Titanium-aluminum dissimilar metal connection additive manufacturing method

Abstract

The invention provides a titanium-aluminum dissimilar metal connection additive manufacturing method which comprises the following steps: S1, preparing a titanium substrate layer, and manufacturing a titanium alloy space lattice structure on the titanium substrate layer; s2, pouring deposition of the lattice space in the aluminum alloy is carried out in an electric arc welding mode to prepare a titanium-aluminum transition layer; and S3, an electric arc swing mode is adopted, and an aluminum additive layer is prepared on the titanium-aluminum transition layer. The titanium alloy dot matrix transition layer is designed, the characteristic that titanium and aluminum are different in melting point is utilized, arc spot welding filling is adopted, and the risk that titanium and aluminum metal generates a brittle phase under high heat input can be avoided; meanwhile, the connection reliability can be greatly improved by adopting the tenon-and-mortise structure, even if the interface is fractured, the tenon-and-mortise structure effectively hinders the expansion of cracks at the interface, and the connection transition layer still has certain strength.

Description

Technical Field

[0001] The present invention relates to the technical field of dissimilar metal joining additive manufacturing, and more particularly, to a method for additive manufacturing of titanium-aluminum dissimilar metal joining. Background Art

[0002] Aluminum alloys and titanium alloys have been widely used in the fields of aerospace and the like due to their advantages such as light weight and high specific strength. In most structural components of these products, the joining problem of aluminum alloys and titanium alloys is particularly important. However, due to the metallurgical incompatibility between aluminum alloys and titanium alloys, traditional welding methods will generate a large amount of intermetallic compounds (hard and brittle phases) when joining these two dissimilar metals. In addition, the huge differences in thermophysical and chemical properties between aluminum alloys and titanium alloys lead to easy occurrence of cracks and failures at the joint, so traditional welding methods face great challenges in joining dissimilar metals. The reliable joining technology of titanium-aluminum dissimilar metals is a current research hotspot, which can bring into play the comprehensive performance advantages of the two metals and has broad application prospects and important application values in the fields of aerospace, rail transit, and the like.

[0003] Due to the problem of titanium-aluminum dissimilar metal joining, currently, mainly three solutions are adopted: bolt connection, special metal transition, and wire composition optimization. Although bolt connection can achieve connection, the structure size increases, the connection strength is low, and it is easy to fall off under the working condition of vibration load, which may lead to catastrophic consequences.

[0004] Chinese patents CN11051093A, CN105382398A, CN103084714A, CN115570295A, etc. disclose welding wires for welding titanium alloys and aluminum alloys. However, these welding wires need to add precious metals or cooperate with vacuum processes, have complex compositions, and are difficult to meet the requirements of large-scale industrial production. In addition, during the large-area joining process, multiple thermal cycles will increase the risk of cracking and failure of the interface layer under the action of stress.

[0005] For the special metal transition solution, the prior art with the publication number CN100358666C discloses an electron beam welding method of titanium-aluminum alloy metal bond compounds with a transition layer. The steps of its welding method are as follows: a. Perform pre-welding stress relief heat treatment on the titanium-aluminum alloy to be welded; b. Physically and chemically clean the surfaces of the welding joints and the metal foil of the titanium-aluminum alloy to be welded; c. Set the metal foil between the welds; d. Scan or defocus and preheat the welds with an electron beam; e. Perform micro-alloying treatment on the welds with an electron beam; f. Naturally cool to room temperature in situ. However, the prior art uses a filler transition metal for connection, but has high equipment costs, high precision requirements, and there is still a risk of generating intermetallic compounds inside, and it is easy to generate crack propagation under the influence of fatigue load. Summary of the Invention

[0006] In view of this, the present invention aims to provide a method for additive manufacturing of dissimilar metal joints, so as to solve the problems in the prior art that when using filler transition metals for connection, the equipment cost is high, the precision requirement is high, and there is still a risk of the generation of intermetallic compounds inside, and crack propagation is likely to occur under the influence of fatigue loads.

[0007] To achieve the above object, the technical solution of the present invention is realized as follows:

[0008] A method for additive manufacturing of titanium-aluminum dissimilar metal joints includes the following steps:

[0009] S1. Prepare a titanium substrate layer and fabricate a titanium alloy space lattice structure on the titanium substrate layer;

[0010] S2. Through the method of arc welding, perform perfusion cladding in the internal lattice space of the aluminum alloy to prepare a titanium-aluminum transition layer;

[0011] S3. Adopt an arc oscillation mode to prepare an aluminum additive layer on the titanium-aluminum transition layer.

