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September 21, 2020

Aviation welders must remain vigilant to avoid making errors during the application of a welding job. If there are any defects in an aircraft's welding, it can be disastrous for the aircraft and the pilot. The aviation welders must show special care for avoiding these common defects during their welding procedures.

Incomplete penetration

One common defect of welding is incomplete penetration. There are three types of defects that fall into this category. The first one is a welding process in which the welding bead doesn't penetrate the base metal. This is why it's called an incomplete penetration. An incomplete penetration causes incomplete welding that's not strong or durable enough.

Another type of defect is when an aviation welding technician can’t interpenetrate two opposing welding beads.

The third type of incomplete penetration refers to a situation where the welding job isn't done to the fillet base but only bridges across it. This defect occurs because of the slow welding current. A simple remedy is to use increased amperage while welding the metal. A faulty torch angle can also be a reason for this.

Lacking fusion

Lack of fusion between the base plate's surface and the weld metal is also a crucial defect in the welding world. It happens when the two surfaces aren’t fused into each other properly due to the improper welding technique used. Experts refer to this defect with different names, too, such as cold shut and cold lapping.

There are several causes of this defect. One probability is that the welding technician has used a larger welding puddle and a very low travel speed. It can also result due to the bending of the weld base in front of the welding arc. If the bead crown is rolled over, it can also result in lacking fusion between the weld metal and base plate. It can also be avoided by keeping the weld joint within the appropriate size, not too small nor too big. Low welding speed and low voltage also cause a lack of fusion.


Undercutting is another common defect seen in the welding process. It results in a groove's appearance on the parent welding metal, along the edges of the weld. This usually happens when you execute a lap fillet or fillet and butt welding joint.

The most common causes of this fault are inappropriate parameters set during the welding procedure. It may include not selecting the right travel speed of the weld. This can cause an improper welding process, and result in this defect. The other reason is choosing the wrong arc voltage for the welding process.

If the travel speed is more than what is prescribed, the weld bead will have a high peak because it'll result in more solidification. An undercut is a spot where the base material has been melted and drawn into the weld, but couldn't wet back due to excessive solidification at a higher speed.


You might have noticed pores on or under the weld surface. These pores can appear in varying shapes and numbers depending on the factors affecting the welding process. These pores are gas pores caused due to more than one reason: contamination in the air, excess of oxidized elements on the welding surfaces, and the inadequacy of deoxidizing alloys in the welding wire. By taking care of the atmosphere in the welding place, most of the porosity’s causes can be prevented.

Acorn Welding promises nothing but the best. We have a team of highly professional and well-trained aviation welding technicians who don't compromise on anything to deliver perfect welding procedures. Get in touch with us by clicking here.