa within 30-35 minutes and held, while the temperature is increased to 700-750℃ at a heating rate of 9℃ / min-11℃ / min and held for 30 minutes; then the pressure is increased to 150MPa-160MPa within 10-12 minutes, and the temperature is increased to 900-950℃ at a heating rate of 11℃ / min-15℃ / min and held for 60 minutes.

[0044] Step 4: Heat treat the hot isostatic pressed billet. ： First, the hot isostatic pressing billet is held at 900℃~950℃ for 1h~3h, and then air-cooled to room temperature; then the hot isostatic pressing billet is heated to 500℃~600℃ at a heating rate of 5K / min~9K / min, and held for 3h~6h before air-cooling to room temperature.

[0045] Finally, the surface of the heat-treated billet sample was mechanically de-clad and ground to obtain a TC21 titanium alloy part with a harmonic structure (Part 1), see [link to article]. Figure 3 The relevant mechanical properties of TC21 titanium alloy parts (I) are as follows: tensile strength R m =1294MPa, yield strength R p0.2 =1194MPa, elongation A% =13.3, reduction of area Z% =39.4, fracture toughness K IC =56.4 MPa·m 1 / 2 .

[0046] Example 2

[0047] This embodiment provides another method for preparing titanium alloy parts with harmonic heterostructures, specifically including the following steps:

[0048] Step 1: Two titanium alloy raw material powders with different particle size distributions are ball-milled and mixed with grinding balls at a set mass ratio. After ball milling and mixing, the grinding balls are separated through a sieve to obtain titanium alloy mixed powders with different particle sizes. Specifically:

[0049] Step 1.1: Weigh 900g of stainless steel balls and put them into the ball mill jar, wherein the mass ratio of stainless steel balls with a diameter of 3mm to 5mm, 5mm to 8mm, and 8mm to 10mm is 5:2:2;

[0050] Step 1.2, Weigh D 50 = TC21 powder with a particle size of 40μm to 53μm and D 50 300g of TC21 powder with a particle size of 150μm to 170μm was placed in a ball mill jar, with the mass ratio of fine powder to coarse powder being 1:2.

[0051] Step 1.3: Transfer the prepared ball mill jar to a planetary ball mill for ball milling. The ball milling speed is 200 r / min and the ball milling time is 2 h.

[0052] Step 1.4: Pass the ball-milled powder through a 250-mesh sieve to separate the stainless steel balls and obtain titanium alloy mixed powder;

[0053] Step 2: Load the titanium alloy powder mixture from Step 1.4 into the steel liner. After the powder is fully loaded and compacted, heat the liner and evacuate it until the vacuum level is less than 1.0 × 10⁻⁶. -3 After the pa, the cladding is sealed with electron beam welding. The welding current is 50mA to 100mA, the welding speed is 120° / min to 300° / min, and the number of welding times is 3 to 4.

[0054] Step 3: Perform hot isostatic pressing (HIP) on the sealed sleeve to obtain a hot isostatic pressing blank; specifically, the HIP process is as follows:

[0055] At the beginning of hot isostatic pressing, the pressure is increased to 85MPa-90MPa within 35-40 minutes and held, while the temperature is increased to 750-800℃ at a heating rate of 9℃ / min-11℃ / min and held for 60 minutes; then the pressure is increased to 160MPa-180MPa within 12-15 minutes, and the temperature is increased to 950-1000℃ at a heating rate of 11℃ / min-15℃ / min and held for 60 minutes.

[0056] Step 4: Heat treat the hot isostatic pressed billet. ：First, the hot isostatic pressing billet is held at 900℃~950℃ for 1h~3h, and then air-cooled to room temperature; then the hot isostatic pressing billet is heated to 500℃~600℃ at a heating rate of 5K / min~9K / min, and held for 3h~6h before air-cooling to room temperature.

[0057] Finally, the surface of the heat-treated billet sample was mechanically de-clad and surface-ground to obtain TC21 titanium alloy part (II) with harmonic structure; the relevant mechanical properties of TC21 titanium alloy part (II) are as follows: tensile strength R m =1186MPa, yield strength R p0.2 =1105MPa, elongation A% =18.3, reduction of area Z% =45.7, fracture toughness K IC = 66.3 MPa·m 1 / 2 .

