Preparation method and application of small-specification titanium alloy pipe

Abstract

The invention belongs to the technical field of metal material preparation, and relates to a preparation method and application of a small-specification titanium alloy pipe, a titanium alloy blank is treated in a cross piercing, circumferential rolling and precision forging mode, and then the titanium alloy pipe is prepared after heat treatment and finish machining. The problems that an existing method for preparing the titanium alloy pipe is low in yield and high in production cost are solved, and the method can be suitable for preparing titanium alloy pipes of various brands such as TC4, TC11 and TA15. And heat treatment is conducted through improved heat treatment parameters, the proportion of crystalline phase components in the titanium alloy is optimized, a good microstructure is obtained, and finally the high-strength small-specification titanium alloy seamless pipe is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material preparation, relates to the preparation of titanium alloy pipes, and specifically relates to a preparation method of small-sized titanium alloy pipes and applications thereof. Background Art

[0002] Titanium and its alloys are widely used in electronics, medical treatment, chemical industry, aerospace and other fields due to their excellent physical and chemical properties. They are ideal materials for the production of bars, pipes and profiles. Titanium alloy pipes have become an indispensable structural component in aerospace.

[0003] Currently, titanium alloy tubes are primarily produced using extrusion and cold rolling. For example, a Chinese patent (publication number: CN105344731A, published on February 24, 2016) discloses a TC11 titanium alloy seamless tube and its production method. This extrusion process involves creating through-holes in a bar, applying an antioxidant, heating, and lubricating it before extrusion. While this process omits the use of a copper-clad extrusion sleeve, the yield rate is relatively low.

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

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a method for preparing small-sized titanium alloy pipes and its application, thereby improving the problems of low yield and high production cost of titanium alloy pipes prepared by the existing process.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] This method for preparing small-size titanium alloy pipes adopts the method of "oblique rolling piercing, circumferential rolling and fine forging" to process the titanium alloy billet, and then completes the preparation of the titanium alloy pipe after heat treatment and fine processing; wherein, the oblique rolling piercing temperature is 10 to 60°C below the phase transformation point, and the holding time is (0.4D3 to 1.0D3) min, D3 is the billet diameter or wall thickness; the circumferential rolling temperature is 10 to 70°C below the phase transformation point, and the holding time is (0.5D4 to 1.0D4) min, D4 is the billet wall thickness after oblique rolling piercing; the fine forging temperature is 20 to 60°C below the phase transformation point, and the holding time is (0.7D5 to 4D5) min, D5 is the billet wall thickness after circumferential rolling.

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

[0009] Step 1: forging the ingot to obtain a blank;

[0010] Step 2, performing multiple-fire upsetting forging on the blank;

[0011] Step 3, performing rough processing on the forged blank;

[0012] Step 4, performing oblique rolling and punching on the rough-processed blank;

[0013] Step 5, performing circumferential rolling on the billet after the oblique rolling and piercing;

[0014] Step 6: Performing precision forging on the billet after the rolling process;

[0015] Step 7: heat treating the pipe after precision forging;

[0016] Step 8: Perform fine processing on the heat-treated pipe to obtain small-sized titanium alloy pipe.

[0017] Specifically, in step 1, the forging temperature of the blank forging is 1000-1200° C., 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 forging is 800-1020° C., 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 circular surface of the blank is ≤6.3 μm.

[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 fine forging.

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

[0022] Specifically, the outer diameter specification of the titanium alloy pipe is 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 pipe meet the requirements of ASTM B861 standard.

[0024] In addition, the present invention also provides the use of the method for preparing small-sized titanium alloy pipes as described in part or in whole in the preparation of TC4 alloy, TC11 alloy, and TA15 alloy pipes.

