Hot isostatic pressure diffusion welding method for copper bar and alloy steel rotating shaft

Abstract

The invention provides a hot isostatic pressure diffusion welding method for a copper bar and an alloy steel rotating shaft, which comprises the following steps: (1) respectively carrying out surface treatment on the copper bar and the alloy steel rotating shaft to obtain a treated copper bar and a treated alloy steel rotating shaft; (2) assembling the treated copper bar and the treated alloy steel rotating shaft, putting the assembled copper bar and alloy steel rotating shaft into a sheath, and welding the sheath; and (3) sequentially carrying out degassing treatment and hot isostatic pressure diffusion welding, removing the sheath, and machining to obtain a finished product. The method is easy to operate, firm welding of dissimilar metal with the curved welding face is achieved, the quality of the welding face is high, the tensile strength of a welding joint is high, and the method is suitable for large-range application and popularization.

Description

Technical Field

[0001] The present invention relates to the technical field of dissimilar metal welding, and in particular to a hot isostatic pressing diffusion welding method for a copper busbar and an alloy steel rotating shaft. Background Art

[0002] Copper, as a metal material with excellent physical and chemical properties, has excellent electrical conductivity, thermal conductivity, and strong anti-magnetic ability, making it an excellent medium plate material. However, copper has low strength and cannot be used as some components that need to bear high loads for connection and fixation. Alloy steel has good mechanical strength and connectivity and is very suitable for high-precision and high-strength working environments, but its thermal conductivity is poor, and its electrical conductivity and anti-magnetic ability are average. The copper-alloy steel composite structure not only has the good mechanical properties and connectivity of alloy steel but also has the excellent thermal conductivity, electrical conductivity, and anti-magnetic property of copper. Therefore, it has broad application prospects in the fields of motor rotating shafts, consumer electronics, new energy, and electric power.

[0003] At present, the welding methods for copper busbar-alloy steel rotating shafts mainly include friction welding, explosion welding, brazing, diffusion welding, and laser welding. When using friction welding, the weld quality is stable, but the welding efficiency is low. Explosion welding cannot meet the requirements of products with high requirements for the deformation amount of the welding surface. Although brazing can achieve the welding between dissimilar metals of copper and alloy steel, and the quality of the welded joint is good, however, the weld is easily affected by the size of the welded workpiece, and the welding efficiency is low and it is not environmentally friendly. The laser welding process is complex and affected by factors such as welding speed, laser power, power density, pulse width, and defocus amount. Diffusion welding is carried out by heating in a vacuum or in a protective atmosphere furnace. During the heat preservation process, the microscopic unevenness on the surfaces of copper and alloy steel produces plastic deformation under high temperature and high pressure, so that they are in close contact, and during the heat preservation process, the mutual diffusion between atoms realizes the welding process of copper and alloy steel. No oxides and other impurities are generated during the welding process, thus ensuring the quality and strength of the welded joint.

[0004] CN116689929A discloses a hot isostatic pressing diffusion bonding method for copper and stainless steel and a copper and stainless steel welded plate. The hot isostatic pressing diffusion bonding method for copper and stainless steel includes the following steps: Step 1: Treat the surfaces of the copper and stainless steel to be joined to make the surfaces to be joined smooth and free of impurities; Step 2: Package the copper and stainless steel obtained in Step 1 with a sheath and vacuum seal; Step 3: Perform hot isostatic pressing diffusion bonding on the sheath obtained in Step 2 to obtain a finished product; wherein, the specific steps of Step 2 are: Load the copper and stainless steel into the sheath for assembly connection, then send it into a vacuum degassing furnace and heat it up to 300-350°C, keep it warm for 3-5 hours, and during this process, evacuate the sheath to form a seal. However, the average tensile strength and the bonding rate of the welded surface of the obtained welded joint are unstable. Laying graphite paper between the copper and stainless steel and the sheath can prevent the copper and stainless steel from sticking to the sheath, but under high temperature and high pressure, the graphite paper has a certain degree of pollution to the weld seam, thereby reducing the welding quality. During the surface treatment before welding, the surfaces to be joined of the copper and stainless steel are polished and leveled, and the surfaces to be joined are immersed in dilute hydrochloric acid or dilute sulfuric acid, and then rinsed with alcohol multiple times, ignoring that copper is easy to oxidize. If the moisture is not fully dried before welding, it will affect the welding quality. During the degassing process, too low heating temperature and holding time cannot completely remove the oxygen and water vapor in the sheath, reducing the tensile strength of the welded joint and the bonding rate of the welded surface.

