Surface defects that impair welding quality
In principle, welding processes have to join materials in accordance with drawings based on appropriate welding design. In addition, it is essential to ensure welding quality, including weld appearance and strength. This page introduces typical surface defects that impair welding quality.
Pits
Pits (open defects) are surface defects produced when gas cavities formed inside the weld metal solidify after the gas escapes from thebead表面。残留在珠粒内部的气体是称为吹孔的内部缺陷。这些缺陷的原因包括使用不当shielding gas; insufficient deoxidizer; oil, rust, plating or other matter adhering to the surface of thegroovein the base material; and moisture contained in the material.
- Pits
- Blow hole
Undercut
Undercut is a groove at the weld toe produced by thebase materialexiting weld. Typical causes are excessively high welding current or welding speed. Too muchweavingwidth may also be the cause of undercut.
- Undercut
Overlap
occ重叠urs when molten metal flows over the surface of thebase materialand then cools without fusing with the base material. A typical cause of overlap is the supply of too much weld metal due to low welding speed. Overlap infillet焊缝是由引力引起的过量熔融金属的下垂引起的。必要的对策是审查焊接条件（例如设定较高的焊接速度或较低焊接电流）。
- Overlap
强化不足
Reinforcement is the weld metal built up above the surface in excess of the required dimension in the groove weld or fillet weld. A typical cause is fast welding speed (moving speed of the heat source) that makes the deposition of the weld metal in thegrooveinsufficient.
- 强化不足
Surface cracking
表面裂化在焊接后立即形成热焊缝表面的裂缝。广泛分为凝固裂化和液化裂缝。焊缝固化时发生凝固裂化。当先前的焊接层通过随后的焊接熔化时，在多层焊接中发生液化裂缝。另一种分类是指裂缝的产生位置和形状，例如纵向开裂，趾裂化，横向裂化，火山口裂解等。
- Longitudinal cracking
- 脚趾开裂
- Transverse cracking
- Crater cracking
Arc strike
This is a defect caused by instantaneously striking an arc on thebase material. In other words, an arc strike is a spot of failed arc ignition which was not fused by subsequent welding and remained on the base material. Arc strike may be the cause of cracking in the base material.
A similar defect may occur when largespatterparticles adhere and remain on the surface.
珠蜿蜒(弯曲/偏差珠)
This defect occurs when thebeadmeanders and deviates from theweld line. Possible causes include the wave or curl in the automatically supplied weld wire not being corrected properly or the directions of the weld line and wire curl being at right angles to each other. This defect may also occur when the settings of the wire supply speed and welding current do not match.
Remaining groove
This is a state where parts of thegrooveare not welded and remain open because the process could not form abeadcontinuing from the start point to the end point of the groove. When this defect is found in robot welding around the start or end point, there may be a problem in the robot control. If the arc, gas or wire supply is unstable, the groove may also remain open in the middle of the bead.