[0025] Compared with the existing technology, the technical solution provided by the present invention has the following beneficial effects: the present invention uses the method of "oblique rolling and piercing, circumferential rolling and fine forging" to process the titanium alloy billet, and then completes the preparation of titanium alloy pipes after heat treatment and fine processing. This improves the problems of low yield rate and high production cost of titanium alloy pipes prepared by the existing method, and is applicable to the preparation of various grades of titanium alloy pipes such as TC4, TC11, and TA15. Specifically:

[0026] The titanium alloy billet is processed by the method of "oblique rolling and piercing, circumferential rolling and precision forging". These three processes cooperate with each other and work together: oblique rolling and piercing lays the foundation for the initial hollow shape of the pipe; circumferential rolling optimizes the wall thickness, outer diameter and other dimensions of the pipe as well as the internal structure on this basis; precision forging further improves the precision and surface quality of the pipe; generally speaking, from oblique rolling and piercing to circumferential rolling to precision forging, the temperature is a process of gradually and reasonably decreasing, and the time of each stage must also be precisely controlled according to the actual processing requirements, pipe specifications, etc. They cooperate with each other and gradually improve the quality of the titanium alloy pipe under appropriate temperature and time conditions, so that it can be processed from the initial billet into a high-quality finished pipe that meets the needs of complex applications. In addition, the preparation method also optimizes the proportion of crystal phase components in the titanium alloy through heat treatment with improved heat treatment parameters, obtains a good microstructure, and finally obtains high-strength small-size titanium alloy seamless pipes. 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 invention.

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

[0029] Figure 1 Flowchart of the method for preparing small-sized titanium alloy pipes provided in Examples 1 to 3 of the present invention;

[0030] Figure 2 Schematic diagram of oblique rolling and piercing of a billet provided in Example 1 of the present invention;

[0031] Figure 3 A schematic diagram of billet circumferential rolling provided in Example 1 of the present invention;

[0032] Figure 4 This is a structural diagram of the titanium alloy tube prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0033] 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.

[0034] The present invention provides a method for preparing small-size titanium alloy pipes, which adopts the method of "oblique rolling piercing, circumferential rolling and fine forging" to process the titanium alloy billet, and then completes the preparation of the titanium alloy pipe after heat treatment and fine processing; wherein, the oblique rolling piercing temperature is 10 to 60°C below the phase transformation point, the holding time is (0.4D3 to 1.0D3) min, and D3 is the billet diameter or wall thickness; the circumferential rolling temperature is 10 to 70°C below the phase transformation point, the holding time is (0.5D4 to 1.0D4) min, and D4 is the billet wall thickness after oblique rolling piercing; the fine forging temperature is 20 to 60°C below the phase transformation point, the holding time is (0.7D5 to 4D5) min, and D5 is the billet wall thickness after circumferential rolling.

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

[0036] Step 1: forging the ingot to obtain a blank;

[0037] Step 2, performing multiple-fire upsetting forging on the blank;

[0038] Step 3, performing rough processing on the forged blank;

[0039] Step 4, performing oblique rolling and punching on the rough-processed blank;

[0040] Step 5, performing circumferential rolling on the billet after the oblique rolling and piercing;

[0041] Step 6: Performing precision forging on the billet after the rolling process;

[0042] Step 7: heat treating the pipe after precision forging;

[0043] Step 8: Perform fine processing on the heat-treated pipe to obtain small-sized titanium alloy pipe.

[0044] Specifically, in step 1, the forging temperature of the blank forging is 1000-1200° C., 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 forging is 800-1020° C., 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 circular surface of the blank is ≤6.3 μm.

[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 fine forging.

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

[0049] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is described in further detail below with reference to the accompanying drawings and embodiments.

[0050] Example 1 (TC4 alloy)

[0051] See also Figure 1 This embodiment provides a method for preparing a titanium alloy pipe. The specification of the titanium alloy pipe is The unit is mm, and the phase transition point is 990°C. The preparation method specifically comprises the following steps:

[0052] Step 1: Forging a Φ600 mm ingot to obtain a blank: the forging temperature is 1000-1180° C., and the holding time is 360-450 min;

[0053] Step 2: The □460mm billet processed in step 1 is subjected to multi-fire upsetting forging: the forging temperature is 920-980°C, and the holding time is 280-345 minutes;

[0054] Step 3: Roughly process the blank obtained by forging in step 2 and flatten the end surface. The processing size is Roughness ≤6.3μm;

[0055] Step 4: Obliquely roll and pierce the blank processed in step 3. Figure 2 The perforation temperature is 930-980℃ (10-50℃ below the phase change point), the holding time is 85-170min, and the size after perforation is

[0056] Step 5: Roll the billet after the oblique rolling and piercing in step 4, see Figure 3 : The rolling temperature is 920-980℃ (10-70℃ below the phase change point), and the temperature is kept for 45-85min. The size after rolling is

[0057]

[0058] Step 6: Forging the billet after step 5: the forging temperature is 930-970℃ (20-60℃ below the phase transition point), the holding time is 15-80min, and the size after forging is

[0059] Step 7: heat-treating the pipe obtained by precision forging in step 6 at a temperature of 790 to 940° C. (50 to 200° C. below the phase transition point) for a holding time of 23 to 65 minutes.

