A method of manufacturing a titanium alloy seamless pipe by introducing an intermediate post-hot deformation

Abstract

The application relates to a method for preparing a titanium alloy seamless pipe by introducing an intermediate post-heat deformation, and belongs to the field of advanced processing technology of titanium alloy materials. First, a titanium alloy ingot is obtained by smelting, the ingot is subjected to blooming and forging to obtain a titanium alloy forged rod, the titanium alloy pipe blank is obtained by machining, then the titanium alloy pipe blank is subjected to heat treatment, the titanium alloy pipe blank is subjected to heat deformation after the heat treatment to obtain a titanium alloy pipe, and then the pipe is sequentially subjected to annealing and surface treatment to obtain a titanium alloy seamless pipe. The method provided by the application has the advantages of short production cycle, no limitation of titanium alloy grades, organization types and sizes, the ability to prepare titanium alloy seamless pipes with different inner hole shapes, sizes, different wall thicknesses and different lengths according to requirements, improved mechanical properties of the titanium alloy seamless pipe, accurate size of the prepared titanium alloy seamless pipe and high yield.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of advanced processing technology of titanium alloy material, and particularly relates to a method for preparing titanium alloy seamless pipe by introducing an intermediate and then hot deforming. BACKGROUND

[0002] China's titanium industry has gradually shifted from traditional chemical industry (alkali production, fertilizer production, and salt production, etc.) as the main demand field to aerospace, shipbuilding, ocean engineering, and high-end chemical equipment as the main demand field after a long period of development. At present, China's titanium materials are mainly used in the fields of chemical industry, aerospace, electric power, ocean engineering, shipbuilding, and metallurgy, among which, the output of titanium alloy pipe accounts for about 20% of the titanium processing materials. Titanium alloy seamless pipe has many advantages over traditional steel pipe, stainless steel pipe, and copper alloy pipe, such as good corrosion resistance, especially good resistance to seawater corrosion and biological corrosion, high specific strength, which can achieve the purpose of weight reduction while ensuring structural strength and stability, a variety of alloy types to meet the use requirements of various fields, good biocompatibility, stable existence in biological tissues, good processing performance, easy to weld, etc.

[0003] At present, domestic titanium alloy seamless pipe is mainly prepared by methods such as extrusion, rolling, drawing, and spinning to prepare finished pipe of different specifications and purposes. However, titanium has poor thermal conductivity, and a large temperature difference is easily generated between the surface layer and the center of the billet during extrusion, which aggravates the unevenness of metal flow, generates a large additional tensile stress on the surface layer, and causes cracks on the surface of the product. In severe cases, a large central extrusion hole may be generated on the extruded bar and pipe. At the same time, the rolling equipment for titanium alloy seamless pipe is complex, the investment is large, the requirements for tools are relatively strict, and special equipment or special jigs are required for manufacturing, the tool replacement is complex, the deformation amount of each pass is small, the drawing pass is multiple, the production cycle is long, the intermediate auxiliary process is multiple, the alloy consumption is large, and the requirements for lubricants are relatively strict, which makes it difficult to produce titanium alloy seamless pipe with low plasticity and high strength by drawing process. Although titanium alloy seamless pipe is favored by various fields due to its excellent performance, its application is limited due to the difficulty in producing titanium seamless pipe, complex processing equipment, long cycle, and low yield.

[0004] Therefore, how to prepare titanium alloy seamless pipe with good comprehensive performance, short preparation cycle, and low cost is one of the key problems to be solved. SUMMARY

[0005] In order to solve the above problems, the application provides a method for preparing a titanium alloy seamless pipe by introducing an intermediate after hot deformation, and a titanium alloy gradient functional material is prepared by a hot pressing technology. The titanium alloy seamless pipe prepared by the application has uniform microstructure, excellent mechanical properties, high yield, and is not limited by size, thereby providing technical support and theoretical guidance for the preparation and application of titanium alloy seamless pipes in China.