[0005] CN116748738A discloses a diffusion welding filler metal and a diffusion welding method for connecting chromium zirconium copper and stainless steel. The filler metal is a Ni-Cr-B-Si-P alloy filler metal, and its components by weight percentage include: Cr 4%-6%, B 0.5%-0.6%, Si 1%-1.5%, P 0.5%-3%, and the balance is Ni. As a connecting material, this alloy filler metal realizes the diffusion brazing connection between chromium zirconium copper and stainless steel by holding at 860°C-930°C for 3-5 minutes under a certain vacuum degree and pressure. Using the Ni-Cr-B-Si-P alloy filler metal, by spraying and assembling methods, a liquid phase is formed by diffusion on the mating surfaces of the chromium zirconium copper main body and the stainless steel main body, realizing the diffusion brazing connection between chromium zirconium copper and stainless steel. The main disadvantage is that the process of spraying the filler metal on the assembly surfaces of the chromium zirconium copper main body and the stainless steel main body is complex, and it is difficult to control the spraying angle and the coating thickness.

[0006] Moreover, the above diffusion welding method is not suitable for welding dissimilar metals with a curved welding surface. Therefore, it is of great significance to develop a hot isostatic pressing diffusion welding method suitable for copper bars and alloy steel rotating shafts. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides a hot isostatic pressing diffusion welding method for a copper busbar and an alloy steel rotating shaft. By surface-treating the copper busbar and the alloy steel rotating shaft before welding, and using high-temperature degassing to fully remove moisture and oxygen in the stainless steel jacket, oxides and other impurities are prevented from being generated. Through hot isostatic pressing diffusion welding, the atoms on the welding surfaces of the copper busbar and the alloy steel rotating shaft are bonded, achieving a dense and stable welding joint with high tensile strength.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] The present invention provides a hot isostatic pressing diffusion welding method for a copper busbar and an alloy steel rotating shaft, and the hot isostatic pressing diffusion welding method includes the following steps:

[0010] (1) Surface-treat the copper busbar and the alloy steel rotating shaft respectively to obtain the treated copper busbar and the treated alloy steel rotating shaft;

[0011] (2) After assembling the treated copper busbar and the treated alloy steel rotating shaft, place them in a jacket and perform jacket welding;

[0012] (3) After performing degassing treatment and hot isostatic pressing diffusion welding in sequence, remove the jacket, and obtain the finished product through machining;

[0013] The heating process of the degassing treatment is divided into two stages. In the first stage, the temperature is raised at a heating rate of 3 - 5 °C / min to 100 - 200 °C; in the second stage, the temperature is raised at a heating rate of 3 - 5 °C / min to 480 - 550 °C.

[0014] The hot isostatic pressing diffusion welding method for a copper busbar and an alloy steel rotating shaft of the present invention fully considers that the welding surface between the copper busbar and the alloy steel rotating shaft is a curved surface, where there are problems such as uneven distribution of heat input, easy occurrence of local overheating or lack of fusion, and easy generation of stress concentration in curved surface welding, increasing the risk of deformation and cracks. First, surface-treating the copper busbar and the alloy steel rotating shaft can effectively remove contaminants, improve flatness, and reduce the oxide layer, ensuring the cleanliness and uniformity of the curved surface area to be welded, which is beneficial to improving the subsequent welding quality and bonding strength; then, after assembling the treated copper busbar and the treated alloy steel rotating shaft and performing jacket welding, two-stage heating degassing treatment is carried out. In the first stage, water vapor, oxygen and other gases adsorbed on the surfaces of the copper busbar and the alloy steel rotating shaft are removed to avoid the formation of pores or inclusions by these gases, which affect the welding quality; in the second stage, hydrogen, oxygen and other gases dissolved in the metal are removed to prevent the internal gases from precipitating during the welding process, resulting in pores or cracks; after the degassing treatment under the specific conditions, the microstructure of the welding joint is more uniform, which can improve the strength, toughness and corrosion resistance of the joint; finally, hot isostatic pressing diffusion welding is carried out to obtain a combined product of a copper busbar and an alloy steel rotating shaft with high welding surface quality and high joint strength.

