High-strength aluminum pipe welding process

Abstract

The invention relates to the technical field of welding processes, in particular to a high-strength aluminum pipe welding process which comprises the following steps: SI, pretreatment of a weldment; s2, preheating a weldment; s3, welding materials are prepared; s4, debugging the equipment; s5, welding; s6, weld joint inspection; according to the welding process, through whole-process standardized control, dynamic parameter adjustment and systematic quality management and control, the technical problems that in the welding process of the high-strength aluminum pipe, oxidation and deformation are prone to occurring, and fusion is difficult are solved, the mechanical property and service reliability of a welded joint are remarkably improved, process advancement and engineering practicability are both achieved, and the application prospect is wide. Important technical support is provided for efficient and high-quality manufacturing of aluminum alloy structural parts, the process is suitable for high-pressure pipelines, aviation structural parts, rail transit profiles and other scenes with high requirements for strength and sealing performance, and a closed loop of high-quality welding, low defect rate and long service life is achieved through process control. And the dual requirements of the modern industry on light weight and reliability are met.

Description

Technical Field

[0001] The invention relates to the technical field of welding technology, in particular to a high-strength aluminum tube welding technology. Background Art

[0002] Traditional aluminum tube welding technology usually refers to the welding method that was widely used in the early days, mainly manual arc welding and non-melting electrode argon arc welding. The process steps are relatively simple, but there are obvious limitations in accuracy, efficiency and quality control.

[0003] The traditional aluminum tube welding process usually adopts manual grinding or simple mechanical processing, and the control of the groove angle is not strict. When the tube diameter is small, angle deviation or surface roughness is prone to occur. For aluminum tubes with a wall thickness of ≥6mm, the groove may not be processed and welded directly, resulting in insufficient penetration; general welding wire is often used during welding, and special welding wire is not matched according to the alloy type of the aluminum tube, resulting in insufficient weld strength or poor corrosion resistance. Some use simple argon arc welding machines with low gas flow control accuracy and insufficient argon purity, which can easily lead to weld oxidation. The current is adjusted by a manual knob with poor stability. The current fluctuates greatly during welding, and some currents are selected based on experience. For example, a 6mm wall thick aluminum tube may uniformly use a current of 200~220A, which is not dynamically adjusted according to the groove depth, ambient temperature, etc., and is prone to burn-through or incomplete penetration, resulting in the inability to weld with high strength, unstable welding quality, and low efficiency.

[0004] Therefore, in view of the problem that the gas flow control accuracy of the above-mentioned aluminum tube welding process is low, the current is not dynamically adjusted according to the groove depth, ambient temperature, etc., and burn-through or incomplete melting is prone to occur, which leads to the inability to weld with high strength. A high-strength aluminum tube welding process can be designed. Summary of the Invention

[0005] In order to overcome the low gas flow control accuracy of the traditional aluminum tube welding process, the current is not dynamically adjusted according to the groove depth, ambient temperature, etc., which is prone to burn-through or incomplete melting, resulting in the inability to weld with high strength.

[0006] The technical solution of the present invention is: a high-strength aluminum tube welding process, the steps of which are as follows:

[0007] S1: Weldment pretreatment

[0008] S11: Beveling

[0009] Use professional groove processing equipment to groove high-strength aluminum tubes. The aluminum tubes are grooved at 45° according to the thickness of the tubes to ensure that the groove surface is flat and smooth without burrs or cracks.

[0010] S12: Surface cleaning

[0011] S2: Preheating of weldment

[0012] Heat the aluminum tube to 400-420℃, and use a thermometer to monitor the temperature change in real time to ensure that the temperature of each part of the aluminum tube is uniform. After reaching the predetermined temperature, keep it warm for 20-30 minutes to make the internal structure of the aluminum tube fully uniform, reduce the thermal stress during welding, and prevent cracks;

[0013] S3: Welding material preparation

[0014] S31: Wire selection

[0015] S32: Use a φ4mm tungsten electrode, sharpened with a dedicated sharpening device, with the tip height controlled at about 1 / 3 of the electrode diameter, i.e. 1.3-1.4mm. The sharpened tungsten electrode is conical in shape, with a smooth surface, no eccentricity, and no cracks.

