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1、 There are three main reasons for slag inclusion in welding seam when automatic welding equipment is used
1. After the backing welding is not complete, the root slag can not completely overflow during the rapid hot welding.
2. The improper method of backing and root cleaning makes the groove on both sides of root pass too deep and W-shaped. In rapid hot welding, the slag flowing to the deep groove has no time to overflow and form slag inclusion.
3. In overhead welding position, too fast arc stopping is easy to produce slag inclusion.
2、 The causes of Blowholes in the welding process of automatic welding equipment are as follows
1. During the cover welding, the molten pool overheats and absorbs a lot of surrounding air.
2. During the cover welding, the swing range of welding rod is too large, and the protection of molten pool is poor.
3. If the root gap is too small, needle shaped bubbles are easy to form at the root.
4. The welding rod is not used up or exposed to the air for a long time.
3、 Causes of weld cracks
1. If the construction section fluctuates greatly and the soil pier is not padded in place in time, the pipe will be in the stress state, and the stress crack is easy to appear at the welding stop point, especially at the 6 o'clock position.
2. In the welding process, if the aligning device is released or withdrawn early, the molten iron in the molten pool will solidify well in the future, and cracks are easy to occur when the welding arc stops.
3. The welder adopts improper arc stopping methods such as direct arc extinguishing at overhead welding position, which leads to the formation of crater cracks due to the incompleteness of molten pool.
4、 Causes of concave in automatic welding equipment
1. The penetration depth of backing welding is not enough.
2. The welding current is too large, and the welding speed is too slow at 5-7 points during hot welding.