[0015] In the heating-up process of the degassing treatment according to the present invention, it is divided into two stages. In the first stage, the heating rate is 3 - 5 °C / min. For example, it can be 3 °C / min, 3.5 °C / min, 3.8 °C / min, 4 °C / min, 4.5 °C / min or 5 °C / min, etc., but it is not limited to the listed values, and other unlisted values within this value range are equally applicable;

[0016] Heat up to 100 - 200 °C. For example, it can be 100 °C, 105 °C, 110 °C, 130 °C, 150 °C, 180 °C or 200 °C, etc., but it is not limited to the listed values, and other unlisted values within this value range are equally applicable;

[0017] In the second stage, the heating rate is 3 - 5 °C / min. For example, it can be 3 °C / min, 3.5 °C / min, 3.8 °C / min, 4 °C / min, 4.5 °C / min or 5 °C / min, etc., but it is not limited to the listed values, and other unlisted values within this value range are equally applicable;

[0018] Heat up to 480 - 550 °C. For example, it can be 480 °C, 490 °C, 500 °C, 510 °C, 520 °C, 530 °C or 550 °C, etc., but it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0019] Preferably, the surface treatment process of the copper bar in step (1) includes performing the first polishing treatment and ultrasonic cleaning in sequence.

[0020] Preferably, the first polishing treatment includes first polishing with 320# sandpaper and then finely grinding with 1000# sandpaper.

[0021] Preferably, the ultrasonic cleaning is carried out with isopropyl alcohol solution for 10 - 15 min. For example, it can be 10 min, 10.5 min, 11 min, 12 min, 13 min, 14 min or 15 min, etc., but it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0022] Preferably, after the ultrasonic cleaning, it is vacuum dried at 60 - 70 °C. For example, it can be 60 °C, 62 °C, 64 °C, 66 °C, 68 °C or 70 °C, etc., but it is not limited to the listed values, and other unlisted values within this value range are equally applicable;

[0023] For 1 - 2 h. For example, it can be 1 h, 1.2 h, 1.5 h, 1.6 h, 1.8 h, 1.9 h or 2 h, etc., but it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0024] Step (1) The surface treatment process of the alloy steel rotating shaft includes performing second polishing treatment and immersion scrubbing in sequence.

[0025] Preferably, the second polishing treatment is carried out using 320# sandpaper.

[0026] Preferably, for the immersion scrubbing, it is carried out by scrubbing after soaking in aviation kerosene for 10 - 15 minutes, for example, it can be 10 minutes, 10.5 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes or 15 minutes, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0027] Preferably, it is dried after the immersion scrubbing.

[0028] The present invention preferably uses a steel brush for scrubbing, and after scrubbing, uses a purification cloth to wipe clean the residual aviation kerosene on the surface of the alloy steel rotating shaft. The immersion scrubbing described in the present invention can be repeated 2 - 3 times as needed until the surface and grooves of the alloy steel rotating shaft are clean.

[0029] Preferably, the sleeve in step (2) includes a 304 stainless steel sleeve, and preferably the upper and lower cover plates are of an inlaid design.

[0030] Preferably, argon is used as the pressure medium for the hot isostatic pressing diffusion welding in step (3).

