1. Pores
(a) External pores; (b) internal pores; (c) continuous pores; (d) dense pores
| Welding mode | Cause of occurrence | Preventive measures |
| Manual arc welding | (1) The welding rod is bad or wet. (2) Welding has moisture, oil stains or rust. (3) The welding speed is very fast. (4) The current is very strong. (5) The arc length is not suitable. (6) The welding thickness is large and the metal cooling is very fast. |
(1) Select the appropriate welding rod and pay attention to drying. (2) Clean the welded part before welding. (3) Reduce the welding speed so that the internal gas can escape easily. (4) Use the appropriate current recommended by the manufacturer. (5) Adjust the appropriate arc length. (6) Perform proper preheating. |
| CO 2 gas shielded welding | (1) The base metal is dirty. (2) The welding wire is rusty or the welding flux is wet. (3) Improper spot welding and improper welding wire selection. (4) The length of the dry extension is too long and the CO2 gas shielding is not careful. (5) The wind speed is high and there is no wind protection device. (6) The welding speed is very fast and the cooling speed is very fast. (7) Sparks splashed into the nozzle, causing gas turbulence. (8) The gas has low purity and contains many diverse products (especially moisture). |
(1) Pay attention to the cleanliness of the welded parts before welding. (2) Select the appropriate welding wire and keep it dry. (3) The spot welding bead must be free from defects and must be clean at the same time, and the size of the welding wire used must be appropriate. (4) Reduce the length of the dry extension and adjust the appropriate gas flow. (5) Install wind protection equipment. (6) Reduce speed to allow internal gas to escape. (7) Pay attention to remove welding slag from the nozzle and apply splash adhesion inhibitor to extend the service life of the nozzle. (8) The purity of CO2 is more than 99.98% and the humidity is less than 0.005%. |
| Submerged Arc Welding | (1) There is rust, oxide film, grease and other organic impurities in the weld. (2) The stream is wet. (3) The stream is contaminated. (4) The welding speed is very fast. (5) Insufficient flow height. (6) The flow height is very high, so the gas is not easy to escape (especially in the case of fine flow particle size). (7) The welding wire is rusty or oil stained. (8) Improper polarity (especially contamination during coupling will produce pores). |
(1) The weld must be ground or burned with a flame and then removed with a wire brush. (2) Dry at about 300 ℃ (3) Pay attention to storing the flux and cleaning the area near the welding part to avoid mixing miscellaneous articles. (4) Reduce the welding speed. (5) The rubber nozzle of the flow outlet should be adjusted higher. (6) The rubber tube at the flux outlet should be adjusted downwards, and the appropriate height should be 30 ~ 40 mm in the case of automatic welding. (7) Replace with clean solder wire. (8) Change direct DC connection (DC -) to reverse DC connection (DC +). |
| Bad equipment | (1) The pressure reducing gauge is cooled and gas cannot flow. (2) The nozzle is blocked by sparks and splashes. (3) The welding wire contains oil and rust. |
(1) When there is no electric heater connected to the gas regulator, install an electric heater and check the flow rate meter at the same time. (2) Always remove the spray from the nozzle. And coated with splash adhesion inhibitor. (3) Do not touch the oil when storing or installing welding wires. |
| Self-shielded flux-cored wire | (1) The voltage 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) Too much steepness of the welding gun drag angle. (5) The movement speed is very fast, especially in transverse welding. |
(1) Reduce voltage. (2) Use according to the instructions for various welding wires. (3) Clean before welding. (4) Reduce the drag angle to about 0° ~ 20°. (5) Adjust correctly. |
Related Reading: How to Choose the Right Welding Rod?
