来源：http://www.chinatvren.com/ 发布时间：2022-04-02 浏览次数：
In the welding process, there are many matters needing attention. Once neglected, it may make a big mistake.
1. Welding construction does not pay attention to the selection of voltage
[phenomenon] during welding, the same arc voltage shall be selected for priming, filling and covering, regardless of groove size. In this way, the required penetration depth and width may not be reached, and defects such as undercut, air hole and splash may appear.
[measures] generally, the corresponding long arc or short arc should be selected according to different situations, so as to obtain better welding quality and work efficiency.
2. Welding does not control welding current
[phenomenon] during welding, in order to speed up the progress, no groove is adopted for the butt weld of medium and thick plate. The strength index decreases, even fails to meet the standard requirements, and cracks appear during bending test, which will make the performance of weld joint unable to be guaranteed and pose potential harm to the structure.
[measures] the welding shall be controlled according to the welding current in the process qualification, 10 ~ 15% floating is allowed, and the blunt edge size of the groove shall not exceed 6mm. During butt joint, when the plate thickness exceeds 6mm, groove shall be made for welding.
3. Do not pay attention to the coordinated use of welding speed, welding current and electrode diameter
[phenomenon] when welding, do not pay attention to controlling the welding speed and welding current, and coordinate the use of electrode diameter and welding position.
For example, when backing welding the full penetration corner seam, due to the narrow size of the root, such as the welding speed is too fast, the root gas and slag inclusion do not have enough time to be discharged, which is easy to produce defects such as incomplete penetration, slag inclusion and pores at the root; During cover welding, if the welding speed is too fast, it is also easy to produce pores; If the welding speed is too slow, the weld reinforcement will be too high and the shape will be irregular; When welding thin plates or welds with small blunt edge size, the welding speed is too slow and it is easy to burn through.
[measures] the welding speed has a significant impact on the welding quality and welding production efficiency. When selecting, the appropriate welding speed shall be selected in combination with the welding current, weld position (backing welding, filler welding, cover welding), weld thickness and groove size. On the premise of ensuring penetration, easy discharge of gas and welding slag, no burn through and good forming, the larger welding speed shall be selected to improve the productivity and efficiency.
4. The arc length is not controlled during welding
[phenomenon] during welding, the arc length is not properly adjusted according to the groove form, number of welding layers, welding form, electrode model, etc. Due to the improper use of welding arc length, it is difficult to obtain high-quality welds.
[measures] in order to ensure the weld quality, short arc operation is generally adopted during welding, but the appropriate arc length can be selected according to different conditions to obtain better welding quality. For example, the first layer of V-groove butt joint and fillet joint should use shorter arc to ensure penetration and no undercut. The second layer can be slightly longer to fill the weld. Short arc should be used when the weld gap is small. When the gap is large, the arc can be slightly longer and the welding speed can be accelerated.