A preparation method for fabricating copper-steel bimetal by TIG twin-wire arc additive manufacturing

Abstract

The present invention relates to a preparation method of a copper-steel dual alloy by TIG twin-wire arc additive manufacturing, belonging to the technical field of additive manufacturing of metal materials. The method is carried out by using a TIG twin-wire additive manufacturing system and a CNC machine tool, and the steps are as follows: fixing a steel substrate in the CNC machine tool and preheating it, and depositing welding wires on the steel substrate by using the TIG twin-wire additive manufacturing system to obtain a copper-steel dual alloy in which the steel side and the copper side are connected; the steel side is obtained by layer-by-layer deposition of a low-alloy steel welding wire, and the copper side is obtained by layer-by-layer deposition of a tin bronze welding wire; in the additive manufacturing of the steel side and the copper side, the parameters required for manufacturing are set as needed. The method uses the TIG twin-wire additive manufacturing system to carry out in-situ manufacturing of the copper-steel dual alloy, and can obtain a copper-steel dual alloy material with good interfacial bonding performance. The interfacial bonding part of the copper-steel dual alloy material has good strength and excellent hardness performance, thereby improving the mechanical properties of the copper-steel dual alloy material.

Description

Technical Field

[0001] The present invention relates to a preparation method of a copper-steel dual alloy by TIG twin-wire arc additive manufacturing, belonging to the technical field of metal material additive manufacturing. Background Art

[0002] As an important metal in industry, copper and copper alloys have excellent properties such as good electrical conductivity, strong thermal conductivity, excellent toughness at low and normal temperatures, and good corrosion resistance. However, they also have problems such as low strength, high specific gravity, and difficulty in reducing the weight of parts. Steel, as the metal material with the largest industrial consumption, has ultra-low-cost components and excellent comprehensive mechanical properties such as high strength and high ductility. Therefore, the dual alloy parts composed of copper and steel can combine the advantages of copper and steel. Furthermore, the copper-steel dual alloy material has good application prospects and can play an important role in fields such as aerospace, nuclear power, shipbuilding, vehicles, and petrochemical industry.

[0003] Although the copper-steel dual alloy material has good functionality and practical value, due to the differences in thermophysical properties between copper and steel, especially the large differences in melting point, linear expansion coefficient, specific heat capacity, thermal conductivity, density, etc., cracks and pores are likely to appear during the preparation of the copper-steel dual alloy, as well as the phenomenon of poor forming or inability to form due to unstable arc. Because of the large property differences between copper and steel, it is difficult to prepare a copper-steel dual alloy material with good interfacial bonding performance by existing methods.

[0004] Wire Arc Additive Manufacturing (WAAM) is a kind of additive manufacturing technology. It uses an arc as the heat source, and through a wire feeding system, the metal wire is transported to the welding torch to heat and melt the metal wire. The molten metal drips according to the path set by the program and is stacked layer by layer for rapid forming. The wire arc additive manufacturing technology has the characteristics of high heat input, fast forming speed, and is suitable for low-cost, high-efficiency and rapid forming of large-size complex components.

[0005] During the preparation process of the dual alloy material, whether using traditional preparation methods or wire arc additive manufacturing technology, the improvement and enhancement of its interfacial bonding performance are worthy of attention. For copper and steel with large differences in thermophysical properties, how to use arc additive manufacturing technology to prepare a copper-steel dual alloy material with good interfacial bonding performance is a technical problem to be solved in this field. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a preparation method for TIG double-wire arc additive manufacturing of copper-steel bimetal. The method uses a TIG double-wire additive manufacturing system to obtain a copper-steel bimetal with better interfacial bonding performance, thereby improving the mechanical properties of the copper-steel bimetal.

[0007] To achieve the purpose of the present invention, the following technical solutions are provided.

