T2 red copper / 304 stainless steel dissimilar metal electron beam welding method
By using electron beam welding method and special preparation steps in the welding of T2 copper and 304 stainless steel, the defect problems caused by material performance differences during welding are solved, and high-strength and defect-free welded joints are achieved.
Patent Information
- Application Number
- CN202311264626.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-28
- Publication Date
- 2025-03-28
AI Technical Summary
The difference in physical and chemical properties of T2 copper and 304 stainless steel leads to prone to defects such as cracks and pores during welding, and thermal cracks and permeability cracks are difficult to avoid.
The electron beam welding method is adopted. Special preparation steps are carried out before welding, such as machining, pickling, removing the micro-oxidation layer, and using titanium slats to fix the copper slats during the welding process. The electron beam is used to weld under a vacuum environment to form a nail-shaped weld to avoid the formation of brittle phases.
The high strength and defects of T2 copper/304 stainless steel different metal welded joints are achieved. The strength of the welded joints can reach 210MPa in the tensile test, and no defects such as pores and cracks are found.
Smart Images
Figure CN119703306A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a welding method, in particular to a T2 copper / 304 stainless steel dissimilar metal electron beam welding method. Background Art
[0002] Dissimilar material composite components have their own unique engineering advantages. They can not only save precious metals and reduce production costs, but also give full play to the performance advantages of different materials and achieve complementary advantages. Even in some special cases, the comprehensive performance of dissimilar material structural parts will far exceed that of single metal structural parts. Therefore, the research on welding of dissimilar materials has great development prospects. Copper and copper alloys have excellent physical, chemical and mechanical properties, strong corrosion resistance in liquid environments such as seawater, and are widely used in the fields of electricity, nuclear energy, electronics, thermal conductive equipment, etc., and are important national strategic resources. The copper content of red copper exceeds 99.5%, and its use is much wider than that of pure iron. Whether it is electrical equipment such as generators, busbars, cables, switchgear, transformers, or heat exchangers, pipelines, flat plate collectors of solar heating devices, etc., red copper can be made. Steel is the most widely used alloy material in actual engineering and family life. Among them, 304 stainless steel is widely used in production due to its high strength, light weight, good overall rigidity and strong deformation ability. Therefore, copper-steel dissimilar material composite components can achieve complementary advantages of copper / steel dissimilar materials in performance and economy.
[0003] The huge difference in physical and chemical properties between T2 copper and 304 stainless steel leads to the occurrence of welding defects such as cracks and pores in the welding of copper-steel dissimilar alloys. The difference in thermal properties between the two will lead to inconsistent melting and solidification processes, resulting in defects such as incomplete penetration or even incomplete fusion; the large difference in linear expansion coefficient will cause large welding residual stress and deformation in the joint after welding. The difference in chemical properties between T2 copper and 304 stainless steel and the penetration of liquid copper into steel will lead to the formation of thermal cracks and penetration cracks. Therefore, how to obtain good weld formation and excellent joint quality is the key to T2 copper / 304 stainless steel dissimilar metal welding. Summary of the invention
[0004] The purpose of the present invention is to provide a T2 copper / 304 stainless steel dissimilar metal electron beam welding method to solve the problem that the physical and chemical properties of copper and steel are quite different, resulting in metallurgical incompatibility, and brittle phases are easily generated during welding, resulting in welding defects.