[0058] Example 3

[0059] This embodiment provides a method for preparing a titanium alloy part with a harmonic heterostructure, specifically including the following steps:

[0060] Step 1: Two titanium alloy raw material powders with different particle size distributions are ball-milled and mixed with grinding balls at a set mass ratio. After ball milling and mixing, the grinding balls are separated through a sieve to obtain titanium alloy mixed powders with different particle sizes. Specifically:

[0061] Step 1.1: Weigh 3000g of stainless steel balls and put them into the ball mill jar, wherein the mass ratio of stainless steel balls with a diameter of 3mm to 5mm, 5mm to 8mm, and 8mm to 10mm is 5:2:2;

[0062] Step 1.2, Weigh D 50 = TC21 powder with a particle size of 40μm to 53μm and D 50 300g of TC21 powder with a particle size of 150μm to 170μm was placed in a ball mill jar, with the mass ratio of fine powder to coarse powder being 1:1.5.

[0063] Step 1.3: Transfer the prepared ball mill jar to a planetary ball mill for ball milling. The ball milling speed is 300 r / min and the ball milling time is 1 hour.

[0064] Step 1.4: Pass the ball-milled powder through a 250-mesh sieve to separate the stainless steel balls and obtain titanium alloy mixed powder;

[0065] Step 2: Load the titanium alloy powder mixture from Step 1.4 into the steel liner. After the powder is fully loaded and compacted, heat the liner and evacuate it until the vacuum level is less than 1.0 × 10⁻⁶. -3After the initial welding (PA), the cladding is subjected to electron beam sealing with a welding current of 50mA to 100mA, a welding speed of 120° / min to 300° / min, and 2 to 3 welding passes. ；

[0066] Step 3: Perform hot isostatic pressing (HIP) on the sealed sleeve to obtain a hot isostatic pressing blank; specifically, the HIP process is as follows:

[0067] At the beginning of hot isostatic pressing, the pressure is increased to 90MPa-100MPa within 40-45 minutes and held, while the temperature is increased to 780-800℃ at a heating rate of 9℃ / min-11℃ / min and held for 50 minutes; then the pressure is increased to 170MPa-180MPa within 13-15 minutes and held, and then the temperature is increased to 980-1000℃ at a heating rate of 11℃ / min-15℃ / min and held for 60 minutes.

[0068] Step 4: Heat treat the hot isostatic pressed billet. ， First, the hot isostatic pressing billet is held at 900℃~950℃ for 1h~3h, and then air-cooled to room temperature; then the hot isostatic pressing billet is heated to 500℃~600℃ at a heating rate of 5K / min~9K / min, held for 3h~6h, and finally air-cooled to room temperature.

[0069] Finally, the surface of the heat-treated billet sample was mechanically de-clad and surface-ground to obtain the TC21 titanium alloy part (III) with harmonic structure; the relevant mechanical properties of the TC21 titanium alloy part (III) are as follows: tensile strength R m =1235MPa, yield strength R p0.2 =1143MPa, elongation A% =14.3, reduction of area Z% =40.7, fracture toughness K IC =58.3 MPa·m 1 / 2 .

[0070] Comparative Example

[0071] Based on Example 2, this comparative example provides a method for preparing titanium alloy parts, which adopts the preparation process disclosed in publication number CN117139622A. The difference between this comparative example and Example 2 is that:

[0072] ① In Example 2, the titanium alloy raw material powder underwent ball milling pretreatment; ② Example 2 used titanium alloy raw material powder made by mixing coarse and fine powders in a certain proportion; ③ The hot isostatic pressing (HIP) treatment regimes were different. Comparative Example 2 used a "heating first, then pressurizing" HIP regime, while Example 2 of this invention used a "pressurizing first, then heating" HIP regime (specifically, the pressure was increased to 80MPa-85MPa within 30-35 minutes and held at that pressure, while the temperature was increased to 700-750℃ at a heating rate of 9℃ / min-11℃ / min and held at that temperature for 3 minutes). The pressure is increased to 150MPa-160MPa within 10-12 minutes, and then the temperature is increased to 900-950℃ at a rate of 11℃ / min-15℃ / min, and held for 60 minutes. This is because TC21 titanium alloy undergoes phase transformation or element segregation at high temperatures. If the temperature is increased before the pressure is increased, the deformation rate of the TC21 titanium alloy powder may be high, and a basketweave structure with lamellar α phases may form at the powder boundaries, resulting in relatively low plasticity and fracture toughness, and unstable material properties. By increasing the pressure before the temperature, the powder deformation rate can be reduced, and the alloy is more likely to undergo dynamic recrystallization, forming a structure with equiaxed α phases at the powder boundaries. This structure has excellent plasticity and fracture toughness.

