Wire for welding large-thickness copper-steel butt joint, method for preparing same, and welding method

Abstract

The application discloses a welding wire for butt welding of copper-steel with large thickness, which comprises a powder and a welding sheath, wherein the powder is composed of the following components in percentage by mass: Ni powder 15-20%, Cr powder 10-20%, Mo powder 5-10%, Zr powder 5-10%, V powder 5-10%, Si powder 5-10%, Mn powder 5-10%, Al powder 1-3%, and the rest is Cu powder, and the sum of the percentage by mass of the above components is 100%. The welding wire solves the problems of joint cracking and performance reduction when copper and steel dissimilar materials are connected. The application further discloses a preparation method of the welding wire for butt welding of copper-steel with large thickness and a copper-steel butt welding method using the welding wire for butt welding of copper-steel with large thickness.

Description

Technical Field

[0001] This invention belongs to the field of metal material welding technology, specifically relating to welding wire for thick copper-steel butt welding. This invention also relates to a method for preparing welding wire for thick copper-steel butt welding and a method for copper-steel butt welding using welding wire for thick copper-steel butt welding. Background Technology

[0002] Dissimilar material joints often possess properties unattainable by joints made of the same material; therefore, promoting welding connections between dissimilar metals is an inevitable trend in industrial development. The welding of copper and steel is a typical example of dissimilar material joining. Although copper and steel do not contain brittle intermetallic compounds, the following problems are prone to occur during their welding process:

[0003] (1) Welds are prone to hot cracking. Because copper and steel form a low-melting-point eutectic and have a large difference in their coefficients of linear expansion, welds are prone to hot cracking and grain boundary segregation (i.e., segregation of low-melting-point eutectic alloys or copper). Therefore, under the action of large welding stress, macroscopic cracks appear during welding.

[0004] (2) Penetration cracks of copper occur in the heat-affected zone. Penetration cracks of copper are prone to occur when copper and copper alloys are welded to stainless steel. To prevent the formation of penetration cracks, it is necessary to select a reasonable welding process and use a small welding heat input; at the same time, it is also necessary to select appropriate filler materials and control the elements that are prone to forming low melting point eutectics (S, P, Cu2O, FeS, FeP).

[0005] (3) The mechanical properties of the welded joint are reduced, which affects the plasticity, toughness and conductivity of the joint.

[0006] The aforementioned reasons limit the widespread application of copper-steel dissimilar material welded joints. These problems are particularly pronounced when welding thick copper and steel plates. Summary of the Invention

[0007] The purpose of this invention is to provide a welding wire for thick copper-steel butt welding, which solves the problems of joint cracking and performance degradation when joining dissimilar materials such as copper and steel.

[0008] Another object of the present invention is to provide a method for preparing welding wire for thick copper-steel butt welding.

[0009] The third objective of this invention is to provide a method for copper-steel butt welding using a thick copper-steel butt welding wire.

[0010] The first technical solution adopted in this invention is a welding wire for thick copper-steel butt welding, comprising flux powder and welding skin, wherein the flux powder is composed of the following components by mass percentage: Ni powder 15-20%, Cr powder 10-20%, Mo powder 5-10%, Zr powder 5-10%, V powder 5-10%, Si powder 5-10%, Mn powder 5-10%, Al powder 1-3%, and the remainder is Cu powder, the sum of the mass percentages of the above components being 100%.

[0011] The invention is further characterized in that,

[0012] The particle size of each core powder is 100-200 mesh.

[0013] The soldering material is T2 copper strip, with a thickness of 0.4mm and a width of 7mm.

[0014] The filling amount of flux-cored welding wire is controlled between 30wt% and 32wt%.

[0015] The second technical solution adopted in this invention is a method for preparing the above-mentioned thick copper-steel butt welding wire, the specific steps of which are as follows:

[0016] Step 1: Weigh the following powders according to their mass percentages: Ni powder 15-20%, Cr powder 10-20%, Mo powder 5-10%, Zr powder 5-10%, V powder 5-10%, Si powder 5-10%, Mn powder 5-10%, Al powder 1-3%, and the remainder is Cu powder. The sum of the mass percentages of the above components is 100%.