[0016] S4: Equipment Debugging

[0017] Open the argon valve and adjust the gas flow to 7-8L / min, then open the cooling water valve and adjust the flow to 1-2L / min. When the wall thickness of the aluminum tube is 6mm, the current is controlled at 240-260A; when the wall thickness is 8mm, the current is controlled at 260-280A; when the wall thickness is 10mm, the current is controlled at 280-310A; when the wall thickness is 12mm, the current is controlled at 320-340A;

[0018] S5: Welding

[0019] S51: Before formal welding, perform positioning welding on the aluminum tube;

[0020] S52: Strike an arc in the groove of the aluminum tube, preheat the welding part appropriately first, and add welding wire when the metal on both sides of the groove begins to melt. When welding, the tungsten electrode and the weldment are at an angle of 20°-30°, and the filler wire and the tungsten electrode are at an angle of about 90°. The tungsten electrode and the weld should be on the same plane. The welding speed is controlled at 3-5mm / s, and the welding gun is slightly swung horizontally to keep the molten pool width at 8-12mm.

[0021] S6: Weld inspection.

[0022] Preferably, in step S11, the groove processing equipment includes a lathe and a groove machine; for aluminum tubes with smaller diameters, manual grinding is used to process the groove, and the angle and dimensional accuracy must be strictly controlled; the detailed steps of S12 are: first use a stainless steel wire brush or sandpaper to grind the groove of the aluminum tube and the range of 20-30mm on both sides to remove the aluminum oxide film until the metallic luster is exposed; then wipe the surface with acetone or alcohol to thoroughly remove oil, dust and impurities.

[0023] Preferably, in step S2, for small batches of aluminum tubes with smaller diameters, a flame heating gun is used for local preheating; for large batches of aluminum tubes with larger diameters, a heating furnace is used for overall preheating.

[0024] As a preference, the detailed steps of S31 are as follows:

[0025] S311: When welding pure aluminum parts, use pure aluminum welding wire, welding wire φ3mm, welding part thickness is 6-8mm, welding wire φ4mm, welding part thickness is 10-12mm;

[0026] When welding S312:102 aluminum parts or 104 aluminum parts, pre-twisted wire is used. The pre-twisted wire is a high-strength alloy welding wire with a diameter of 3mm. The thickness of the welded parts is 10 to 12mm.

[0027] Preferably, in step S4, a gas flow meter is used to monitor the argon flow rate to ensure that the flow rate is stable, and ventilation is carried out for 3-5 minutes in advance to purge the welding gun nozzle and welding area to remove air and prevent oxidation during the welding process; after step S4, before formal welding, high-strength aluminum tubes and welding materials with the same specifications as those in actual production are used for trial welding. Through the trial welding, the parameters of current, argon flow rate, and water flow are further adjusted, the formation of the weld is observed, and the presence of defects such as pores, cracks, and slag inclusions is checked. Only when the quality of the trial weld meets the requirements can formal production be carried out.

[0028] Preferably, in step S51, the spacing of the tack welds is determined according to the diameter and wall thickness of the aluminum tube, and is in the range of 100-150 mm. The length of the weld point is 5-10 mm. During tack welding, ensure that the misalignment of the aluminum tube is ≤1 mm and the gap is uniform, i.e., between 2-3 mm, to ensure the quality of the weld joint.

[0029] Preferably, in step S52, it is strictly forbidden to strike an arc on the base material outside the weld to prevent the arc from scratching the base material and causing cracks; during the welding process, uniform welding is adopted, and the changes in the molten pool are closely observed. The welding speed and welding current are adjusted in time according to the shape and temperature of the molten pool to ensure that the shape of the molten pool is consistent and to avoid defects such as lack of fusion and burn-through; by controlling the welding current and the swing amplitude of the welding gun, the molten pool temperature is kept within a suitable range, and it is appropriate for the molten metal to be in a "mirror" shape. When it is found that the molten pool temperature is too high and there is a tendency to collapse, the welding speed is appropriately increased or the welding current is reduced; when the molten pool temperature is too low and there is a lack of fusion, the welding speed is appropriately slowed down or the welding current is increased; during the welding process, if cracks, slag inclusions, and lack of fusion are found in the weld, welding needs to be stopped immediately, and the defects should be cleaned with a grinder or other suitable tools until the metallic luster is exposed. Then, preheating and welding are performed again according to the welding process requirements to ensure that the defects are completely repaired.