[0008] A preparation method for TIG double-wire arc additive manufacturing of copper-steel bimetal, the method is carried out using a tungsten inert gas shielded welding double-wire additive manufacturing system (abbreviation: TIG double-wire additive manufacturing system) and a computer numerical control machine tool (abbreviation: CNC machine tool), and the method steps are as follows:

[0009] Fix the steel substrate in the CNC machine tool and preheat it. Use the TIG double-wire additive manufacturing system to deposit the welding wire on the steel substrate to obtain a copper-steel bimetal with the steel side and the copper side connected; the steel side is obtained by layer-by-layer deposition of low-alloy steel welding wire, and the copper side is obtained by layer-by-layer deposition of tin bronze welding wire;

[0010] During the additive manufacturing of the steel side and the copper side, the welding torch scanning speed of the TIG double-wire additive manufacturing system is 80 mm / min to 120 mm / min, the pulse frequency is 1.5 Hz, and the wire feeding speed is 80 cm / min to 100 cm / min; the shielding gas is argon, and the argon gas flow rate is 18 L / min to 22 L / min;

[0011] The additive manufacturing parameters of the steel side are: after starting deposition, after each layer of deposition is completed, lower the peak current, peak duty cycle time, and base current duty cycle until the peak current is 160 A to 180 A, the peak duty cycle time is 15% to 17%, and the base current duty cycle is 24% to 26%. Continue to deposit more than one layer under the above adjusted parameters until the deposition of the steel side is completed; when the number of layers deposited continuously under the above adjusted parameters is more than one layer, the adjusted number of deposition layers is determined according to the application requirements;

[0012] The additive manufacturing parameters of the copper side are: after starting deposition, after each layer of deposition is completed, lower the peak current, peak duty cycle time, and base current duty cycle until the peak current is 110 A to 130 A, the peak duty cycle time is 14% to 16%, and the base current duty cycle is 23% to 25%. Continue to deposit more than one layer under the above adjusted parameters until the deposition of the copper side is completed; when the number of layers deposited continuously under the above adjusted parameters is more than one layer, the adjusted number of deposition layers is determined according to the application requirements.

[0013] Preferably, a TIG twin-wire additive manufacturing system is used to deposit a low-alloy steel wire layer by layer onto a steel substrate to obtain a steel side, and then a tin bronze wire is deposited layer by layer onto the upper surface of the steel side to obtain a copper side. After the additive manufacturing is completed, it is cooled to room temperature to obtain a copper-steel dual alloy.

[0014] Preferably, the additive manufacturing parameters for the steel side are as follows: First, deposit under the conditions that the peak current is 200A - 240A, the peak duty cycle is 18% - 22%, and the base current duty cycle is 27% - 33%. Then, after the deposition of each layer is completed, lower the peak current, peak duty cycle, and base current duty cycle, and ensure that the change in the average arc voltage is ≤1V during each adjustment until the peak current is 160A - 180A, the peak duty cycle is 15% - 17%, and the base current duty cycle is 24% - 26%. Continue to deposit more than one layer under the above adjusted parameters until the deposition of the steel side is completed. When the number of layers deposited under the above adjusted parameters is more than one layer, the number of adjusted deposition layers is determined according to application requirements.

[0015] The additive manufacturing parameters for the copper side are as follows: First, deposit under the conditions that the peak current is 160A - 180A, the peak duty cycle is 15% - 17%, and the base current duty cycle is 24% - 26%. Then, during the deposition of each subsequent layer, lower the peak current, peak duty cycle, and base current duty cycle, and ensure that the change in the average arc voltage is ≤1V during each adjustment until the peak current is 110A - 130A, the peak duty cycle is 14% - 16%, and the base current duty cycle is 23% - 25%. Continue to deposit more than one layer under the above adjusted parameters until the deposition of the copper side is completed. When the number of layers deposited under the above adjusted parameters is more than one layer, the number of adjusted deposition layers is determined according to application requirements.

[0016] Preferably, the low-alloy steel wire is an ER50-3 low-alloy steel wire, and the tin bronze wire is an SCu5210 tin bronze wire. The diameters of both wires are 1.0mm - 1.5mm.

[0017] Preferably, the process parameters for preheating the steel substrate are as follows: the welding torch scanning speed is 100mm / min - 120mm / min, the peak current is 200A - 240A, the peak duty cycle is 18% - 22%, the base current duty cycle is 28% - 32%, and the pulse frequency is 1.5Hz. The number of preheating passes for the steel substrate is 2 passes.

