A welding method of a Ti2AlNb alloy additive manufacturing part

Abstract

The present application relates to the technical field of welding, in particular to a welding method of Ti2AlNb alloy additive manufacturing part. The welding method of Ti2AlNb alloy additive manufacturing part comprises the following steps: welding the Ti2AlNb alloy additive manufacturing part to be welded; in the process of welding, the off-focus light spot is used for cyclic scanning after each weld joint is welded. The welding method of Ti2AlNb alloy additive manufacturing part can significantly reduce the welding thermal stress, reduce the deformation and cracking tendency by cyclic scanning of the weld joint after welding, and can be used for welding of Ti2AlNb alloy additive manufacturing part with more weld joints in a small area, and can obviously reduce the generation of weld cracking phenomenon.

Description

Technical Field

[0001] This invention relates to the field of laser welding technology, and in particular to a welding method for Ti2AlNb alloy additive manufacturing parts. Background Technology

[0002] In recent years, with the further development of materials science, especially in fields such as aerospace, increasingly higher requirements have been placed on the performance of materials. Ti-Al alloys, with their excellent comprehensive properties, have become one of the important materials in the aerospace field. Among them, Ti2AlNb-based alloys, as an important category of Ti-Al alloys, are lightweight, high-temperature resistant structural materials with advantages such as high specific strength, high fracture toughness, good oxidation resistance, excellent heat resistance and flame retardancy. They can be used for extended periods in the range of 650–800℃, and short-term operating temperatures can exceed 900℃, thus attracting widespread attention.

[0003] However, Ti2AlNb alloys are intermetallic compounds, and the mixed bonding of metallic and covalent bonds in Ti2AlNb alloys makes them extremely difficult to process, while giving them excellent high-temperature performance.

[0004] Ti2AlNb alloys have low thermal conductivity and high welding stress. For Ti2AlNb alloy additive parts, deformation or even cracking is highly likely when there are many welds per unit area. Due to the large number of welds in a small area, the welding heat input is large. The intrinsic thermal conductivity of Ti2AlNb alloy is poor, and the thermal stress and structural stress are superimposed. Under confined conditions, the welding stress cannot be released, which easily leads to weld cracking and fails to meet the application requirements.

[0005] In view of this, this invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a welding method for Ti2AlNb alloy additive parts. During the welding process, the weld seam is cyclically scanned by using a defocused spot, which significantly reduces the welding thermal stress and reduces the tendency to deform and crack due to an excessive number of weld seams in a small area.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0008] This invention provides a welding method for Ti2AlNb alloy additive manufacturing parts, comprising the following steps:

[0009] The Ti2AlNb alloy additive parts to be welded are welded; during the welding process, each weld seam is cyclically scanned using a defocused spot after welding.

[0010] Furthermore, the defocusing amount of the cyclic scanning is +30 to +60 mm, the laser power is 0.5 to 1 kW, and the scanning speed is 6 to 9 m / min.

[0011] Furthermore, the surface temperature of the weld after the cyclic scanning is 400–700°C.

[0012] Furthermore, the center-to-center distance between adjacent welds of the Ti2AlNb alloy additive manufacturing part is ≤8mm.

[0013] Furthermore, the Ti2AlNb alloy additive manufacturing part has several flow channels inside, and welds are provided between adjacent flow channels.

[0014] Furthermore, the cross-sectional area of ​​the flow channel is 4–24 mm. 2 .

[0015] Furthermore, the cover plate is fixed to the Ti2AlNb alloy structural component by spot welding to obtain the Ti2AlNb alloy additive part to be welded; the first weld and the second weld above the flow channel of the Ti2AlNb alloy additive part to be welded are welded in sequence.

[0016] The length direction of the first weld is perpendicular to the length direction of the flow channel; the length direction of the second weld is parallel to the length direction of the flow channel.