[0030] Preferably, after step S5, for high-strength aluminum tube weldments with high mechanical property requirements, stress relief annealing treatment is performed after welding. The weldments are heated to 300-350°C, kept warm for 1-2 hours, and then cooled with the furnace. Through post-weld heat treatment, the residual stress generated during the welding process is eliminated, and the toughness and fatigue resistance of the welded joint are improved.

[0031] Preferably, in step S6, after welding is completed, the weld is visually inspected. The weld surface is fine and uniform in the shape of fish scales. The low point of the fish scales is 1-2 mm higher than the plane of the welded workpiece. The weld width is uniform and there is no undercut, that is, the undercut depth is ≤ 0.5 mm, weld nodules, or defects such as pores. A method combining visual inspection and measuring tools is used to observe the forming of the weld surface with the naked eye to check whether there are obvious defects. A weld inspection ruler is used to measure the weld's excess height, width, and undercut depth to ensure that they meet the process requirements, and at the same time, flaw detection is performed.

[0032] Preferably, if defects are found in the welded parts during the above inspection, a reasonable repair plan shall be formulated according to the nature and severity of the defects. For minor surface defects, grinding and repair welding shall be used for repair; for internal defects, the location and size of the defects shall be determined first, and then the defects shall be removed mechanically, and then re-welded according to the welding process requirements. The number of reworks for the same part shall not exceed 2 times. If it fails to meet the requirements after 2 times, it shall be scrapped.

[0033] Beneficial effects of the present invention:

[0034] The welding process of the present invention processes a 45° groove according to the thickness of the pipe, and selects a lathe, groove machine or manual grinding for different pipe diameters to ensure the groove angle and dimensional accuracy, increase the welding fusion area, reduce stress concentration, and use a double cleaning method of stainless steel wire brush / sandpaper grinding + acetone / alcohol wiping to thoroughly remove the aluminum oxide film and oil stains, avoiding defects such as welding porosity and slag inclusions.

[0035] Preheat to 400-420°C and hold for 20-30 minutes to homogenize the base metal temperature, reduce thermal stress during welding, minimize cracking risks, and improve aluminum plasticity and fusion. Set the current range from 240-340A based on a wall thickness of 6-12mm to ensure sufficient penetration without burn-through. Use an argon flow rate of 7-8L / min and a cooling water flow rate of 1-2L / min to stabilize the arc and protect the tungsten electrode.

[0036] The tack welding spacing is 100-150mm, the weld point length is 5-10mm, and the misalignment is strictly controlled to be ≤1mm and the gap is 2-3mm to ensure the joint assembly accuracy and avoid welding deformation and uneven stress. The tungsten electrode is inclined at a 20°-30° angle to the weldment, and the welding wire is at a 90° angle to the tungsten electrode to ensure arc stability and uniform molten pool filling. The welding gun is slightly swung horizontally, and the molten pool width is 8-12mm to promote fusion and control weld formation.

[0037] For weldments with high mechanical property requirements, heat to 300-350℃ after welding and keep warm for 1-2 hours while cooling with the furnace to eliminate welding residual stress, improve joint toughness and fatigue resistance, and be suitable for harsh working conditions such as high pressure and dynamic load;

[0038] This process solves technical difficulties such as easy oxidation, easy deformation, and difficult fusion in the welding of high-strength aluminum tubes through standardized control of the entire process, dynamic parameter adjustment, and systematic quality control. It significantly improves the mechanical properties and service reliability of the welded joints. It combines technological advancement with engineering practicality, providing important technical support for the efficient and high-quality manufacturing of aluminum alloy structural parts. The process is suitable for scenarios with high requirements for strength and sealing, such as high-pressure pipelines, aviation structural parts, and rail transit profiles. Through process control, it achieves a closed loop of "high-quality welding-low defect rate-long service life", meeting the dual needs of modern industry for lightweighting and reliability. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to the embodiments.