[0017] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at a temperature of 150℃~180℃ for 1h~3h to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1h~2h.

[0018] Step 3: Use alcohol to remove the grease from the surface of the T2 copper strip, and use a flux-cored wire drawing device to wrap the flux powder prepared in step 2 inside the T2 copper strip. The diameter of the first drawing die is 2.6mm.

[0019] Step 4: After the first drawing process is completed, the die hole diameter is gradually reduced during drawing, and the final diameter of the flux-cored wire is 1.0 to 1.2 mm.

[0020] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0021] The invention is further characterized in that,

[0022] In step 1, the particle size of each core powder is 100-200 mesh.

[0023] In step 3, the T2 copper strip is used as the welding layer, with a thickness of 0.4 mm and a width of 7 mm; the filling amount of the flux-cored welding wire is controlled between 30 wt% and 32 wt%.

[0024] The third technical solution adopted in this invention is a method for copper-steel butt welding using a thick copper-steel butt welding wire, specifically:

[0025] S1: For welding copper and steel plates, use an asymmetrical X-shaped bevel and preheat the copper side at a temperature of 250℃~350℃.

[0026] S2: Use the thick copper-steel butt welding wire to perform the first weld pass at the bevel on the copper-steel side. Select the CMT welding power source and the welding current is 200A~250A.

[0027] S3: Flip the copper-steel test plate, and use the above-mentioned thick copper-steel butt welding wire to perform the second weld at the bevel on the other side of the copper-steel. Select the CMT welding power source and the welding current is 200A~250A; control the interpass temperature at 250℃~350℃.

[0028] S4: Proceed with steps S2 and S3 in sequence, repeating steps S2 and S3 until the bevel is completely filled.

[0029] The invention is further characterized in that,

[0030] In step S1, the thickness of both the copper plate and the steel plate is between 10mm and 20mm; an asymmetrical X-shaped bevel is made for welding the copper plate and the steel plate, specifically: the angle of the bevel on the copper side is 30°±5°, the angle of the bevel on the steel side is 10°±5°, and the gap reserved during welding is 0.5mm to 1.0mm.

[0031] The beneficial effects of this invention are:

[0032] (1) The flux-cored wire of the present invention has a relatively small diameter. The flux-cored wire with a diameter of 1.0 to 1.2 mm is widely applicable. It can be used for both TIG welding and MIG welding.

[0033] (2) The flux-cored welding wire of the present invention has a higher cladding efficiency than ordinary solid welding wires because it wraps the flux powder with T2 copper strip, has good molten pool fluidity, and produces a beautiful weld after welding.

[0034] (3) The main element of the flux-cored welding wire of this invention is Cu, which has good weldability with the base materials (steel and copper) on both sides. Ni, Cr, Mo, Zr, V, Si, Mn, and Al are added to the welding wire to adjust the fluidity and strength of the copper-based flux-cored welding wire. Cr and Zr can further improve the strength of the weld through subsequent heat treatment. The combined addition of Si and Mn also has a deoxidizing effect, reducing the tendency of weld porosity.

[0035] (4) The method of the present invention adopts reasonable welding process parameters based on the thermophysical properties of copper and steel to ensure the smooth progress of the welding process, thereby obtaining high-quality, defect-free copper-steel dissimilar joints.

[0036] (5) The flux-cored welding wire of the present invention has fewer alloy elements, the preparation process is simple, and it is easy to carry out large-scale mass production.

[0037] (6) This invention aims to solve the cracking problem that occurs when copper and steel plates are butt-welded by developing a flux-cored welding wire for copper-steel butt welding. This invention also develops a welding method for butt welding, thereby further reducing weld cracking and improving joint performance. Attached Figure Description

[0038] Figure 1 This refers to the bevel form of the thick copper-copper butt joint in the method of this invention;

[0039] Figure 2 This is a schematic diagram illustrating the welding sequence of a thick copper-steel butt joint in the method of this invention;

[0040] Figure 3 This describes the microstructure of penetrating cracks appearing on the steel side during copper-steel dissimilar material welding in the method of this invention.

