Welding defects can be said to be the irregularities formed in a given weld metal as a result of incorrect welding patterns, wrong welding process, or due to poor welding skills from the welder’s part. Weld flaws may come in different sizes, shapes, and degrees of severity.
There are different types of welding defects that can transpire during the welding process. From porosity and cracking, to burn through and undercut, each has several causes.
However, regardless of the application and material on which they occur, one thing remains true to all of them; they’re common, costly, cause downtime and loss of productivity.
Luckily enough, there are various remedies that can help welders minimize these welding defects. In this article, we shall be discussing the seven most common welding defects, causes, and remedies plus 2 others.
What Are Welding Defects?
Welding defects/flaws can be defined as weld surface irregularities, imperfections, discontinuities, or inconsistencies that are formed in welded parts.
These defects differ from the desired weld bead size, shape, and quality. Welding defects could occur either from the outside or inside the weld metal.
Defects in weld joints could cause the rejection of parts and assemblies, an increase in the cost of maintenance, a reduction in performance and could cause catastrophic failures posing the risks of loss of life and property.
What Are The Causes Of Weld Defects?
There are a number of factors that can lead to welding defects. Some of the most common causes include:
- Improper Welding Procedure:
An improper welding process will result in a defective weld. Some examples of such welding procedures include lack of shielding gas, incorrect electrode extension (too long or too short), incorrect shielding gas for the particular material you are welding, and an inappropriate arc length (too small or too large).
- Inadequate Weld Preparation:
Proper preparation is essential for any successful project, especially a welding project. If your materials aren’t adequately cleaned before being welded, that can lead to many problems, including contamination and porosity in the finished product. Remember that when you’re planning your next home improvement project? When was the last time you did some cleaning and sanding, getting rid of rust and paint? Well, this is precisely what you should be doing. This way, when it comes time for welding, your only concern will be the proper preparation of your materials to make sure they are free from contaminants.
- Poor Weld Joint Design:
Welding defects can also occur if the joints are improperly designed in relation to each other or reference to their structural loads or applications. For example, suppose a heavy smooth pipe is connected to a thin-walled flange that has been designed with too small of a radius for added strength in that area which may eventually result in a high stress in that localized region due to corrosion or overheating. In that case, you have poor weld joint design and should consider re-designing the pipe section to eliminate any high stresses.
- Contaminated Welds:
Contamination can be caused by a number of contaminants that get into the welding zone, including dirt, sand, rust, and paint chips, to name a few. Other sources of contamination include fluxes and coatings such as oil. The main problem is that these contaminants create porosity in the finished part or contribute to cracking and ultimately reduce the strength of your welded joints, leading to other issues later on. If you suspect you have contaminated welds, it’s best to clean up your weld and re-weld it if necessary. If you find that isn’t possible, it may be best just to scrap it and start over.
- Incorrect Welder Settings:
Welding defects can be the result of incorrect welder settings. One such defect is called undercut, and it occurs when the arc length is too small for a given electrode extension resulting in searing and melting the base metal at the toe, which leaves a concave fillet underneath. It could also be that you are welding with an electrode extension that is too long which could cause weak spots or porosity because of poor fusion between layers of metal, especially if two pieces of metal don’t melt together correctly due to lack of penetration. When this happens, it’s best to reduce the amount of electrode extension, change electrodes or increase current flow depending on your welder settings.
- Substandard Welding Materials:
Like any other construction project, using substandard welding materials is a recipe for disaster. Using low-quality electrodes or fluxes, for example, can lead to weld defects. It’s essential to use quality materials specifically designed for welding to ensure the best results.
- Operator Error:
The last reason for weld defects is operator error. This could be anything from not following proper welding procedures to not being familiar with the welder you’re using. Whatever the reason, operator error is one of the leading causes of welding defects and should be avoided whenever possible.
Types Of Welding Defects
The main types of welding defects are:
- Lack Of Fusion:
This occurs when the weld material doesn’t fuse together properly, resulting in a weak joint. Lack of fusion is often caused by poor preparation, incorrect welding settings, or contamination. It can be remedied by cleaning the weld zone and re-welding if necessary.
- Poor Weld Penetration:
Poor weld penetration occurs when the weld metal doesn’t enter the joint fully and results in a weak joint. This can be caused by incorrect welding settings, the wrong welding processor, and the wrong electrode. It can be remedied by adjusting your welder settings, changing the electrode, or using a different welding process.
