Common defects in the welding zone of spiral steel pipes
Air bubbles mostly occur in the center of the weld bead, and hydrogen is still hidden in the weld metal in the form of air bubbles. The main reason is that the surface of the welding wire and flux has moisture, which is used directly without drying treatment. There is also a small current in the welding process, the welding speed is too fast, and this will also happen with accelerated solidified metals.
Undercut is a V-shaped groove at the edge of the weld along the center line of the weld. The main reason is that the welding speed, current, voltage and other conditions are not suitable. Among them, the welding speed is too high and it is easy to cause undercut defects.
The cause of thermal cracking is when the stress of the weld is very high, or when the SI silicon element in the weld metal is very high, there is also a sulfur crack, the billet is a plate with strong sulfur segregation zone (belonging to soft boiling Steel), cracks caused by sulfide entering the weld metal during the welding proces
The overlap between the internal and external weld metal is insufficient, and sometimes it is not fully penetrated.
Post time: May-21-2020