Common welding defects in aluminum alloy welding and their solutions

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The selection of aluminum and aluminum alloy welding wires is primarily based on the type of base material, taking into account requirements regarding the crack resistance, mechanical properties, and corrosion resistance of the joint. Sometimes, when a certain issue becomes the main problem, the selection of welding wire focuses on addressing this primary issue while also taking into account other requirements. In general, for welding aluminum and aluminum alloys, welding wires of the same or similar grade to that of the base material are used, which helps to achieve better corrosion resistance ； However, when heat-treating aluminum alloys with a high tendency to weld heat cracking, the selection of welding wire is primarily aimed at improving crack resistance; in such cases, there is a significant difference in composition between the welding wire and the base material. Common defects (welding issues) and preventive measures 1. Burn-through Causes: a. Excessive heat input ； b、Improper groove preparation and excessive assembly gap in the welded parts ； c. During spot welding, the spacing between solder joints is too large, resulting in significant deformation during the welding process. Preventive measures: a. Appropriately reduce the welding current and arc voltage, and increase the welding speed ； b. Size of the large blunt edge, to reduce the root gap ； c. Appropriately reduce the solder joint spacing during spot welding. 2. Porosity: Causes: a. Oil, rust, dirt, scale, etc. on the base material or welding wire ； b. The air circulation at the welding site is high, which is not conducive to gas protection ； c. The welding arc is too long, reducing the effectiveness of gas protection ； d. The distance between the nozzle and the workpiece is too large, resulting in reduced gas protection effectiveness ； e. Improper selection of welding parameters ； f. Porosity occurs at the repeated arc start point ； g. The purity of the shielding gas is low, resulting in poor gas shielding effect ； h. The humidity of the surrounding air is high. Preventive measures: a. Thoroughly clean the surface of the welding wire and the workpiece of oil, dirt, rust, scale, and oxide films before welding; use welding wire with a high content of deoxidizers ； b. Select the welding location appropriately ； c. Appropriately reduce the arc length ； d. Maintain a proper distance between the nozzle and the workpiece ； e. Try to use thicker welding wires, and at the same time increase the thickness of the root face of the workpiece groove. This allows for the use of higher current levels; the WeChat official account is: Weld King. It also reduces the proportion of welding wire in the weld metal, which is effective in lowering the porosity rate ； f. Try to avoid starting the arc in the same area repeatedly; if it is necessary to do so, grind or scrape the area where the arc is initiated ； Once welding begins on a weld seam, it is necessary to weld as long as possible; avoid stopping the welding process arbitrarily in order to reduce the amount of joint. A certain overlap area in the weld seam is required at the joint ； g. Change the protective gas ； h. Check the airflow volume ； i. Preheating the base material ； j. Check for any air leaks and damage to the trachea ； k. Weld in low air humidity, or use a heating system. 3. Unstable arc. Causes: faulty power cable connections, dirt, or wind. Preventive measures: a. Inspect all conductive parts and keep their surfaces clean ； b. Remove the dirt from the joint ； c. Try not to weld in areas where air currents can be disrupted. 4. Poor weld shape. Causes: a. Inappropriate selection of welding parameters ； b、Incorrect welding torch angle ； c、The welder is not skilled in operating the equipment ； d. The aperture of the conductive nozzle is too large ； e. Moisture is present in the welding wire, weldment, and shielding gas. Preventive measures: a. Conduct repeated adjustments to select the appropriate welding parameters ； b. Maintain an appropriate welding torch angle ； c. Select an appropriate aperture for the conductive nozzle ； d. Thoroughly clean the welding wire and workpiece before welding to ensure the purity of the gas. 5. Incomplete penetration. Causes: a. Excessively fast welding speed, overly long arc ； b、Improper groove machining, excessive clearance in the equipment ； c、The welding specifications are too low ； d. The welding current is unstable. Preventive measures: a. Appropriately reduce the welding speed and lower the arc voltage ； b. Appropriately reduce the blunt edge or increase the root gap ； c. Increase the welding current and arc voltage to ensure sufficient heat input to the base material ； d. Install a voltage stabilizing device. e. Fine welding wires help increase penetration, while thick welding wires increase the amount of material deposited; the choice should be made as appropriate. 6. Lack of fusion. Causes: a. Oxide films or rust on the welding area were not removed thoroughly ； b. Insufficient heat input. Preventive measures: a. Clean the surface of the area to be welded before welding; b. Increase the welding current and arc voltage, and reduce the welding speed ； c. U-shaped joints are used for thick plates, while V-shaped joints are generally not used. 7. Cracks: Causes: a. Unreasonable structural design, with welds concentrated in too many areas, resulting in excessive restraint stresses at the welded joints ； b. Excessively large molten pool, overheating, and significant loss of alloying elements ； c. The crater at the end of the weld cools rapidly ； d. The wire composition does not match that of the base material ； e. The weld depth-to-width ratio is too high. Preventive measures: a. Properly design the welded structure, arrange the welds in a suitable manner to keep them away from stress concentration areas, and select the welding sequence appropriately ； b. Reduce the welding current or appropriately increase the welding speed ； c. The arc extinguishing operation must be performed correctly; an arc starting plate should be used or a current attenuation device employed to fill the arc pit ； d. Select the appropriate welding wire.