Titanium alloy workpiece with harmonic heterostructure as well as preparation method and application of titanium alloy workpiece

Abstract

The invention belongs to the technical field of metal processing and manufacturing, and relates to a titanium alloy workpiece with a harmonic heterostructure and a preparation method and application of the titanium alloy workpiece. The method comprises the steps that 1, two kinds of titanium alloy raw material powder with different particle size distribution and grinding balls are subjected to ball-milling mixing according to a set mass ratio, and after ball-milling mixing, the grinding balls are separated through a screen to obtain titanium alloy mixed powder with different particle sizes; 2, the titanium alloy mixed powder is contained in a sheath, after the titanium alloy mixed powder is filled and compacted through vibration, the sheath is heated and vacuumized, and after the vacuum degree is smaller than 1.0 * 10 <-3 > Pa, the sheath is sealed and welded; step 3, carrying out hot isostatic pressing treatment on the sealed and welded sheath by adopting a mode of firstly increasing pressure and then increasing temperature, so as to obtain a hot isostatic pressing blank; and 4, the hot isostatic pressing blank is subjected to heat treatment, then the surface of the blank subjected to heat treatment is subjected to machining, sheath removal and surface coping, and preparation of the titanium alloy workpiece with the harmonic heterostructure is completed.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal processing and manufacturing, and relates to titanium alloy material processing, and in particular to a titanium alloy product with a harmonic heterogeneous structure, and a preparation method and application thereof. Background Art

[0002] As an important metal structural material, titanium alloy has demonstrated wide application potential in many key fields such as national defense, aviation, aerospace, high-end automobiles and submarines due to its unique advantages such as high strength, high specific strength, low density and excellent corrosion resistance. However, titanium alloy is not without flaws. Similar to traditional uniform structural materials, improving the strength of titanium alloy usually leads to a decrease in plastic toughness, making it difficult to achieve both high strength and high plasticity.

[0003] In recent years, with the continuous development of materials science, heterogeneous structural materials, especially materials with harmonic structures, have gradually become a research hotspot. Harmonic structure refers to the characteristics of specific periodic changes in the distribution of elements and tissues inside the material, which has been proven to significantly improve the strength and plasticity of the material. Therefore, it is crucial to successfully prepare harmonic titanium alloys with excellent performance through advanced preparation processes to solve the problems of titanium alloys in specific applications. Summary of the invention

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

[0005] To achieve the above object, the present invention provides the following technical solutions:

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

[0007] Step 1, mixing two titanium alloy raw material powders with different particle size distributions with grinding balls according to a set mass ratio by ball milling, and separating the grinding balls through a sieve to obtain titanium alloy mixed powders with different particle sizes;

[0008] Step 2: Put the titanium alloy mixed powder into the bag, and after the titanium alloy mixed powder is filled and compacted, heat and evacuate the bag until the vacuum degree is less than 1.0×10 -3 After Pa, the package is sealed and welded;

[0009] Step 3, hot isostatic pressing the sealed and welded package by first increasing the pressure and then increasing the temperature to obtain a hot isostatic pressed blank;

[0010] Step 4: heat-treating the hot isostatic pressed blank, and then machining and removing the sheath and grinding the surface of the blank after the heat treatment to complete the preparation of the titanium alloy part with a harmonic heterogeneous structure.

[0011] Specifically, in step 1, the titanium alloy raw material powder is prepared by 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 powder particle size D of the fine powder 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 balls 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 mixing is 100 r / min to 300 r / min.

[0015] Specifically, in step 2, the package is sealed by electron beam sealing welding process; in the electron beam sealing welding process, 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 4 times.

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

[0017] First, the pressure is increased to 80MPa-100MPa within 30-45min and then maintained, and at the same time, the temperature is increased to 700-800°C at a rate of 9-11°C / min and then maintained for 30-60min;

[0018] Then, the pressure is increased to 150MPa-180MPa within 10min-15min and the pressure is maintained, and then the temperature is increased to 900°C-1000°C at a rate of 11°C / min-15°C / min and the temperature is maintained for 1h-6h.

[0019] Specifically, in step 4, the specific process of the heat treatment is: first, the hot isostatically pressed blank is kept at a temperature of 900°C to 950°C for 1h to 3h, and then air-cooled to room temperature; then, the hot isostatically pressed blank is heated to 500°C to 600°C at a heating rate of 5K / min to 9K / min, and kept at this temperature for 3h to 6h, and finally air-cooled to room temperature.

