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Defects such as pores, slag inclusions, incomplete penetration, and undercuts often occur during the welding process. Today we will share the causes and solutions to welding defects. Causes and preventive measures for welding methods Manual arc welding (1) The welding rod is defective or wet. (2) The weldment contains moisture, oil stains or rust. (3) The welding speed is too fast. (4) The current is too strong. (5) The arc length is not suitable. (6) The thickness of the weldment is large and the metal cools too quickly. (1) Select appropriate welding rods and pay attention to drying. (2) Clean the welded part before welding. (3) Reduce the welding speed to allow the internal gas to escape easily. (4) Use the appropriate current recommended by the manufacturer. (5) Adjust the appropriate arc length. (6) Carry out appropriate preheating work. CO2 gas shielded welding (1) The base metal is unclean. (2) The welding wire is rusty or the welding flux is wet. (3) Poor spot welding and improper selection of welding wire. (4) The dry extension is too long and the CO2 gas protection is not thorough. (5) The wind speed is high and there is no wind blocking device. (6) The welding speed is too fast and the cooling is rapid. (7) Sparks splash and stick to the nozzle, causing gas turbulence. (8) The gas purity is poor and contains a lot of impurities (especially moisture). (1) Pay attention to cleaning the welded parts before welding. (2) Select appropriate welding wire and keep it dry. (3) The spot welding bead must not be defective, must be clean, and the size of the welding wire used must be appropriate. (4) Reduce the dry extension length and adjust the appropriate gas flow rate. (5) Install wind blocking equipment. (6) Reduce the speed to allow internal gas to escape. (7) Pay attention to clearing the welding slag from the nozzle and applying anti-spatter adhesion agent to extend the life of the nozzle. (8) CO2 purity is above 99.98%, and moisture is below 0.005%. Submerged arc welding (1) The weld seam contains rust, oxide film, grease and other organic impurities. (2) The flux is wet. (3) The flux is contaminated. (4) The welding speed is too fast. (5) The flux height is insufficient. (6) The height of the flux is too large, making it difficult for gas to escape (especially when the flux particle size is fine). (7) The welding wire is rusty or oily. (8) Improper polarity (especially contamination during docking will produce pores). (1) The welds need to be ground or burned with a flame, and then cleaned with a wire brush. (2) It needs to be dried at about 300°C. (3) Pay attention to the storage of flux and the cleaning of the area near the welding part to avoid the mixing of debris. (4) Reduce the welding speed. (5) The rubber nozzle of the flux outlet should be adjusted higher. (6) The flux outlet rubber tube should be adjusted lower, and the appropriate height is 30~40mm in automatic welding. (7) Replace with clean welding wire. (8) Change the direct current connection (DC-) to the direct current reverse connection (DC+). Defective equipment (1) The pressure reducing gauge is cooled and the gas cannot flow out. (2) The nozzle is blocked by spark splash. (3) The welding wire has oil and rust. (1) When the gas regulator is not equipped with an electric heater, an electric heater must be installed and the flow rate of the meter must be checked at the same time. (2) Remove nozzle spatter frequently. And apply anti-spatter adhesion agent. (3) Oil should not come into contact with the welding wire when storing or installing the welding wire. The voltage of the self-shielded flux cored wire (1) is too high. (2) The protruding length of the welding wire is too short. (3) There is rust, paint, and moisture on the surface of the steel plate. (4) The drag angle of the welding gun is too tilted. (5) The moving speed is too fast, especially for horizontal welding. (1) Reduce the voltage. (2) Use according to the instructions of various welding wires. (3) Clean before welding. (4) Reduce the drag angle to approximately 0°~20°. (5) Adjust appropriately. 2Defect name: Causes of undercut welding and preventive measures for manual arc welding (1) The current is too strong. (2) The welding rod is not suitable. (3) The arc is too long. (4) Improper operation methods. (5) The base material is unclean. (6) The base material is overheated. (1) Use lower current. (2) Select the appropriate type and size of welding rod. (3) Maintain appropriate arc length. (4) Use the correct angle, slower speed, shorter arc and narrower running method. (5) Remove oil stains or rust from the base material. (6) Use welding rods with smaller diameters. CO2 gas shielded welding (1) The arc is too long and the welding speed is too fast. (2) During fillet welding, the alignment of the welding rod is incorrect. (3) Vertical welding swings or poor operation causes insufficient filling on both sides of the weld bead, resulting in undercuts. (1) Reduce arc length and speed. (2) During horizontal fillet welding, the position of the welding wire should be 1~2mm away from the intersection point. (3) Correct the operating method. 