2. Undercut
| Welding mode | Cause of occurrence | Preventive measures |
| Manual arc welding | (1) The current is too strong. (2) The electrodes are not suitable. (3) The arc is too long. (4) Improper operation method. (5) The base metal is dirty. (6) Overheating of the base metal. |
(1) Use a lower current. (2) Select appropriate types and sizes of welding rods. (3) Maintain proper arc length. (4) Adopt correct angle, slower speed, shorter arc and narrower operation method. (5) Remove oil or rust stains from the base metal. (6) Use electrodes with a smaller diameter. |
| CO 2 gas shielded welding | (1) The arc is too long and the welding speed is too fast. (2) During fillet welding, the welding rod is not aligned correctly. (3) Welding vertical oscillation or poor operation, resulting in insufficient filling of both sides of the weld bead and undercut. |
(1) Reduce arc length and speed. (2) During horizontal fillet welding, the position of the welding wire should be 1 ~ 2 mm away from the intersection. (3) Correct the operation method. |
3. Slag inclusion
| Welding mode | Cause of occurrence | Preventive measures |
| Manual electricityArc welding | (1) The welding slag of the previous layer is not completely removed. (2) The welding current is too low. (3) The welding speed is too slow. (4) The electrode oscillates a lot. (5) Poor combination of welding and design clearance. |
(1) Completely remove the welding slag from the previous layer. (2) Adopt higher current. (3) Improve welding speed. (4) Reduce the turning width of the welding rod. (5) Correct the proper groove angle and |
| CO 2 gas arc welding | (1) The tilting (sloping) of the base metal causes the welding slag to advance. (2) After the previous welding, the welding slag is not cleaned. (3) The current is very small, the speed is slow, and there is a lot of welding. (4) When welding with direct method, the welding slag in the groove is too far forward. |
(1) Place the welding in a horizontal position as much as possible. (2) Pay attention to the cleanliness of each weld bead. (3) Increase the current and welding speed to make the welding slag float easily. (4) Improve welding speed. |
| Submerged Arc Welding | (1) The welding direction is inclined with respect to the base metal, so that the welding slag flows forward. (2) During multilayer welding, the surface of the groove is dissolved by the welding wire, and the welding wire is very close to the side of the groove. (3) Slag inclusion is easy to occur on site with the guide plate at the welding starting point. (4) When there is small welding slag in the second layer, it is easy to produce cracks. (5) The welding speed is too low to advance the welding slag. (6) Finally, the arc voltage of the finished layer is too high, which causes the free welding slag to stir at the end of the weld bead. |
(1) Change the welding direction to the opposite direction or change the base metal to the horizontal direction as much as possible. (2) The distance between the grooved side and the welding wire must be at least greater than the diameter of the welding wire. (3) The thickness and shape of the guide plate groove must be the same as that of the base metal. (4) Increase the welding current to facilitate the melting of residual welding slag. (5) Increase the welding current and welding speed. (6) Reduce voltage or increase welding speed. If necessary, the cover layer is changed from single-pass welding to multi-pass welding. |
| Self-shielded flux-cored wire | (1) Arc voltage is too low. (2) Improper oscillation of the welding wire arc. (3) The welding wire extends too much. (4) The current is too low and the welding speed is too slow. (5) The first welding slag was not completely removed. (6) The first course is poorly combined. (7) The groove is too narrow. (8) The weld is tilted downward. |
(1) Adjust correctly. (2) Practice more. (3) Follow the instructions of various welding wires. (4) Adjust welding parameters. (5) Completely clear (6) Use proper voltage and pay attention to arc swing. (7) Correct the proper groove angle and gap. (8) Flatten or move faster. |
4. Incomplete penetration
| Welding mode | Cause of occurrence | Preventive measures |
| Manual arc welding | (1) Improper welding rod selection. (2) The current is too low. (3) The welding speed is too fast, the temperature rise is not enough, and the welding speed is too slow. The arc impulse is blocked by the welding slag and cannot be transmitted to the base metal. (4) Incorrect weld design and combination. |
(1) Select the welding rod with relatively penetrating force. (2) Use appropriate current. (3) Use appropriate welding speed. (4) Increase the groove degree, increase the clearance and reduce the root depth. |
| CO 2 gas shielded welding | (1) The arc is too small and the welding speed is too slow. (2) The arc is too long. (3) Poor groove design. |
(1) Increase the current and welding speed. (2) Reduce arc length. (3) Increase the groove degree. Increase the gap and reduce the root depth. |
| Self-shielded flux-cored wire | (1) The current is too low. (2) The welding speed is too slow. (3) The voltage is too high. (4) Improper arc oscillation. (5) Incorrect groove angle. |
