Preparation method of small-size titanium alloy pipe and application thereof

Abstract

The application belongs to the technical field of metal material preparation, and relates to a preparation method of small-specification titanium alloy pipe and application thereof. The titanium alloy blank is processed in a mode of "oblique rolling piercing, weekly rolling and precision forging", and then the preparation of the titanium alloy pipe is completed after heat treatment and finishing, so that the problems of low yield and high production cost of the titanium alloy pipe prepared by the existing method are solved, and the preparation of titanium alloy pipes of various grades such as TC4, TC11 and TA15 can be applicable. The titanium alloy is heat treated by improved heat treatment parameters, the proportion of crystal phase components in the titanium alloy is optimized, good microstructure is obtained, and finally high-strength small-specification titanium alloy seamless pipe is obtained.

Description

Technical Field

[0001] This invention belongs to the field of metal material preparation technology, and relates to the preparation of titanium alloy pipes, specifically to a method for preparing small-diameter titanium alloy pipes and their applications. Background Technology

[0002] Titanium and its alloys are widely used in electronics, medical, chemical and aerospace fields due to their excellent physical and chemical properties. They are ideal materials for producing bars, tubes and profiles, and titanium alloy tubes have become an indispensable structural component in aerospace.

[0003] Currently, titanium alloy tubes are mainly manufactured using extrusion and cold rolling methods. For example, existing Chinese patent literature (publication number: CN105344731A, publication date: February 24, 2016) discloses a TC11 titanium alloy seamless tube and its manufacturing method, which uses an extrusion process. This process requires drilling through holes in the bar, coating with an antioxidant, heat treatment, coating with a lubricant, and then extruding. Although the entire manufacturing process omits the extrusion method using a copper sleeve, the yield is relatively low.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing small-diameter titanium alloy pipes and their application, thereby improving the problems of low yield and high production cost of titanium alloy pipes prepared by existing processes.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The preparation method of this small-diameter titanium alloy tube involves processing the titanium alloy billet using a process of "skew rolling piercing, circumferential rolling, and precision forging," followed by heat treatment and precision machining to complete the preparation of the titanium alloy tube. Specifically, the skew rolling piercing temperature is 10–60°C below the phase transformation point, with a holding time of (0.4D3–1.0D3) min, where D3 is the billet diameter or wall thickness; the circumferential rolling temperature is 10–70°C below the phase transformation point, with a holding time of (0.5D4–1.0D4) min, where D4 is the billet wall thickness after skew rolling piercing; and the precision forging temperature is 20–60°C below the phase transformation point, with a holding time of (0.7D5–4D5) min, where D5 is the billet wall thickness after circumferential rolling.

[0008] Furthermore, the preparation method includes the following steps:

[0009] Step 1: Forging the ingot to obtain the billet;

[0010] Step 2: Perform multi-fire upsetting and drawing forging on the billet;

[0011] Step 3: Perform rough machining on the forged billet;

[0012] Step 4: Perform skew rolling and piercing on the rough-machined billet;

[0013] Step 5: Perform circumferential rolling on the billet after skew rolling and piercing;

[0014] Step 6: Perform precision forging on the rolled billet;

[0015] Step 7: Heat treat the precision-forged pipe.

[0016] Step 8: Perform precision machining on the heat-treated pipe to obtain small-diameter titanium alloy pipe.

[0017] Specifically, in step 1, the forging temperature of the billet forging is 1000-1200℃, and the holding time is (0.6D0-0.75D0) min, where D0 is the ingot diameter or thickness.

[0018] Specifically, in step 2, the forging temperature of the upsetting and drawing forging is 800-1020℃, and the holding time is (0.6D1-0.75D1) min, where D1 is the billet diameter or thickness.

[0019] Specifically, in step 3, after rough machining, the roughness of the outer cylindrical surface of the blank is ≤6.3μm.

