03 Mar 2022
Welding plays a very important role in modern industrial production. It is more advantageous when manufacturing large structures or complex machine parts, because it can be used to prepare blanks in a simple way, and then assemble them one by one. The welding method is small and large, which is difficult to achieve by other process methods, and argon tungsten arc welding is a commonly used welding technology. When working with a TIG welding machine, if you want to get a more perfect weld, you need to know more relevant technical knowledge. Below we will specifically talk about the operation taboos and common weld defects and preventive measures of tungsten tungsten arc welding.
First of all, let's talk about the taboos of argon tungsten arc welding. The first is to avoid the use of DC reverse welding when argon tungsten arc welding is generally used. Second, when the welding current is too large, it is forbidden to use the tungsten electrode with a sharp cone angle, because the welding current will cause the end of the tungsten electrode to overheat and melt and increase the burning loss. At the same time, the arc drift is unstable, which affects the welding seam formation. Third, the contact arc ignition method should not be used in argon tungsten arc welding, because the reliability of the contact arc ignition method is poor, the tungsten electrode is easy to burn, and the metal tungsten mixed into the weld will cause tungsten inclusion defects. Fourth, the gas flow rate and nozzle diameter are beyond the proper range. If the airflow is too large or the nozzle diameter is too small, turbulence will be formed due to the high airflow speed, which will not only reduce the protection range, but also involve air and reduce the protection effect. . Fifth, the joints and endings of the weld should avoid difficult-to-weld locations, such as between the two pipes of the row of pipes. The arc at the end should be delayed to extinguish the arc, and the arc should be led to the groove after the molten pool is filled; after the arc is extinguished, the argon gas should be continuously supplied for 3s to 5s, and then the welding torch should be removed. Sixth, short arc welding should be used to keep the arc stable, and long arc welding should be avoided as much as possible. Seventh, the welding wire must not collide with the end of the tungsten electrode, and the welding wire should always be within the gas protection zone to prevent oxidation of the hot end of the welding wire. Eighth, the top of the tungsten electrode must not be in contact with the molten pool to prevent tungsten inclusion defects. Ninth, the welding of the groove weld should not be completed in one layer, generally not less than two layers, otherwise it will not guarantee the penetration of the root, and it will easily cause defects. Tenth, when welding in winter, be sure to use compressed air to blow out the water in the entire water cooling system, and replace the antifreeze, so as not to freeze the pipes in the water cooling system. Eleventh, tungsten electrodes for argon arc welding, especially thorium tungsten electrodes, should have a dedicated storage location, be stored in lead boxes, and be distributed by special personnel. The twelfth, when the welder grinds the tungsten electrode, it is necessary to wear personal protective equipment and perform it in a well-ventilated place. After sanding, wash your hands and face immediately. Thirteenth, do not adjust or replace the nozzle and tungsten electrode of the welding torch with bare hands without cutting off the power of the high-frequency oscillator and the high-frequency generator, so as to avoid electric shock accidents.
Then talk about the main reasons and preventive measures for defects in tungsten tungsten arc welding. Common defects in manual tungsten argon arc welding include tungsten inclusion in the weld, burn-through, incomplete penetration, undercut, porosity, weld flash, serious oxidation of black ash in the weld, shrinkage cavities, arc scratches and poor weld formation of cracks, etc. . The first is the inclusion of tungsten in the weld. The main reasons are: the tungsten electrode is in contact with the workpiece; the wire filling technology is not good; the welding current is too large, which makes the tungsten electrode melt. The preventive measures are: when striking the arc, there must be a certain distance between the tungsten electrode and the workpiece; improve the wire filling method; reduce the welding current, or increase the diameter of the tungsten electrode. The second, burn through. During the welding process, the molten metal flows out from the back of the groove to form a perforation defect, which is called burn-through. The main reasons are: large welding current; slow welding speed; too large assembly gap or too small blunt edge. The preventive measures are: reduce the welding current; speed up the welding speed; correctly design the size of the welding groove to ensure the assembly quality. The third type, pores. The main reasons: impure argon; trachea rupture or moisture in the gas path; the welding wire or workpiece is too dirty; the wire feeding method destroys the argon protection zone; the tungsten electrode extends too long or the nozzle height is too large; the tungsten electrode is bent or Deviate from the center of the nozzle; the electrode jacket and tungsten electrode clip are twisted and deformed. Preventive measures are: replace pure argon gas; check gas path; keep welding wire and workpiece to be welded area clean; improve wire feeding method; reduce tungsten electrode extension length and nozzle height; replace tungsten electrode; replace electrode jacket and tungsten electrode clamp . The fourth, welding flash. The main reasons are: too large gap; too fast wire feeding; too large welding current; too slow welding speed, resulting in high molten pool temperature. Preventive measures: pay attention to the assembly gap; use an appropriate wire feeding speed; reduce the welding current; use an appropriate welding speed, and observe the change of the molten pool at all times. Fifth, undercut. The main reasons: the angle of the welding torch is incorrect; the arc voltage is too high; the wire feeding is too little, the welding speed is too fast; the swing of the welding torch is uneven. Preventive measures: adjust the angle of the welding torch; reduce the arc length; appropriately increase the wire feeding speed or reduce the welding speed; keep the swing evenly. Sixth, the black ash of the weld is seriously oxidized. The main reasons are: small flow of argon gas; slow welding speed; high molten pool temperature or high current. Preventive measures: increase the flow of argon gas; increase the welding speed; appropriately reduce the welding current. Seventh, shrinkage. The main reason: the method of arc ending is wrong; the continuous air supply time is short when ending the arc. Preventive measures: Change the arc ending method and increase the continuous wire feeding time. The eighth type is not fully welded. The main reasons: the welding current is small; the welding speed is fast; the wire feeding is too fast. Preventive measures: increase the welding current; slow down the welding speed, slow down the wire feeding speed. The ninth, arc scratches. The main reasons are: inaccurate arc striking, arc striking outside the weld of the workpiece; poor ground contact. Preventive measures: The arc should be accurate, and the arc should not be struck on the surface of the workpiece; the ground wire should be connected tightly. Tenth, the welding seam is not neatly formed. The main manifestations are that the external dimensions exceed the specified range, the height and width are different, and the back is concave. Poor weld formation will affect the strength of the welded joint and cause hazards such as stress concentration. The main reasons for uneven welding seam formation: uneven wire feeding speed; uneven welding speed; uneven welding torch swing. Preventive measures: uniform wire feeding; welding speed should be uniform; welding torch swing should be uniform.
If you have mastered the above content, I believe you can operate TIG welding well and obtain higher quality welds. We are a manufacturer specializing in the development and production of digital welding and cutting power sources. Our brand is kingsiri. Our engineers can write the source code of the welding machine and create new functions according to the needs of customers. Adhering to the culture of innovation in traditional welding technology, we are committed to building an innovative technology-based enterprise. Excellent R&D team, superb technology, hope to get your recognition and affirmation.
Keywords: welding machine
Originally published 03 Mar 2022, updated 03 Mar 2022.