Common defects in welding area of spiral steel tube
Common defects of spiral steel pipe welding zone
1. Bubbles
Most of the bubbles appear in the center of the weld, and the hydrogen is still hidden in the weld metal in the form of bubbles. The main reason is that there is moisture and flux on the surface of the welding wire, which can be used directly without drying. There is also a relatively large current during the welding process. It is small, the welding speed is too fast, and accelerated solidification of the metal may also occur.
2. Undercut
Undercut occurs along the center-line of the weld. V-grooves appear at the edge of the weld. The main reason is that the welding speed, current and voltage are not suitable. The welding speed is too high to be more suitable than the current welding speed. It is easy to cause undercut defects.
3. Hot crack
The cause of thermal cracking is when the welding stress is high or when the Si element in the welding metal is high. There is also a sulfur crack. The blank is a plate with a strong sulfur segregation zone. Cracks caused by sulfide entering the welding metal during welding.
4. Insufficient penetration
There is not enough overlap between the inside and outside of the weld metal, and sometimes it will not be fully penetrated.
1. Bubbles
Most of the bubbles appear in the center of the weld, and the hydrogen is still hidden in the weld metal in the form of bubbles. The main reason is that there is moisture and flux on the surface of the welding wire, which can be used directly without drying. There is also a relatively large current during the welding process. It is small, the welding speed is too fast, and accelerated solidification of the metal may also occur.
2. Undercut
Undercut occurs along the center-line of the weld. V-grooves appear at the edge of the weld. The main reason is that the welding speed, current and voltage are not suitable. The welding speed is too high to be more suitable than the current welding speed. It is easy to cause undercut defects.
3. Hot crack
The cause of thermal cracking is when the welding stress is high or when the Si element in the welding metal is high. There is also a sulfur crack. The blank is a plate with a strong sulfur segregation zone. Cracks caused by sulfide entering the welding metal during welding.
4. Insufficient penetration
There is not enough overlap between the inside and outside of the weld metal, and sometimes it will not be fully penetrated.
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