[0012] By designing a titanium alloy lattice transition layer and utilizing the characteristics of the melting point differences between titanium and aluminum, and adopting arc spot welding filling, the present invention can avoid the risk of generating brittle phases in titanium-aluminum metals under high heat input; meanwhile, adopting the mortise and tenon structure form can greatly improve the connection reliability. Even in the case of fracture at the interface, the mortise and tenon structure effectively hinders the crack propagation at the interface, and the connection transition layer still has a certain strength.

[0013] Further, the titanium alloy space lattice structure is obtained by machining or by laser cladding printing.

[0014] Further, the thickness of the titanium-aluminum transition layer is 5-25 mm.

[0015] Further, the process parameters adopted for the titanium-aluminum transition layer are as follows: current 50-80 A, voltage 10-14 V, cladding speed 120-300 mm / min, wire feeding speed 4-6 m / min.

[0016] Further, the oscillation mode of the aluminum additive layer is triangular oscillation, the oscillation amplitude is 2-6 mm, and the step size is 1-3 mm.

[0017] Further, the specific perfusion process of the titanium-aluminum transition layer is as follows: move the welding torch to the center of an XY lattice, then lower the welding wire to the center position in the Z direction inside the lattice, set an automatic arc cladding program, after cladding is completed, lift the Z axis of the welding wire, and move the welding torch to the next lattice position.

[0018] Further, the arc cladding time is 0.2-2 seconds.

[0019] Furthermore, the titanium alloy space lattice structure has multiple patterns.

[0020] Furthermore, the titanium alloy space lattice structure is a combination of multiple types including frames, pyramids, and shell surfaces.

[0021] Furthermore, the volume ratio of aluminum to titanium in the transition layer is 0.4 - 0.9.

[0022] Furthermore, the tensile strength of the titanium-aluminum dissimilar metal connection additive manufacturing is 130 - 230 MPa.

[0023] Compared with the prior art, the titanium-aluminum dissimilar metal connection additive manufacturing method of the present invention has the following advantages:

[0024] 1) By designing a titanium alloy lattice transition layer and taking advantage of the melting point difference between titanium and aluminum, and using arc spot welding for filling, the present invention can avoid the risk of brittle phase formation in titanium-aluminum metals under high heat input. At the same time, the mortise and tenon structure can greatly improve the connection reliability. Even in the case of fracture at the interface, the mortise and tenon structure effectively hinders the crack propagation at the interface, and the connection transition layer still has a certain strength.

[0025] 2) The method of the present invention can greatly improve the tensile strength of parts. At the same time, this method can be extended and applied to the connection and integrated manufacturing of components such as plate parts and cylindrical parts, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the titanium-aluminum additive manufacturing structure of the present invention;

[0027] Figure 2 It is a structural diagram of the titanium alloy SLM selective laser melting / machining manufactured lattice sample of the present invention;

[0028] Figure 3 It is a schematic diagram of the arc perfusion cladding structure of the present invention;

[0029] Figure 4 It is a space lattice structure diagram manufactured by the SLM technology of the present invention;

[0030] Figure 5 It is a diagram of moving the welding wire to the center position of the lattice to be clad of the present invention;

[0031] Figure 6 It is a diagram of starting the welding torch to perform internal lattice cladding filling of the present invention;

[0032] Figure 7 It is a diagram of completing the internal space filling of the lattice of the present invention;

[0033] Figure 8It is a diagram of a titanium-aluminum dissimilar metal additive manufacturing sample for Embodiment 1 of the present invention;

[0034] Figure 9 It is a cross-sectional view of a titanium-aluminum dissimilar metal additive manufacturing sample for Embodiment 1 of the present invention.

[0035] Explanation of reference numerals:

[0036] 1 - Titanium layer, 2 - Titanium-aluminum transition layer, 3 - Aluminum layer, 4 - Welding torch. Detailed implementation manners

[0037] To make the above objects, features and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings.