[0041] Figure 4 The image shows the microstructure of the weld seam when the flux-cored welding wire prepared in Example 2 is used for welding a thick copper-steel butt joint.

[0042] In the diagram, 1 represents the first weld bead, and 2 represents the second weld bead. Detailed Implementation

[0043] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0044] This invention provides a welding wire for thick copper-steel butt welding, comprising flux powder and welding skin, wherein the flux powder is composed of the following components by mass percentage: Ni powder 15-20%, Cr powder 10-20%, Mo powder 5-10%, Zr powder 5-10%, V powder 5-10%, Si powder 5-10%, Mn powder 5-10%, Al powder 1-3%, and the remainder is Cu powder, the sum of the mass percentages of the above components being 100%.

[0045] The particle size of each core powder is 100-200 mesh.

[0046] The soldering material is T2 copper strip, with a thickness of 0.4mm and a width of 7mm.

[0047] The filling amount of flux-cored welding wire is controlled between 30wt% and 32wt%.

[0048] The roles and functions of each component in this flux-cored welding wire are as follows:

[0049] (1) Cu is the most important element in welding wire. According to the Cu-Fe binary phase diagram, the two do not form a brittle phase. Therefore, when welding dissimilar materials such as copper and steel, selecting Cu-based welding wire can ensure excellent metallurgical bonding with the base materials on both sides.

[0050] (2) A certain amount of Ni element is added to this invention. According to the Ni-Fe binary phase diagram, the two can dissolve indefinitely to form an austenitic structure; according to the Ni-Cu binary phase diagram, the two can also dissolve indefinitely. Therefore, adding Ni element to the welding wire will not have an adverse effect on the weld. On the contrary, since the thermophysical properties of Ni are between those of Fe and Cu, using Ni as the main element can reduce the residual stress in copper-steel dissimilar joints.

[0051] (3) A certain amount of Cr element is added in this invention. According to the Cr-Fe binary phase diagram, Cr can be infinitely dissolved in Fe to form an austenitic structure, and the dissolved Cr can improve the bonding strength with the Fe side; according to the Cr-Cu binary phase diagram, although both have low solid solubility, they do not form brittle phases. Therefore, adding Cr to the flux-cored welding wire can improve the strength of copper-based welds and enhance their resistance to high-temperature oxidation.

[0052] (4) A certain amount of Mo is added to the welding wire of this invention. According to the Mo-Cu binary phase diagram, neither element will form a brittle phase. The addition of Mo can improve the fluidity of nickel-based welds. According to the Mo-Fe binary phase diagram, although the solid solubility of Mo in Fe is limited, even if a brittle phase is formed after exceeding the solid solubility, it will be dispersed in the nickel-based weld and will not deteriorate the performance; on the contrary, it will improve the strength of the nickel-based weld. The effect of Mo is similar to that of Cr, but the combined addition of the two is better than the single addition of the same element.

[0053] (5) A certain amount of Zr element is added to the welding wire of the present invention. The addition of Zr has a solid solution strengthening effect, which improves the strength of copper-based welds. On the other hand, the dissolution of Zr in the copper matrix changes with temperature. Therefore, this characteristic of Zr can be used to heat-treat the copper-steel butt joints to be welded later, thereby further improving their strength.

[0054] (6) The welding wire of this invention incorporates Si and Mn elements. The combined addition of Si and Mn can deoxidize and reduce the formation of porosity in the weld. In addition, Mn can stabilize the β phase in copper-based welds and prevent spontaneous tempering brittleness. The addition of Si can also improve the heat resistance, corrosion resistance and wear resistance of the weld.