[0017] Furthermore, after welding the second welds at both ends of the Ti2AlNb alloy additive manufacturing part to be welded, the second weld in the middle of the Ti2AlNb alloy additive manufacturing part to be welded is welded, and then the symmetrical second welds on both sides of the middle of the Ti2AlNb alloy additive manufacturing part to be welded are alternately welded.

[0018] Furthermore, the welding includes laser welding.

[0019] Furthermore, the laser power for laser welding is 1.5–2 kW, and the scanning speed is 3–6 m / min.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The welding method for Ti2AlNb alloy additive parts of the present invention significantly reduces welding thermal stress and decreases deformation and cracking tendency by cyclically scanning the weld after welding.

[0022] In the welding method of the Ti2AlNb alloy additive manufacturing of the present invention, by using a defocusing method to control a large spot of energy dispersion, and with appropriate defocusing height, laser power and scanning speed, a synchronous heat treatment temperature for stress removal can be obtained, so that the surface temperature of the weld is between 400 and 700°C. Timely removal of weld thermal stress and release of structural stress can avoid deformation or even cracking caused by stress superposition between multiple welds.

[0023] The welding method for Ti2AlNb alloy additive parts of the present invention can be used for welding Ti2AlNb alloy additive parts with a large number of weld seams in a small area, which significantly reduces the occurrence of weld cracking after welding. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a top view of the Ti2AlNb alloy additive manufacturing part of the present invention.

[0026] Figure 2 This is a side view of the Ti2AlNb alloy additive manufacturing part of the present invention.

[0027] Figure 3 This is an image of the Ti2AlNb alloy additive manufacturing part after welding in Embodiment 1 of the present invention.

[0028] Figure 4 This is an image of the welded Ti2AlNb alloy additive part in Comparative Example 1 of the present invention.

[0029] Figure label:

[0030] 1-First weld; 2-Second weld;

[0031] 3-Flow channel. 4-Cover plate. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0033] See Figure 1 and Figure 2 In some embodiments of the present invention, a welding method for Ti2AlNb alloy additive manufacturing is provided, comprising the following steps:

[0034] Welding was performed on the Ti2AlNb alloy additive parts to be welded; during the welding process, each weld seam was cyclically scanned using a defocused spot after welding.

[0035] The welding method for Ti2AlNb alloy additive parts of the present invention involves, during the welding process, a large defocused spot cyclic scanning of the welded seam after each weld is performed, that is, the welding step and the post-weld cyclic scanning step are performed alternately.

[0036] The welding method for Ti2AlNb alloy additive parts of the present invention significantly reduces welding thermal stress and decreases deformation and cracking tendency by using a defocused spot to cyclically scan the weld seam during the welding process.

[0037] In some embodiments of the present invention, the defocus amount of the cyclic scanning is +30 to +60 mm; typically, but not limitingly, for example, the defocus amount of the cyclic scanning can be a range of +30 mm, +35 mm, +40 mm, +45 mm, +50 mm, +55 mm, +60 mm, or any combination thereof.

[0038] Defocus refers to the distance between the laser focus and the workpiece. In the laser welding process, defocus has an important impact on the welding quality. The defocus (defocus height) of this invention is positive defocus, with the focus located above the workpiece.

[0039] In some embodiments of the present invention, the laser power for cyclic scanning is 0.5 to 1 kW; typically, but not limitingly, for example, the laser power for cyclic scanning can be a range of 0.5 kW, 0.6 kW, 0.7 kW, 0.8 kW, 0.9 kW, 1 kW, or any combination thereof.

[0040] In some embodiments of the present invention, the scanning speed of the cyclic scan is 6 to 9 m / min; typically, but not limitingly, for example, the scanning speed of the cyclic scan can be a range of 6 m / min, 7 m / min, 8 m / min, 9 m / min or any combination thereof.

[0041] This invention achieves a large, energy-dispersed light spot by using a defocusing method. With appropriate defocusing height, laser power, and scanning speed, a synchronous heat treatment temperature for stress removal can be obtained. During the welding process, alternating cyclic scanning is performed on each weld seam, which significantly reduces welding thermal stress and decreases the tendency for deformation and cracking.