[0038] Embodiment 1

[0039] This embodiment provides a method for additive manufacturing of titanium-aluminum dissimilar metal connection. As Figure 1 shown, it is divided into three layers in total: a titanium substrate layer 1, a titanium-aluminum transition layer 2, and an aluminum additive layer 3. The specific steps of the manufacturing method are as follows:

[0040] S1. Preparation of the titanium substrate layer; The titanium alloy space lattice structure as Figure 2 shown is manufactured by using selective laser melting or machining manufacturing technology. The lattice structure in this embodiment is the mortise and tenon framework structure as Figure 3 shown.

[0041] S2. Preparation of the titanium-aluminum transition layer; As Figure 4 shown, after the lattice manufacturing is completed, the internal lattice space of the aluminum alloy is filled and deposited by arc welding. The process is as Figure 3 shown. Move the welding torch 4 to the XY center of the lattice. As Figure 5 shown, then lower the welding wire to the Z-direction center position inside the lattice, set the automatic deposition program, and the arc deposition time is 2 seconds. As Figure 6 shown, turn on the welding torch to perform internal deposition filling of the lattice. As Figure 7 shown, complete the filling of the internal space of the lattice. After the deposition is completed, lift the Z-axis upward and move the welding torch to the next lattice position. By repeating the above steps in sequence through the automatic program, efficient deposition perfusion of the titanium-aluminum transition layer can be achieved. Among them, the filling process parameters of the titanium-aluminum transition layer are shown in Table 1 below.

[0042] S3. Preparation of the aluminum additive layer; Since the melting point of the aluminum alloy (667 °C) is lower than that of the titanium alloy (1600 °C), by adjusting the arc heat input, the temperature of the aluminum alloy molten pool can be controlled within (1000 - 1300 °C), thereby avoiding the melting of the titanium alloy lattice structure and effectively reducing the risk of cracks.

[0043] After the titanium-aluminum transition layer is manufactured, the arc oscillation mode is adopted, which can effectively improve the spreadability of the metal solution, avoid the problem of unstable arc length caused by the flow of the aluminum alloy molten pool, and further improve the filling effect of the aluminum alloy solution in the lattice area. The process parameters for the preparation of the aluminum additive layer are shown in Table 1 below. At the same time, when preparing the titanium-aluminum transition layer, the aluminum-titanium volume ratio is controlled to be 0.4-0.6.

[0044] Table 1

[0045] Step Current (A) Voltage (V) Deposition Rate (mm / min) Wire Feeding Speed (m / min) Titanium-Aluminum Transition Layer 60 12 250 5 Aluminum Additive Layer 100 15 400 6

[0046] The oscillation mode of the aluminum additive layer is triangular oscillation, the oscillation amplitude is 4 mm, and the step size is 2 mm.

[0047] Typical specimens were prepared using TC4 titanium alloy and 5183 aluminum alloy. As Figure 8 shown, it can be seen from the figure that the manufacturing process is stable, the forming is good, and no defects such as cracks are found on the surface; the cross-sectional view of the specimen is as Figure 9 shown. It can be seen from the figure that the titanium alloy lattice is well connected to the aluminum alloy; and the specimens were sampled and tested. The tensile strength in the tensile properties is 198 MPa. The corresponding thicknesses of the TC4 titanium alloy, 5183 aluminum alloy, and the transition layer in this example are 50 mm, 15 mm, and 70 mm. The method of the present invention avoids the problems of low tensile strength and easy cracking due to the formation of intermetallic compounds in the traditional welding connection of titanium-aluminum dissimilar metals. At the same time, the mortise and tenon structure adopted greatly improves the crack propagation resistance under the working conditions of fatigue cyclic loading, and has the advantages of low cost, high material utilization rate, high efficiency, and good reliability. This method is applicable to the connection of large frame structures and can meet the low-cost and high-efficiency manufacturing of complex parts.

[0048] Example 2

[0049] This example provides a method for additive manufacturing of titanium-aluminum dissimilar metal connections. As Figure 1 shown in the structure, it is divided into three layers: a titanium substrate layer 1, a titanium-aluminum transition layer 2, and an aluminum additive layer 3. The specific steps of the manufacturing method are as follows:

[0050] S1. Preparation of the titanium substrate layer; The titanium alloy lattice structure as Figure 2 shown is manufactured by using selective laser melting or machining manufacturing technology. The lattice structure in this example is the mortise and tenon skeleton structure as Figure 3 shown.

