CN115673516A - Ti 2 Direct diffusion welding method of AlNb alloy - Google Patents
Ti 2 Direct diffusion welding method of AlNb alloy Download PDFInfo
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- CN115673516A CN115673516A CN202211246036.9A CN202211246036A CN115673516A CN 115673516 A CN115673516 A CN 115673516A CN 202211246036 A CN202211246036 A CN 202211246036A CN 115673516 A CN115673516 A CN 115673516A
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Abstract
Ti 2 A direct diffusion welding method of AlNb alloy by using Ti 2 The surface of the AlNb alloy is pre-polished, sa and Sz are used for representing the surface quality of a sample, the Sa of the polished surface of the sample is 0.5-0.7 mu m, and the Sz of the polished surface of the sample is 7-9 mu m, and vacuum diffusion welding is carried out after cleaning and assembling. According to the invention, the sample with larger surface roughness is used, and the plastic deformation and recrystallization of the surface of the sample are utilized to promote the healing of the holes at the connecting surface, so that the dependence on element diffusion is reduced, and further, a high-quality welding joint is obtained. Meanwhile, the sample polished by the machine is directly welded, so that the uniformity of the surface quality of the sample is ensured, the stability of the welding process is realized, and the welding efficiency is improved. Final resulting weldmentThe tensile strength and the elongation can reach 95 percent and 70 percent of the parent metal respectively.
Description
Technical Field
The invention relates to the technology in the field of alloy welding, in particular to Ti 2 A direct diffusion welding method of AlNb alloy.
Background
Ti 2 AlNb-based alloys are a general term for a class of intermetallic materials based on orthorhombic O-phases, having a density of about 5.3g/cm 3 Can be used for a long time at 650-750 ℃ and has good comprehensive mechanical property and process property. Using Ti 2 The AlNb-based alloy replaces nickel-based high-temperature alloy to be used as a high-temperature structural member of the aircraft engine, the weight of the engine can be obviously reduced, the thrust-weight ratio of the engine is improved, and important parts of a plurality of parts of the new-generation aircraft engine in China are made of the material. Compared with other connection methods, the solid-state diffusion welding process is simple, does not involve melting of materials, does not form solidification defects such as air holes and the like, does not generate a heat affected zone with remarkably reduced performance, and has an irreplaceable position under certain specific process requirements.
In order to promote the diffusion of atoms at the joint surface and obtain a good welding effect, the currently reported direct diffusion welding has a high requirement on the smoothness of the surface of a sample. It is generally achieved by manual grinding that the sample surface is as smooth as possible, which not only increases the process cost but also increases process instability. For Ti 2 As an intermetallic compound, alNb alloy has a high melting point and an ordered structure of a strengthening phase O phase, and element diffusion is very difficult in a solid state, so that the difficulty of direct diffusion welding of the AlNb alloy is increased, and the AlNb alloy is difficult to realize good diffusion welding by only relying on atomic diffusion at a connecting surfaceThe welding quality of (2).
Disclosure of Invention
Aiming at the defects and shortcomings of the existing same material welding technology, the invention provides Ti 2 The direct diffusion welding method of the AlNb alloy promotes the healing of holes at the connecting surface by using a sample with larger surface roughness and utilizing the plastic deformation and recrystallization of the surface of the sample, reduces the dependence on element diffusion and further obtains a high-quality welding joint. Meanwhile, the sample polished by the machine is directly welded, so that the uniformity of the surface quality of the sample is ensured, the stability of the welding process is realized, and the welding efficiency is improved. The tensile strength and the elongation of the finally obtained weldment can respectively reach 95 percent and 70 percent of the base material.
The invention is realized by the following technical scheme:
the invention relates to a Ti 2 Diffusion welding method of AlNb alloy by applying Ti 2 The surface of the AlNb alloy is pre-polished, sa and Sz are used for representing the surface quality of a sample, the Sa of the polished surface of the sample is 0.5-0.7 mu m, and the Sz of the polished surface of the sample is 7-9 mu m, and vacuum diffusion welding is carried out after cleaning and assembling.