[0042] In some embodiments of the present invention, the surface temperature of the weld after cyclic scanning is 400–700°C.

[0043] The principle behind this invention for reducing welding thermal stress and minimizing deformation and cracking is as follows:

[0044] Higher temperatures result in better stress relief, but the introduction of phase transformation can easily lead to stress superposition and cracking. Cyclic scanning keeps the weld surface temperature between 400 and 700°C. Short-term thermal cycling does not produce phase transformation, which is the optimal stress relief temperature. Timely removal of weld thermal stress and release of structural stress can avoid deformation or even cracking caused by stress superposition between multiple welds.

[0045] The weld microstructure is a single-phase B2 phase. The heat-affected zone of the weld is very narrow and almost unobservable. The cyclical scanning to remove welding stress is also to remove the structural stress concentration caused by thermal stress without causing phase transformation. The goal is to prevent phase transformation, so no phase transformation will occur, that is, no change in microstructure composition will occur.

[0046] This invention determines the cyclic scanning temperature range by cyclically scanning the oxidation color under atmospheric conditions without a protective atmosphere, thus obtaining a combination of defocus height, laser power, and scanning speed.

[0047] In some embodiments of the present invention, the center-to-center distance between adjacent welds of the Ti2AlNb alloy additive manufacturing part is ≤8mm; preferably, the center-to-center distance between adjacent welds of the Ti2AlNb alloy additive manufacturing part is 4 to 6mm.

[0048] In some embodiments of the present invention, the Ti2AlNb alloy additive manufacturing part has a plurality of flow channels 3 inside, and a weld is provided between adjacent flow channels 3.

[0049] In some embodiments of the present invention, the cross-sectional area of ​​the flow channel 3 is 4–24 mm. 2 Typical, but not limiting, for example, the cross-sectional area of ​​flow channel 3 can be 4 mm. 2 6mm 28mm 2 9mm 2 10mm 2 12mm 2 15mm 2 18mm 2 20mm 2 22mm 2 24mm 2 Or a range of values ​​consisting of any two of them.

[0050] In some embodiments of the present invention, the cross-sectional dimensions of the flow channel 3 are (2-4) mm × (2-6) mm.

[0051] The Ti2AlNb alloy additive manufacturing part of the present invention is a thin-walled part with multiple internal flow channels 3, and a large number of welds within a small area, with one weld between two flow channels 3. The welding method of the Ti2AlNb alloy additive manufacturing part of the present invention can be used for Ti2AlNb alloy additive manufacturing parts with the above structure, reducing the occurrence of weld cracking caused by an excessive number of welds within a small area.

[0052] In some embodiments of the present invention, the cover plate 4 is fixed to the Ti2AlNb alloy structural component by spot welding to obtain the Ti2AlNb alloy additive component to be welded; the first weld 1 and the second weld 2 above the flow channel 3 of the Ti2AlNb alloy additive component to be welded are welded in sequence.

[0053] The length direction of the first weld 1 is perpendicular to the length direction of the flow channel 3; the length direction of the second weld 2 is parallel to the length direction of the flow channel 3.

[0054] In some embodiments of the present invention, the welding method of the second weld includes symmetrical and alternating welding.

[0055] In some embodiments of the present invention, after welding the second weld seams 2 at both ends of the Ti2AlNb alloy additive manufacturing part to be welded, the second weld seam 2 in the middle of the Ti2AlNb alloy additive manufacturing part to be welded is welded, and then the second weld seams 2 symmetrically arranged on both sides of the middle of the Ti2AlNb alloy additive manufacturing part to be welded are alternately welded.

[0056] In some embodiments of the present invention, welding specifically includes the following steps:

[0057] The cover plate 4 is fixed by spot welding, with spot welding performed diagonally at the four corners.