[0031] Preferably, the temperature of the hot isostatic pressing diffusion welding in step (3) is 900 - 1000 °C, for example, it can be 900 °C, 920 °C, 940 °C, 960 °C, 980 °C or 1000 °C, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0032] Preferably, the pressure of the hot isostatic pressing diffusion welding in step (3) is 100 - 180 MPa, for example, it can be 100 MPa, 110 MPa, 130 MPa, 150 MPa, 160 MPa, 170 MPa or 180 MPa, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0033] The present invention preferably has the temperature of the hot isostatic pressing diffusion welding as 900 - 1000 °C, which can promote atomic diffusion, accelerate the interfacial reaction and reduce the yield strength; the pressure of the hot isostatic pressing diffusion welding is 100 - 180 MPa, which can make the welding surface in close contact, reduce voids and defects, promote plastic deformation, increase the atomic diffusion rate, and accelerate the bonding of the welding interface. Moreover, the combination of the temperature and pressure within this specific range can not only control the microstructure of the welding area, improve the material properties, but also achieve high-quality welding, ensuring good interfacial bonding and no defects.

[0034] Preferably, the heat isostatic pressing diffusion welding in step (3) has a heat preservation and pressure holding time of 5 to 8 hours. For example, it can be 5 hours, 5.2 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 8 hours, etc., but it is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0035] Preferably, the tensile strength of the welded joint of the finished product in step (3) > 200 MPa. For example, it can be 201 MPa, 210 MPa, 220 MPa, 250 MPa, 300 MPa, 400 MPa, etc., but it is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0036] As a preferred technical solution of the present invention, the heat isostatic pressing diffusion welding method includes the following steps:

[0037] (1) The copper busbar is sequentially subjected to the first polishing treatment and ultrasonic cleaning to obtain the treated copper busbar;

[0038] The first polishing treatment includes first polishing with 320# sandpaper and then fine grinding with 1000# sandpaper; the ultrasonic cleaning is carried out with isopropyl alcohol solution for 10 - 15 minutes; after the ultrasonic cleaning, it is vacuum dried at 60 - 70 °C for 1 - 2 hours;

[0039] The alloy steel rotating shaft is sequentially subjected to the second polishing treatment and immersion scrubbing to obtain the treated alloy steel rotating shaft;

[0040] The second polishing treatment is carried out with 320# sandpaper; the immersion scrubbing is carried out by soaking in aviation kerosene for 10 - 15 minutes and then scrubbing; after the immersion scrubbing, it is dried;

[0041] (2) After the treated copper busbar and the treated alloy steel rotating shaft are assembled, they are placed in a 304 stainless steel jacket and the jacket is welded;

[0042] (3) After degassing treatment and heat isostatic pressing diffusion welding with a pressure of 100 - 180 MPa, a temperature of 900 - 1000 °C, and a heat preservation and pressure holding time of 5 - 8 hours, the jacket is removed, and after machining, a finished product with a tensile strength of the welded joint > 200 MPa is obtained;

[0043] The temperature rising process of the degassing treatment is divided into two stages. The first stage rises to 100 - 200 °C at a temperature rising rate of 3 - 5 °C / min; the second stage rises to 480 - 550 °C at a temperature rising rate of 3 - 5 °C / min;

[0044] Argon is used as the pressure medium for the heat isostatic pressing diffusion welding.

[0045] Compared with the prior art, the present invention has at least the following beneficial effects:

[0046] The hot isostatic pressing diffusion welding method for copper busbars and alloy steel rotating shafts provided by the present invention is simple to operate, realizes the firm welding of dissimilar metals with a curved welding surface, has a high-quality welding surface and a high tensile strength of the welded joint, and is suitable for wide promotion and application. Specific Embodiments

[0047] To facilitate the understanding of the present invention, the following examples are listed. Those skilled in the art should understand that the said examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0048] The present invention will be further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the patent protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0049] The following are typical but non-limiting embodiments of the present invention:

[0050] Example 1

[0051] This example provides a hot isostatic pressing diffusion welding method for copper busbars and alloy steel rotating shafts. The hot isostatic pressing diffusion welding method includes the following steps:

[0052] (1) The copper busbar is successively subjected to a first polishing treatment and ultrasonic cleaning to obtain a treated copper busbar;

[0053] The first polishing treatment includes first polishing with 320# sandpaper and then finely grinding with 1000# sandpaper; the ultrasonic cleaning is carried out with isopropyl alcohol solution for 13 minutes; after the ultrasonic cleaning, it is vacuum dried at 65°C for 1.2 hours;