[0055] The present invention also provides a method for preparing the above-mentioned thick copper-steel butt welding wire, the specific steps of which are as follows:

[0056] Step 1: Weigh the following powders according to their mass percentages: Ni powder 15-20%, Cr powder 10-20%, Mo powder 5-10%, Zr powder 5-10%, V powder 5-10%, Si powder 5-10%, Mn powder 5-10%, Al powder 1-3%, and the remainder is Cu powder. The sum of the mass percentages of the above components is 100%. In Step 1, the particle size of each core powder is 100-200 mesh.

[0057] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at a temperature of 150℃~180℃ for 1h~3h to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1h~2h.

[0058] Step 3: Remove the grease from the surface of the T2 copper strip with alcohol, and wrap the flux powder prepared in Step 2 inside the T2 copper strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm. In Step 3, the T2 copper strip is the welding skin, with a thickness of 0.4 mm and a width of 7 mm. The filling amount of the flux-cored wire is controlled between 30 wt% and 32 wt%.

[0059] Step 4: After the first drawing process is completed, the die hole diameter is gradually reduced during drawing, and the final diameter of the flux-cored wire is 1.0 to 1.2 mm.

[0060] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0061] The present invention also provides a method for copper-steel butt welding using the above-mentioned thick copper-steel butt welding wire, specifically as follows:

[0062] S1: For welding copper and steel plates, use an asymmetrical X-shaped bevel and preheat the copper side at a temperature of 250℃~350℃.

[0063] S2: Using the above-mentioned thick copper-steel butt welding wire, perform the first weld pass 1 at the bevel on the copper-steel side. Select CMT welding power source and the welding current is 200A~250A.

[0064] S3: Flip the copper-steel test plate, and use the welding wire for the thick copper-steel butt welding to perform the second weld pass 2 at the bevel on the other side of the copper-steel. Select the CMT welding power source and the welding current is 200A~250A; control the interpass temperature at 250℃~350℃.

[0065] S4: Proceed with steps S2 and S3 in sequence, repeating steps S2 and S3 until the bevel is completely filled.

[0066] In step S1, the thickness of both the copper plate and the steel plate is between 10mm and 20mm; an asymmetrical X-shaped bevel is made for welding the copper plate and the steel plate, specifically: the angle of the bevel on the copper side is 30°±5°, the angle of the bevel on the steel side is 10°±5°, and the gap reserved during welding is 0.5mm to 1.0mm.

[0067] Example 1

[0068] Step 1: Weigh the following powders according to their mass percentages: Ni powder 15%, Cr powder 10%, Mo powder 5%, Zr powder 5%, V powder 5%, Si powder 5%, Mn powder 5%, Al powder 1%, and the remainder is Cu powder. The sum of the mass percentages of the above components is 100%. In Step 1, the particle size of each core powder is 100 mesh.

[0069] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at 150℃ for 1 hour to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1 hour.

[0070] Step 3: Remove the grease from the surface of the T2 copper strip with alcohol, and wrap the flux powder prepared in Step 2 inside the T2 copper strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm. In Step 3, the T2 copper strip is the welding skin, with a thickness of 0.4 mm and a width of 7 mm. The filling amount of the flux-cored wire is controlled at 30 wt%.

[0071] Step 4: After the first drawing process is completed, the die hole diameter is gradually reduced during drawing, and the final diameter of the flux-cored wire is 1.0 to 1.2 mm.

[0072] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0073] The copper plate and steel plate are welded together using the aforementioned thick copper-steel butt welding wire. The specific steps are as follows (e.g.) Figure 2 As shown):

[0074] S1: For welding copper and steel plates, use an asymmetrical X-shaped bevel and preheat the copper side at a temperature of 250℃~350℃.

[0075] S2: Using the above-mentioned thick copper-steel butt welding wire, perform the first weld pass 1 at the bevel on the copper-steel side. Select CMT welding power source and the welding current is 200A~250A.

[0076] S3: Flip the copper-steel test plate, and use the welding wire for the thick copper-steel butt welding to perform the second weld pass 2 at the bevel on the other side of the copper-steel. Select the CMT welding power source and the welding current is 200A~250A; control the interpass temperature at 250℃~350℃.

