Cold metal transition electric arc additive manufacturing process matched with 5R59 aluminum-scandium welding wire

Abstract

The invention relates to a cold metal transition electric arc additive manufacturing process matched with a 5R59 aluminum scandium welding wire, and belongs to the technical field of electric arc additive manufacturing. The method is characterized in that a 7A52 aluminum alloy is used as a substrate, a 5R59 aluminum scandium welding wire is used as a wire material, parameters are set on a CMT welding power source, and a reciprocating scanning forming path is adopted; protective gas is adopted for protection, the first three layers are added in a large-current decreasing mode, and when the first three layers are arranged on the third layer, normal setting parameters are returned to stabilize material adding; and after each layer of additive material is finished, the welding gun is lifted upwards by 1.5-3 mm, after the welding gun stays for 80-100 s, welding of the next layer continues to be conducted on the basis that the additive material layer is finished, and so on until the additive material part is manufactured. The method has the advantages that the additive part is good in formability and mechanical property, energy-saving, low in cost, good in appearance forming, tight in layer-to-layer combination and high in controllability. The mechanical property of an additive manufacturing structural part based on the process is outstanding, the tensile strength Rm is larger than or equal to 400 MPa, the yield strength Rp0.2 is larger than or equal to 200 MPa, and the ductility A is larger than or equal to 20%.

Description

Technical Field

[0001] The invention relates to a cold metal transfer arc additive manufacturing process matched with a 5R59 aluminum-scandium welding wire, belonging to the technical field of arc additive manufacturing. Background Art

[0002] Wire arc additive manufacturing (WAAM) technology has attracted considerable attention in the production of Al-Mg alloys due to its unique advantages, including low cost, high material utilization, and flexible equipment and processes. However, the WAAM process is limited to the production of existing Al-Mg alloy grades. Furthermore, the resulting alloys have poor mechanical properties, with tensile strengths below 300 MPa, making them difficult to use in practical applications (Journal of Materials Engineering and Performance, 26 (2017) 621-629). Sc (scandium), the most effective modifier in aluminum alloys, acts as a nucleation center during matrix solidification, promoting grain refinement. Adding Sc can significantly improve the mechanical properties of Al-Mg alloys.

[0003] Currently, there have been many studies on Al-Mg-Sc alloys, including the development of various grades and corresponding welding wires (Acta Materialia, 117 (2016) 43-50). However, there are few reports on the use of WAAM to prepare Al-Mg-Sc alloy parts. Ren et al. (Metals and Materials International, 27 (2021) 68-77) studied the effect of different Sc contents on the properties of additively manufactured Al-Mg-Sc alloys. Ren et al. (3D Printing and Additive Manufacturing, 9 (2022) 301-310) used the CMT twin-wire process to additively manufacture Al-Mg-Sc alloys. Ma et al. (Thin-Walled Structures, 186 (2023) 110674) used laser arc hybrid technology to additively manufacture Al-Mg-Sc alloys.

[0004] While these studies have partially filled a gap in the field of WAAM-based Al-Mg-Sc alloy preparation, the effects of different WAAM process parameters on the properties of Al-Mg-Sc alloys have not yet been reported. Furthermore, the strength of the additively manufactured Al-Mg-Sc alloys reported in these studies still lags behind that of cast Al-Mg-Sc alloys.

[0005] WAAM differs significantly from traditional preparation methods, involving factors such as arc temperature, small droplet transfer, rapid melting and cooling, layer-by-layer deposition, repeated remelting, and cyclic heating. The amount, size, and distribution of the Al3Sc phase are also closely related to the preparation process. Therefore, the influence of different WAAM process parameters on the microstructure and properties of the produced Al-Mg-Sc alloy deposits is crucial. Summary of the Invention

[0006] The purpose of the present invention is to provide a cold metal transfer arc additive manufacturing process that matches the 5R59 aluminum-scandium welding wire, which utilizes a CMT heat source to melt the ER5R59 aluminum-scandium welding wire, adopts a reciprocating layer-by-layer deposition method, and performs arc additive manufacturing by adjusting various welding process parameters and improving the process environment.

