The Causes and Control of Bead-type Blowholes in Welds

- May 14, 2018 -

The Causes and Control of Bead-type Blowholes in Welds

The cause of the pinch-type pores is that the pores and slags are generated at the bottom of the molten pool during the internal welding to form the pore-welded slag. At this time, the quality of the pores including the welding slag is larger than the pure pores, and the welding speed is faster, so the weld pool is welded to the inner shell. The bead-type pores formed near the bottom are difficult to float and escape, thereby forming defects. The influencing factors are: Rust During welding, rust releases H2 and O2. On the one hand, oxidation is enhanced on the molten pool, and CO pores are generated during crystallization; on the other hand, the possibility of generating H2 pores is increased. A source of air holes is provided. 2. Welding process Through carbon arc gouging processing and analysis, it was found that the air hole is close to the inner welding position and is formed during the inner welding process. When the external weld was found in the pipe section of the external welded joint, the internal weld had already formed a bead-type blowhole, indicating that the bead-type blowhole was an internal weld defect. 3, gap forming seams forming a large seam, or tightly closed within the forming seam, resulting in the internal welding before the welding of some of the welding flux into the forming seam, in particular the gap between the forming seam is not suitable to contain a large number of rust powder solder clip In the forming seam, resulting in the welding process to produce beads in the welding process. Based on the above analysis, the basic measures to solve the bead-type pinhole defects of the weld should be as follows: 1. To ensure the stability of the weld pipe and the appearance of the wrong edge, adjust the gap of the weld pipe forming gap to be as small as possible to make the flux. Can not enter the forming seam. 2, adjust the forming joint tightly outside the loose, so that there is a slight outside the mouth, so that welding is not easy to fall into the forming seam. 3, adjust the milling edge angle, so that the angle of the inner welding groove becomes smaller, the flux is trapped shallower, and thus more easily from the molten pool.


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