Last Updated on Nov 19, 2022
Welding is a process of joining two materials, typically thermoplastics or metals, by inducing coalescence. Workpieces are melted, and a filler material is added to form a molten material pool (the weld pool), which cools to form a rigid joint. However, welding also causes various problems that can affect the quality of the weld. This guide will discuss some of the most common welding problems and how to troubleshoot them.
Lack of Fusion
This is one of the most common welding problems and occurs when the weld metal does not adhere properly to the base metal or when there is insufficient penetration of the weld metal into the base metal. This can be caused by a variety of factors, including incorrect welding parameters, rod size issues, wrong temperatures, contaminated electrodes, wrong speed, faulty preparation, or incorrect joint design.
There are a few ways that you can fix this issue:
- Use the correct welding parameters: One of the most common causes of lack of fusion is using incorrect welding parameters. Make sure you use the correct amperage, voltage, and speed for your weld.
- Use clean electrodes: Another common cause of lack of fusion is using contaminated electrodes. Make sure you use clean electrodes free of rust, dirt, and other contaminants.
- Use the correct joint design: If you are having trouble with a lack of fusion, it may be due to incorrect joint design. Make sure that you are using the correct joint design for your application.
- Make use of constant fanning motion and pressure. Moreover, clamp the pieces securely.
- Use a large rod at the top and a tiny rod at the root.
- Preheat the materials where needed.
Porosity is another common welding problem and occurs when there are voids or bubbles in the weld metal. This can be caused by factors such as contamination, welding in an environment with too much moisture, welding at a fast pace, improper bead crossing, entrapped gas impurities, oil film on the base metal, defected hose or hose with loose connections, improper start or stops, or using incorrect welding parameters.
To fix the porosity issue following measures can be taken:
- Use contact tip to gas cup spacer: One way to help reduce porosity is to use a contact tip to gas cup spacer. This will help create a gas barrier between the weld metal and the atmosphere, which will help prevent contamination.
- Use dry shields: Another way to reduce porosity is to use dry shields. Dryshields are placed over the welding area and help absorb moisture before reaching the weld pool.
- Use the correct welding parameters: Porosity can also be caused by using incorrect welding parameters. Make sure you use the correct amperage, voltage, and speed for your weld.
- Use a proper rod: A proper welding rod is also important to reduce porosity. Make sure that you are using a welding rod that is of the correct diameter and is made of the correct material.
- After cleaning, check to see if the base metal is dried. If you’re going to use a chemical cleaning, ensure it doesn’t break up in the arc.
- Use the rod in a uniform fanning motion, and don’t forget to check for temperature changes.
- Weld the beads in a proper sequence and cut the rod at an angle, but wait until it cools before releasing it.
- Before striking the arc, clear the lines of air. Remove any moisture that has condensed on the lines. Inert gas of welding quality (99.9%) should be used. Make sure you’re using the proper shield gas combination.
Spatter is a problem that occurs when molten droplets of metal are ejected from the welding arc. This can be caused by incorrect welding parameters, contaminated electrodes, or a dirty welding gun.
There are a few ways that you can fix the spatter issue:
- Use the correct welding parameters. This includes setting the correct current, voltage, and wire feed speed.
- Make sure that your electrodes are clean and not contaminated.
- Keep your welding gun clean. You can do this by using a wire brush to remove any dirt or debris.
Warping is a common problem when the weld joint cools and shrinks unevenly, causing the workpieces to deform. This can be caused by factors such as welding two dissimilar materials, welding on thin material, or welding in an environment with high humidity.
To fix the warping issue, do this:
- If you’re welding two dissimilar materials, try using a spacer between the two pieces to distribute heat evenly.
- If you’re welding thin material, try using a low amperage setting and weld slowly to avoid overheating the material.
- If you’re welding in an environment with high humidity, try using a fan to blow away any moisture from the area.
Cracking is a serious welding problem that can occur in both the weld metal and the heat-affected zone (HAZ). This can be caused by factors such as welding two dissimilar materials, undue stress on the weld, welding on contaminated material, chemical attack, improper welding temperature, using incorrect welding parameters, or degradation or oxidation of the weld.
To fix the cracking issues, follow this:
- Keep the weld area clean by removing all rust, paint, oil, or other contaminants before welding.
- Use the correct welding parameters for the materials being welded.
- Weld, in short, quick passes to minimize heat input and prevent warping or distortion.
- Use proper welding techniques to avoid creating excessive stresses in the weld.