[0040] When using the process of this technical solution, the steps are as follows:

[0041] S1: Weldment pretreatment

[0042] S11: Beveling

[0043] Professional beveling equipment is used to bevel high-strength aluminum tubes. Aluminum tubes are beveled at 45° according to the thickness of the tube. Beveling equipment includes lathes and beveling machines. For aluminum tubes with smaller diameters, manual grinding is used to process the bevels, and the angle and dimensional accuracy must be strictly controlled.

[0044] S12: Surface cleaning

[0045] First, use a stainless steel wire brush or sandpaper to polish the aluminum tube groove and the 20-30mm range on both sides to remove the aluminum oxide film until the metallic luster is exposed; then wipe the surface with acetone or alcohol to thoroughly remove oil, dust and impurities;

[0046] S2: Preheating of weldment

[0047] For small batches of aluminum tubes with smaller diameters, use a flame heating gun for local preheating; for large batches of aluminum tubes with larger diameters, use a heating furnace for overall preheating. Heat the aluminum tubes to 400-420°C, and use a thermometer to monitor the temperature changes in real time to ensure that the temperature of each part of the aluminum tube is uniform. After reaching the predetermined temperature, keep the temperature for 20-30 minutes.

[0048] S3: Welding material preparation

[0049] S31: Wire selection

[0050] S311: When welding pure aluminum parts, use pure aluminum welding wire, welding wire φ3mm, welding part thickness is 6-8mm, welding wire φ4mm, welding part thickness is 10-12mm;

[0051] S312: When welding 102 aluminum parts or 104 aluminum parts, use pre-twisted wire, which is a high-strength alloy welding wire with a diameter of 3mm. The thickness of the weldment is 10 to 12mm.

[0052] S32: Use a φ4mm tungsten electrode, sharpened with a dedicated sharpening device, with the tip height controlled at about 1 / 3 of the electrode diameter, i.e. 1.3-1.4mm. The sharpened tungsten electrode is conical in shape, with a smooth surface, no eccentricity, and no cracks.

[0053] S4: Equipment Debugging

[0054] Open the argon valve and adjust the gas flow to 7-8L / min. Then open the cooling water valve and adjust the flow to 1-2L / min. When the wall thickness of the aluminum tube is 6mm, the current is controlled at 240-260A. When the wall thickness is 8mm, the current is controlled at 260-280A. When the wall thickness is 10mm, the current is controlled at 280-310A. When the wall thickness is 12mm, the current is controlled at 320-340A. Use a gas flow meter to monitor the argon flow to ensure that the flow is stable. Ventilate for 3-5 minutes in advance to purge the welding gun nozzle and welding area to remove air and prevent oxidation during welding.

[0055] S5: Welding

[0056] S51: Before formal welding, use high-strength aluminum tubes and welding materials with the same specifications as those in actual production for trial welding. Through trial welding, further adjust the parameters of current, argon flow rate, and water flow, observe the formation of the weld, and check whether there are defects such as pores, cracks, and slag inclusions. Only when the quality of the trial weld meets the requirements can formal production be carried out; then, tack weld the aluminum tube. The spacing of the tack welds is determined according to the diameter and wall thickness of the aluminum tube, ranging from 100-150mm, and the length of the weld point is 5-10mm. During tack welding, ensure that the misalignment of the aluminum tube is ≤1mm and the gap is uniform, that is, between 2-3mm, to ensure the quality of the weld joint;