[0077] S4: Proceed with steps S2 and S3 in sequence, repeating steps S2 and S3 until the bevel is completely filled.

[0078] Copper-steel butt welding was performed using the thick copper-steel butt welding wire prepared in Example 1. The thickness of both the copper and steel plates was 10 mm, and an asymmetrical X-shaped bevel was made (e.g., ...). Figure 1 As shown in the figure, the single-sided bevel angle of the copper side is 25°, the single-sided bevel angle of the steel side is 5°, and the reserved gap during welding is 0.5mm.

[0079] When welding dissimilar materials such as copper and steel, the weld formation is aesthetically pleasing and the post-weld deformation is minimal.

[0080] Tests showed that the copper-steel butt joint had no cracks or porosity defects. The mechanical properties of the joint were: tensile strength of 215 MPa, fracture in the heat-affected zone of the copper side of the base material, and elongation after fracture of 21%.

[0081] Example 2

[0082] Step 1: Weigh the following powders according to their mass percentages: Ni powder 20%, Cr powder 20%, Mo powder 10%, Zr powder 10%, V powder 10%, Si powder 10%, Mn powder 10%, Al powder 3%, and the remainder is Cu powder. The sum of the mass percentages of the above components is 100%. In Step 1, the particle size of each core powder is 200 mesh.

[0083] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at 180℃ for 3 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 2 hours.

[0084] Step 3: Remove the grease from the surface of the T2 copper strip with alcohol, and wrap the flux powder prepared in Step 2 inside the T2 copper strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm. In Step 3, the T2 copper strip is the welding skin, with a thickness of 0.4 mm and a width of 7 mm. The filling amount of the flux-cored wire is controlled at 32 wt%.

[0085] Step 4: After the first drawing process is completed, the die hole diameter is gradually reduced during drawing, and the final diameter of the flux-cored wire is 1.0 to 1.2 mm.

[0086] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0087] The copper plate and steel plate are welded together using the aforementioned thick copper-steel butt welding wire. The specific steps are as follows (e.g.) Figure 2 As shown):

[0088] S1: For welding copper and steel plates, use an asymmetrical X-shaped bevel and preheat the copper side at a temperature of 250℃~350℃.

[0089] S2: Using the above-mentioned thick copper-steel butt welding wire, perform the first weld pass 1 at the bevel on the copper-steel side. Select CMT welding power source and the welding current is 200A~250A.

[0090] S3: Flip the copper-steel test plate, and use the above-mentioned thick copper-steel butt welding wire to perform the second weld pass 2 at the bevel on the other side of the copper-steel. Select the CMT welding power source and the welding current is 200A~250A; control the interpass temperature at 250℃~350℃.

[0091] S4: Proceed with steps S2 and S3 in sequence, repeating steps S2 and S3 until the bevel is completely filled.

[0092] Copper-steel butt welding was performed using the thick copper-steel butt welding wire prepared in Example 2. The thickness of the copper and steel plates was 10-20 mm, and an asymmetrical X-shaped bevel was made (e.g., Figure 1 As shown in the figure, the single-sided bevel angle of the copper side is 35°, the single-sided bevel angle of the steel side is 15°, and the reserved gap during welding is 1.0mm.

[0093] When welding dissimilar materials such as copper and steel, the weld formation is aesthetically pleasing and the post-weld deformation is minimal.

[0094] Tests showed that the copper-steel butt joint had no cracks or porosity defects. The mechanical properties of the joint were: tensile strength of 223 MPa, fracture in the heat-affected zone of the copper side of the base material, and elongation after fracture of 20.5%.

[0095] Figure 3 When using commercially available pure copper welding wire for copper-steel butt joint welding, penetration cracks were found at the steel side interface (liquid copper entered the grain boundaries of the heat-affected zone on the steel side).

[0096] Figure 4 The image shows the microstructure of a copper-steel butt joint welded using the welding wire of Example 2. As can be seen from the image, the microstructure is uniformly distributed, without defects, and is mainly composed of columnar dendrites.

