Now that you are familiar with welding techniques, you must know the problems you face before and after welding. If not, then why not study and observe welding defects?
What will you do if you encountered these problems at your workplace? If your weld is not done carefully, there is a high probability of an issue occurring during the weld.
And even if it goes smoothly, the resulting weld will start to show the result of your carelessness over time.
Especially, as a beginner, your weld will have these defects. With timely practice, you will be able to pinpoint all the little things to avoid any problems.
- Welding defects
- Categories of welding defects
- Internal welding defects
- Other welding defects
- Wrapping up
You can easily define welding defects as the irregularities that might happen during the time welding. What is the reason for the occurrence of these defects? We will discuss all of these concerns in detail.
The carelessness of the welder can be on the top of the list. If the welder is not doing his job properly, the resulting weld will not give us the expected result. If the welder is not trained properly, then his poor technique will cause the weld to be weak and defective.
Other factors involve the choice of the right material. As you know that each welding technique gives its best performance only when it is done on the right material. And in case you are using a metal that is not suitable for a specific job, then it is quite obvious. It will result in a faulty weld.
Besides, you might face some structural problems, equipment failure, or any environmental issues.
Categories of welding defects
Now, welding defects can occur in different ways. Some of them you will find easy to recover and some will cause you a headache. But some of them are very hard to find because it might be an internal defect.
Welding defects are categorized into two main types:
- External welding defects
- Internal welding defects
External welding defects
As the name suggests, the defects that appear on the outer part of the weld are categorized under external defects. Some of the external defects are:
- Weld crack
Overlapping occurs when the filler material is applied a little extra on the edges of the base metal. It stays there without bonding and the resulting angle is less than 90 degrees.
Solutions for overlapping defect
- Carefully choose the welding technique following the metal used for welding.
- Training should be done for a specific period until you gain experience. Practicing a lot is important.
- Choosing the right size of the electrode will ensure weld safety.
- The touch angle should be maintained correctly.
- The welding current should be suitable for the welding process.
During welding, as a result of using arc, tiny metal particles will be emitted from the surface of the base metal. These particles began to accumulate on the surface of the base metal.
Along with the length of the weld bead, these particles start to get stuck on the metal surface as the welding is being done. This issue is named spattering. You will encounter it most often during MIG welding.
Solution for spattering defect
- Before welding, the metal surface should be cleaned properly to remove all the dust and contaminants.
- Using a short-length arc can help in avoiding such an issue.
- The polarity of the material should be adjusted before working on it.
- Gas shielding should be done carefully and properly.
Weld cracks are considered to be quite dangerous and must be avoided at all costs. Because it directly compromises the structure of the metal. If used for construction purposes, it can be life-threatening.
Weld cracks might appear on the weld surface, or in the base metal. If a certain area of metal is exposed to a large amount of heat directly, there are high chances of weld cracks.
Types of weld cracks
Weld cracks are categorized into three types:
- Hot cracks
- Crater cracks
- Cold cracks
This type of weld crack occurs when the temperature exceeds 10,000C during the welding process.
Crater cracks are more likely to occur when the welding process is about to end. When the welder is about to finish the weld, these cracks might appear in the welding area.
This type of crack occurs when the weld is completed and the metal has been cooled down. They occur at that time or maybe after a couple of days. When there is any deformation in the structure of the weld, cold cracks appear.
Solutions for cracking defect
- Use non-ferrous metals along with hydrogen. Suitable metals can give us the desired outcome.
- Apply welding current according to the requirement.
- Design concepts should be prepared thoughtfully.
- Metal should be preheated before using welding on it.
- Use the concentration of sulfur and carbon in the right proportions.
- Weld joints should have a minimum gap in between them.
During the welding process, when the base metal is melted, there is a groove formation. Its shape is similar to a notch. It can make the weld weaker because the cross-sectional area is decreased in this case.
Solutions for undercut defect
- Use a low voltage arc along with decreasing the arc length.
- With respect to the standing leg, the angle of the electrode should be 30 to 35 degrees.
- Electrode size should be according to the base metal.
- The travel speed of the electrode should be controlled. It should not be fast or too slow.
- Select the shielding gas that will best suit the metal and the welding technique you are using.
The formation of small bubbles or blowholes in the welding area can make the weld porous. Weld strength can reduce immediately due to porosity. During welding, if gases are trapped inside the welding zone causes the weld to be porous.
Solutions for porosity
- Filler material and electrode should be selected carefully according to the base metal and welding technique.
- Metal surfaces should be free from rust or oil so they should be cleaned thoroughly.
- To allow all the gases to escape the welding zone, welding should be done nicely and slowly.
- Moreover, arc length should be small for effective welding.
Internal welding defects
Above, we have discussed some of the welding defects that cause issues externally. Let’s have a detailed overview of internal defects.
Internal defects are indeed hard to be noticed because they occur inside the welding zone. Removal of these defects is itself a problem. Because it requires a lot of effort and technique to avoid or remove these types of welding defects.
Some of the few internal welding defects are:
- Incomplete penetration
- Incomplete fusion
- Slag formation
- Necklace cracking
In the welding process, we can understand penetration as a distance between the base and the uppermost surface of the base metal.
Incomplete penetration occurs when the base portion of the metal remained unfilled with metal weld. Metal weld doesn’t reach the joint thickness and a little area is left empty.
Solutions for incomplete penetration
- Deposition of weld metal is done thoroughly.
- Metals joints should be connected in the right way.
- The size of the electrode and its working position should be according to the welding process.
This mainly happens due to the carelessness of the welder. As a result, a visible gap is left between the joints because the molten metal is not filled inside the joint.
Solutions for incomplete fusion
- The welding area should be free from contaminants.
- Lower the speed and increase the welding current to ensure complete fusion.
- The deposition rate should be lowered.
- The welding torch and electrode should be used at a proper angle.
It straightforwardly affects the toughness and structural performance of the weld and the metal itself. The resulting joint will be weaker in strength.
Solutions for slag formation
- The current density should be increased.
- Welding speed should be adjusted accordingly to avoid the mixing of weld pool and slag.
- After welding, it should be cooled properly.
- Also, clean the metal to remove all unwanted particles to avoid slag.
This problem occurs during electron beam welding. It occurs because the weld does not penetrate all around the welding zone. The cavity is not filled with molten metal and it causes necklace cracking.
Solutions for necklace cracking
- The speed of the electron beam should be uniform throughout the welding process.
- The material should be selected properly.
- Lastly, electron beam welding requires an experienced person to guarantee efficient welds.
Other welding defects
Besides the welding defects that we have discussed above, there are some other problems as well that you might encounter at work.
You might encounter distortion, hot tears, mechanical damage, lamellar tearing, misalignment, whiskers, excess reinforcement, etc.
If ignored, they might cause no problem for the time being. But as time passes, the weld will automatically show its weakness. So make sure whenever you are welding, do it properly.
With all that being said, making an effective and strong weld should be a welder’s priority. And this can only happen if you master the technique with effort and practice.
In case you are being careless, it will not only effects the weld badly but also increase the risk of structural failure. This way, not only you but also other people will be at risk. Weld can rust or break causing different problems.
A welder’s job is considered quite important because they play a major role in making our surrounding environment. That is why avoiding all the problems is the best solution.