[0054] The alloy steel rotating shaft is successively subjected to a second polishing treatment and immersion scrubbing to obtain a treated alloy steel rotating shaft;

[0055] The second polishing treatment is carried out with 320# sandpaper; the immersion scrubbing is carried out by soaking in aviation kerosene for 13 minutes and then scrubbing; after the immersion scrubbing, it is dried;

[0056] (2) After assembling the treated copper busbar and the treated alloy steel rotating shaft, they are placed in a 304 stainless steel sheath and the sheath is welded;

[0057] (3) After successively carrying out degassing treatment and hot isostatic pressing diffusion welding at a pressure of 150 MPa, a temperature of 960°C, and a holding pressure time of 5.8 hours, the sheath is removed and the finished product is obtained through machining;

[0058] The heating process of the degassing treatment is divided into two stages. In the first stage, the temperature is raised to 160°C at a heating rate of 4°C / min; in the second stage, the temperature is raised to 520°C at a heating rate of 3.5°C / min;

[0059] The hot isostatic pressing diffusion welding uses argon as the pressure medium.

[0060] Example 2

[0061] This example provides a hot isostatic pressing diffusion welding method for a copper busbar and an alloy steel rotating shaft. The hot isostatic pressing diffusion welding method includes the following steps:

[0062] (1) The copper busbar is successively subjected to a first polishing treatment and ultrasonic cleaning to obtain a treated copper busbar;

[0063] The first polishing treatment includes first polishing with 320# sandpaper and then finely grinding with 1000# sandpaper; the ultrasonic cleaning is carried out with an isopropanol solution for 10 minutes; after the ultrasonic cleaning, it is vacuum dried at 70 °C for 1 hour;

[0064] The alloy steel rotating shaft is successively subjected to a second polishing treatment and immersion brushing to obtain a treated alloy steel rotating shaft;

[0065] The second polishing treatment is carried out with 320# sandpaper; the immersion brushing is carried out by soaking in aviation kerosene for 15 minutes and then brushing; after the immersion brushing, it is dried;

[0066] (2) After assembling the treated copper busbar and the treated alloy steel rotating shaft, they are placed in a 304 stainless steel sheath and the sheath is welded;

[0067] (3) After successively carrying out degassing treatment and hot isostatic pressing diffusion welding at a pressure of 180 MPa, a temperature of 900 °C, and a holding pressure time of 8 hours, the sheath is removed and the finished product is obtained through machining;

[0068] The heating process of the degassing treatment is divided into two stages. In the first stage, the temperature is raised to 200 °C at a heating rate of 3 °C / min; in the second stage, the temperature is raised to 480 °C at a heating rate of 5 °C / min;

[0069] The hot isostatic pressing diffusion welding uses argon as the pressure medium.

[0070] Example 3

[0071] This example provides a hot isostatic pressing diffusion welding method for a copper busbar and an alloy steel rotating shaft. The hot isostatic pressing diffusion welding method includes the following steps:

[0072] (1) The copper busbar is successively subjected to a first polishing treatment and ultrasonic cleaning to obtain a treated copper busbar;

[0073] The first polishing treatment includes first polishing with 320# sandpaper and then finely grinding with 1000# sandpaper; the ultrasonic cleaning is carried out with an isopropanol solution for 15 minutes; after the ultrasonic cleaning, it is vacuum dried at 60 °C for 2 hours;

[0074] The alloy steel rotating shaft is subjected to a second polishing treatment and an immersion scrubbing in sequence, and the alloy steel rotating shaft after treatment;

[0075] The second polishing treatment is carried out with 320# sandpaper; the immersion scrubbing is carried out by soaking in aviation kerosene for 10 minutes and then scrubbing; after the immersion scrubbing, it is dried.