[0097] Therefore, by using the welding wire of the present invention, the generation of penetration cracks can be avoided, and the problem of joint cracking and performance degradation when joining dissimilar materials such as copper and steel can be solved.

[0098] Example 3

[0099] Step 1: Weigh the following powders according to their mass percentages: Ni powder 17%, Cr powder 15%, Mo powder 7%, Zr powder 7%, V powder 7%, Si powder 7%, Mn powder 7%, Al powder 2%, and the remainder is Cu powder. The sum of the mass percentages of the above components is 100%. In Step 1, the particle size of each core powder is 200 mesh.

[0100] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at 170℃ for 2 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1.5 hours.

[0101] Step 3: Remove the grease from the surface of the T2 copper strip with alcohol, and wrap the flux powder prepared in Step 2 inside the T2 copper strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm. In Step 3, the T2 copper strip is the welding skin, with a thickness of 0.4 mm and a width of 7 mm. The filling amount of the flux-cored wire is controlled at 31 wt%.

[0102] Step 4: After the first drawing process is completed, the die hole diameter is gradually reduced during drawing, and the final diameter of the flux-cored wire is 1.0 to 1.2 mm.

[0103] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0104] The copper plate and steel plate are welded together using the aforementioned thick copper-steel butt welding wire. The specific steps are as follows (e.g.) Figure 2 As shown):

[0105] S1: For welding copper and steel plates, use an asymmetrical X-shaped bevel and preheat the copper side at a temperature of 250℃~350℃.

[0106] S2: Using the above-mentioned thick copper-steel butt welding wire, perform the first weld pass 1 at the bevel on the copper-steel side. Select CMT welding power source and the welding current is 200A~250A.

[0107] S3: Flip the copper-steel test plate, and use the welding wire for the thick copper-steel butt welding to perform the second weld pass 2 at the bevel on the other side of the copper-steel. Select the CMT welding power source and the welding current is 200A~250A; control the interpass temperature at 250℃~350℃.

[0108] S4: Proceed with steps S2 and S3 in sequence, repeating steps S2 and S3 until the bevel is completely filled.

[0109] Copper-steel butt welding was performed using the thick copper-steel butt welding wire prepared in Example 3. The thickness of the copper and steel plates was 10-20 mm, and an asymmetrical X-shaped bevel was made (e.g., Figure 1 As shown in the figure, the single-sided bevel angle of the copper side is 35°, the single-sided bevel angle of the steel side is 5°, and the reserved gap during welding is 0.7mm.

[0110] When welding dissimilar materials such as copper and steel, the weld formation is aesthetically pleasing and the post-weld deformation is minimal.

[0111] Tests showed that the copper-steel butt joint had no cracks or porosity defects. The mechanical properties of the joint were: tensile strength of 218 MPa, fracture in the heat-affected zone of the copper side of the base material, and elongation after fracture of 22.4%.

[0112] Example 4

[0113] Step 1: Weigh the following powders according to their mass percentages: Ni powder 16%, Cr powder 17%, Mo powder 6%, Zr powder 6%, V powder 6%, Si powder 6%, Mn powder 6%, Al powder 1.3%, and the remainder is Cu powder. The sum of the mass percentages of the above components is 100%. In Step 1, the particle size of each core powder is 100 mesh.

[0114] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at 160℃ for 1.3 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1.2 hours.

[0115] Step 3: Remove the grease from the surface of the T2 copper strip with alcohol, and wrap the flux powder prepared in Step 2 inside the T2 copper strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm. In Step 3, the T2 copper strip is the welding skin, with a thickness of 0.4 mm and a width of 7 mm. The filling amount of the flux-cored wire is controlled at 30 wt%.

[0116] Step 4: After the first drawing process is completed, the die hole diameter is gradually reduced during drawing, and the final diameter of the flux-cored wire is 1.0 to 1.2 mm.