[0060] Step 8: Finish the pipe after heat treatment in step 7: Specifically, the finishing size is Roughness ≤ 3.2μm, so that both the inner and outer surfaces meet the requirements for forgings, see Figure 4 , completing the preparation of TC4 titanium alloy pipe.

[0061] The titanium alloy tube prepared in this embodiment was tested in accordance with GB / T228 "Metallic Materials Room Temperature Tensile Test Method" and GB6395 "Metal High Temperature Tensile Endurance Test Method". The various properties are shown in Table 1 below:

[0062] Table 1 TC4 titanium alloy pipe properties

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

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

[0065] Example 2 (TC11 alloy)

[0066] See also Figure 1 This embodiment provides a method for preparing a titanium alloy pipe. The specification of the titanium alloy pipe is The unit is mm, and the phase transition point is 1005°C. The preparation method specifically comprises the following steps:

[0067] Step 1: Forging a Φ700 mm ingot to obtain a blank: the forging temperature is 1020-1200° C., and the holding time is 420-525 min;

[0068] Step 2: The □525mm billet processed in step 1 is subjected to multi-fire upsetting forging: the forging temperature is 900-995°C, and the holding time is 315-390 minutes;

[0069] Step 3: Roughly process the blank obtained by forging in step 2 and flatten the end surface. The processing size is Roughness ≤6.3μm;

[0070] Step 4: The billet processed in step 3 is subjected to oblique rolling and punching: the oblique rolling and punching temperature is 945-995℃ (10-60℃ below the phase change point), the holding time is 100-180min, and the size after punching is

[0071] Step 5: Roll the billet after the oblique rolling and piercing in step 4. The rolling temperature is 935-995℃ (10-70℃ below the phase change point), and the temperature is kept for 110-220min. The size after rolling is

[0072] Step 6: Forging the billet after step 5: the forging temperature is 945-985℃ (20-60℃ below the phase transition point), the holding time is 20-110min, and the size after forging is

[0073] Step 7: heat-treating the pipe obtained by precision forging in step 6: the heat treatment system is as follows: primary annealing temperature 805-955°C (50-200°C below the phase transition point), holding time 35-105 minutes, secondary annealing temperature 500-550°C, holding time 300-360 minutes;

[0074] Step 8: Finish the pipe after heat treatment in step 7: Specifically, the finishing size is The roughness is ≤3.2μm, so that both the inner and outer surfaces meet the requirements for forging use.

[0075] The titanium alloy tube prepared in this embodiment was tested in accordance with GB / T228 "Metallic Materials Room Temperature Tensile Test Method" and GB6395 "Metal High Temperature Tensile Endurance Test Method". The various properties are shown in Table 2 below:

[0076] Table 2 TC11 titanium alloy pipe properties

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

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

[0079] Example 3 (TA15 alloy)

[0080] See also Figure 1 This embodiment provides a method for preparing a titanium alloy pipe. The specification of the titanium alloy pipe is The unit is mm, and the phase transition point is 985°C. The preparation method specifically comprises the following steps:

[0081] Step 1: Forging a Φ600 mm ingot to obtain a blank: the forging temperature is 1050-1200° C., and the holding time is 360-450 min;

[0082] Step 2: The 460 mm billet processed in step 1 is subjected to multi-fire upsetting forging: the forging temperature is 900-975°C, and the holding time is 280-345 minutes;

[0083] Step 3: Roughly process the blank obtained by forging in step 2 and flatten the end surface. The processing size is Roughness ≤6.3μm;