[0057] S52: Strike the arc in the groove of the aluminum tube. It is strictly forbidden to strike the arc on the base material outside the weld to prevent the arc from scratching the base material and causing cracks. During the welding process, use uniform welding speed, closely observe the changes in the molten pool, and adjust the welding speed and welding current in time according to the shape and temperature of the molten pool to ensure the consistency of the molten pool shape to avoid defects such as lack of fusion and burn-through. Preheat the welding part properly first, and add welding wire when the metal on both sides of the groove begins to melt. When welding, the tungsten electrode and the weldment are at an angle of 20°-30°, and the filler wire and the tungsten electrode are at an angle of about 90°. The tungsten electrode and the weld should be on the same plane. The welding speed is controlled at 3-5mm / s, and the welding gun is swung slightly horizontally to make the weldment smooth. The molten pool width should be maintained at 8-12mm. By controlling the welding current and the swing amplitude of the welding torch, the molten pool temperature should be kept within the appropriate range, preferably with the molten metal showing a "mirror" surface. If the molten pool temperature is found to be too high and there is a tendency for collapse, the welding speed should be increased or the welding current should be reduced appropriately. If the molten pool temperature is too low and there is a lack of fusion, the welding speed should be slowed down or the welding current should be increased appropriately. During the welding process, if cracks, slag inclusions, or lack of fusion are found in the weld, welding should be stopped immediately and the defects should be cleaned with a grinder or other appropriate tools until the metallic luster is exposed. Then, preheating and welding should be repeated according to the welding process requirements to ensure that the defects are completely repaired.

[0058] For high-strength aluminum tube weldments with high mechanical property requirements, stress relief annealing treatment is performed after welding. The weldment is heated to 300-350℃, kept warm for 1-2 hours, and then cooled with the furnace. Through post-weld heat treatment, the residual stress generated during the welding process is eliminated and the toughness and fatigue resistance of the welded joint are improved.

[0059] S6: Weld Inspection

[0060] After welding is completed, the weld is visually inspected. The weld surface is fine and uniform in the shape of fish scales, with the lowest point of the scales 1-2mm higher than the plane of the welded workpiece. The weld width is uniform, and there are no undercuts (i.e., undercut depth ≤ 0.5mm), weld bumps, or pores. A combination of visual inspection and measuring tools is used to observe the weld surface with the naked eye to check for obvious defects. A weld gauge is used to measure the weld reinforcement, width, and undercut depth to ensure that they meet the process requirements. At the same time, flaw detection is performed.

[0061] If defects are found in the welded parts during the inspection, a reasonable repair plan will be formulated according to the nature and severity of the defects. For minor surface defects, grinding and repair welding are used for repair; for internal defects, the location and size of the defects are first determined, and then the defects are removed mechanically, and then re-welded according to the welding process requirements. The number of reworks for the same part should not exceed 2 times. If it is still not repaired to a qualified standard after 2 times, it will be scrapped.

[0062] The limits of the untoleranced dimensions of welded parts shall comply with the provisions of Table 1 below. The deviation values apply to the length, width, internal and external dimensions and center distance of welded parts. Table 1 is as follows:

[0063]

[0064] Table 1

[0065] The limit deviation of the untoleranced angle of the welded parts shall comply with the provisions of Table 2 below. If the angle is marked on the drawing, the angle deviation in the table can be used. If the angle is not marked on the drawing and only the basic size is marked, the limit deviation is measured in mm / n. Table 2 is as follows:

[0066] Basic size (b) b≤315 315＜b≤1000 1000＜b≤2000 Angular limit deviation ±45＇ ±30＇ ±20＇ Mm / m Limit deviation ±13 ±9 ±6

[0067] Table 2

[0068] Experimental example

[0069] High-strength aluminum tubes of the same specifications, with a wall thickness of 10 mm and a length of 300 mm, were selected. The above embodiment was used as Experimental Example 1, and the traditional aluminum tube welding process on the market was used as Experimental Example 2. Ten specimens were prepared for each process. The experimental environment temperature was maintained at 20±5°C, the relative humidity was ≤60%, and the wind speed was ≤2m / s, ensuring that the two groups of experiments were conducted in the same environment.