[0007] The technical solutions of the present invention are as follows: (1) In a dry and windless experimental environment, use 7A52 aluminum alloy as the substrate and 5R59 aluminum-scandium welding wire as the wire. First clean the substrate surface and then fix the substrate to the experimental platform with a clamp; (2) Set the wire feed speed to 5.5-7.5 m / min, the current to 73-109 A, and the voltage to 12.3-14.3 V on the CMT (cold metal transfer) welding power source, set the welding speed to 30-70 cm / min on the operating handle panel, and use a reciprocating scanning forming path; (3) Using shielding gas protection, the wire extension length is 8 to 10 mm, and the height and position of the welding gun are adjusted so that the welding wire is perpendicular to the substrate and the tip is 3 to 5 mm away from the substrate. The first three layers of additive manufacturing are started in a decreasing manner with a large current. During this period, the welding parameters need to be adjusted. When the third layer is added, the parameters are returned to the normal setting to stabilize the additive manufacturing. After each layer of additive manufacturing is completed, the welding gun is raised 1.5 to 3 mm in height, and after staying for 80 to 100 seconds, the next layer of welding is continued on the basis of the finished additive layer, and so on until the additive manufacturing is completed.

[0008] The substrate specifications are: length * width * thickness = 350 * 200 * 20mm; The diameter of the 5R59 aluminum-scandium welding wire is 1.2 mm; The substrate surface is cleaned by first cleaning the substrate with a handheld grinder, and then cleaning the substrate with an acetone solution to remove oxide scale and oil stains; The protective gas is 99.999% argon, and the gas flow rate is set at 15-20 L / min; The first three layers of material addition are started in a decreasing manner with a large current. During this period, the welding parameters need to be adjusted as follows: the current is 150A for the first layer, and is gradually reduced to 119A for the second layer. At the third layer, the parameters are returned to the normal setting to stabilize the material addition.

[0009] The beneficial effects of the present invention are: Using a CMT heat source to melt ER5R59 aluminum-scandium welding wire, the process is then formed layer by layer using a reciprocating deposition process. Arc additive manufacturing (AM) is achieved by adjusting various welding process parameters and improving the process environment. The resulting parts exhibit excellent formability and mechanical properties, filling a gap in the field of preparing Al-Mg-Sc alloys using different WAAM process parameters. The optimized process parameters provide a reference for the arc additive manufacturing of 5R59 aluminum-scandium welding wire. CMT technology also addresses the issues of arc instability and uncontrollable wire feeding in arc AM of aluminum alloys.

[0010] This process is based on the particularity of the arc additive manufacturing process and saves the energy and time cost of preheating the substrate. It uses a large current layer-by-layer reduction method to add the first three layers of welds. It can not only preheat the substrate but also provide a good deposition base for the additive thin-walled specimens, avoiding the bending or even detachment of the specimens due to poor bonding between the bottom and the substrate during the subsequent additive manufacturing process.

[0011] The aluminum-scandium alloy additive parts produced by this process have good appearance, close bonding between layers, few pore defects, less spheroidization, no biting, edge collapse and other welding defects, and high controllability. The mechanical properties of the additively manufactured structural parts based on this process are outstanding, with a tensile strength Rm≥400MPa and a yield strength R p0.2 ≥200MPa, elongation A≥20%.