[0051] S2. Preparation of the titanium-aluminum transition layer; As Figure 4 shown, after the lattice manufacturing is completed, the internal lattice space of the aluminum alloy is filled and deposited by arc welding. The process is as Figure 3As shown, move the welding torch 4 to the center of the dot matrix XY, then lower the welding wire to the center position in the Z direction inside the dot matrix. Set the automated cladding program, with the arc cladding time being 1.5 seconds. After cladding, lift the Z-axis upward and move the welding torch to the next dot matrix position. By repeating the above steps successively through the automated program, efficient cladding perfusion of the titanium-aluminum transition layer can be achieved. Among them, the filling process parameters of the titanium-aluminum transition layer are shown in Table 2 below. At the same time, when preparing the titanium-aluminum transition layer, control the aluminum-titanium volume ratio to be 0.65 - 0.85.

[0052] S3. Preparation of the aluminum additive layer; Since the melting point of aluminum alloy (667 °C) is lower than that of titanium alloy (1600 °C), by adjusting the arc heat input, the temperature of the aluminum alloy molten pool can be controlled within (1000 - 1300 °C), thereby avoiding the melting of the titanium alloy dot matrix structure and effectively reducing the risk of cracks.

[0053] After completing the manufacture of the titanium-aluminum transition layer, start using the arc oscillation mode, which can effectively improve the spreadability of the metal solution, and at the same time avoid the problem of unstable arc length caused by the flow of the aluminum alloy molten pool, further improving the filling effect of the aluminum alloy solution in the dot matrix area. Among them, the process parameters for the preparation of the aluminum additive layer are shown in Table 2 below.

[0054] Table 2

[0055] Step Current (A) Voltage (V) Deposition Rate (mm / min) Wire Feeding Speed (m / min) Titanium-Aluminum Transition Layer 80 14 300 6 Aluminum Additive Layer 120 16 600 10

[0056] The oscillation mode of the aluminum additive layer is triangular oscillation, with an oscillation amplitude of 6 mm and a step size of 3 mm.

[0057] Typical specimens were prepared using TC4 titanium alloy and 5183 aluminum alloy, and the specimens were sampled and tested. The joint strength in the tensile properties was 224 MPa. In this example, the thicknesses of the TC4 titanium alloy, 5183 aluminum alloy, and the transition layer corresponded to 40 mm, 10 mm, and 50 mm.

[0058] Example 3

[0059] This example provides a method for additive manufacturing of titanium-aluminum dissimilar metal joints. As Figure 1 shown in the structure, it is divided into three layers: a titanium substrate layer 1, a titanium-aluminum transition layer 2, and an aluminum additive layer 3. The specific steps of the manufacturing method are as follows:

[0060] S1. Preparation of the titanium substrate layer; The titanium alloy dot matrix structure as Figure 2 shown is manufactured using laser selective melting or machining manufacturing technology. The dot matrix structure in this example is the mortise and tenon framework structure as Figure 3 shown.

[0061] S2. Preparation of the titanium-aluminum transition layer; As Figure 4As shown, after the lattice manufacturing is completed, the internal lattice space of the aluminum alloy is filled and deposited by arc welding. The process is as follows Figure 3 As shown, move the welding torch 4 to the XY center of the lattice, then lower the welding wire to the Z - direction center position inside the lattice. Set the automatic deposition program. The arc deposition time is 1 second. After deposition, lift the Z - axis upward and move the welding torch to the next lattice position. By repeating the above steps in sequence through the automatic program, efficient deposition filling of the titanium - aluminum transition layer can be achieved. Among them, the filling process parameters of the titanium - aluminum transition layer are shown in Table 3 below. At the same time, when preparing the titanium - aluminum transition layer, control the aluminum - titanium volume ratio to be 0.55 - 0.75.

[0062] S3. Preparation of the aluminum additive layer; Since the melting point of the aluminum alloy (667 °C) is relatively low and that of the titanium alloy (1600 °C), by adjusting the arc heat input, the molten pool temperature of the aluminum alloy can be controlled within (1000 - 1300 °C), thereby avoiding the melting of the titanium alloy lattice structure and effectively reducing the risk of cracks.