[0020] Specifically, in step 7, the heat treatment temperature is 50 to 200°C below the phase transformation point of the titanium alloy, and the holding time is (1D6 to 3D6) min, where D6 is the wall thickness of the pipe after precision forging.

[0021] Specifically, in step 8, the roughness of both the inner and outer circular surfaces of the pipe after finishing is ≤3.2μm.

[0022] Specifically, the outer diameter specification of the titanium alloy tube is as follows: The wall thickness ranges from 12 to 120 mm, and the length ranges from 1800 to 6500 mm.

[0023] Specifically, the room temperature mechanical properties of the titanium alloy tubing meet the requirements of ASTM B861 standard.

[0024] In addition, the present invention also provides the application of the preparation method of small-diameter titanium alloy tubing as described in part or all of the above in the preparation of TC4 alloy, TC11 alloy, and TA15 alloy tubing.

[0025] Compared with existing technologies, the technical solution provided by this invention has the following beneficial effects: This invention uses a "skew rolling piercing, circumferential rolling, and precision forging" method to process titanium alloy billets, followed by heat treatment and precision machining to complete the preparation of titanium alloy tubes. This improves upon the problems of low yield and high production cost in existing methods for preparing titanium alloy tubes, and is applicable to the preparation of various grades of titanium alloy tubes such as TC4, TC11, and TA15. Specifically:

[0026] The titanium alloy billet is processed using a combination of three processes: skew rolling piercing, circumferential rolling, and precision forging. Skew rolling piercing establishes the initial hollow shape of the tube; circumferential rolling optimizes the tube's wall thickness, outer diameter, and internal structure; and precision forging further improves the tube's precision and surface quality. Overall, the temperature gradually decreases from skew rolling piercing to circumferential rolling and then to precision forging. The time for each stage is precisely controlled according to actual processing requirements and tube specifications. These processes work synergistically to gradually improve the quality of the titanium alloy tube under suitable temperature and time conditions, transforming the initial billet into a high-quality finished tube that meets complex application requirements. Furthermore, this preparation method utilizes improved heat treatment parameters to optimize the proportion of crystalline phases in the titanium alloy, obtaining a favorable microstructure and ultimately producing high-strength, small-diameter seamless titanium alloy tubes. 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 the preparation method of the small-diameter titanium alloy tubing provided in Embodiments 1-3 of the present invention;

[0030] Figure 2 This is a schematic diagram of the skew rolling piercing of the billet provided in Embodiment 1 of the present invention;

[0031] Figure 3 This is a schematic diagram of the circumferential rolling of the billet provided in Embodiment 1 of the present invention;

[0032] Figure 4 This is a structural diagram of the titanium alloy tube obtained in Example 1 of the present invention. Detailed Implementation

[0033] 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.

[0034] The present invention provides a method for preparing small-diameter titanium alloy tubes, which involves processing titanium alloy billets through "skew rolling piercing, circumferential rolling, and precision forging," followed by heat treatment and precision machining to complete the preparation of the titanium alloy tubes. Specifically, the skew rolling piercing temperature is 10–60°C below the phase transformation point, and the holding time is (0.4D3–1.0D3) min, where D3 is the billet diameter or wall thickness; the circumferential rolling temperature is 10–70°C below the phase transformation point, and the holding time is (0.5D4–1.0D4) min, where D4 is the billet wall thickness after skew rolling piercing; the precision forging temperature is 20–60°C below the phase transformation point, and the holding time is (0.7D5–4D5) min, where D5 is the billet wall thickness after circumferential rolling.

[0035] Furthermore, the preparation method includes the following steps:

[0036] Step 1: Forging the ingot to obtain the billet;

[0037] Step 2: Perform multi-fire upsetting and drawing forging on the billet;

[0038] Step 3: Perform rough machining on the forged billet;

[0039] Step 4: Perform skew rolling and piercing on the rough-machined billet;

[0040] Step 5: Perform circumferential rolling on the billet after skew rolling and piercing;

[0041] Step 6: Perform precision forging on the rolled billet;

[0042] Step 7: Heat treat the precision-forged pipe.