[0006] In order to achieve the above object, the technical scheme of the application is:

[0007] A method for preparing a titanium alloy seamless pipe by introducing an intermediate after hot deformation, comprising the following steps:

[0008] (1) Ingot smelting

[0009] First, the titanium alloy raw materials are uniformly mixed and pressed into electrodes, and a vacuum consumable arc furnace is used to smelt the electrodes to obtain titanium alloy ingots;

[0010] (2) Breaking down and forging

[0011] The smelted titanium alloy ingots are broken down and forged to obtain titanium alloy forged rods;

[0012] (3) Preparation of pipe blank

[0013] The titanium alloy forged rod is first drilled by mechanical processing, and then the inner surface is polished to prepare a titanium alloy pipe blank;

[0014] (4) Heat treatment of pipe blank

[0015] The titanium alloy pipe blank is placed in a heating furnace for heat treatment;

[0016] (5) Hot deformation

[0017] The titanium alloy pipe blank after heat treatment is subjected to hot deformation to obtain a titanium alloy pipe, and the specific implementation process is as follows: the inner surface of the titanium alloy pipe blank after heat treatment is coated with glass lubricant, then assembled with an intermediate, then subjected to hot deformation, and the intermediate is removed after hot deformation to obtain a titanium alloy pipe;

[0018] (6) Annealing treatment

[0019] The titanium alloy pipe is subjected to annealing treatment to eliminate internal stress;

[0020] (7) Surface treatment

[0021] The inner and outer surfaces of the titanium alloy pipe are subjected to surface treatment by mechanical processing to obtain a titanium alloy seamless pipe.

[0022] The method is not limited by titanium alloy grade, organization type and size, and can prepare titanium alloy seamless pipes with different inner hole shapes, sizes, different wall thicknesses and different lengths according to requirements.

[0023] In step (1), the titanium alloy ingot is melted for three times to ensure the uniformity of the composition of the ingot.

[0024] In step (2), the ingot is forged by a manipulator after being discharged from the furnace, and the hammer is full during each stroke in the forging process; the titanium alloy forged rod has a single drum-shaped protrusion at both ends.

[0025] In step (3), the titanium alloy pipe blank is prepared by drilling the titanium alloy forged rod, concentric with the inner hole of the forged rod, and then polishing the inner surface; the inner surface of the titanium alloy pipe blank is smooth and has no processing marks, and the roughness Ra is 0.05-1.6 μm.

[0026] In step (4), the heat treatment temperature of the titanium alloy pipe blank is 700-1000℃, and the holding time is 2-3h.

[0027] In step (5), the length of the intermediate body is 120%-150% of the length of the target titanium alloy pipe, and the cross-sectional area is 90%-95% of the cross-sectional area of the inner hole of the titanium alloy pipe blank; the intermediate body is made of a metal material with poor plasticity and high strength compared with the titanium alloy pipe blank; the intermediate body and the titanium alloy pipe blank are assembled at room temperature; the titanium alloy pipe blank is uniformly deformed in the axial direction during the hot deformation process, and the radial direction does not deform, and the intermediate body does not deform; the titanium alloy pipe blank is easily separated after the hot deformation is completed.

[0028] In step (6), the titanium alloy pipe is annealed at a temperature of 500-900℃ for 1-2h.

[0029] In step (7), the surface treatment process is as follows: the titanium alloy pipe after annealing is first cut by a wire cutting machine, and then the inner and outer surfaces of the pipe are sequentially turned and polished, and finally the pipe is sequentially cleaned with petroleum ether and alcohol to remove impurities, thereby obtaining a titanium alloy seamless pipe.

[0030] The titanium alloy seamless pipe has a smooth surface and no processing marks, and the roughness Ra of the inner and outer surfaces of the pipe is 0.05-1.6 μm.

[0031] The prepared titanium alloy seamless pipe is fully broken in the hot deformation process, effectively weakens the adverse texture in the titanium alloy seamless pipe, and improves the mechanical properties of the titanium alloy seamless pipe.