(1) Increase the current. (2) Improve welding speed. (3) Reduce voltage. (4) Practice more. (5) Adopt a larger groove angle. |
5. Crack
| Welding mode | Cause of occurrence | Preventive measures |
| Manual arc welding | (1) Weldments contain a lot of 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 bus material contains a lot of sulfur and is not suitable for welding. (5) Insufficient construction preparation. (6) The thickness of the base metal is large and the cooling speed is very fast. (7) The current is very strong. (8) The first pass is insufficient to resist the shrinkage stress. |
(1) Use low hydrogen welding rod. (2) The welding rod must be dry and suitable for use. (3) Improve the structural design, pay attention to the welding sequence, and carry out heat treatment after welding. (4) Avoid using bad steel. (5) Preheating or postheating must be considered during welding. (6) Preheat the base metal and cool it slowly after welding. (7) Use appropriate current. (8) The weld metal of the first weld must fully resist the shrinkage stress. |
| Protected welding with CO2 gas | (1) If the groove angle is too small, pear-shaped and weld bead cracks will occur during high current welding. (2) The carbon content of base metal and other alloys is very high (welding bead and hot shadow area). (3) In multilayer welding, the first pass is very small. (4) Improper welding sequence resulting in too strong bond strength. (5) The welding wire is wet and hydrogen invades the weld bead. (6) The sleeve plate is poorly connected, resulting in uneven height and stress concentration. (7) Due to the excessive amount of welding of the first layer, cooling is slow (stainless steel, aluminum alloy, etc.). |
(1) Pay attention to the correspondence between the appropriate groove angle and chain, and increase the groove angle if necessary. (2) Low carbon electrodes should be used. (3) The first weld metal must be sufficiently resistant to shrinkage stresses. (4) Improve the structural design, pay attention to the welding sequence, and carry out heat treatment after welding. (5) Pay attention to the storage of welding wire. (6) Pay attention to the accuracy of welding assembly. (7) Pay attention to the correct current and welding speed. |
| Submerged Arc Welding | (1) The combination of welding wire and flux used for welding base metal is inappropriate (the carbon content of the base metal is too large and the manganese content of the welding wire metal is too small). (2) The weld bead cools quickly and hardens the heat-affected zone. (3) Welding wire contains a lot of carbon and sulfur. (4) The strength of the weld bead generated in the first layer of multilayer welding is not sufficient to resist the shrinkage stress. (5) Excessive penetration or segregation during fillet welding. (6) The welding construction sequence is incorrect and the bonding force of the base metal is large. (7) The shape of the weld bead is inappropriate and the ratio of the width of the weld bead to the depth of the weld bead is too large or too small. |
(1) When using welding wire with high manganese content, preheating measures must be taken when the carbon content of the base metal is high. (2) The welding current and voltage should be increased, the welding speed should be reduced, and the base metal should be heated. (3) Replace the welding wire. (4) The welding metal of the first pass must fully resist the shrinkage stress. (5) Reduce welding current and speed, and change polarity. (6) Pay attention to the specified construction methods and provide construction guidelines for welding operation. (7) The ratio of weld bead width to depth is about 1:1:25, the current decreases and the voltage increases. |
6. Deformation
| Welding mode | Cause of occurrence | Preventive measures |
| Manual weldingCO2 gas shielded weldingWelding with self-shielded flux cored wireAutomatic submerged arc welding | (1) Many layers of welding. (2) Inadequate welding sequence. (3) Insufficient construction preparation. (4) The cooling of the base metal is very rapid. (5) Overheating of the base metal. (sheet) (6) Inadequate weld design. (7) A lot of metal is welded. (8) The form of containment is not precise. |
(1) Use electrodes with larger diameter and higher current. (2) Correct welding sequence (3) Before welding, secure the welding with a fixture to prevent warping. (4) Avoid cooling too quickly or preheating the base metal. (5) Select welding materials with low penetration. (6) Reduce the weld gap and groove degree. (7) Pay attention to the welding size and do not make the weld bead too large. (8) Pay attention to the fixing measures to avoid deformation. |
7. Other welding defects
| Welding mode | Cause of occurrence | Preventive measures |
| Overlay | (1) The current is too low. (2) The welding speed is too slow. |
(1) Use appropriate current. (2) Use appropriate speed. |
| Poor appearance and shape of the weld bead | (1) Bad welding rod. (2) Improper operation method. (3) The welding current is too high and the electrode diameter is too thick. (4) Welding overheating. (5) In the weld bead, the melt filling method is poor. (6) The conductor nozzle is worn out. (7) The extension length of the welding wire remains unchanged. |