[0043] Step 8: Perform precision machining on the heat-treated pipe to obtain small-diameter titanium alloy pipe.

[0044] Specifically, in step 1, the forging temperature of the billet forging is 1000-1200℃, and the holding time is (0.6D0-0.75D0) min, where D0 is the ingot diameter or thickness.

[0045] Specifically, in step 2, the forging temperature of the upsetting and drawing forging is 800-1020℃, and the holding time is (0.6D1-0.75D1) min, where D1 is the billet diameter or thickness.

[0046] Specifically, in step 3, after rough machining, the roughness of the outer cylindrical surface of the blank is ≤6.3μm.

[0047] Specifically, in step 7, the heat treatment temperature is 50 to 200°C below the phase transformation point of the titanium alloy, and the holding time is (1D6 to 3D6) min, where D6 is the wall thickness of the pipe after precision forging.

[0048] Specifically, in step 8, the roughness of both the inner and outer circular surfaces of the pipe after finishing is ≤3.2μm.

[0049] 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.

[0050] Example 1 (TC4 Alloy)

[0051] See Figure 1 This embodiment provides a method for preparing a titanium alloy tube, the specifications of which are as follows: The unit is mm, and the phase transition point is 990℃; the preparation method specifically includes the following steps:

[0052] Step 1: Forge the Φ600mm ingot to obtain the billet: the forging temperature is 1000~1180℃, and the holding time is 360~450min;

[0053] Step 2: Perform multi-fire upsetting and drawing forging on the □460mm billet processed in Step 1: the forging temperature is 920~980℃ and the holding time is 280~345min;

[0054] Step 3: Roughly machine the billet obtained from forging in Step 2 to flatten the end face. The machining dimensions are as follows: Roughness ≤ 6.3 μm;

[0055] Step 4: Perform skew rolling and piercing on the billet processed in Step 3, see [link / reference]. Figure 2 The piercing temperature is 930–980℃ (10–50℃ below the phase transition point), the holding time is 85–170 min, and the dimensions after piercing are as follows:

[0056] Step 5: Perform circumferential rolling on the billet after the skew rolling and piercing in Step 4, see [link to step 5]. Figure 3 The circumferential rolling temperature is 920–980℃ (10–70℃ below the phase transformation point), and the holding time is 45–85 minutes. The dimensions after circumferential rolling are as follows:

[0057]

[0058] Step 6: Perform precision forging on the billet rolled in Step 5: the precision forging temperature is 930–970℃ (20–60℃ below the phase transformation point), the holding time is 15–80 min, and the dimensions after precision forging are as follows:

[0059] Step 7: Heat treat the pipes precision forged in Step 6: the heat treatment temperature is 790-940℃ (50-200℃ below the phase transformation point), and the holding time is 23-65 min;

[0060] Step 8: Perform finishing on the pipe after heat treatment in Step 7: Specifically, the finishing dimensions are as follows: A surface roughness of ≤3.2μm ensures that both the inner and outer surfaces meet the requirements for forging use. See [reference needed]. Figure 4 The preparation of TC4 titanium alloy tubing was completed.

[0061] The titanium alloy tubing prepared in this embodiment was tested according to GB / T228 "Metallic materials - Tensile testing at room temperature" and GB6395 "Metallic materials - Tensile creep testing at high temperature". Its various properties are shown in Table 1 below:

[0062] Table 1 Properties of TC4 Titanium Alloy Tubes

[0063] Rm(MPa) R0.2 (MPa) A(％) <![CDATA[Aku(J / cm 2 )]]> 920 850 22 42

[0064] As can be seen from the above test results, the performance of the titanium alloy pipe produced in this embodiment fully meets the requirements of ASTM B861 seamless titanium alloy pipe.