The Sa and the Sz are parameters for characterizing the surface quality of the sample, wherein: sa represents the arithmetic mean of the absolute values of the heights from the mean plane of the surface, and Sz represents the distance between the highest point and the lowest point of the surface.
The Sa and the Sz are obtained by analyzing after three-dimensional imaging of the surface of the sample by using a white light interference laser microscope system.
The vacuum diffusion welding comprises three stages of vacuum heating, pressurizing and high-temperature welding, and specifically comprises the following steps: when the vacuum degree reaches 10 -3 Heating to 300 ℃ at the speed of 10 ℃/min under the environment of Pa, preserving heat for 30min, heating to 600 ℃ at the speed of 10 ℃/min, preserving heat for 30min, and then carrying out heat treatment on Ti 2 Applying a predetermined pressure (40-60 MPa) on the surface of the AlNb alloy, then heating to the welding temperature (960-980 ℃) at the speed of 5 ℃/min, removing the pressure after keeping the temperature for a specified time (150-210 min), and cooling to the room temperature along with the furnace.
In the vacuum diffusion welding, the sample is in a high vacuum state in the whole connecting process.
And in the vacuum diffusion welding, in order to prevent the sample from unstably dumping in the welding process, the diffusion welding tool is used for assembling and fixing the workpiece to be welded.
The cleaning is preferably carried out by drying after ultrasonic cleaning by using acetone.
And the grinding is carried out by adopting but not limited to a grinding machine so as to ensure that the surface of the sample is flat and smooth.
Technical effects
The invention abandons the over-high requirement on the surface smoothness of the sample, uses the sample with larger roughness to carry out direct diffusion welding, utilizes the plastic deformation and recrystallization of the surface of the sample to promote the healing of holes at the connecting surface, forms a recrystallization zone near the connecting surface, reduces the dependence on element diffusion, and further obtains a high-quality welding joint which is Ti 2 AlNb-based alloy direct diffusion welding provides a new approach.
Drawings
FIG. 1 is a three-dimensional topography of the surface of a sample polished in an example;
FIG. 2 is a schematic view of a diffusion welding tool according to an embodiment;
FIG. 3 is a microstructure diagram of the welded joint surface in the example;
FIG. 4 is a graph of engineering stress-strain for a weld joint in an example.
Detailed Description
The present example relates to a Ti 2 The AlNb alloy direct diffusion welding method has the advantages that the size of a welding sample is 15 × 30mm, and the 15 × 15mm face is a welding face.
Step 1: the surface of a sample is polished by using a grinding machine, so that the surface of the sample is smooth, the same polishing process is adopted for different samples, the surface quality of the sample is uniform, the Sa (arithmetic mean of absolute values of heights from the average surface of the surface) and the Sz (distance between the highest point and the lowest point of the surface) of the welded surface of the polished sample are respectively 0.56 μm and 8.43 μm, and the Sa and the Sz are respectively shown in figure 1 and are a three-dimensional topography map of the surface of the polished sample.
Step 2: and (3) putting the ground sample into acetone for ultrasonic cleaning to ensure that the surface of the sample is clean and pollution-free, and then drying and storing.
And step 3: in order to prevent the sample from unstably toppling over in the welding process, the die sleeve shown in fig. 2 is used for assembling and fixing the workpiece to be welded.
And 4, step 4: putting the assembled sample to be welded into a vacuum furnace, vacuumizing the furnace body, and when the vacuum degree of the furnace body is less than 10 -3 After Pa, heating was performed according to a set program. In order to ensure that the temperature of the sample in the furnace is uniformly increased, the temperature is increased to 300 ℃ at the speed of 10 ℃/min during heating, the temperature is maintained for 30min, then the temperature is increased to 600 ℃ at the speed of 10 ℃/min, the temperature is maintained for 30min, meanwhile, the pressure of 60MPa is applied to the sample, then the temperature is increased to 960 ℃ at the speed of 5 ℃/min, the pressure is removed after the temperature is maintained for 210min, and the temperature is cooled to room temperature along with the furnace. In the whole connection process, the sample is in a high vacuum state.