[0032] The hot deformation process is performed by a precision forging machine, which has high forming precision, high material yield and low cost.

[0033] The design idea of the present application is:

[0034] Firstly, the titanium alloy raw material is uniformly mixed and pressed into an electrode, and the electrode is melted by a vacuum self-consumption arc furnace to obtain a titanium alloy ingot, and the melting is performed for 3 times to ensure the uniformity of the composition of the ingot; the melted titanium alloy ingot is subjected to blooming and forging, after the ingot is discharged, the ingot is clamped by an operating machine for forging, and the hammer must be full when the hammer is lowered to ensure that the two ends are single drum-shaped convex to obtain a titanium alloy forged rod; when the titanium alloy pipe blank is processed, the titanium alloy forged rod is first drilled, the inner hole is concentric with the forged rod, and then the inner surface is polished to ensure that the inner surface is smooth and no processing marks are left, and the roughness Ra of the inner surface is 0.05-1.6 μm; the titanium alloy pipe blank is placed in a heating furnace for heat treatment, the inner surface of the titanium alloy pipe blank after heat treatment is coated with glass lubricant, and then combined with an intermediate body, and then subjected to hot deformation, the length of the intermediate body is 120-150% of the length of the target titanium alloy pipe, and the cross-sectional area is 90-95% of the inner hole of the titanium alloy pipe blank, and the intermediate body is taken out after the hot deformation to obtain a titanium alloy pipe; the titanium alloy pipe is subjected to annealing treatment to eliminate internal stress; the inner and outer oxidation layers of the titanium alloy pipe are removed by machining, and finally a titanium alloy seamless pipe is obtained. When the titanium alloy seamless steel pipe is prepared, the hot deformation method is used to prepare the titanium alloy seamless steel pipe, which ensures the uniformity of the structure, is beneficial to eliminating the adverse texture, and fully breaks the grains during the deformation process, thereby improving the comprehensive mechanical properties of the titanium alloy seamless steel pipe. The intermediate body is selected to have poor plasticity and high strength compared with the titanium alloy pipe blank, and is in a room temperature state when assembled with the titanium alloy pipe blank, so as to ensure that the titanium alloy pipe blank is deformed uniformly during the hot deformation process, and the titanium alloy pipe blank and the intermediate body are easily separated after the hot deformation is completed.

[0035] The present application has the advantages and beneficial effects that:

[0036] The present application provides a method for preparing a titanium alloy seamless pipe by introducing an intermediate body for hot deformation, first obtaining a titanium alloy ingot by melting, blooming and forging the ingot to obtain a titanium alloy forged rod, using a machining method to obtain a titanium alloy pipe blank, then heat treating the titanium alloy pipe blank, and then obtaining a titanium alloy pipe by hot deformation, and then sequentially annealing and surface treating the pipe to obtain a titanium alloy seamless pipe.

[0037] 1. The method provided in the present application is not limited to titanium alloy grades, structure types and size restrictions, and can be used to prepare titanium alloy seamless pipes of any grade and structure type.

[0038] 2. The titanium alloy seamless pipe prepared by the method has the advantages of full grain crushing in the hot deformation process, effective weakening of the adverse texture in the titanium alloy seamless pipe, improved mechanical properties of the titanium alloy seamless pipe, high size accuracy, high yield, and short production cycle.

[0039] 3. The titanium alloy seamless pipe prepared by the method is not limited by size and equipment, and can be prepared in different inner hole shapes, different wall thicknesses, and different lengths according to requirements, thereby providing technical support and theoretical guidance for promoting the application of the titanium alloy seamless pipe. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a process flowchart of the application;

[0041] Figure 2 is a titanium alloy seamless pipe prepared by an extrusion method;

[0042] Figure 3 is a hot deformation process for preparing the titanium alloy seamless pipe by hot deformation;

[0043] Figure 4 is a titanium alloy seamless pipe prepared by hot deformation. DETAILED DESCRIPTION