- Apply the proper temperature.
- Allow the expansion and contraction without putting any pressure on the weld joint.
- Use inert gas and similar materials for welding
Distortion is a welding problem that occurs when the weld joint cools and shrinks unevenly, causing the workpieces to deform. This can be caused by factors such as welding two dissimilar materials, welding on thin material, slow welding, small pool, joint over-heating, or welding in an environment with high humidity.
It is important first to identify the root cause to fix this issue. Once the root cause has been identified, steps can be taken to prevent distortion from happening again. Some ways to prevent distortion include:
- Welding two similar materials together, using thicker material.
- Welding in a dry environment.
- For Joint overheating, allow for each bead to cool first.
- Try to weld at a constant speed by using a speed tip.
- Try not to weld in improper sequence and offset pieces before welding.
- Use a large triangular-shaped rod to avoid a small pool issue.
Poor Weld Appearance
Poor weld appearance can be caused by several factors, such as incorrect welding parameters, uneven pressure & heating, excessive stretching, or contaminated workpiece. There are a few ways to troubleshoot these issues:
- Start by checking your welding parameters. Ensure you use the correct amperage, voltage, and wire speed.
- If the problem persists, check for uneven pressure or heating. This can be caused by an incorrect cutting torch angle or poor gas coverage. So weld by heating both material and rod in a slow and uniform fanning motion.
- Another possibility is that the metal is being stretched too much during welding. This can be avoided by using the correct torch angle and travel speed.
- Contamination is a common cause of poor weld appearance. Be sure to clean the workpiece before welding and use clean, dry welding equipment.
An undercut is a hole or notch that weakens the metal and makes it more susceptible to breakage. The most common cause of undercuts is incorrect torch angle or incorrect welding technique. Undercuts can also be caused by excessive heat, too much filler metal, or weld beads that are too large.
To avoid undercuts, do the following:
- Make sure to use the correct torch angle and welding technique.
- If you are using too much heat, try reducing the welding current.
- If you are using too much filler metal, try using a smaller electrode.
- If you have weld beads that are too large, try using a smaller electrode or decreasing the welding current.
Incomplete penetration is a common welding problem that can be caused by several factors, such as large rods, faulty preparation, fast welding, and not enough root gap.
To fix this problem, you can:
- Increase the welding current
- Use a smaller rod at the root
- Weld slower and meanwhile check for flow lines.
- Use a tacking tip or leave a 1/32′′ root gap between the pieces and fasten them together.
A brittle weld is one that has low ductility and fracture toughness. This type of weld can occur for various reasons, including incorrect welding parameters, poor weld preparation, bare electrodes, use of excessive weld current, or the presence of contaminants.
To troubleshoot a brittle weld, check the welding parameters to ensure they are correct for the materials being used.
- Inspect the weld area for any contaminants that may be present.
- Make sure the weld is properly prepared, with the correct bevel angle and root opening.
- Use shielded arc electrodes and avoid using excessive weld currents.
- Use a multilayer approach while welding.
Weld metal and heat-affected zones are particularly susceptible to corrosion. The main types of corrosion that can occur during or after welding are:
- Rusting: This is the most common form of corrosion caused by oxygen in the air reacting with the iron in the metal.
- Galvanic corrosion occurs when two different metals are in contact with each other in the presence of an electrolyte, such as water. The more electrically active metal will corrode faster than the less active metal.
- Stress corrosion cracking: This is a form of corrosion caused by the combination of tensile stress and a corrosive environment.
- Intergranular corrosion: This is a form of corrosion that attacks the grain boundaries of the metal.
To avoid the corrosion issue:
- Use bare electrodes or shield arc electrodes.
- Use a filler rod with a composition that is similar to the base metal.
- Follow the correct welding procedure to avoid carbide precipitation.
- Do carefully and extensively clean all the slag left after welding.
When welding in the horizontal or flat position, the molten weld pool can be blown away from the weld’s root by the electrode’s magnetic field.
The most common remedy for this condition is to:
- Weld in the uphill or vertical-up position. If this does not correct the problem, increase the welding current.
- Use an electrode with a smaller tip or change to a bigger diameter electrode.
- Keep the electrode as close to perpendicular as possible.
- Reduce the welding speed.
- Use a stringer bead technique rather than a weaving technique.
If you are experiencing any of the problems mentioned above, it is important to troubleshoot the cause so that you can make the necessary corrections. Doing so can improve the quality of your welds and avoid potential safety hazards.