[0012] This process provides a reference for new manufacturing methods for independent construction of industrial arc additive manufacturing and the use of 5R59 aluminum-scandium alloy in complex component forming and industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a macroscopic image of the additively manufactured specimen of Example 1; Figure 2 is a metallographic image of the additively manufactured sample of Example 1; Figure 3 is a macroscopic image of the additively manufactured specimen of Example 2; Figure 4 is a metallographic image of the additively manufactured sample of Example 2; Figure 5 is a macroscopic image of the additively manufactured specimen of Example 3; Figure 6 This is the metallographic image of the additively manufactured sample of Example 3. DETAILED DESCRIPTION

[0014] The present invention is further described below with reference to the embodiments, but does not constitute a limitation to the scope of protection of the present invention: Example 1

[0015] The method described in this process is used for manufacturing, and the implementation process is as follows: 7A52 aluminum alloy is used as the substrate, 5R59 aluminum-scandium welding wire is used as the wire material, the substrate specifications are: length * width * thickness = 350 * 200 * 20mm, and the diameter of 5R59 aluminum-scandium welding wire is 1.2mm. Clean the substrate, remove oxides and oil stains on the surface of the substrate with a handheld angle grinder, wipe it with acetone and fix it on the laboratory table; select CMT mode on the CMT welding power supply and adjust the wire feed speed to 9.5m / min, current to 155A, and voltage to 15.6V; adjust the welding speed of the welding gun to 70cm / min through the operating handle panel, and use a reciprocating scanning forming path in its welding program programming, and set the inter-layer waiting time to 90s; adjust the position of the welding gun so that it is located at one end above the substrate, adjust the welding gun angle and height so that the central axis of the welding gun is perpendicular to the upper surface of the substrate at 90°, adjust the welding wire dry extension to 10mm, the welding wire tip is 5mm away from the substrate, and adjust the shielding gas flow rate to 20L / min; start the arc at one end of the substrate to start the first layer of additive deposition; After one layer of deposition is completed, the welding gun is lifted up by 2.5mm. During the waiting time, the wire feeding speed is adjusted to 8m / min, the current is 119A, and the voltage is 14.7V. After the adjustment is completed and the waiting time between layers is over, the second layer of deposition is started. After the second layer of deposition is completed, the welding gun is lifted up by 2.3mm. During the waiting time, the wire feeding speed is adjusted to 6.5m / min, the current is 91A, and the voltage is 13.3V. After the adjustment is completed and the waiting time between layers is over, the third layer of deposition is started. After the third layer of deposition is completed, the welding gun is lifted up by 2mm. Thereafter, according to the set stable parameters, that is, the wire feeding speed is 6.5m / min, the current is 91A, the voltage is 13.3V, and the interlayer is lifted by 2mm. This is until the 80mm high additive sample is completed.

[0016] Figure 1 This is a macroscopic picture of the additively manufactured sample of Example 1. It can be seen that the appearance is well formed, the layers are tightly bonded, there are few pore defects, and there are no welding defects such as biting and edge collapse.

[0017] Figure 2 This is a metallographic image of the additively manufactured sample of Example 1. It can be seen that there are few pores in its structure and the size of some pores is also small.

[0018] In order to test the mechanical properties of the additive specimens, plate-shaped tensile specimens were cut longitudinally and transversely by wire cutting. Static tensile tests were carried out at room temperature with a tensile speed of 1 mm / min. The results showed that the longitudinal tensile strength of the additive specimens reached 406 MPa, the yield strength reached 211 MPa, and the elongation reached 24%; the transverse tensile strength reached 402 MPa, the yield strength reached 206 MPa, and the elongation reached 22%, which can meet the requirements of practical applications. Example 2