[0044] In the specific implementation process, the application first melts the electrode by using a vacuum consumable arc furnace to obtain a titanium alloy ingot, melts 3 times to ensure uniform composition of the ingot, performs blooming and forging on the melted titanium alloy ingot, prepares a titanium alloy pipe blank by a machining method, then grinds the inner surface of the titanium alloy pipe blank to ensure that the inner surface is smooth and no machining marks are left, places the titanium alloy pipe blank in a heating furnace for heat treatment, performs hot deformation on the titanium alloy pipe blank after heat treatment, finally removes the inner and outer oxidation layers of the titanium alloy pipe by a machining method, and finally obtains a titanium alloy seamless pipe, and the process flow is as shown in Figure 1 .

[0045] Next, the application is further described in detail through a comparative example and an example.

[0046] Comparative Example

[0047] The specific process of the comparative example is as follows: first, a TC4 titanium alloy rod is prepared into a TC4 titanium alloy pipe blank by using an extrusion forming method, then the pipe blank is subjected to pack extrusion in the two-phase region of the TC4 titanium alloy, and finally a titanium alloy pipe as shown in Figure 2 is obtained through surface treatment and stress relief annealing. Figure 2 As can be seen from , a large number of cracks are generated on the surface of the TC4 titanium alloy pipe.

[0048] Example

[0049] The specific process of the embodiment is as follows: first, the TC4 titanium alloy raw material is uniformly mixed and pressed into an electrode, and the electrode is melted for three times by a vacuum consumable arc furnace to obtain a TC4 titanium alloy ingot. After the TC4 titanium alloy ingot is discharged from the furnace, it is clamped by an operating machine for blooming and forging, and the hammer is full every time during the forging process. The obtained TC4 titanium alloy forged rod has a single drum-shaped protrusion at both ends. A TC4 titanium alloy pipe blank is prepared by machining. First, the titanium alloy forged rod is drilled to make the inner hole concentric with the forged rod, and then the inner surface is polished to ensure that the inner surface is smooth and no processing marks are left. The TC4 titanium alloy pipe blank with a bonding surface roughness Ra of 1.6 μm is obtained. The TC4 titanium alloy pipe blank is placed in a heating furnace for heat treatment, the heat treatment temperature is 960℃, the holding time is 2h, and after the holding is completed, the inner surface of the TC4 titanium alloy pipe blank is coated with a glass lubricant, and then assembled with an intermediate TC11 titanium alloy at room temperature. The length of the intermediate TC11 titanium alloy is 150% of the length of the required TC4 titanium alloy pipe, and the cross-sectional area is 90% of the inner hole of the TC4 titanium alloy pipe blank. Subsequently, it is placed under a precision forging machine for hot deformation as shown in Figure 3 The intermediate TC11 titanium alloy is removed after hot deformation to obtain a TC4 titanium alloy pipe. Subsequently, the TC4 titanium alloy pipe is annealed at a temperature of 500℃ for 1h. The TC4 titanium alloy pipe after annealing is first removed from both ends by wire cutting, and then the inner and outer surfaces are turned by a lathe to remove all oxide scales. Then the inner and outer surfaces are polished to ensure that the inner and outer surfaces are smooth and no processing marks are left. The roughness of the inner and outer surfaces is Ra=1.6 μm. The pipe is cleaned with petroleum ether and alcohol in sequence until all surfaces are free of contaminants. The obtained TC4 titanium alloy seamless pipe is shown in Figure 4 As can be seen from the figure, the obtained TC4 titanium alloy seamless pipe has no cracks and other defects, and has high forming quality.

[0050] The above is only the best case of the present application, and does not limit the present application. Any simple modification, change and equivalent change made according to the technical essence of the application to the above embodiments are still within the protection scope of the technical solution of the present application.