[0018] Preferably, the single-layer deposition height of the steel side is 1.1mm - 1.5mm, and the single-layer deposition height of the copper side is 1.0mm - 1.4mm.

[0019] In the present invention, the base current duty cycle is the percentage of the base current to the peak current.

[0020] Beneficial effects

[0021] 1. The present invention provides a preparation method for TIG twin - wire arc additive manufacturing of copper - steel bimetal. The method uses a TIG twin - wire additive manufacturing system for in - situ manufacturing of copper - steel bimetal, and under the parameters of the present invention, a copper - steel bimetal material with good interfacial bonding performance can be obtained. The interfacial bonding part of the copper - steel bimetal material has good strength and excellent hardness performance, thereby improving the mechanical properties of the copper - steel bimetal material. The method is prepared using a TIG twin - wire additive manufacturing system, which simplifies the preparation process of the copper - steel bimetal material and improves work efficiency.

[0022] 2. The present invention provides a preparation method for TIG twin - wire arc additive manufacturing of copper - steel bimetal. The method is based on the principle of layer - by - layer stacking. The previous deposited layer plays a good pre - heating role for the subsequent deposited layer, and the subsequent deposited layer plays a good heat - treatment role for the previous layer, making the structures on the steel side and the copper side more uniform and finer. At the same time, the mechanical properties at the copper - steel interface connection are also improved.

[0023] 3. The present invention provides a preparation method for TIG twin - wire arc additive manufacturing of copper - steel bimetal. The preferred deposition sequence of the method is to deposit low - alloy steel first and then tin bronze. The tin bronze with a lower melting point melts first in the molten pool. Due to the action of capillary effect, the liquid copper fills into the cracks inside the steel deposition layer, achieving self - repair in structure, realizing crack self - healing, effectively preventing the further growth of cracks, better improving the interfacial bonding force, and thus significantly enhancing the mechanical properties of the whole structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the macroscopic morphology diagram of the copper - steel bimetal thin - wall part prepared in Example 1.

[0025] Figure 2 It is the microscopic morphology diagram of the copper - steel interface in the copper - steel bimetal thin - wall part prepared in Example 1.

[0026] Figure 3 It is the micro - hardness distribution diagram of the copper - steel bimetal thin - wall part prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present invention will be further described below in conjunction with the drawings and specific embodiments. Among them, the methods are all conventional methods unless otherwise specified, and the raw materials can all be obtained from public commercial channels or prepared according to the literature unless otherwise specified.

[0028] In the following embodiments, the base - current ratio is the percentage of the base current to the peak current.

[0029] Example 1

[0030] A preparation method of a copper-steel dual alloy by TIG twin-wire arc additive manufacturing. The method is carried out by using a tungsten inert gas shielded welding twin-wire additive manufacturing system (abbreviation: TIG twin-wire additive manufacturing system) and a computer numerical control machine tool (abbreviation: CNC machine tool). The steps of the method are as follows:

[0031] Fix a steel substrate with a length of 300 mm, a width of 300 mm, and a thickness of 3 mm in the CNC machine tool and preheat it. Then, use the TIG twin-wire additive manufacturing system to deposit low alloy steel welding wire layer by layer on the steel substrate to obtain the steel side. Next, deposit tin bronze welding wire layer by layer on the upper surface of the steel side to obtain the copper side. After the additive manufacturing is completed, cool it to room temperature to obtain a copper-steel dual alloy thin-walled part;

[0032] During the additive manufacturing of the steel side and the copper side, the welding torch scanning speed of the TIG twin-wire additive manufacturing system is 100 mm / min, the pulse frequency is 1.5 Hz, and the wire feeding speed is 90 cm / min; the shielding gas is argon, and the argon gas flow rate is 20 L / min;

[0033] The additive manufacturing parameters of the steel side are: first deposit layer by layer under the conditions of a peak current of 220 A, a peak duty cycle time of 20%, and a base current duty ratio of 30%. Then, after the deposition of each layer is completed, lower the peak current, peak duty cycle time, and base current duty ratio, and ensure that the change in the average arc voltage is ≤1 V during each adjustment until the peak current is 170 A, the peak duty cycle time is 16%, and the base current duty ratio is 25%. Continue to deposit more than one layer under the above adjusted parameters until the deposition of the steel side is completed. In this embodiment, 7 layers are continuously deposited under the above adjusted parameters;