3Defect name: Reasons for slag inclusion welding and preventive measures for manual arc welding (1) The front layer of welding slag is not completely removed. (2) The welding current is too low. (3) The welding speed is too slow. (4) The welding rod swings too wide. (5) Poor weld combination and design. (1) Thoroughly remove the front layer of welding slag. (2) Use higher current. (3) Increase the welding speed. (4) Reduce the swing width of the welding rod. (5) Correct the appropriate bevel angle and gap. CO2 gas arc welding (1) The base metal is tilted (downhill) to advance the welding slag. (2) After the previous welding, the welding slag was not cleaned. (3) The current is too small, the speed is slow, and the amount of welding is large. (4) When welding by the forward method, the welding slag in the slot is much ahead. (1) Place the weldment in a horizontal position as much as possible. (2) Pay attention to the cleanliness of each welding pass. (3) Increase the current and welding speed to make the welding slag float easily. (4) Increase the welding speed. Submerged arc welding (1) The welding direction is inclined toward the base metal, so the welding slag flows ahead. (2) During multi-layer welding, the slotted surface is melted by the welding wire, and the welding wire is too close to the side of the slot. (3) Slag inclusions are likely to occur at the guide plate at the starting point of welding. (4) If the current is too small, there will be welding slag remaining between the second layers, which will easily cause cracks when welding thin plates. (5) The welding speed is too low, causing the welding slag to advance. (6) The arc voltage of the final finishing layer is too high, causing free welding slag to swirl at the end of the weld bead. (1) Change the welding direction to the opposite direction, or change the base metal to be welded in the horizontal direction as much as possible. (2) The distance between the groove side and the welding wire must be at least greater than the diameter of the welding wire. (3) The thickness and slot shape of the guide plate must be the same as the base material. (4) Increase the welding current to make the residual welding slag melt easily. (5) Increase the welding current and welding speed. (6) Reduce the voltage or increase the welding speed. If necessary, change the cover layer from single-pass welding to multi-pass welding. The arc voltage of the self-shielded flux cored wire (1) is too low. (2) The arc of the welding wire is improperly swung. (3) The welding wire extends too long. (4) The current is too low and the welding speed is too slow. (5) The first pass of welding slag was not fully removed. (6) The first combination is poor. (7) The slope is too narrow. (8) The weld is inclined downward. (1) Adjust appropriately. (2) Practice more * . (3) Follow the instructions for using various welding wires. (4) Adjust welding parameters. (5) Completely clear (6) Use appropriate voltage and pay attention to arc swing. (7) Correct the appropriate bevel angle and gap. (8) Lay it flat or move faster. 4Defect name: Causes and preventive measures for incomplete penetration welding in manual arc welding (1) Improper selection of welding rods. (2) The current is too low. (3) The welding speed is too fast and the temperature does not rise enough, and the welding speed is too slow. The arc impulse is blocked by the welding slag and cannot be transferred to the base metal. (4) The weld design and combination are incorrect. (1) Choose a welding rod with greater penetrating power. (2) Use appropriate current. (3) Use appropriate welding speed instead. (4) Increase the groove degree, increase the gap, and reduce the root depth. CO2 gas shielded welding (1) The arc is too small and the welding speed is too low. (2) The arc is too long. (3) Poor slotting design. (1) Increase welding current and speed. (2) Reduce arc length. (3) Increase the groove degree. Increased clearance reduces root depth. Self-shielded flux-cored wire (1) current is too low. (2) The welding speed is too slow. (3) The voltage is too high. (4) Improper arc swing. (5) Improper bevel angle. (1) Increase the current. (2) Increase the welding speed. (3) Reduce the voltage. (4) Practice more * . (5) Use a larger slotting angle. 