Claims

1. A method of producing a titanium alloy seamless pipe by introducing an intermediate post-heat deformation, characterized in that, The method comprises the following steps: Step 1. Ingot smelting: after the titanium alloy raw materials are uniformly mixed, the titanium alloy raw materials are pressed into electrodes, the electrodes are smelted by using vacuum self-consumption arc, and titanium alloy ingots are obtained; Step 2. Breaking down and casting: the titanium alloy ingots are broken down and forged to obtain titanium alloy forged rods; Step 3. Preparing a pipe blank: by using mechanical processing, first, the titanium alloy forged rod is drilled, and then the inner surface thereof is polished to obtain a titanium alloy pipe blank; Step 4. Heat treatment of the pipe blank: the pipe blank is placed in a heating furnace for heat treatment; Step 5. Hot deformation: the titanium alloy pipe blank after heat treatment is subjected to hot deformation to obtain a titanium alloy pipe, and the specific implementation process is as follows: the inner surface of the titanium alloy pipe blank after heat treatment is coated with glass lubricant, then the titanium alloy pipe blank is assembled with an intermediate body, then hot deformation is performed, and finally the intermediate body is removed to obtain the titanium alloy pipe; Step 6. Annealing treatment: the titanium alloy pipe is subjected to annealing treatment to eliminate internal stress; Step 7. Surface treatment: the inner and outer surfaces of the titanium alloy pipe are treated by using mechanical processing to obtain a titanium alloy seamless pipe. The intermediate body is made of a metal material which has poor plasticity and high strength compared with the titanium alloy pipe blank; The method is not limited by the titanium alloy grade, the organizational type and the size, and can prepare titanium alloy seamless pipes with different inner hole shapes, sizes, wall thicknesses and lengths according to requirements; In step 3, the inner surface of the titanium alloy pipe blank is smooth and has no processing trace, and the roughness Ra thereof is 0.05 μm-1.6 μm; In step 5, the length of the intermediate body is 120%-150% of the length of the target titanium alloy pipe, and the cross-sectional area of the intermediate body is 90%-95% of the cross-sectional area of the inner hole of the titanium alloy pipe blank; the hot deformation process is performed by using a precision forging machine; the assembling process is performed at room temperature; in the hot deformation process, the pipe blank is uniformly deformed in the axial direction and does not change in the radial direction, and the intermediate body does not deform; The titanium alloy seamless pipe is smooth and has no processing trace, and the roughness Ra of the inner and outer surfaces of the pipe is 0.05 μm-1.6 μm.

2. A method of producing a titanium alloy seamless pipe by introducing an intermediate post-heat forming according to claim 1, characterized in that, In step 1, the smelting is performed for 3 times.

3. A method of producing a titanium alloy seamless pipe by introducing an intermediate post-heat forming according to claim 1, characterized in that, In step 2, during the breaking down and forging, the ingot is clamped by using an operating machine for forging, and the hammer is fully struck each time during the forging process. The titanium alloy forged rod has single drum-shaped protrusions at both ends.

4. A method of producing a titanium alloy seamless pipe by introducing an intermediate post-heat forming according to claim 1, characterized in that, In step 3, the inner hole obtained by drilling is concentric with the forged rod.

5. A method of producing a titanium alloy seamless pipe by introducing an intermediate post-heat forming according to claim 1, characterized in that, In step 4, during the heat treatment process, the temperature is 700-1000 ℃, and the holding time is 2-3 h.

6. A method of producing a titanium alloy seamless pipe by introducing an intermediate post-heat forming according to claim 1, characterized in that, In step 6, during the annealing treatment process, the annealing temperature is 500-900 ℃, and the holding time is 1-2 h.

7. A method of producing a titanium alloy seamless pipe by introducing an intermediate post-heat forming according to claim 1, characterized in that, In step 7, the surface treatment process is as follows: after the titanium alloy pipe is annealed, the two ends of the titanium alloy pipe are removed by using wire cutting, then the inner and outer surfaces of the pipe are sequentially subjected to turning and polishing, and finally the pipe is sequentially cleaned by using petroleum ether and alcohol until no pollutants are present.

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