[0034] The additive manufacturing parameters of the copper side are: first deposit layer by layer under the conditions of a peak current of 170 A, a peak duty cycle time of 16%, and a base current duty ratio of 25%. Then, after the deposition of each layer is completed, lower the peak current, peak duty cycle time, and base current duty ratio, and ensure that the change in the average arc voltage is ≤1 V during each adjustment until the peak current is 120 A, the peak duty cycle time is 15%, and the base current duty ratio is 24%. Continue to deposit more than one layer under the above adjusted parameters until the deposition of the copper side is completed. In this embodiment, 16 layers are continuously deposited under the above adjusted parameters.

[0035] The low alloy steel welding wire is an ER50-3 low alloy steel welding wire, and the tin bronze welding wire is an SCu5210 tin bronze welding wire. The diameters of both welding wires are 1.0 mm.

[0036] The parameters for preheating the steel substrate are as follows: the welding torch scanning speed is 100 mm / min, the peak current is 220 A, the peak duty cycle time is 20%, the base current duty ratio is 30%, and the pulse frequency is 1.5 Hz; the number of preheating passes for the steel substrate is 2 passes.

[0037] The single-layer deposition height on the steel side is 1.3 mm, and the number of deposition layers is 25; the single-layer deposition height on the copper side is 1.2 mm, and the number of deposition layers is 25.

[0038] The macroscopic morphology diagram of the copper-steel dual-alloy thin-walled part prepared in this embodiment is as Figure 1 shown. The shape of the prepared copper-steel dual-alloy thin-walled part is a cuboid cylinder, and its dimensions are: length 55 mm, width 29 mm, height 54 mm, and wall thickness 4 mm. The copper-steel dual-alloy thin-walled part prepared by the TIG twin-wire arc additive manufacturing method in this embodiment has a dense layer deposition morphology, good structural formability, and no obvious welding defects such as cracks and pores.

[0039] Use an Instron 5966 universal testing machine to conduct mechanical property tests on ER50-3 low-alloy steel thin-walled parts and SCu5210 tin bronze thin-walled parts obtained with the same additive manufacturing parameters corresponding to this embodiment, as well as the copper-steel dual-alloy thin-walled part prepared in this embodiment at room temperature: at room temperature, the tensile strength of the copper-steel interface of the copper-steel dual-alloy thin-walled part is 370.1 MPa; the tensile strength of the ER50-3 low-alloy steel thin-walled part is 512.7 MPa; the tensile strength of the SCu5210 tin bronze thin-walled part is 314.2 MPa; according to the mechanical property test results, the tensile strength of the interface of the copper-steel dual-alloy thin-walled part is between the two base metals. Compared with the prior art, the interface strength of the copper-steel dual-alloy thin-walled part prepared in this embodiment has been further improved.

[0040] Use a Hitachi Regulus 8230 scanning electron microscope to observe the microscopic morphology of the copper-steel interface of the copper-steel dual-alloy thin-walled part, as Figure 2 shown. In the copper-steel dual-alloy thin-walled part, there is a copper-steel transition zone with a width of about 1 mm and obvious boundaries between the low-alloy steel and the tin bronze. The reason for the formation of this copper-steel transition zone is that the liquid metal copper infiltrates along the grain boundaries of the steel to the steel side, and the liquid copper has a filling effect on the cracks inside the steel-side deposition layer, achieving self-repair in terms of structure, realizing the self-healing of cracks, being able to effectively prevent the further growth of cracks, improving the interfacial bonding force, and thus significantly enhancing the mechanical properties of the entire structure.