[0019] The method described in this process is used for manufacturing, and the implementation process is as follows: 7A52 aluminum alloy is used as the substrate, 5R59 aluminum-scandium welding wire is used as the wire material, the substrate specifications are: length * width * thickness = 350 * 200 * 20mm, and the diameter of 5R59 aluminum-scandium welding wire is 1.2mm. Clean the substrate, remove oxides and oil stains on the surface of the substrate with a handheld angle grinder, wipe it with acetone and fix it on the laboratory table; select CMT mode on the CMT welding power supply and adjust the wire feed speed to 9.5m / min, current to 155A, and voltage to 15.6V; adjust the welding speed of the welding gun to 50cm / min through the operating handle panel, and use a reciprocating scanning forming path in its welding program programming, and set the inter-layer waiting time to 90s; adjust the position of the welding gun so that it is located at one end above the substrate, adjust the welding gun angle and height so that the central axis of the welding gun is perpendicular to the upper surface of the substrate at 90°, adjust the welding wire dry extension to 8mm, the welding wire tip is 4mm away from the substrate, and adjust the shielding gas flow rate to 20L / min; start the arc at one end of the substrate and start the first layer of additive deposition; the first After the layer deposition is completed, lift the welding gun 3mm upwards, and during the waiting time, adjust the wire feeding speed to 8m / min, the current to 119A, and the voltage to 14.7V; after the adjustment is completed and the waiting time between layers is over, start the second layer deposition; after the second layer deposition is completed, lift the welding gun 3mm upwards, and during the waiting time, adjust the wire feeding speed to 7.0m / min, the current to 100A, and the voltage to 13.8V; after the adjustment is completed and the waiting time between layers is over, start the third layer deposition; after the third layer deposition is completed, lift the welding gun 2.5mm upwards, and then follow the set stable parameters, that is, the wire feeding speed is 7.0m / min, the current is 100A, the voltage is 13.8V, and the interlayer is raised by 2.5mm; until the 80mm high additive sample is completed.

[0020] Figure 3 This is a macroscopic picture of the additively manufactured sample of Example 2. It can also be seen that the appearance is well formed, the layers are tightly bonded, there are few pore defects, and there are no welding defects such as biting and edge collapse.

[0021] Figure 4 This is a metallographic picture of the additively manufactured sample of Example 2. It can be seen that there are fewer pores in its structure, and the size of some pores is not large.

[0022] In order to test the mechanical properties of the additive specimens, plate-shaped tensile specimens were cut longitudinally and transversely by wire cutting. Static tensile tests were carried out at room temperature with a tensile speed of 1 mm / min. The results showed that the longitudinal tensile strength of the additive specimens reached 409 MPa, the yield strength reached 215 MPa, and the elongation reached 25%; the transverse tensile strength reached 401 MPa, the yield strength reached 209 MPa, and the elongation reached 21%, which can meet the requirements of practical applications. Example 3

[0023] The method described in this process is used for manufacturing, and the implementation process is as follows: 7A52 aluminum alloy is used as the substrate, 5R59 aluminum-scandium welding wire is used as the wire material, the substrate specifications are: length * width * thickness = 350 * 200 * 20mm, and the diameter of 5R59 aluminum-scandium welding wire is 1.2mm. Clean the substrate, remove oxides and oil stains on the surface of the substrate with a handheld angle grinder, wipe it with acetone and fix it on the laboratory table; select CMT mode on the CMT welding power supply and adjust the wire feed speed to 9.5m / min, current to 155A, and voltage to 15.6V; adjust the welding speed of the welding gun to 60cm / min through the operating handle panel, and use a reciprocating scanning forming path in its welding program programming, and set the inter-layer waiting time to 90s; adjust the position of the welding gun so that it is located at one end above the substrate, adjust the welding gun angle and height so that the central axis of the welding gun is perpendicular to the upper surface of the substrate at 90°, adjust the welding wire dry extension to 8mm, the welding wire tip is 4mm away from the substrate, and adjust the shielding gas flow rate to 20L / min; start the arc at one end of the substrate to start the first layer of additive deposition; After one layer of deposition is completed, the welding gun is lifted up by 3mm. During the waiting time, the wire feeding speed is adjusted to 8m / min, the current is 119A, and the voltage is 14.7V. After the adjustment is completed and the waiting time between layers is over, the second layer of deposition is started. After the second layer of deposition is completed, the welding gun is lifted up by 3mm. During the waiting time, the wire feeding speed is adjusted to 6.0m / min, the current is 82A, and the voltage is 12.8V. After the adjustment is completed and the waiting time between layers is over, the third layer of deposition is started. After the third layer of deposition is completed, the welding gun is lifted up by 2.5mm. Thereafter, according to the set stable parameters, that is, the wire feeding speed is 6.5m / min, the current is 91A, the voltage is 13.3V, and the interlayer is lifted by 2.5mm. This is until the 80mm high additive sample is completed.