5Defect name: Causes of crack welding methods and preventive measures Manual arc welding (1) The weldment contains excessive carbon, manganese and other alloying elements. (2) The welding rod is of poor quality or wet. (3) The restraint stress of the weld is too large. (4) The parent bar material contains too much sulfur and is not suitable for welding. (5) Insufficient preparation for construction. (6) The base material is thicker and cools too quickly. (7) The current is too strong. (8) The first weld bead is insufficient to resist shrinkage stress. (1) Use low-hydrogen welding rods. (2) Use appropriate welding rods and pay attention to dryness. (3) Improve the structural design, pay attention to the welding sequence, and perform heat treatment after welding. (4) Avoid using bad steel. (5) Preheating or postheating needs to be considered when welding. (6) Preheat the base metal and slowly cool it after welding. (7) Use appropriate current. (8) The welding metal of the first welding pass must fully resist shrinkage stress. CO2 gas shielded welding (1) The groove angle is too small, which will cause pear-shaped and weld bead cracks during high current welding. (2) The carbon content and other alloy content of the base metal are too high (weld bead and heat shadow area). (3) When multi-layer welding, the first layer of weld bead is too small. (4) Improper welding sequence results in excessive binding force. (5) The welding wire is wet and hydrogen gas invades the weld bead. (6) The sleeve plates are not tightly connected, resulting in unevenness and stress concentration. (7) Due to too much welding in the first layer, cooling is slow (stainless steel, aluminum alloy, etc.). (1) Pay attention to the appropriate coordination between the slotting angle and the current, and increase the slotting angle if necessary. (2) Use welding rods with low carbon content. (3) The first welding metal must be able to fully resist shrinkage stress. (4) Improve the structural design, pay attention to the welding sequence, and perform heat treatment after welding. (5) Pay attention to the storage of welding wire. (6) Pay attention to the accuracy of the weldment assembly. (7) Pay attention to the correct current and welding speed. Submerged arc welding (1) The combination of welding wire and flux used for the weld base metal is inappropriate (the base metal contains too much carbon, and the welding wire metal contains too little manganese). (2) The weld bead is rapidly cooled, causing the heat-affected zone to harden. (3) The welding wire contains too much carbon and sulfur. (4) The weld bead force generated in the first layer of multi-layer welding is not enough to resist shrinkage stress. (5) Excessive penetration or segregation during fillet welding. (6) The welding construction sequence is incorrect and the base material is highly constrained. (7) The shape of the weld bead is inappropriate, and the ratio of weld bead width to weld bead depth is too large or too small. (1) When using welding wire with a high manganese content, preheating measures must be taken when the base metal contains a lot of carbon. (2) The welding current and voltage need to be increased, the welding speed reduced, and the base material needs to be heated. (3) Replace the welding wire. (4) The welding metal of the first layer of weld bead must fully resist shrinkage stress. (5) Reduce the welding current and welding speed and change the polarity. (6) Pay attention to the prescribed construction methods and provide guidance on welding operations. (7) The ratio of weld bead width to depth is about 1:1:25, the current decreases and the voltage increases. 6Defect name: Causes of deformation welding methods Prevention measures Hand welding CO2 gas shielded welding Self-shielded flux cored wire welding Automatic submerged arc welding (1) Too many welding layers. (2) Improper welding sequence. (3) Insufficient preparation for construction. (4) The base material cools too quickly. (5) The base material is overheated. (Thin plate) (6) Improper weld design. (7) Too much metal is welded. (8) The restraint method is unreliable. (1) Use larger diameter welding rods and higher current. (2) Correct the welding sequence (3) Before welding, use clamps to fix the weldment to avoid warping. (4) Avoid cooling too quickly or preheating the base metal. (5) Choose welding materials with low penetration power. (6) Reduce the weld gap and reduce the number of grooves. (7) Pay attention to the welding size and do not make the weld bead too large. (8) Pay attention to fixing measures to prevent deformation. 7 Causes of other welding defects in welding methods and preventive measures for overlapping (1) The current is too low. (2) The welding speed is too slow. (1) Use appropriate current. (2) Use appropriate speed. The appearance and shape of the weld bead is poor (1) The welding rod is defective. (2) The operating method is inappropriate. (3) The welding current is too high and the diameter of the electrode is too thick. (4) The weldment is overheated. (5) In the weld bead, the filling method is poor. (6) Contact tip wear. (7) The extension length of the welding wire remains unchanged. (1) Select a dry welding rod of appropriate size and good quality. (2) Use uniform and appropriate speed and welding sequence. (3) Select welding with appropriate current and appropriate diameter. (4) Reduce the current. (5) Practice more * . (6) Replace the contact tip. (7) Maintain a fixed length and be proficient. Dent (1) Improper use of welding rod. (2) The welding rod is wet. (3) The base material cools too quickly. (4) Dirty welding rods and segregation of weldments. (5) The carbon