[0041] The microhardness of the copper-steel bimetallic thin-walled part prepared in this example was characterized using a micro Vickers hardness tester model HVST-1000Z from Shanghai Juhui Instrument Manufacturing Co., Ltd. The hardness distribution map is as Figure 3 shown. It can be seen from Figure 3 that the average hardness of the ER50-3 low alloy steel deposition layer is 167 HV 0.5 , the average hardness of the SCu5210 tin bronze deposition layer is 85 HV 0.5 , and the average hardness of the copper-steel interface transition zone is 234 HV 0.5 . Thus, it can be known that the average hardness of the copper-steel interface transition zone is significantly higher than that of the two base metals. According to the common knowledge in the art, the hardness of the interface transition zone generally lies between the two base metals. However, this example has verified that a copper-steel bimetallic alloy with excellent hardness at the interface can be obtained by using a TIG twin-wire additive manufacturing system under the corresponding preparation conditions.

[0042] The present invention includes but is not limited to the above embodiments. Any equivalent replacement or partial improvement made under the principle of the spirit of the present invention will be regarded as within the protection scope of the present invention.

Claims

1. A preparation method for TIG double-wire arc additive manufacturing of copper-steel dual alloy, characterized in that: The method is carried out by using a TIG twin-wire additive manufacturing system and a CNC machine tool, and the steps are as follows: Fix the steel substrate in the CNC machine tool and preheat it. First, use the TIG twin-wire additive manufacturing system to deposit the low-alloy steel wire layer by layer onto the steel substrate to obtain the steel side, and then deposit the tin bronze wire layer by layer onto the upper surface of the steel side to obtain the copper side. After the additive manufacturing is completed, cool it to room temperature to obtain a copper-steel dual alloy with the steel side and the copper side connected; the steel side is obtained by depositing the low-alloy steel wire layer by layer, and the copper side is obtained by depositing the tin bronze wire layer by layer; During the additive manufacturing of the steel side and the copper side, the welding torch scanning speed of the TIG twin-wire additive manufacturing system is 80 mm / min to 120 mm / min, the pulse frequency is 1.5 Hz, and the wire feeding speed is 80 cm / min to 100 cm / min; the shielding gas is argon, and the argon gas flow rate is 18 L / min to 22 L / min; The additive manufacturing parameters of the steel side are: first deposit under the conditions of a peak current of 200 A to 240 A, a peak duty cycle time of 18% to 22%, and a base current duty cycle of 27% to 33%. Then, after the deposition of each layer is completed, lower the peak current, peak duty cycle time, and base current duty cycle, and ensure that the change in the average arc voltage is ≤1 V during each adjustment until the peak current is 160 A to 180 A, the peak duty cycle time is 15% to 17%, and the base current duty cycle is 24% to 26%. Continue to deposit more than one layer under the above adjusted parameters until the deposition of the steel side is completed; The additive manufacturing parameters of the copper side are: first deposit under the conditions of a peak current of 160 A to 180 A, a peak duty cycle time of 15% to 17%, and a base current duty cycle of 24% to 26%. Then, after the deposition of each layer is completed, lower the peak current, peak duty cycle time, and base current duty cycle, and ensure that the change in the average arc voltage is ≤1 V during each adjustment until the peak current is 110 A to 130 A, the peak duty cycle time is 14% to 16%, and the base current duty cycle is 23% to 25%. Continue to deposit more than one layer under the above adjusted parameters until the deposition of the copper side is completed.

2. The preparation method of a copper-steel dual-alloy by TIG twin-wire arc additive manufacturing according to claim 1, wherein: The low-alloy steel wire is an ER50-3 low-alloy steel wire, and the tin bronze wire is an SCu5210 tin bronze wire. The diameters of both wires are 1.0 mm to 1.5 mm.

3. The preparation method of a copper-steel dual alloy by TIG twin-wire arc additive manufacturing according to claim 2, characterized in that: The process parameters for preheating the steel substrate are: the welding torch scanning speed is 100 mm / min to 120 mm / min, the peak current is 200 A to 240 A, the peak duty cycle time is 18% to 22%, the base current duty cycle is 28% to 32%, and the pulse frequency is 1.5 Hz; the number of preheating passes of the steel substrate is 2 passes.

4. A preparation method of a copper-steel dual alloy by TIG twin-wire arc additive manufacturing according to claim 3, characterized in that: The single-layer deposition height of the steel side is 1.1 mm to 1.5 mm, and the single-layer deposition height of the copper side is 1.0 mm to 1.4 mm.

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