[0117] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0118] The copper plate and steel plate are welded together using the aforementioned thick copper-steel butt welding wire. The specific steps are as follows (e.g.) Figure 2 As shown):

[0119] S1: For welding copper and steel plates, use an asymmetrical X-shaped bevel and preheat the copper side at a temperature of 250℃~350℃.

[0120] S2: Using the above-mentioned thick copper-steel butt welding wire, perform the first weld pass 1 at the bevel on the copper-steel side. Select CMT welding power source and the welding current is 200A~250A.

[0121] S3: Flip the copper-steel test plate, and use the welding wire for the thick copper-steel butt welding to perform the second weld pass 2 at the bevel on the other side of the copper-steel. Select the CMT welding power source and the welding current is 200A~250A; control the interpass temperature at 250℃~350℃.

[0122] S4: Proceed with steps S2 and S3 in sequence, repeating steps S2 and S3 until the bevel is completely filled.

[0123] Copper-steel butt welding was performed using the thick copper-steel butt welding wire prepared in Example 4. The thickness of the copper and steel plates was 10-20 mm, and an asymmetrical X-shaped bevel was made (e.g., Figure 1 As shown in the figure, the single-sided bevel angle of the copper side is 25°, the single-sided bevel angle of the steel side is 5°, and the reserved gap during welding is 0.8mm.

[0124] When welding dissimilar materials such as copper and steel, the weld formation is aesthetically pleasing and the post-weld deformation is minimal.

[0125] Tests showed that the copper-steel butt joint had no cracks or porosity defects. The mechanical properties of the joint were: tensile strength of 237 MPa, fracture in the heat-affected zone of the copper side of the base material, and elongation after fracture of 19.5%.

[0126] Example 5

[0127] Step 1: Weigh the following powders according to their mass percentages: Ni powder 19%, Cr powder 18%, Mo powder 9%, Zr powder 6.5%, V powder 9%, Si powder 7.5%, Mn powder 5.5%, Al powder 2.5%, and the remainder is Cu powder. The sum of the mass percentages of the above components is 100%. In Step 1, the particle size of each core powder is 200 mesh.

[0128] Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at 155℃ for 2.6 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1.7 hours.

[0129] Step 3: Remove the grease from the surface of the T2 copper strip with alcohol, and wrap the flux powder prepared in Step 2 inside the T2 copper strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm. In Step 3, the T2 copper strip is the welding skin, with a thickness of 0.4 mm and a width of 7 mm. The filling amount of the flux-cored wire is controlled at 30 wt%.

[0130] Step 4: After the first drawing process is completed, the die hole diameter is gradually reduced during drawing, and the final diameter of the flux-cored wire is 1.0 to 1.2 mm.

[0131] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0132] The copper plate and steel plate are welded together using the aforementioned thick copper-steel butt welding wire. The specific steps are as follows (e.g.) Figure 2 As shown):

[0133] S1: For welding copper and steel plates, use an asymmetrical X-shaped bevel and preheat the copper side at a temperature of 250℃~350℃.

[0134] S2: Using the above-mentioned thick copper-steel butt welding wire, perform the first weld pass 1 at the bevel on the copper-steel side. Select CMT welding power source and the welding current is 200A~250A.

[0135] S3: Flip the copper-steel test plate, and use the above-mentioned thick copper-steel butt welding wire to perform the second weld pass 2 at the bevel on the other side of the copper-steel. Select the CMT welding power source and the welding current is 200A~250A; control the interpass temperature at 250℃~350℃.

[0136] S4: Proceed with steps S2 and S3 in sequence, repeating steps S2 and S3 until the bevel is completely filled.

[0137] Copper-steel butt welding was performed using the thick copper-steel butt welding wire prepared in Example 5. The thickness of the copper and steel plates was 10-20 mm, and an asymmetrical X-shaped bevel was made (e.g., Figure 1 As shown in the figure, the single-sided bevel angle of the copper side is 25°, the single-sided bevel angle of the steel side is 15°, and the reserved gap during welding is 0.9mm.

[0138] When welding dissimilar materials such as copper and steel, the weld formation is aesthetically pleasing and the post-weld deformation is minimal.