After welding, the structural performance of the welded piece is analyzed, as shown in fig. 3, excellent connection among different samples is realized through diffusion welding, unwelded holes do not exist at the welding seam, and a recrystallization area exists in the center of the welding seam and a large number of equiaxed grains exist due to the recrystallization phenomenon in the welding process. Table 1 summarizes the mechanical properties of the base material and the welded joint, and it can be seen from table 1 that the welded joint has good properties, the tensile strength of which reaches 96% of the base material, and the elongation of which is 72% of the base material. FIG. 4 is a graph of engineering stress strain for a post weld joint.
TABLE 1
The existing direct diffusion welding mainly utilizes atomic diffusion on the surface of a sample to obtain a welding joint due to Ti 2 The diffusion of elements in the AlNb-based alloy is difficult, a good welding joint is difficult to obtain, the requirement of the existing direct diffusion welding on the surface quality of a sample is high, the sample is usually required to be polished manually, the generation cost is increased, and the efficiency is low.
Compared with the prior art, the invention develops a new method, abandons the over-high requirement on the surface smoothness of the sample, uses the sample with larger roughness to carry out direct diffusion welding, and utilizesThe plastic deformation and recrystallization of the surface of the sample promote the healing of the holes at the connecting surface, a recrystallization zone is formed near the connecting surface, the dependence on element diffusion is reduced, the welding efficiency can be improved while a high-quality welding joint is obtained, the stability of the welding process is ensured, and Ti is used as Ti 2 AlNb-based alloy direct diffusion welding provides a new approach.
The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims (7)
1. Ti 2 A diffusion welding method of AlNb alloy is characterized in that Ti is subjected to diffusion welding 2 Pre-polishing the surface of the AlNb alloy, using Sa and Sz to represent the surface quality of a sample, cleaning and assembling the polished surface of the sample, and then carrying out vacuum diffusion welding, wherein the Sa and the Sz of the polished surface of the sample are 0.5-0.7 mu m and 7-9 mu m;
the Sa and the Sz are arithmetic means, namely Sa, of absolute height values from a surface mean plane after three-dimensional imaging is carried out on the surface of a sample by using a white light interference laser microscope system; the distance between the highest point and the lowest point of the surface, namely Sz, is calculated.
2. The Ti of claim 1 2 The diffusion welding method of the AlNb alloy is characterized by comprising three stages of vacuum heating, pressurizing and high-temperature welding.
3. The Ti of claim 1 or 2 2 The diffusion welding method of the AlNb alloy is characterized in that the vacuum diffusion welding specifically comprises the following steps: when the vacuum degree reaches 10 -3 Heating to 300 deg.C at a speed of 10 deg.C/min under Pa, maintaining for 30min, heating to 600 deg.C at a speed of 10 deg.C/min, maintaining for 30min, and treating Ti 2 Applying 40-60Mpa pressure on the surface of AlNb alloy, heating to 960-980 ℃ at the speed of 5 ℃/min, and withdrawing after heat preservation for 150-210minAnd (5) cooling the pin pressure to room temperature along with the furnace.
4. The Ti of claim 1 or 2 2 The AlNb alloy diffusion welding method is characterized in that in the vacuum diffusion welding, a sample is in a high vacuum state in the whole connecting process.
5. The Ti of claim 1 or 2 2 The diffusion welding method of the AlNb alloy is characterized in that in order to prevent a sample from unstably toppling over in the welding process, the diffusion welding tool is used for assembling and fixing a workpiece to be welded.
6. The Ti of claim 1 2 The diffusion welding method of the AlNb alloy is characterized in that the AlNb alloy is cleaned by adopting acetone for ultrasonic cleaning and then dried.
7. The Ti of claim 1 2 The diffusion welding method of the AlNb alloy is characterized in that the polishing is carried out by adopting a grinding machine so as to ensure that the surface of a sample is flat and smooth.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211246036.9A CN115673516A (en) | 2022-10-12 | 2022-10-12 | Ti 2 Direct diffusion welding method of AlNb alloy |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211246036.9A CN115673516A (en) | 2022-10-12 | 2022-10-12 | Ti 2 Direct diffusion welding method of AlNb alloy |
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| CN202211246036.9A Pending CN115673516A (en) | 2022-10-12 | 2022-10-12 | Ti 2 Direct diffusion welding method of AlNb alloy |
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