[0084] Step 4: The billet processed in step 3 is subjected to oblique rolling and punching: the oblique rolling and punching temperature is 925-975℃ (10-60℃ below the phase change point), the holding time is 100-175min, and the size after punching is

[0085] Step 5: Roll the billet after the oblique rolling and piercing in step 4. The rolling temperature is 915-975℃ (10-70℃ below the phase change point), and the temperature is kept for 110-220min. The size after rolling is

[0086] Step 6: Forging the billet after step 5: the forging temperature is 925-965℃ (20-60℃ below the phase transition point), the holding time is 20-110min, and the size after forging is

[0087] Step 7: heat-treating the pipe obtained by precision forging in step 6: the heat treatment system is as follows: annealing temperature is 785-935°C (50-200°C below the phase transition point), and holding time is 55-165 minutes;

[0088] Step 8: Finish the pipe after heat treatment in step 7: Specifically, the finishing size is The roughness is ≤3.2μm, so that both the inner and outer surfaces meet the requirements for forging use.

[0089] The titanium alloy tube prepared in this embodiment was tested according to GB / T228 "Metallic Materials Room Temperature Tensile Test Methods", and its various properties are shown in Table 3 below:

[0090] Table 3 TC11 titanium alloy pipe properties

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

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

[0093] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present 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 present invention.

[0094] 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 a small-sized titanium alloy pipe, characterized in that: The titanium alloy billet is processed by "oblique rolling piercing, circumferential rolling and fine forging", and then the titanium alloy pipe is prepared after heat treatment and fine processing; wherein, the oblique rolling piercing temperature is 10-60°C below the phase transformation point, the holding time is (0.4D3-1.0D3) min, D3 is the billet diameter or wall thickness; the circumferential rolling temperature is 10-70°C below the phase transformation point, the holding time is (0.5D4-1.0D4) min, D4 is the billet wall thickness after oblique rolling piercing; the fine forging temperature is 20-60°C below the phase transformation point, the holding time is (0.7D5-4D5) min, and D5 is the billet wall thickness after circumferential rolling.

2. The method for preparing small-sized titanium alloy pipe according to claim 1, characterized in that: It is characterized by comprising the following steps: Step 1, forging the ingot to obtain a blank; Step 2, performing multiple-time upsetting forging on the blank; Step 3, rough processing the forged blank; Step 4, performing oblique rolling and punching on the rough-processed blank; Step 5, performing circumferential rolling on the billet after oblique rolling and piercing; Step 6, performing precision forging on the billet after the rolling; Step 7, heat treating the pipe after precision forging; Step 8: Perform fine processing on the heat-treated pipe to obtain a small-sized titanium alloy pipe.

3. The method for preparing small-sized titanium alloy pipe according to claim 2, characterized in that: In step 1, the forging temperature of the blank forging is 1000-1200° C., the holding time is (0.6D0-0.75D0) min, and D0 is the ingot diameter or thickness.

4. The method for preparing small-sized titanium alloy pipe according to claim 2, characterized in that: In step 2, the forging temperature of the upsetting forging is 800-1020° C., the holding time is (0.6D1-0.75D1) min, and D1 is the billet diameter or thickness.

5. The method for preparing small-sized titanium alloy pipe according to claim 2, characterized in that: In step 3, after rough machining, the roughness of the outer cylindrical surface of the blank is ≤6.3 μm.

6. The method for preparing small-sized titanium alloy pipe according to claim 2, characterized in that: In step 7, the heat treatment temperature is 50 to 200° C. below the phase transformation point of the titanium alloy, the holding time is (1D6 to 3D6) min, and D6 is the wall thickness of the pipe after fine forging.

7. The method for preparing small-sized titanium alloy pipe according to claim 2, characterized in that: In step 8, the roughness of the inner and outer surfaces of the pipe after finishing treatment is ≤3.2 μm.

8. The method for preparing a small-sized titanium alloy tube according to any one of claims 1 to 7, characterized in that: The outer diameter of the titanium alloy pipe is Φ1700 +3 ~Φ2300 +5 mm, wall thickness range is 12~120mm, length is 1800~6500mm.

9. Use of the method for preparing small-sized titanium alloy pipes according to any one of claims 1 to 8 in preparing TC4 alloy, TC11 alloy, and TA15 alloy pipes.

Images