[0076] (2) Assemble the treated copper bar and the treated alloy steel rotating shaft and put them into a 304 stainless steel sheath, and perform sheath welding;

[0077] (3) After degassing treatment and hot isostatic pressing diffusion welding with a pressure of 100 MPa, a temperature of 1000 °C, and a holding and pressurizing time of 5 h in sequence, remove the sheath, and obtain the finished product through machining;

[0078] The heating process of the degassing treatment is divided into two stages. In the first stage, the temperature is raised to 100 °C at a heating rate of 5 °C / min; in the second stage, the temperature is raised to 550 °C at a heating rate of 3 °C / min.

[0079] Argon is used as the pressure medium for the hot isostatic pressing diffusion welding.

[0080] From the comprehensive implementation of Examples 1 to 3, it can be seen that the hot isostatic pressing diffusion welding method for copper bars and alloy steel rotating shafts provided by the present invention is simple to operate, and finally a finished product with a high-quality welding surface and a tensile strength of the welded joint > 200 MPa is obtained.

[0081] Example 4

[0082] This example provides a hot isostatic pressing diffusion welding method for copper bars and alloy steel rotating shafts. Except that the pressure of the hot isostatic pressing diffusion welding in step (3) is 90 MPa and the temperature is 800 °C, the rest are the same as in Example 1.

[0083] Example 5

[0084] This example provides a hot isostatic pressing diffusion welding method for copper bars and alloy steel rotating shafts. Except that the pressure of the hot isostatic pressing diffusion welding in step (3) is 190 MPa and the temperature is 1100 °C, the rest are the same as in Example 1.

[0085] From the comprehensive implementation of Example 1 and Examples 4 to 5, it can be seen that in Example 4, both the pressure and temperature of the hot isostatic pressing diffusion welding are relatively low, which will cause voids on the welding surface, reduce the atomic diffusion rate, and finally result in a decrease in the surface quality of the welded joint and a tensile strength < 200 MPa; in Example 5, both the pressure and temperature of the hot isostatic pressing diffusion welding are relatively high, which will cause deformation of the welding surface, cracks in severe cases, and also cause grain growth in the metal interior, resulting in a significant decrease in the tensile strength.

[0086] Comparative Example 1

[0087] This comparative example provides a hot isostatic pressing diffusion welding method for a copper busbar and an alloy steel rotating shaft. Except that in step (3), the degassing treatment is heated to 520°C at a heating rate of 4°C / min at one time, the rest are the same as in Example 1.

[0088] Comparative Example 2

[0089] This comparative example provides a hot isostatic pressing diffusion welding method for a copper busbar and an alloy steel rotating shaft. Except that in step (3), the heating process of the degassing treatment is divided into two stages. In the first stage, it is heated to 160°C at a heating rate of 10°C / min; in the second stage, it is heated to 520°C at a heating rate of 10°C / min, the rest are the same as in Example 1.

[0090] Comparative Example 3

[0091] This comparative example provides a hot isostatic pressing diffusion welding method for a copper busbar and an alloy steel rotating shaft. Except that in step (3), the heating process of the degassing treatment is divided into two stages. In the first stage, it is heated to 230°C at a heating rate of 4°C / min; in the second stage, it is heated to 580°C at a heating rate of 10°C / min, the rest are the same as in Example 1.

[0092] From a comprehensive comparison of Example 1 and Comparative Examples 1 to 3, it can be seen that the degassing treatment in Comparative Example 1 is heated at one time, the heating rate of the degassing treatment in Comparative Example 2 is relatively fast, and the temperatures of the two stages of the degassing treatment in Comparative Example 3 are relatively high, all of which will lead to a deterioration of the degassing effect, affecting the subsequent hot isostatic pressing diffusion welding treatment effect. The surface quality of the obtained welded joint is poor and the tensile strength is much less than 200 MPa.

[0093] The applicant declares that the above description is only a specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A hot isostatic pressing diffusion welding method for a copper busbar and an alloy steel shaft, characterized in that: The hot isostatic pressing diffusion welding method comprises the following steps: (1) performing surface treatment on the copper busbar and the alloy steel shaft respectively to obtain a treated copper busbar and a treated alloy steel shaft; (2) Assembling the treated copper bar and the treated alloy steel shaft and placing them in a sheath for sheath welding; (3) After degassing and hot isostatic pressing diffusion welding, the package is removed and the finished product is obtained by machining; The temperature rise process of the degassing treatment is divided into two stages. The first stage is to heat up to 100-200°C at a heating rate of 3-5°C / min; the second stage is to heat up to 480-550°C at a heating rate of 3-5°C / min.