[0070] Experimental Example 2 used a general-purpose pure aluminum welding wire with a diameter of 3 mm and an ordinary tungsten electrode that was not finely sharpened. The welding equipment used a simple argon arc welder. The groove was processed by manual grinding without strict control of the angle. Only sandpaper was used to polish the surface of the aluminum tube. The aluminum tube was locally preheated using a flame heating gun. The temperature and time were controlled based on experience. The argon gas flow rate and current were then adjusted based on experience to a current of approximately 240-260 A. Formal welding was carried out directly without a test weld. The tack weld, welding angle, and speed were not strictly controlled, and no stress relief annealing was performed.

[0071] Use a weld gauge to measure weld reinforcement, width, and undercut depth, record the data, and count the number of defects, including pores and weld bumps. Use a flaw detector to inspect the specimens and record internal defects. Perform a tensile test on the specimens to measure tensile strength. Perform a bending test to observe bending deformation and the presence of cracks. Record the total time required to complete the welding of a single specimen for each process, from pretreatment to post-weld treatment. The experimental data are shown below:

[0072] 1) Welding quality comparison table:

[0073]

[0074] 2) Mechanical properties comparison table:

[0075]

[0076] 3) Welding efficiency comparison table:

[0077]

Claims

1. High-strength aluminum tube welding process, characterized in that: The steps are as follows: S1: Weldment pretreatment S11: Beveling Use professional groove processing equipment to groove high-strength aluminum tubes, and process the grooves of aluminum tubes at 45° according to the thickness of the tubes; S12: Surface cleaning S2: Preheating of weldment Heat the aluminum tube to 400-420℃, use a thermometer to monitor the temperature change in real time to ensure that the temperature of each part of the aluminum tube is uniform. After reaching the predetermined temperature, keep it warm for 20-30 minutes; S3: Welding material preparation S31: Wire selection S32: Use a φ4mm tungsten electrode, sharpened with a dedicated sharpening device, with the tip height controlled at about 1 / 3 of the electrode diameter, i.e. 1.3-1.4mm. The sharpened tungsten electrode is conical in shape, with a smooth surface, no eccentricity, and no cracks. S4: Equipment Debugging Open the argon valve and adjust the gas flow to 7-8L / min, then open the cooling water valve and adjust the flow to 1-2L / min. When the wall thickness of the aluminum tube is 6mm, the current is controlled at 240-260A; when the wall thickness is 8mm, the current is controlled at 260-280A; when the wall thickness is 10mm, the current is controlled at 280-310A; when the wall thickness is 12mm, the current is controlled at 320-340A; S5: Welding S51: Before formal welding, perform positioning welding on the aluminum tube; S52: Strike an arc in the groove of the aluminum tube, preheat the welding part appropriately first, and add welding wire when the metal on both sides of the groove begins to melt. When welding, the tungsten electrode and the weldment are at an angle of 20°-30°, and the filler wire and the tungsten electrode are at an angle of about 90°. The tungsten electrode and the weld should be on the same plane. The welding speed is controlled at 3-5mm / s, and the welding gun is slightly swung horizontally to keep the molten pool width at 8-12mm. S6: Weld inspection.

2. The high-strength aluminum tube welding process according to claim 1, characterized in that: In step S11, the groove processing equipment includes a lathe and a groove machine; for aluminum tubes with smaller diameters, manual grinding is used to process the groove, and the angle and dimensional accuracy must be strictly controlled; the detailed steps of S12 are: first use a stainless steel wire brush or sandpaper to grind the groove of the aluminum tube and the 20-30mm range on both sides to remove the aluminum oxide film until the metallic luster is exposed; then wipe the surface with acetone or alcohol to thoroughly remove oil, dust and impurities.

3. The high-strength aluminum tube welding process according to claim 1, characterized in that: In step S2, for small batches of aluminum tubes with smaller diameters, a flame heating gun is used for local preheating; for large batches of aluminum tubes with larger diameters, a heating furnace is used for overall preheating.