[0065] Example 2 (TC11 Alloy)

[0066] See Figure 1 This embodiment provides a method for preparing a titanium alloy tube, the specifications of which are as follows: The unit is mm, and the phase transition point is 1005℃; the preparation method specifically includes the following steps:

[0067] Step 1: Forge the Φ700mm ingot to obtain the billet: forging temperature is 1020~1200℃, and holding time is 420~525min;

[0068] Step 2: Perform multi-heat upsetting and drawing forging on the □525mm billet processed in Step 1: the forging temperature is 900~995℃ and the holding time is 315~390min;

[0069] Step 3: Roughly machine the billet obtained from forging in Step 2 to flatten the end face. The machining dimensions are as follows: Roughness ≤ 6.3 μm;

[0070] Step 4: Perform skew rolling piercing on the billet processed in Step 3: The skew rolling piercing temperature is 945–995℃ (10–60℃ below the phase transformation point), and the holding time is 100–180 min. The dimensions after piercing are as follows:

[0071] Step 5: Perform circumferential rolling on the billet after skew rolling and piercing in Step 4: circumferential rolling temperature is 935-995℃ (10-70℃ below the phase transformation point), holding for 110-220 minutes. The dimensions after circumferential rolling are...

[0072] Step 6: Perform precision forging on the billet rolled in Step 5: the precision forging temperature is 945–985℃ (20–60℃ below the phase transformation point), the holding time is 20–110 min, and the dimensions after precision forging are as follows:

[0073] Step 7: Heat treat the pipes precision forged in Step 6. The heat treatment process is as follows: primary annealing temperature 805-955℃ (50-200℃ below the phase transformation point), holding time 35-105min; secondary annealing temperature 500-550℃, holding time 300-360min.

[0074] Step 8: Perform finishing on the pipe after heat treatment in Step 7: Specifically, the finishing dimensions are as follows: The surface roughness is ≤3.2μm, ensuring that both the inner and outer surfaces meet the requirements for forging use.

[0075] The titanium alloy tubing prepared in this embodiment was tested according to GB / T228 "Metallic materials - Tensile testing at room temperature" and GB6395 "Metallic materials - Tensile creep testing at high temperature". Its various properties are shown in Table 2 below:

[0076] Table 2 Properties of TC11 Titanium Alloy Tubes

[0077] Rm(MPa) R0.2 (MPa) A(％) <![CDATA[Aku(J / cm 2 )]]> 1145 935 15 35

[0078] As can be seen from the above test results, the performance of the titanium alloy pipe produced in this embodiment fully meets the requirements of ASTM B861 seamless titanium alloy pipe.

[0079] Example 3 (TA15 alloy)

[0080] See Figure 1 This embodiment provides a method for preparing a titanium alloy tube, the specifications of which are as follows: The unit is mm, and the phase transition point is 985℃; the preparation method specifically includes the following steps:

[0081] Step 1: Forge the Φ600mm ingot to obtain the billet: forging temperature is 1050~1200℃, and holding time is 360~450min;

[0082] Step 2: Perform multi-fire upsetting and drawing forging on the □460mm billet processed in Step 1: the forging temperature is 900~975℃ and the holding time is 280~345min;

[0083] Step 3: Roughly machine the billet obtained from forging in Step 2 to flatten the end face. The machining dimensions are as follows: Roughness ≤ 6.3 μm;

[0084] Step 4: Perform skew rolling piercing on the billet processed in Step 3: The skew rolling piercing temperature is 925–975℃ (10–60℃ below the phase transformation point), and the holding time is 100–175 min. The dimensions after piercing are as follows:

[0085] Step 5: Perform circumferential rolling on the billet after skew rolling and piercing in Step 4: circumferential rolling temperature is 915-975℃ (10-70℃ below the phase transformation point), holding for 110-220 minutes. The dimensions after circumferential rolling are...