[0073] To further verify the effectiveness of the technical solution provided by this invention, the tensile strength and fracture toughness of the TC21 titanium alloy parts prepared in Examples 1-3 and the comparative example were compared, as detailed in the table below:

[0074]

[0075]

[0076] As can be seen from the table above, the TC21 titanium alloy parts prepared by the method provided by this invention have better tensile strength and fracture toughness than the comparative example. This will provide strong support for the safe service and expanded application of titanium alloys in a wider range of fields, and has important social significance and economic value.

[0077] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily 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 invention.

[0078] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing a titanium alloy part with a harmonic heterostructure, characterized in that, Specifically, the following steps are included: Step 1: Two titanium alloy raw material powders with different particle size distributions are ball-milled and mixed with grinding balls at a set mass ratio. After ball milling and mixing, the grinding balls are separated through a sieve to obtain titanium alloy mixed powders with different particle sizes. The titanium alloy raw material powders are prepared by plasma rotating electrode method. The titanium alloy raw material powders include fine powder and coarse powder, and the mass ratio of fine powder to coarse powder is 1:(0.5~2). The fine powder has a particle size D. 50 =40μm~53μm, the particle size D of the coarse powder 50 =150μm~170μm; the mass ratio of the grinding ball to the titanium alloy raw material powder is 3:1~10:1; the grinding ball is composed of stainless steel balls with particle sizes of 3mm~5mm, 5mm~8mm, and 8mm~10mm in a mass ratio of (4~5):(1~2):(1~2); Step 2: Load the titanium alloy powder mixture into the packaging sleeve. After the sleeve is fully filled and compacted, heat and evacuate it until the vacuum level is less than 1.0 × 10⁻⁶. -3 After Pa, the cladding is sealed by welding; the cladding is sealed by electron beam welding process; in the electron beam welding process, the welding current is 50mA~100mA, the welding speed is 120° / min~300° / min, and the number of welding times is 2 to 4. Step 3: The sealed sleeve is subjected to hot isostatic pressing (HIP) by first increasing the pressure and then increasing the temperature to obtain a hot isostatic pressing blank. The specific process of the HIP is as follows: First, the pressure is increased to 80MPa~100MPa within 30min~45min and then held at that pressure. At the same time, the temperature is increased to 700℃~800℃ at a rate of 9℃ / min~11℃ / min and then held at that temperature for 30min~60min. Then, the pressure is increased to 150MPa~180MPa within 10min~15min and held at that pressure. Then the temperature is increased to 900℃~1000℃ at a rate of 11℃ / min~15℃ / min and held at that temperature for 1h~6h. Step 4: Heat-treat the hot isostatic pressed billet, then machine the surface of the heat-treated billet to remove the cladding and grind the surface to complete the preparation of the titanium alloy part with harmonic heterostructure; the specific process of the heat treatment is as follows: first, hold the hot isostatic pressed billet at a temperature of 900℃~950℃ for 1h~3h, then air-cool it to room temperature; then heat the hot isostatic pressed billet to 500℃~600℃ at a heating rate of 5K / min~9K / min, hold it for 3h~6h, and finally air-cool it to room temperature; The prepared titanium alloy part has a harmonic structure in which equiaxed α phases surround lamellar α phases, and its properties are: tensile strength R m ≥1186MPa, yield strength R p0.2 ≥1105MPa, elongation A%≤18.3, reduction of area Z%≤45.7, fracture toughness K IC ≥56.4MPa•m 1 / 2 .

2. The method for preparing a titanium alloy part with a harmonic heterostructure according to claim 1, characterized in that, In step 1, the rotation speed of the ball mill used for ball milling is 100 r / min to 300 r / min.

3. The application of the preparation method of titanium alloy parts with harmonic heterostructure according to claim 1 or 2 in the preparation of TC21 titanium alloy parts.

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