[0020] In a second aspect, the present invention also provides a titanium alloy part produced by part or all of the production method as described above, wherein the titanium alloy part has a harmonic structure in which an equiaxed α phase surrounds a lamellar α phase, and the produced titanium alloy has a better strength-toughness match.

[0021] In addition, the present invention also provides an application of the preparation method described in part or in whole in the preparation of a TC21 titanium alloy product, wherein the tensile strength R m 1186MPa~1294MPa, fracture toughness K IC 56.4MPa·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-treating the titanium alloy raw material powder by ball milling, that is, increasing the pre-deformation amount on the surface of the titanium alloy raw material powder by ball milling, thereby improving the surface distortion energy of the titanium alloy raw material powder, so that during the hot isostatic pressing deformation process, the surface of the titanium alloy mixed powder is recrystallized to form an equiaxed α phase with a smaller grain size and more uniform distribution;

[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 changing the deformation of the titanium alloy mixed powder particles during hot isostatic pressing, and then adjusting the volume fraction of the equiaxed α phase to achieve the purpose of adjusting the mechanical properties of titanium alloy parts;

[0025] 3) The hot isostatic pressing treatment is carried out by "pressurizing first and then heating". "Pressure increasing first" is conducive to improving the shape stability and deformation uniformity of titanium alloy parts, and ensuring the consistency of powder deformation at different positions;

[0026] In general, the preparation method provided by the present invention can produce titanium alloy parts with a harmonic structure of equiaxed α phases surrounding lamellar α phases compared to the traditional titanium alloy forging process. This structure is conducive to achieving heterogeneous deformation-induced strengthening, improving plasticity, and achieving a synergistic improvement in strength and plasticity. The successful development of the preparation method involved in the present invention 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. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0029] Figure 1 A flow chart of a method for preparing a titanium alloy product having a harmonic heterostructure provided by the present invention;

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

[0031] Figure 3 This is a microstructure photograph of the TC21 titanium alloy with harmonic heterostructure provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] Here, exemplary embodiments will be described in detail, and the embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples consistent with some aspects of the present invention described in detail in the appended claims.

[0033] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0034] Example 1

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

[0036] Step 1: Mix two titanium alloy raw material powders with different particle size distributions with grinding balls according to a set mass ratio by ball milling, and separate the grinding balls 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 a ball mill, wherein the mass ratio of 3mm-5mm, 5mm-8mm, and 8mm-10mm stainless steel balls is 4:1:1;

[0038] Step 1.2, weigh D 50 = 40μm~53μm TC21 powder and D 50 = TC21 powder of 150 μm to 170 μm, a total of 300 g, is put into a ball mill, wherein the mass ratio of fine powder to coarse powder is 1:0.5;

[0039] Step 1.3, transfer the configured ball mill jar to a planetary ball mill for ball milling, the ball milling speed is 100r / min, and the ball milling time is 3h;

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

[0041] Step 2: Put the titanium alloy mixed powder in step 1.4 into the steel bag. After the powder is filled and compacted, heat and evacuate the bag. When the vacuum degree is less than 1.0×10 -3 After pa, the package is electron beam sealed with welding, the welding current is 50mA ~ 100mA, the welding speed is 120° / min ~ 300° / min, and the number of welding is 2 ~ 3 times;

[0042] Step 3: Hot isostatic pressing the sealed and welded package to obtain a hot isostatic pressed blank; specifically, see Figure 2 , the hot isostatic pressing process is:

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

[0044] Step 4, heat treating the hot isostatically pressed blank: first, heat the hot isostatically pressed blank at 900°C to 950°C for 1h to 3h, and then air-cool to room temperature; then, heat the hot isostatically pressed blank to 500°C to 600°C at a heating rate of 5K / min to 9K / min, heat for 3h to 6h, and then air-cool to room temperature;

[0045] Finally, the surface of the heat-treated blank sample was mechanically de-sheathed and surface-grinded to obtain a TC21 titanium alloy part with a harmonic structure (I), see 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, section shrinkage Z% = 39.4, fracture toughness K IC =56.4MPa·m 1 / 2 .