[0086] Step 6: Perform precision forging on the billet rolled in Step 5: the precision forging temperature is 925–965℃ (20–60℃ below the phase transformation point), the holding time is 20–110 min, and the dimensions after precision forging are as follows:

[0087] Step 7: Heat treat the pipes precision forged in Step 6: The heat treatment process is as follows: annealing temperature is 785-935℃ (50-200℃ below the phase transformation point), and holding time is 55-165 min.

[0088] Step 8: Perform finishing on the pipe after heat treatment in Step 7: Specifically, the finishing dimensions are as follows: The surface roughness is ≤3.2μm, ensuring that both the inner and outer surfaces meet the requirements for forging use.

[0089] The titanium alloy tubing prepared in this embodiment was tested according to GB / T228 "Metallic materials - Tensile testing at room temperature", and its properties are shown in Table 3 below:

[0090] Table 3 Properties of TC11 Titanium Alloy Tubes

[0091] Rm(MPa) R0.2 (MPa) A(％) <![CDATA[Aku(J / cm 2 )]]> 950 880 20 52

[0092] As can be seen from the above test results, the performance of the titanium alloy pipe produced in this embodiment fully meets the requirements of ASTM B861 seamless titanium alloy pipe.

[0093] 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.

[0094] 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 small-diameter titanium alloy tubing, characterized in that, Titanium alloy billets are processed using a combination of skew rolling piercing, circumferential rolling, and precision forging. After heat treatment and precision machining, titanium alloy tubes are produced. The skew rolling piercing temperature is 10–60°C below the phase transformation point, with a holding time of (0.4D3–1.0D3) min, where D3 is the billet diameter or wall thickness. The circumferential rolling temperature is 10–70°C below the phase transformation point, with a holding time of (0.5D4–1.0D4) min, where D4 is the billet wall thickness after skew rolling piercing. The precision forging temperature is 20–60°C below the phase transformation point, with a holding time of (0.7D5–4D5) min, where D5 is the billet wall thickness after circumferential rolling. Includes the following steps: Step 1: Forging the ingot to obtain the billet; Step 2: Perform multi-fire upsetting and drawing forging on the billet; Step 3: Perform rough machining on the forged billet; Step 4: Perform skew rolling and piercing on the rough-machined billet; Step 5: Perform circumferential rolling on the billet after skew rolling and piercing; Step 6: Perform precision forging on the rolled billet; Step 7: Heat treat the precision-forged pipe. Step 8: Perform precision machining on the heat-treated pipe to obtain small-diameter titanium alloy pipe; In step 7, the heat treatment temperature is 50~200℃ below the phase transformation point of titanium alloy, and the holding time is (1D6~3D6) min, where D6 is the wall thickness of the pipe after precision forging. The outer diameter of the titanium alloy tube is Φ1700. +3 ~Φ2300 +5 mm, wall thickness ranges from 10 to 40 mm, and length ranges from 1800 to 6500 mm.

2. The method for preparing small-diameter titanium alloy tubing according to claim 1, characterized in that, In step 1, the forging temperature of the billet forging is 1000~1200℃, and the holding time is (0.6D0~0.75D0) min, where D0 is the ingot diameter or thickness.

3. The method for preparing small-diameter titanium alloy tubing according to claim 1, characterized in that, In step 2, the forging temperature of the upsetting and drawing forging is 800~1020℃, and the holding time is (0.6D1~0.75D1) min, where D1 is the billet diameter or thickness.

4. The method for preparing small-diameter titanium alloy tubing according to claim 1, characterized in that, In step 3, after rough machining, the roughness of the outer cylindrical surface of the blank is ≤6.3μm.

5. The method for preparing small-diameter titanium alloy tubing according to claim 1, characterized in that, In step 8, the roughness of the inner and outer circular surfaces of the pipe after finishing is ≤3.2μm.

6. The application of the method for preparing small-diameter titanium alloy tubing as described in any one of claims 1 to 5 in the preparation of TC4 alloy, TC11 alloy, and TA15 alloy tubing.

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