[0005] In order to solve the above-mentioned technical problems, the technical solution adopted by the present invention is: A T2 copper / 304 stainless steel dissimilar metal electron beam welding method includes a pre-welding preparation step and a welding process step, wherein the pre-welding preparation step includes the following steps: Step 1, take the copper plate to be welded and the steel plate to be welded and perform machining, after machining, the thickness difference between the copper plate to be welded and the steel plate to be welded is 0-0.5mm, then clean the remaining oil stains on the copper plate to be welded and the steel plate to be welded by pickling, then wipe the area to be welded with acetone, and finally use a grinding head machine to remove the micro-oxidation layer on the surface of the copper plate to be welded and the steel plate to be welded within 24 hours before welding; Step 2: Use a tool to fit the welding positions of the copper plate to be welded and the steel plate to be welded and then fix them on the tool, the welding positions of the copper plate to be welded and the steel plate to be welded are exposed outside the tool, and the gap between the copper plate to be welded and the steel plate to be welded is not greater than 0.2 mm; Step 3, a titanium strip is pressed on the welding position of the copper plate to be welded and the steel plate to be welded, the center line of the copper strip is located on the plate to be welded, and the distance between the center line of the steel strip and the welding position of the copper plate to be welded and the steel plate to be welded is defined as L, and L is 1-6mm. After the assembly is completed, the copper strip is fixed on the steel plate to be welded by spot welding; Step 4: Use the tooling to fix the assembled workpiece on the workbench of the electron beam welding machine, and the pre-welding preparation steps are completed; The welding process comprises the following steps: Step 1, extracting the vacuum degree in the vacuum chamber of the electron beam welding machine to be better than 5×10-2Pa; Step 2: Raise the high voltage of the electron beam welder to the required acceleration voltage, use a small beam flow to find the position and focus point flow corresponding to the focus of the electron beam surface, and then input the obtained focused beam flow into the welding program; Step 3, move the welding workbench, move the weld seam of the workpiece to be welded to the focus of the electron beam through the observation function of the CCD imaging software, mark the beam focus position, and determine the weld seam position; Step 4: Move the welding workbench again to move the electron beam spot focus to the center line of the titanium strip; Step 5, start the welding program, so that the electron beam is welded at the center line of the titanium plate strip at a distance L from the weld, and the electron beam welding forms a molten weld on the steel plate side, and the heat of the molten weld is transferred to the copper plate to be welded by heat conduction, so that the copper plate to be welded is hot-melted and attached to the titanium plate to be welded; Step 6: After welding is completed, vacuum cool for 10 minutes, remove the vacuum and take out the welded test piece, and the whole welding work is completed; Step 7: After welding is completed, the steel strips on the welding workpiece are removed by machining to obtain the required copper-steel welding joint.
[0006] In step 5 of the welding process, the electron beam welding is controlled to form a nail-shaped weld parallel section located on the steel plate to be welded.
[0007] The beneficial effect of the present invention is that no defects such as pores, cracks, inclusions, etc. are found in the low-magnification metallographic structure of the T2 copper / 304 stainless steel dissimilar metal joint connected by the electron beam welding method for copper-steel dissimilar metals provided by the present invention. Through tensile test testing, the joint strength can reach 210MPa.
[0008] Compared with the prior art, the present invention has the following significant advantages: 1. Electron beam welding is used to avoid melting copper and steel at the same time, directly reducing the direct contact between liquid Fe and Al atoms to form brittle phases such as FeAl and Fe3Al2; 2. Electron beams with concentrated energy, small heat input, strong penetration ability and good controllability are used as welding heat sources, which can control the heat input during welding. At the same time, the welding process is carried out in a vacuum chamber, avoiding the influence of harmful gases in the atmosphere on the performance of the welded joint, and effectively improving the comprehensive performance of the joint; 3. A special joint structure is designed to obtain parallel welds on the titanium side, achieve uniform heat transfer, and avoid defects such as cracks caused by the reaction of aluminum and titanium in the liquid state. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 This is a schematic diagram of the welding tooling and workpiece assembly structure.
[0010] Figure 2 Schematic diagram of the electron beam welding joint of the specimen.
[0011] Figure 3 Schematic diagram of the copper-steel dissimilar metal welding process.
[0012] Figure 4 This is a high-magnification morphology image of the T2 copper / 304 stainless steel alloy interface.