[0058] Weld the welds above the flow channels 3 on both sides of the Ti2AlNb alloy additive part, i.e., weld the first weld 1;

[0059] Two second welds 2 at both ends of the Ti2AlNb alloy additive part;

[0060] A second weld 2 is made in the middle region of a Ti2AlNb alloy additive part.

[0061] The remaining second weld 2 on the Ti2AlNb alloy additive part is welded, and the second welds 2 on both sides of the already welded second weld in the middle are welded symmetrically and alternately.

[0062] During the welding process, cross-welds and symmetrical welding can be used to make the temperature field more uniform, the consistency of each weld better, and reduce the degree of stress concentration.

[0063] In some embodiments of the invention, welding includes laser welding.

[0064] In some embodiments of the present invention, the laser power for laser welding is 1.5 to 2 kW; typically, but not limitingly, for example, the laser power for laser welding can be a range of 1.5 kW, 1.6 kW, 1.7 kW, 1.8 kW, 1.9 kW, 2 kW, or any combination thereof.

[0065] In some embodiments of the present invention, the scanning speed of laser welding is 3 to 6 m / min; typically, but not limitingly, for example, the scanning speed of laser welding can be a range of 3 m / min, 4 m / min, 5 m / min, 6 m / min or any combination thereof.

[0066] In some embodiments of the present invention, the laser welding line energy E≥200J / cm.

[0067] In some embodiments of the present invention, laser welding employs a focused laser spot.

[0068] Due to the low thermal conductivity and high welding stress of Ti2AlNb alloy, the laser welding process with relatively low heat input can improve the quality of the weld and give it excellent performance for Ti2AlNb alloy additive parts.

[0069] The embodiments of the present invention will now be described in detail with reference to specific examples and comparative examples.

[0070] Example 1

[0071] The welding method for Ti2AlNb alloy additive manufacturing provided in this embodiment includes the following steps:

[0072] The cover plate 4 was fixed to the Ti2AlNb alloy structural component by spot welding. After spot welding along the four diagonals, the Ti2AlNb alloy additive component to be welded was obtained.

[0073] Welding of the Ti2AlNb alloy additive parts to be welded:

[0074] Two first welds 1 are welded above the flow channels 3 on both sides, and the length direction of the first welds 1 is perpendicular to the length direction of the flow channels 3.

[0075] The two second welds 2 at both ends are welded, and the length direction of the second welds 2 is parallel to the length direction of the flow channel 3;

[0076] Weld the second weld 2 in the middle;

[0077] Alternate welding is performed on the second weld seam 2, which is symmetrical on both sides of the middle.

[0078] During the above welding process, after each weld is welded, a large defocused spot is used to cyclically scan the welded seam. The welding steps and the post-weld cyclic scanning are performed alternately.

[0079] The welding method is laser welding, and the parameters for laser welding are: focused spot, laser power of 1.5kw, and scanning speed of 3.6m / min;

[0080] The parameters for cyclic scanning are: defocusing amount of +40 to 50 mm, laser power of 0.8 kW, and scanning speed of 7 m / min.

[0081] The Ti2AlNb alloy additive manufacturing part has a flow channel 3 inside, the size of which is (2~4)mm×(2~6)mm. A weld is provided between adjacent flow channels 3, and the center distance between adjacent welds is 4~6mm. The material of the Ti2AlNb alloy additive manufacturing part is Ti-22Al-25Nb.

[0082] Images of Ti2AlNb alloy additive parts welded using the above welding method are shown below. Figure 3 As shown, the weld did not show obvious deformation or cracking.

[0083] Example 2

[0084] The welding method for Ti2AlNb alloy additive manufacturing provided in this embodiment includes the following steps:

[0085] The cover plate 4 was fixed to the Ti2AlNb alloy structural component by spot welding. After spot welding along the four diagonals, the Ti2AlNb alloy additive component to be welded was obtained.

[0086] Welding of the Ti2AlNb alloy additive parts to be welded:

[0087] Two first welds 1 are welded above the flow channels 3 on both sides, and the length direction of the first welds 1 is perpendicular to the length direction of the flow channels 3.

