28.5. What are the causes of edge biting defects?

During the welding process, if a depression forms at the edge of the weld, causing the weld seam to be lower than the base material, this depression is known as edge burn-through defect. There are many reasons that can cause edge burn-through defects. For instance, if the welding speed is too fast or a high welding current is used during the process, it can enhance the arc and trigger such defects. Additionally, issues with the welding machine's weld pool can cause fluctuations in welding depth during the process. In this case, it becomes difficult for the weld metal to fill properly, leading to significant strain phenomena. Therefore, when performing spiral steel pipe welding operations, it is crucial to avoid the occurrence of edge burn-through defects as much as possible.