[0013] Graphic markings: 1. Copper plate to be welded; 2. Steel plate to be welded; 3. Steel plate strip; 4. Tooling base plate. DETAILED DESCRIPTION
[0014] As shown in the figure, the specific implementation is as follows: A T2 copper / 304 stainless steel dissimilar metal electron beam welding method includes a pre-welding preparation step and a welding process step, wherein the pre-welding preparation step includes the following steps: Step 1, take the copper plate to be welded and the steel plate to be welded and perform machining, after machining, the thickness difference between the copper plate to be welded and the steel plate to be welded is 0-0.5mm, then clean the remaining oil stains on the copper plate to be welded and the steel plate to be welded by pickling, then wipe the area to be welded with acetone, and finally use a grinding head machine to remove the micro-oxidation layer on the surface of the copper plate to be welded and the steel plate to be welded within 24 hours before welding; Step 2: Use the tooling to align the welding positions of the copper plate and the steel plate to be welded and then fix them on the tooling. The tooling can be made of Figure 1The tooling or other forms of tooling, the copper plate to be welded and the steel plate to be welded are fixedly pressed on the tooling base plate, and a groove is provided on the tooling base plate just below the welding position of the copper plate to be welded and the steel plate to be welded, so that the welding position of the copper plate to be welded and the steel plate to be welded is exposed outside the tooling, and the gap between the copper plate to be welded and the steel plate to be welded is not greater than 0.2mm; Step 3: Press a titanium strip on the welding position of the copper plate and the steel plate to be welded, and the center line of the titanium strip is located on the titanium plate to be welded, such as Figure 1 As shown in the figure, one of the titanium strips is fixed above the copper plate to be welded and the steel plate to be welded, and the other titanium strip passes through the groove of the tooling base plate and is fixed below the copper plate to be welded and the steel plate to be welded. The distance between the center line of the titanium strip and the welding position of the copper plate to be welded and the steel plate to be welded is defined as L, and L is 1-6mm. After the assembly is completed, the copper strip is fixed on the copper plate to be welded by spot welding using argon arc welding; Step 4: Use the tooling to fix the assembled workpiece on the workbench of the electron beam welding machine. During the installation process, adjust the horizontality of the work surface to be welded so that the welding gun is perpendicular to the work surface to be welded. At the same time, adjust the working distance of the welding gun as needed, that is, keep its stroke within 300-1500mm, usually 600-800mm, and the pre-welding preparation steps are completed; The welding process comprises the following steps: Step 1, extracting the vacuum degree in the vacuum chamber of the electron beam welding machine to be better than 5×10-2Pa; Step 2: Raise the high voltage of the electron beam welder to the required acceleration voltage, such as controlling it at 150KV, use a small beam flow to find the position and focus point flow corresponding to the focus of the electron beam surface, and then input the obtained focused beam flow into the welding program; Step 3, move the welding workbench, move the weld seam of the workpiece to be welded to the focus of the electron beam through the observation function of the CCD imaging software, mark the beam focus position, and determine the weld seam position; Step 4: Move the welding workbench again to move the electron beam spot focus to the center line of the titanium strip; Step 5, start the welding program, so that the electron beam is welded at the center line of the copper strip at a distance L from the weld, and the electron beam welding forms a molten weld on the copper side. The heat of the molten weld is transferred to the aluminum plate to be welded in the form of heat conduction, so that the aluminum plate to be welded is hot-melted and attached to the titanium plate to be welded. The welding process can be carried out in a single or multiple repeated welding mode. The specific process can be adjusted according to the thickness of the weld. Usually, a single welding is used when the weld thickness is 3-4mm; multiple welding is used when the weld thickness is 4-10mm, because when the weld thickness is too large, the heat generated by the molten weld is not enough to make the steel plate to be welded hot-melted and attached to the steel plate to be welded, so multiple welding is required to increase the heat; During electron beam welding, a nail-shaped weld will be formed. Try to keep the electron beam nail head within the selected copper strip. Figure 2 In the h1 position shown, as many parallel welds as possible are formed on the copper plate section to be welded; electron beam welding forms a molten weld on the copper plate side, such as Figure 3 The area d1 at the far right of the copper plate and away from the weld is the electron beam welding heat affected zone, which is a non-melting zone, but the temperature will reach the melting point of aluminum alloy above 660°C, and the melting point of titanium alloy is usually above 1000°C; the heat of the heat affected zone will be transferred to the steel alloy side through heat conduction, and the steel alloy side area d2 will form a local melt and adhere to the copper alloy plate; by utilizing the physical properties of copper and steel alloys with large differences in melting points, this method can effectively avoid direct contact between the melting zones of copper alloy and steel alloy, thereby avoiding the formation of brittle phases; When the plate thickness is greater than 30mm, the adhesion of the steel plate is poor when welding on one side. Double-sided welding can be used to improve the adhesion of the steel plate. Step 6: After welding is completed, vacuum cool for 10 minutes, remove the vacuum and take out the welded test piece, and the whole welding work is completed; Step 7: After welding, remove the copper strips on the welded workpiece by machining. Figure 2 Remove component 3 in the figure to obtain the required copper-steel welded joint.