[0088] The two second welds 2 at both ends are welded, and the length direction of the second welds 2 is parallel to the length direction of the flow channel 3;

[0089] Weld the second weld 2 in the middle;

[0090] Alternate welding is performed on the second weld seam 2, which is symmetrical on both sides of the middle.

[0091] During the above welding process, after each weld is welded, a large defocused spot is used to cyclically scan the welded seam. The welding steps and the post-weld cyclic scanning are performed alternately.

[0092] The welding method is laser welding, and the parameters for laser welding are: focused spot, laser power of 2 kW, and scanning speed of 4.8 m / min.

[0093] The parameters for cyclic scanning are: defocusing amount of +45 to 55 mm, laser power of 1 kW, and scanning speed of 8 m / min.

[0094] The Ti2AlNb alloy additive manufacturing part has a flow channel 3 inside, the size of which is (2~4)mm×(2~6)mm. A weld is provided between adjacent flow channels 3, and the center distance between adjacent welds is 4~6mm. The material of the Ti2AlNb alloy additive manufacturing part is Ti-22Al-25Nb.

[0095] The Ti2AlNb alloy additive parts welded using the above-mentioned welding method did not exhibit significant deformation or cracking.

[0096] Comparative Example 1

[0097] The welding method for the Ti2AlNb alloy additive parts provided in this comparative example is the same as that in Example 1, except that the Ti2AlNb alloy additive parts to be welded are welded sequentially from one end to the other, without using an alternating welding method.

[0098] Images of Ti2AlNb alloy additive parts welded using the above welding method are shown below. Figure 4 As shown, excessive stress and deformation during the welding process led to cracking.

[0099] This description is intended to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A welding method for Ti2AlNb alloy additive manufacturing parts, characterized in that, Includes the following steps: The Ti2AlNb alloy additive parts to be welded are welded; during the welding process, each weld seam is cyclically scanned using a defocused spot after welding. The Ti2AlNb alloy additive part has several flow channels inside, and welds are provided between adjacent flow channels; The cover plate is fixed to the Ti2AlNb alloy structural component by spot welding to obtain the Ti2AlNb alloy additive part to be welded; the first weld and the second weld above the flow channel of the Ti2AlNb alloy additive part to be welded are welded in sequence. The length direction of the first weld is perpendicular to the length direction of the flow channel; the length direction of the second weld is parallel to the length direction of the flow channel.

2. The welding method for Ti2AlNb alloy additive manufacturing parts according to claim 1, characterized in that, The defocusing amount of the cyclic scanning is +30~+60mm, the laser power is 0.5~1kw, and the scanning speed is 6~9m / min.

3. The welding method for Ti2AlNb alloy additive manufacturing parts according to claim 1, characterized in that, The surface temperature of the weld after the cyclic scanning is 400~700℃.

4. The welding method for Ti2AlNb alloy additive manufacturing parts according to claim 1, characterized in that, The center-to-center distance between adjacent welds of the Ti2AlNb alloy additive manufacturing part is ≤8mm.

5. The welding method for Ti2AlNb alloy additive manufacturing parts according to claim 1, characterized in that, The cross-sectional area of ​​the flow channel is 4~24mm. 2 .

6. The welding method for Ti2AlNb alloy additive manufacturing parts according to claim 1, characterized in that, After welding the second welds at both ends of the Ti2AlNb alloy additive manufacturing part to be welded, the second weld in the middle of the Ti2AlNb alloy additive manufacturing part to be welded is welded, and then the second welds symmetrically arranged on both sides of the middle of the Ti2AlNb alloy additive manufacturing part to be welded are alternately welded.

7. The welding method for Ti2AlNb alloy additive manufacturing parts according to claim 1, characterized in that, The welding includes laser welding.

8. The welding method for Ti2AlNb alloy additive manufacturing parts according to claim 7, characterized in that, The laser power for laser welding is 1.5~2kw, and the scanning speed is 3~6m / min.

Images