[0046] Example 2

[0047] This embodiment provides another method for preparing a titanium alloy product having a harmonic heterostructure, which specifically comprises the following steps:

[0048] Step 1: Mix two titanium alloy raw material powders with different particle size distributions with grinding balls according to a set mass ratio by ball milling, and separate the grinding balls 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 a ball mill, wherein the mass ratio of 3mm-5mm, 5mm-8mm, and 8mm-10mm stainless steel balls is 5:2:2;

[0050] Step 1.2, weigh D 50 = 40μm~53μm TC21 powder and D 50 = TC21 powder of 150 μm to 170 μm, a total of 300 g, is put into a ball mill, wherein the mass ratio of fine powder to coarse powder is 1:2;

[0051] Step 1.3, transfer the configured ball mill jar to a planetary ball mill for ball milling, the ball milling speed is 200r / min, and the ball milling time is 2h;

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

[0053] Step 2: Put the titanium alloy mixed powder in step 1.4 into the steel bag. After the powder is filled and compacted, heat and evacuate the bag. When the vacuum degree is less than 1.0×10 -3 After pa, the package is electron beam sealed with welding, the welding current is 50mA ~ 100mA, the welding speed is 120° / min ~ 300° / min, and the number of welding is 3 to 4 times;

[0054] Step 3: hot isostatic pressing the sealed and welded package to obtain a hot isostatic pressed blank; specifically, the hot isostatic pressing process is as follows:

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

[0056] Step 4, heat treating the hot isostatically pressed blank: first, heat the hot isostatically pressed blank at 900°C to 950°C for 1h to 3h, and then air-cool to room temperature; then, heat the hot isostatically pressed blank to 500°C to 600°C at a heating rate of 5K / min to 9K / min, heat for 3h to 6h, and then air-cool to room temperature;

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

[0058] Example 3

[0059] This embodiment provides a method for preparing a titanium alloy product having a harmonic heterostructure, which specifically comprises the following steps:

[0060] Step 1: Mix two titanium alloy raw material powders with different particle size distributions with grinding balls according to a set mass ratio by ball milling, and separate the grinding balls 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 a ball mill, wherein the mass ratio of 3mm-5mm, 5mm-8mm, and 8mm-10mm stainless steel balls is 5:2:2;

[0062] Step 1.2, weigh D 50 = 40μm~53μm TC21 powder and D 50 = TC21 powder of 150 μm to 170 μm, a total of 300 g, is put into a ball mill, wherein the mass ratio of fine powder to coarse powder is 1:1.5;

[0063] Step 1.3, transfer the configured ball mill jar to a planetary ball mill for ball milling, the ball milling speed is 300r / min, and the ball milling time is 1h;

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

[0065] Step 2: Put the titanium alloy mixed powder in step 1.4 into the steel bag. After the powder is filled and compacted, heat and evacuate the bag. When the vacuum degree is less than 1.0×10 -3After pa, the package is electron beam sealed with welding, the welding current is 50mA ~ 100mA, the welding speed is 120° / min ~ 300° / min, and the number of welding is 2 ~ 3 times;

[0066] Step 3: hot isostatic pressing the sealed and welded package to obtain a hot isostatic pressed blank; specifically, the hot isostatic pressing process is as follows:

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

[0068] Step 4, heat treating the hot isostatically pressed blank, firstly keeping the hot isostatically pressed blank at a temperature of 900°C to 950°C for 1h to 3h, and then air cooling to room temperature; then heating the hot isostatically pressed blank to 500°C to 600°C at a heating rate of 5K / min to 9K / min, keeping it for 3h to 6h, and finally air cooling it to room temperature;

[0069] Finally, the surface of the heat-treated blank sample was mechanically de-sheathed and surface-grinded to obtain a TC21 titanium alloy part (III) with a 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, section shrinkage Z% = 40.7, fracture toughness K IC =58.3MPa·m 1 / 2 .

[0070] Comparative Example

[0071] On the basis of Example 2, this comparative example provides a method for preparing a titanium alloy part, and its preparation process adopts the preparation process disclosed in Publication No. CN117139622A. The difference between this comparative example and Example 2 is that:

[0072] ① In Example 2, the titanium alloy raw material powder was pre-treated by ball milling; ② In Example 2, a titanium alloy raw material powder in which coarse powder and fine powder were mixed in proportion was used; ③ The hot isostatic pressing treatment system was different. Comparative Example 2 adopted a hot isostatic pressing system of "first heating and then pressurizing", while Example 2 of the present invention adopted a hot isostatic pressing system of "first pressurizing and then heating" (the specific process is: the pressure is increased to 80MPa-85MPa within 30min-35min and then the pressure is maintained, and at the same time, the temperature is increased to 700℃-750℃ at a heating rate of 9℃ / min-11℃ / min and then kept for 3 0min; then the pressure is increased to 150MPa~160MPa within 10min~12min, and then the temperature is increased to 900℃~950℃ at a heating rate of 11℃ / min~15℃ / min, and kept warm for 60min). This is because: TC21 titanium alloy will undergo phase transformation or element segregation at high temperature. If the temperature is increased first and then the pressure is increased, the deformation rate of TC21 titanium alloy powder may be high, and a basket structure with lamellar α phase will be formed at the powder boundary. Its plasticity and fracture toughness are relatively low, and the material properties are unstable. By increasing the pressure first and then the temperature, the powder deformation rate can be reduced, the alloy is prone to dynamic recrystallization, and an equiaxed α phase structure will be formed at the powder boundary. This structure has excellent plasticity and fracture toughness.

[0073] In order to further verify the effectiveness of the technical solution provided by the present invention, the tensile strength and fracture toughness of the TC21 titanium alloy parts prepared in Examples 1 to 3 and the comparative example are compared, as shown in the following table:

[0074]

[0075]

[0076] It can be seen from the above table that the tensile strength and fracture toughness of the TC21 titanium alloy parts finally obtained by the preparation method provided by the present invention are better than those of the control example, which 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 only a specific embodiment of the present invention, so that those skilled in the art can 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 can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0078] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may 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 product having a harmonic heterostructure, characterized in that: The specific steps include: Step 1, mixing two titanium alloy raw material powders with different particle size distributions with grinding balls according to a set mass ratio by ball milling, and separating the grinding balls through a sieve to obtain titanium alloy mixed powders with different particle sizes; Step 2: Put the titanium alloy mixed powder into the bag, and after the titanium alloy mixed powder is filled and compacted, heat and evacuate the bag until the vacuum degree is less than 1.0×10 -3 After Pa, the package is sealed and welded; Step 3, hot isostatic pressing the sealed and welded package by first increasing the pressure and then increasing the temperature to obtain a hot isostatic pressed blank; Step 4: heat-treating the hot isostatically pressed blank, and then machining and removing the sheath and surface grinding the surface of the blank after the heat treatment to complete the preparation of the titanium alloy part with a harmonic heterogeneous structure.

2. The method for preparing a titanium alloy product having a harmonic heterostructure according to claim 1, characterized in that: In step 1, the titanium alloy raw material powder is prepared by 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 powder particle size D of the fine powder is 50 =40μm~53μm, the particle size D of the coarse powder 50 =150μm~170μm.

3. The method for preparing a titanium alloy product having a harmonic heterostructure according to claim 1, characterized in that: In step 1, the mass ratio of the grinding balls to the titanium alloy raw material powder is 3:1 to 10:

1.

4. The method for preparing a titanium alloy product having a harmonic heterostructure according to claim 3, characterized in that: 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).

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

6. The method for preparing a titanium alloy product having a harmonic heterostructure according to claim 1, characterized in that: In step 2, the package is sealed by electron beam sealing welding process; in the electron beam sealing welding process, 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 4 times.

7. The method for preparing a titanium alloy product having a harmonic heterostructure according to claim 1, characterized in that: In step 3, the specific process of the hot isostatic pressing treatment is as follows: First, the pressure is increased to 80MPa-100MPa within 30-45min and then maintained, and at the same time, the temperature is increased to 700-800°C at a rate of 9-11°C / min and then maintained for 30-60min; Then, the pressure is increased to 150MPa-180MPa within 10min-15min and the pressure is maintained, and then the temperature is increased to 900°C-1000°C at a rate of 11°C / min-15°C / min and the temperature is maintained for 1h-6h.

8. The method for preparing a titanium alloy product having a harmonic heterostructure according to claim 1, characterized in that: In step 4, the specific process of the heat treatment is: first, the hot isostatically pressed blank is kept at a temperature of 900°C to 950°C for 1h to 3h, and then air-cooled to room temperature; then, the hot isostatically pressed blank is heated to 500°C to 600°C at a heating rate of 5K / min to 9K / min, and kept at this temperature for 3h to 6h, and finally air-cooled to room temperature.

9. A titanium alloy part having a harmonic heterostructure, characterized in that: The titanium alloy product is prepared by the preparation method according to any one of claims 1 to 8, and has a harmonic structure in which an equiaxed α phase surrounds a lamellar α phase.

10. Use of the method for preparing a titanium alloy product with a harmonic heterostructure according to any one of claims 1 to 8 in preparing a TC21 titanium alloy product.

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