[0015] The technical solutions and implementation modes listed in the present invention are not limiting, and solutions that are equivalent to or have the same effects as the technical solutions and implementation modes listed in the present invention are all within the scope of protection of the present invention.
Claims
1. A T2 copper / 304 stainless steel dissimilar metal electron beam welding method, comprising a pre-welding preparation step and a welding process step, characterized in that: The welding preparation steps include the following steps: Step 1, take the copper plate to be welded and the steel plate to be welded and perform machining, after machining, the thickness difference between the copper plate to be welded and the steel plate to be welded is 0-0.5mm, then clean the remaining oil stains on the copper plate to be welded and the steel plate to be welded by pickling, then wipe the area to be welded with acetone, and finally use a grinding head machine to remove the micro-oxidation layer on the surface of the copper plate to be welded and the steel plate to be welded within 24 hours before welding; Step 2: Use a tool to fit the welding positions of the copper plate to be welded and the steel plate to be welded and then fix them on the tool, the welding positions of the copper plate to be welded and the steel plate to be welded are exposed outside the tool, and the gap between the copper plate to be welded and the steel plate to be welded is not greater than 0.2 mm; Step 3, a copper strip is pressed on the welding position of the copper plate to be welded and the steel plate to be welded, the center line of the steel strip is located on the titanium plate to be welded, and the distance between the center line of the copper strip and the welding position of the copper plate to be welded and the steel plate to be welded is defined as L, and L is 1-6mm. After the assembly is completed, the copper strip is fixed on the copper plate to be welded by spot welding; Step 4: Use the tooling to fix the assembled workpiece on the workbench of the electron beam welding machine, and the pre-welding preparation steps are completed; The welding process comprises the following steps: Step 1, extracting the vacuum degree in the vacuum chamber of the electron beam welding machine to be better than 5×10-2Pa; Step 2: Raise the high voltage of the electron beam welder to the required acceleration voltage, use a small beam flow to find the position and focus point flow corresponding to the focus of the electron beam surface, and then input the obtained focused beam flow into the welding program; Step 3, move the welding workbench, move the weld seam of the workpiece to be welded to the focus of the electron beam through the observation function of the CCD imaging software, mark the beam focus position, and determine the weld seam position; Step 4: Move the welding workbench again and move the electron beam spot focus to the center line of the copper strip; Step 5, start the welding procedure, so that the electron beam is welded at the center line of the copper strip at a distance L from the weld, and the electron beam welding forms a molten weld on the copper side, and the heat of the molten weld is transferred to the steel plate to be welded by heat conduction, so that the aluminum plate to be welded is hot-melted and attached to the copper plate to be welded; Step 6: After welding is completed, vacuum cool for 10 minutes, remove the vacuum and take out the welded test piece, and the whole welding work is completed; Step 7: After welding is completed, the copper strips on the welding workpiece are removed by machining to obtain the required copper-steel welding joint.
2. A T2 copper / 304 stainless steel dissimilar metal electron beam welding method according to claim 1, characterized in that: In step 5 of the welding process, the electron beam welding is controlled to form a nail-shaped weld with a parallel section located on the copper plate to be welded.