(1) Dry electrodes of appropriate size and good quality should be selected. (2) Adopt uniform and appropriate welding speed and sequence. (3) Select welding with appropriate current and diameter. (4) Reduce the current. (5) Practice more. (6) Replace the conductive nozzle. (7) Maintain fixed length and proficiency. |
| Tooth | (1) Improper use of welding rods. (2) The welding rod is wet. (3) The cooling of the base metal is very rapid. (4) Dirty electrode and welding segregation. (5) The carbon and manganese content of welding is very high. |
(1) Use a suitable welding rod. If it cannot be eliminated, use a low hydrogen welding rod. (2) Use dry electrodes. (3) Reduce the welding speed and avoid quenching. It is best to preheat or postheat. (4) Use a good electrode with low hydrogen content. (5) Electrodes with high basicity must be used. |
| Arc Deviation | (1) During DC welding, the magnetic field generated by welding is irregular, which deflects the arc. (2) Poor position of the ground wire. (3) The leakage 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 high. (7) The welding speed is very fast. |
(1) Put a ground wire on one side of the arc, or weld on the other side, or use a short arc, or correct the magnetic field to make it uniform, or use AC welding (2) Adjust the position of the ground wire. (3) Reduce the drag angle of the welding gun. (4) Increase the length of the welding wire extension. (5) Reduce voltage and arc. (6) Adjust and use the appropriate current. (7) Slow welding speed. |
| Burn | (1) When there is slot welding, the current is very large. (2) The weld gap is too large due to poor groove. |
(1) Reduce the current. (2) Reduce the weld gap. |
| Irregular weld bead | (1) The conductive nozzle is worn and the welding wire output fluctuates. (2) Unqualified operation of the welding gun. | (1) Replace the welding nozzle with a new one. (2) Practice more. |
| Welding slots | (1) The current is too large and the welding speed is too slow. (2) The arc is too short and the weld bead is too high. (3) Incorrect welding wire alignment. (during fillet welding) |
(1) Select the correct welding current and speed. (2) Increase the arc length. (3) The welding wire should not be too far from the intersection. |
| Excessive spark splash | (1) Bad welding rod. (2) The arc is too long. (3) The current is too high or too low. (4) Arc voltage is too high or too low. (5) The welding wire protrudes too much. (6) The welding gun tilts excessively and the drag angle is too large. (7) Excessive moisture absorption of the welding wire. (8) The welding machine is in poor condition. |
(1) Use a suitable dry welding rod. (2) Use a shorter arc. (3) Use appropriate current. (4) Adjust correctly. (5) Follow the instructions of various welding wires. (6) Stay as vertical as possible and avoid excessive leaning. (7) Pay attention to the storage conditions of the warehouse. (8) Repair and pay attention to maintenance during the week. |
| The weld bead is serpentine. | (1) The welding wire extends too much. (2) The welding wire is twisted. (3) Poor linear operation. |
(1) Appropriate length should be adopted, such as solid welding wire, which extends 20 to 25 mm in case of high current. During self-shielded welding, the extension length is about 40~50mm. (2) Replace the welding wire with a new one or correct the distortion. (3) When operating in a straight line, the welding gun must be kept vertical. |
| Arch instability | (1) The conductive nozzle at the front end of the welding gun is much larger than the core diameter of the welding wire. (2) The conductor nozzle is worn out. (3) The welding wire curls. (4) The welding wire carrier does not rotate smoothly. (5) The groove of the welding wire conveyor wheel is worn. (6) The pressure wheel is not pressed firmly. (7) The strength of the conduit joint is too high. |
(1) The core diameter of the welding wire must match the conductive nozzle. (2) Replace the conductive nozzle. (3) Coil and straighten the welding wire. (4) Add oil to the conveyor shaft to lubricate the rotation. (5) Replace the conveyor wheel. (6) The pressure must be appropriate, too loose, inadequate wire feeding, too tight and the welding wire is damaged. (7) If the conduit is bent too much, adjust to reduce the bend value. |
| Arc between nozzle and base metal | (1) Short circuit between nozzle, conduit or conductive nozzle. | (1) Excess sparks and spatter adhered to the nozzle must be removed, or use the ceramic tube with insulating protection of the welding gun. |
| Overheating of the welding gun nozzle | (1) Cooling water cannot flow completely. (2) Excessive current. |
(1) The cooling water pipe is blocked. If the cooling water pipe is blocked, it must be removed so that the water pressure increases and flows normally. (2) The welding gun must be used within the allowable current range and utilization rate. |
| The welding wire adheres to the conductive nozzle | (1) The distance between the conductive nozzle and the base metal is too short. (2) Excessive conduit resistance and poor wire feed. (3) The current is too small and the voltage is too high. |
(1) Use the appropriate distance or a little more to start the arc and then adjust to the appropriate distance. (2) Clean the inside of the conduit to allow smooth delivery. (3) Adjust the appropriate value of current and voltage. |
