What is Undercut? How To Avoid Undercut Defect in Welding?

Undercut in Welding

As YENA Engineering, in our topic today, we will talk about what undercut welds, how they occur, and how to prevent them. They are grooves or notches that occur in areas close to the junction zones of the welding seam and the welding base metal and parallel to the welding seam. During solidification, undercut are formed, since these zones cannot be filled with liquid welding metal. It is caused by excessive welding speed and excessive welding current. Since it will create a notch effect in dynamic loads, this type of error is one of the major errors that will negatively affect the installation. Undercut usually occurs parallel to the weld seam. Usually, if the amount of gas released during welding is large, this causes a sudden increase in volume, that is, an explosion. With a sudden increase in volume, grooves may form on the edges of the weld seam.

We often hear the question of what is undercut in welding and what problems it leads to. The strength of notched welding seams subjected to dynamic stress is very weak. In this regard, the slightest notch or groove should not be allowed. The notches or grooves of the trustee without burning can be repaired by filling them. After this filling process, the slag and debris that will affect the merger should be removed with a chisel. Especially in high-strength steel, it is necessary that the working method used when repairing this defect complies with the welding technique recommended for welding steel.

Reasons of Undercut

The answer to the question of what causes undercutting in welding is listed below.

  • High current intensity
  • Extremely fast operation of the welder
  • Making too many zigzag movements on the electrode
  • Holding the electrode at the wrong angle
  • The base metal is extremely rusty and the electrode is damp
  • One of the parameters is the voltage value, that is, the voltage value is too high.

An undercut welding defect may occur for such reasons. To prevent undercut welding causes, reduction in cross-section and change of direction of force lines, especially in dynamic forces, combustion grooves should not be allowed.

Example of Deep Corrugated Undercut in Welding
Example of Deep Corrugated Undercut in Welding

How to Avoid Undercut Defects in Welding?

  • The appropriate voltage value must be selected.
  • The height of the arc is high. The arc distance can be reduced.
  • Incorrect torch or electrode angle. Weld pieces should be approached at angles between 30° and 45°.
  • Consumables with lower diameters should be selected.
  • The welding speed may be too low. The welding speed should be increased slightly.
Other Example of Undercut in Welding
Other Example of Undercut in Welding

Solutions of Undercut

Grooves formed due to combustion can be repaired by filling. Particles formed after this additional filling must be cleaned. The redrawn fill should match the welded area as much as possible.

Such situations can lead to bad consequences for companies and factories. For example, if such situations occur in the welding process of pipes, they can cause bad consequences depending on the type of substance passing through them. However, if these companies use pipe flanges, they will be able to prevent such situations. Click here for detailed information on pipe flanges.

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