[0063] After the manufacturing of the titanium - aluminum transition layer is completed, start using the arc oscillation mode, which can effectively improve the spreadability of the metal solution, and at the same time avoid the problem of unstable arc length caused by the flow of the aluminum alloy molten pool, further improving the filling effect of the aluminum alloy solution in the lattice area. Among them, the process parameters for the preparation of the aluminum additive layer are shown in Table 3 below.

[0064] Table 3

[0065] Step Current (A) Voltage (V) Deposition Rate (mm / min) Wire Feeding Speed (m / min) Titanium-Aluminum Transition Layer 50 10 120 4 Aluminum Additive Layer 70 13 200 4

[0066] The oscillation mode of the aluminum additive layer is triangular oscillation, the oscillation amplitude is 2 mm, and the step size is 1 mm.

[0067] Typical samples were prepared using TC4 titanium alloy and 5183 aluminum alloy, and the samples were sampled and tested. The tensile strength in the tensile properties was 207 MPa. The corresponding thicknesses of the TC4 titanium alloy, 5183 aluminum alloy, and the transition layer in this example are 60 mm, 20 mm, and 70 mm respectively.

[0068] Comparative Example 1

[0069] Typical samples were prepared using TC4 titanium alloy and 5183 aluminum alloy, and the samples were sampled and tested. Traditional arc welding was used. For the specific welding process, please refer to the journal Journal of Manufacturing Processes, with the title Microstructure and mechanical properties of wire and arc additive manufactured Ti-6Al-4V and AlSi5 dissimilar alloys using cold metal transfer welding. The tensile strength in the tensile properties was 79 MPa.

[0070] It can be clearly seen from Examples 1 to 3 and Comparative Example 1 that the method of the present invention can significantly improve the tensile strength of parts. At the same time, this method can be extended and applied to the connection and integrated manufacturing of components such as plate parts and cylindrical parts, and has good application prospects.

[0071] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A method for additive manufacturing of titanium-aluminum dissimilar metal joints, characterized in that, It includes the following steps: S1. Prepare a titanium substrate layer and fabricate a titanium alloy space lattice structure on the titanium substrate layer; S2. Prepare a titanium-aluminum transition layer by means of perfusion cladding in the internal lattice space of aluminum alloy through arc welding; S3. Prepare an aluminum additive layer on the titanium-aluminum transition layer by adopting an arc oscillation mode.

2. The additive manufacturing method for connecting titanium and aluminum dissimilar metals according to claim 1, characterized in that, The titanium alloy space lattice structure is obtained by machining or printing through laser cladding.

3. The additive manufacturing method for joining titanium and aluminum dissimilar metals according to claim 1, wherein The thickness of the titanium-aluminum transition layer is 5 - 25 mm.

4. A method for additive manufacturing of titanium-aluminum dissimilar metal connection according to claim 1, characterized in that, The process parameters adopted for the titanium-aluminum transition layer are as follows: current 50 - 80 A, voltage 10 - 14 V, cladding speed 120 - 300 mm / min, wire feeding speed 4 - 6 m / min.

5. A method for additive manufacturing of titanium-aluminum dissimilar metal joints according to claim 1, characterized in that, The oscillation mode of the aluminum additive layer is triangular oscillation, the oscillation amplitude is 2 - 6 mm, and the step size is 1 - 3 mm.

6. The additive manufacturing method for joining titanium and aluminum dissimilar metals according to claim 1, wherein The specific perfusion process of the titanium-aluminum transition layer is as follows: move the welding torch to the center of an XY lattice point, then lower the welding wire to the center position in the Z direction inside the lattice point, set an automated arc cladding program, lift the Z axis of the welding wire after cladding is completed, and move the welding torch to the next lattice point position.

7. A method for additive manufacturing of titanium-aluminum dissimilar metal connection according to claim 6, characterized in that The arc cladding time is 0.2 - 2 seconds.

8. A method for additive manufacturing of titanium-aluminum dissimilar metal connection according to claim 1, characterized in that The titanium alloy space lattice structure is a combination of multiple types such as a frame, a pyramid, and a shell surface.

9. The additive manufacturing method for joining titanium and aluminum dissimilar metals according to claim 1, wherein, The volume ratio of aluminum to titanium in the transition layer is 0.4 - 0.

9.

10. A method for additive manufacturing of titanium-aluminum dissimilar metal connection according to claim 1, characterized in that, The tensile strength of the titanium-aluminum dissimilar metal connection additive is 130 - 230 MPa.

Images