4. The high-strength aluminum tube welding process according to claim 1, characterized in that: The detailed steps of S31 are as follows: S311: When welding pure aluminum parts, use pure aluminum welding wire, welding wire φ3mm, welding part thickness is 6-8mm, welding wire φ4mm, welding part thickness is 10-12mm; When welding S312:102 aluminum parts or 104 aluminum parts, pre-twisted wire is used. The pre-twisted wire is a high-strength alloy welding wire with a diameter of 3mm. The thickness of the welded parts is 10 to 12mm.

5. The high-strength aluminum tube welding process according to claim 1, characterized in that: In step S4, a gas flow meter is used to monitor the argon flow rate to ensure that the flow rate is stable. Ventilate for 3-5 minutes in advance to purge the welding gun nozzle and welding area to remove air and prevent oxidation during the welding process. After step S4, before formal welding, high-strength aluminum tubes and welding materials with the same specifications as those in actual production are used for trial welding. Through trial welding, the parameters of current, argon flow, and water flow are further adjusted, the formation of the weld is observed, and defects such as pores, cracks, and slag inclusions are checked. Only when the quality of the trial weld meets the requirements can formal production be carried out.

6. The high-strength aluminum tube welding process according to claim 1, characterized in that: In step S51, the spacing of the tack welds is determined according to the diameter and wall thickness of the aluminum tube, and is in the range of 100-150 mm. The length of the weld spot is 5-10 mm. During tack welding, ensure that the misalignment of the aluminum tube is ≤1 mm and the gap is uniform, that is, between 2-3 mm, to ensure the quality of the weld joint.

7. The high-strength aluminum tube welding process according to claim 1, characterized in that: In step S52, it is strictly forbidden to strike an arc on the base material outside the weld to prevent the arc from scratching the base material and causing cracks. During the welding process, uniform welding is adopted, and the changes in the molten pool are closely observed. The welding speed and welding current are adjusted in time according to the shape and temperature of the molten pool to ensure that the molten pool shape is consistent and to avoid defects such as lack of fusion and burn-through. By controlling the welding current and the swing amplitude of the welding gun, the molten pool temperature is kept within an appropriate range, preferably with the molten metal presenting a "mirror" shape. When it is found that the molten pool temperature is too high and there is a tendency to collapse, the welding speed is appropriately increased or the welding current is reduced. When the molten pool temperature is too low and there is a lack of fusion, the welding speed is appropriately slowed down or the welding current is increased. During the welding process, if cracks, slag inclusions, and lack of fusion are found in the weld, welding needs to be stopped immediately and the defects should be cleaned with a grinder or other suitable tools until the metallic luster is exposed. Then, preheating and welding are performed again according to the welding process requirements to ensure that the defects are completely repaired.

8. The high-strength aluminum tube welding process according to claim 1, characterized in that: After step S5, for high-strength aluminum tube weldments with high mechanical property requirements, stress relief annealing treatment is performed after welding. The weldment is heated to 300-350°C, kept warm for 1-2 hours, and then cooled with the furnace. Through post-weld heat treatment, the residual stress generated during the welding process is eliminated and the toughness and fatigue resistance of the weld joint are improved.

9. The high-strength aluminum tube welding process according to claim 1, characterized in that: In step S6, after welding is completed, the weld is visually inspected. The weld surface is fine and uniform in the shape of fish scales. The low point of the fish scales is 1-2 mm higher than the plane of the welded workpiece. The weld width is uniform and there are no undercuts, that is, the undercut depth is ≤ 0.5 mm, weld bumps, or pores. A method combining visual inspection and measuring tools is used to observe the forming of the weld surface with the naked eye to check whether there are obvious defects. A weld inspection ruler is used to measure the weld's excess height, width, and undercut depth to ensure that they meet the process requirements, and flaw detection is performed at the same time.

10. The high-strength aluminum tube welding process according to claim 9, characterized in that: If defects are found in the welded parts during the above inspection, a reasonable repair plan will be formulated based on the nature and severity of the defects. For minor surface defects, grinding and repair welding are used for repair; for internal defects, the location and size of the defects are first determined, and then the defects are removed mechanically, and then re-welded according to the welding process requirements. The number of reworks for the same part should not exceed 2 times. If it is still not repaired to a qualified standard after 2 times, it will be scrapped.

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