[0024] Figure 5 This is a macroscopic picture of the additively manufactured sample of Example 3. It can also be seen that the appearance is well formed, the layers are tightly bonded, there are few pore defects, and there are no welding defects such as biting and edge collapse.

[0025] Figure 6This is a metallographic image of the additively manufactured sample of Example 3. It can be seen that there are very few pores in its structure, and the size of some pores is also very small.

[0026] In order to test the mechanical properties of the additive specimens, plate-shaped tensile specimens were cut longitudinally and transversely by wire cutting. Static tensile tests were carried out at room temperature with a tensile speed of 1 mm / min. The results showed that the longitudinal tensile strength of the additive specimens reached 404 MPa, the yield strength reached 204 MPa, and the elongation reached 21%; the transverse tensile strength reached 400 MPa, the yield strength reached 201 MPa, and the elongation reached 20%, which can meet the requirements of practical applications.

Claims

1. A cold metal transfer arc additive manufacturing process compatible with 5R59 aluminum-scandium welding wire, characterized by: (1) In a dry and windless experimental environment, use 7A52 aluminum alloy as the substrate and 5R59 aluminum-scandium welding wire as the wire. First clean the substrate surface and then fix the substrate to the experimental platform with a clamp; (2) Set the wire feed speed to 5.5-7.5 m / min, the current to 73-109 A, and the voltage to 12.3-14.3 V on the CMT welding power source, set the welding speed to 30-70 cm / min on the operating handle panel, and adopt a reciprocating scanning forming path; (3) Using shielding gas protection, the wire extension length is 8 to 10 mm, and the height and position of the welding gun are adjusted so that the welding wire is perpendicular to the substrate and the tip is 3 to 5 mm away from the substrate. The first three layers of additive manufacturing are started in a decreasing manner with a large current. During this period, the welding parameters need to be adjusted. When the third layer is added, the parameters are returned to the normal setting to stabilize the additive manufacturing. After each layer of additive manufacturing is completed, the welding gun is raised 1.5 to 3 mm in height, and after staying for 80 to 100 seconds, the next layer of welding is continued on the basis of the finished additive layer, and so on until the additive manufacturing is completed.

2. The cold metal transfer arc additive manufacturing process compatible with the 5R59 aluminum-scandium welding wire according to claim 1, characterized in that: The specifications of the substrate are: length*width*thickness=350*200*20mm.

3. The cold metal transfer arc additive manufacturing process compatible with the 5R59 aluminum-scandium welding wire according to claim 2, characterized in that: The diameter of the 5R59 aluminum-scandium welding wire is 1.2 mm.

4. The cold metal transfer arc additive manufacturing process compatible with the 5R59 aluminum-scandium welding wire according to claim 1, characterized in that: The substrate surface is cleaned by first cleaning the substrate with a handheld grinder, and then cleaning the substrate with an acetone solution to remove oxide scale and oil stains.

5. The cold metal transfer arc additive manufacturing process compatible with the 5R59 aluminum-scandium welding wire according to claim 1, characterized in that: The protective gas is 99.999% argon, and the gas flow rate is set at 15 to 20 L / min.

6. The cold metal transfer arc additive manufacturing process compatible with the 5R59 aluminum-scandium welding wire according to claim 3, characterized in that: The first three layers of material addition are started in a decreasing manner with a large current. During this period, the welding parameters need to be adjusted as follows: the current is 150A for the first layer, and is gradually reduced to 119A for the second layer. At the third layer, the parameters are returned to the normal setting to stabilize the material addition.

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