and manganese content of the weldment is too high. (1) Use appropriate welding rods. If it cannot be eliminated, use low-hydrogen welding rods. (2) Use dried welding rods. (3) Reduce the welding speed and avoid rapid cooling. It is best to apply preheating or postheating. (4) Use good low-hydrogen welding rods. (5) Use welding rods with higher salinity. Arc deflection (1) During DC welding, the magnetic field generated by the weldment is uneven, causing the arc to deflect. (2) The grounding wire is not in good position. (3) The drag angle of the welding gun is too large. (4) The extension length of the welding wire is too short. (5) The voltage is too high and the arc is too long. (6) The current is too large. (7) The welding speed is too fast. (1) Place a ground wire on one side of the arc, or weld directly to the side of the arc, or use a short arc, or correct the magnetic field to make it uniform, or switch to AC welding (2) Adjust the position of the ground wire. (3) Reduce the drag angle of the welding gun. (4) Increase the extension length of the welding wire. (5) Reduce voltage and arc. (6) Adjust and use appropriate current. (7) The welding speed slows down. Burn-through (1) The current is too large when welding with slots. (2) The weld gap is too large due to poor slotting. (1) Reduce the current. (2) Reduce the weld gap. Uneven weld bead (1) The contact tip is worn and the welding wire output swings. (2) Unskilled in operating the welding gun. (1) Replace the welding contact tip with a new one. (2) Practice more operations * . Welding tears (1) The current is too large and the welding speed is too slow. (2) The arc is too short and the weld bead is high. (3) The welding wire is not properly aligned. (When filling welding) (1) Select the correct current and welding speed. (2) Increase the arc length. (3) The welding wire should not be too far away from the intersection point. Excessive sparks and splashes (1) Defective welding rod. (2) The arc is too long. (3) The current is too high or too low. (4) The arc voltage is too high or too low. (5) The welding wire protrudes too long. (6) The welding gun is tilted excessively and the drag angle is too large. (7) The welding wire absorbs excessive moisture. (8) The welding machine is in poor condition. (1) Use dry and suitable welding rods. (2) Use a shorter arc. (3) Use appropriate current. (4) Adjust appropriately. (5) Follow the instructions for using various welding wires. (6) Keep it as vertical as possible and avoid excessive tilt. (7) Pay attention to warehouse storage conditions. (8) Repair and pay attention to daily maintenance. The weld bead is in a serpentine shape (1) The welding wire extends too long. (2) The welding wire is twisted. (3) Poor linear operation. (1) Use an appropriate length. For example, the solid welding wire extends 20~25mm when the current is high. The extended length during self-protection welding is approximately 40~50mm. (2) Replace with new welding wire or correct the distortion. (3) When operating in a straight line, the welding gun should be kept vertical. Arc instability (1) The contact tip at the front of the welding gun is much larger than the core diameter of the welding wire. (2) The contact tip is worn. (3) The welding wire is curled. (4) The welding wire conveyor does not rotate smoothly. (5) The groove of the welding wire conveying wheel is worn. (6) The pressurized wheel is poorly pressed. (7) The resistance of the conduit joint is too great. (1) The core diameter of the welding wire must match the contact tip. (2) Replace the contact tip. (3) Curl and straighten the welding wire. (4) Add oil to the conveyor shaft to lubricate the rotation. (5) Replace the conveyor wheel. (6) The pressure should be appropriate. If it is too loose, the wire feeding will be poor, and if it is too tight, the wire will be damaged. (7) The catheter is too bent, adjust to reduce the amount of bending. Arc occurs between the nozzle and the base material (1) Short circuit occurs between the nozzle, conduit or contact nozzle. (1) Excessive spark spatter adhering to the nozzle must be removed, or a ceramic tube with insulation protection for the welding gun must be used. The welding gun nozzle is overheated (1) The cooling water cannot flow out sufficiently. (2) The current is too large. (1) The cooling water pipe is blocked. If the cooling water pipe is blocked, it must be cleared to increase the water pressure and increase the flow rate to normal. (2) The welding gun is used within the allowable current range and usage rate. The welding wire sticks to the contact tip (1) The distance between the contact tip and the base material is too short. (2) The resistance of the catheter is too large and the wire feeding is poor. (3) The current is too small and the voltage is too high. (1) Use an appropriate distance or slightly longer to start the arc, and then adjust to the appropriate distance. (2) Clear the inside of the catheter to enable smooth transportation. (3) Adjust appropriate current and voltage values.