[0139] Tests showed that the copper-steel butt joint had no cracks or porosity defects. The mechanical properties of the joint were: tensile strength of 211 MPa, fracture in the heat-affected zone of the copper side of the base material, and elongation after fracture of 23%.

Claims

1. A welding wire for thick copper-steel butt welding, characterized in that, The welding wire is a copper-based flux-cored welding wire, consisting of flux powder and a welding skin. The flux powder is composed of the following components by mass percentage: Ni powder 15~19%, Cr powder 10~20%, Mo powder 5~9%, Zr powder 5~10%, V powder 5~9%, Si powder 5~10%, Mn powder 5~10%, Al powder 1~3%, and the remainder is Cu powder. The sum of the mass percentages of the above components is 100%. The welding skin is T2 copper strip.

2. The welding wire for thick copper-steel butt welding according to claim 1, characterized in that, The particle size of each core powder is 100-200 mesh.

3. The welding wire for thick copper-steel butt welding according to claim 1, characterized in that, The copper strip is 0.4mm thick and 7mm wide.

4. The welding wire for thick copper-steel butt welding according to claim 1, characterized in that, The filling amount of flux-cored welding wire is controlled at 30wt%~32wt%.

5. The welding wire for thick copper-steel butt welding according to claim 1, characterized in that, The specific steps for preparing welding wire are as follows: Step 1: Weigh the following powders according to their mass percentages: Ni powder 15~20%, Cr powder 10~20%, Mo powder 5~10%, Zr powder 5~10%, V powder 5~10%, Si powder 5~10%, Mn powder 5~10%, Al powder 1~3%, and the remainder is Cu powder. The sum of the mass percentages of the above components is 100%. Step 2: Place the core powder weighed in Step 1 into a vacuum heating furnace and heat it at a temperature of 150℃~180℃ for 1h~3h; place the dried powder into a powder mixer for thorough mixing for 1h~2h. Step 3: The flux powder prepared in step 2 is wrapped in T2 copper strip using a flux-cored wire drawing machine. The diameter of the first drawing die is 2.6mm. Step 4: After the first drawing process is completed, the die hole diameter is gradually reduced during drawing, and the final diameter of the flux-cored wire is 1.0~1.2mm. Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

6. The welding wire for thick copper-steel butt welding according to claim 5, characterized in that, In step 1, the particle size of each core powder is 100-200 mesh.

7. The welding wire for thick copper-steel butt welding according to claim 5, characterized in that, In step 3, the T2 copper strip is used as the welding skin, with a thickness of 0.4 mm and a width of 7 mm; the filling amount of the flux-cored welding wire is controlled at 30wt%~32wt%.

8. A method for copper-steel butt welding using thick copper-steel butt welding wire, characterized in that, Specifically: S1: For welding copper and steel plates, use an asymmetrical X-shaped bevel and preheat the copper side at a temperature of 250℃~350℃. S2: Using the welding wire for thick copper-steel butt welding as described in any one of claims 1-4, the first weld pass is performed at the bevel on the copper-steel side. A CMT welding power source is selected, and the welding current is 200A~250A. S3: Flip the copper-steel test plate, and use the welding wire for thick copper-steel butt welding as described in any one of claims 1-4 to perform the second weld pass at the bevel on the other side of the copper-steel. Select a CMT welding power source and the welding current is 200A~250A; control the interpass temperature at 250℃~350℃. S4: Proceed with steps S2 and S3 in sequence, repeating steps S2 and S3 until the bevel is completely filled.

9. The method for copper-steel butt welding using a thick copper-steel butt welding wire according to claim 8, characterized in that, In step S1, the thickness of both the copper plate and the steel plate is 10 mm to 20 mm. The copper plate and the steel plate are welded with an asymmetrical X-shaped bevel, specifically: the bevel angle on the copper side is 30°±5°, the bevel angle on the steel side is 10°±5°, and the gap reserved during welding is 0.5 mm to 1.0 mm.

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