2. The hot isostatic pressing diffusion welding method according to claim 1, characterized in that: The surface treatment process of the copper busbar in step (1) includes sequentially performing a first polishing treatment and an ultrasonic cleaning; Preferably, the first polishing process includes first polishing with 320# sandpaper and then fine grinding with 1000# sandpaper; Preferably, the ultrasonic cleaning is performed using an isopropanol solution for 10 to 15 minutes; Preferably, the ultrasonic cleaning is followed by vacuum drying at 60-70° C. for 1-2 hours.

3. The hot isostatic pressing diffusion welding method according to claim 1 or 2, characterized in that: The surface treatment process of the alloy steel shaft in step (1) includes sequentially performing a second polishing treatment and soaking and brushing; Preferably, the second polishing process is performed using 320# sandpaper; Preferably, the immersion and brushing is performed by soaking in aviation kerosene for 10 to 15 minutes before brushing; Preferably, the soaking and brushing are followed by blow-drying.

4. The hot isostatic pressing diffusion welding method according to any one of claims 1 to 3, characterized in that: The sheath in step (2) comprises a 304 stainless steel sheath.

5. The hot isostatic pressing diffusion welding method according to any one of claims 1 to 4, characterized in that: The hot isostatic pressing diffusion welding in step (3) uses argon as the pressure medium.

6. The hot isostatic pressing diffusion welding method according to any one of claims 1 to 5, characterized in that: The temperature of the hot isostatic pressing diffusion welding in step (3) is 900-1000°C.

7. The hot isostatic pressing diffusion welding method according to any one of claims 1 to 6, characterized in that: The pressure of the hot isostatic pressing diffusion welding in step (3) is 100 to 180 MPa.

8. The hot isostatic pressing diffusion welding method according to any one of claims 1 to 7, characterized in that: The heat preservation and pressure holding time of the hot isostatic pressing diffusion welding in step (3) is 5 to 8 hours.

9. The hot isostatic pressing diffusion welding method according to any one of claims 1 to 8, characterized in that: The tensile strength of the welded joint of the finished product in step (3) is >200MPa.

10. The hot isostatic pressing diffusion welding method according to any one of claims 1 to 9, characterized in that: The hot isostatic pressing diffusion welding method comprises the following steps: (1) performing a first polishing treatment and an ultrasonic cleaning in sequence on the copper busbar to obtain a treated copper busbar; The first polishing treatment includes first polishing with 320# sandpaper and then fine grinding with 1000# sandpaper; the ultrasonic cleaning uses isopropyl alcohol solution for cleaning for 10 to 15 minutes; after the ultrasonic cleaning, vacuum drying is performed at 60 to 70°C for 1 to 2 hours; The alloy steel shaft is subjected to a second polishing treatment and an immersion and brushing treatment in sequence, and the alloy steel shaft is subjected to the treatment; The second polishing treatment is performed using 320# sandpaper; the soaking and brushing is performed using aviation kerosene soaking for 10 to 15 minutes and then brushing; and the soaking and brushing are then blown dry; (2) Assembling the treated copper bar and the treated alloy steel shaft and placing them in a 304 stainless steel sheath for sheath welding; (3) After degassing and hot isostatic pressing diffusion welding at a pressure of 100 to 180 MPa, a temperature of 900 to 1000°C, and a heat preservation and pressure holding time of 5 to 8 hours, the jacket is removed and the finished product with a tensile strength of the welded joint greater than 200 MPa is obtained by machining; The degassing treatment temperature rise process is divided into two stages. In the first stage, the temperature is raised to 100-200°C at a rate of 3-5°C / min; in the second stage, the temperature is raised to 480-550°C at a rate of 3-5°C / min. The hot isostatic pressing diffusion welding uses argon as the pressure medium.