Overlap is created when the weld metal extends past the weld joint. It can be caused by incorrect welding procedures, incorrect welder settings, or poor joint design. It can be remedied by re-designing the weld joint to eliminate any high stresses, reducing the amount of weld metal used, or increasing current flow depending on your welder settings.
- Weld Porosity:
Weld porosity is created when gas bubbles are trapped in the weld zone, resulting in a weak joint. It can be caused by too much moisture or flux, contaminants, or incorrect welding procedures. You can avoid porosity by keeping your work area clean, using the proper flux and gas mix for the welding material, and ensuring that all weld joints are free of contamination.
- Weld Metal Blow Through:
Weld metal blow-through occurs when the molten weld metal penetrates through the backside of the base plate due to high heat input causing it to run out onto the sides, leaving an unprotected spot on your finished product that will rust easily. Blow-throughs can also occur at the root pass if enough heat is used, but not enough filler rod is added to this area properly. This defect can be caused by using too much heat, the wrong arc length, incorrect polarity, or amperage settings. It can be remedied by adjusting your welder settings and ensuring that you have good shielding gas coverage on both sides of the weld area.
- Heat Affected Zone Cracks:
The heat-affected zone (HAZ) cracks occur when a base metal is heated to a specific temperature, which changes its properties and causes brittleness or softness. It can be caused by welding or post-weld heat treatment on low alloy materials, such as quenching a hot steel part with oil to induce stress relief cracking intentionally. HAZ cracks are permanent and cannot be repaired. In cases, they may not need welding, but you should consult a professional to diagnose the problem.
Welding Defects And Remedies
Mistakes sometimes occurs during a welding process. These could lead to different forms of welding defects. As a guide, We present to you the seven most common welding defects and their preventive measures.
Porosity usually occurs as a result of weld contamination. This happens when gas is trapped inside or along the surface of the weld metal. Just like other weld defects, Porosity results in weak welds that may easily collapse.
• Causes of Porosity:
Often, Contaminated or inadequate shielding gas is the common cause of porosity.
However, Porosity could also be caused by using too high gas flow, longer arc, inadequate electrode deoxidant, and the presence of paint, rust, grease, or oil.
At the same time, having a dirty base metal or extending the welding far beyond the nozzle could cause porosity.
Additionally, air currents from cooling fans may contaminate the shielding gas envelope around the weld-puddle, thereby causing porosity.
Another common cause of this welding flaw is poor seal (loose-fitting) in the shielding gas channel.
• Remedies for Porosity:
You can remedy the porosity of a weld by; cleaning the materials to be welded before you begin welding, using correct arc distance, employing the proper welding technique, and using the right electrodes.
Again, ensure that there is adequate gas flow and replace any gas hoses that may be causing leaks. Also, when welding outside or in drafty areas, place a welding screen around the work area. This will help ameliorate porosity issues.
Undercutting is a crater or groove that is formed near the toe of the weld. In this case, the weld metal fails to fill-in the grooved area resulting in a weak-weld that is liable to cracking along the toes.
• Causes of Undercutting:
Wrong filler metal, excessive heat, fast weld speed, as well as poor welding technique, may all leads to undercut welding defect on a welding joint.
Also, very high weld current, incorrect use of shielding gas and using the wrong electrode could cause undercuts.
• Remedies for Undercutting:
Undercutting in welding can be avoided by employing the right welding technique that does not involve excessive weaving.
Lowering the arc length and minimizing the travel speed of the electrode can also help prevent undercutting.
Another remedy to undercutting problem is adjusting the angle of the gun to point directly towards the weld joint.
3. Burn Through
As the name implies, burn through occurs when the weld metal penetrates through the base metal, burning through it. This kind of welding flaw is most common with soft or thin metals, especially those that are 1/4″ or less. Also too much weld penetration can often lead to burn through.
• Causes of burn through:
The primary cause of burn through is excessive heat. Also having too large root opening on the weld joint can results in burn through.
• Remedies for burn through:
When burn through occurs, the easiest way to rectify the problem is to lower the voltage and the wire feed speed.
Also increasing the travel pace can help remedy the problem, especially when welding on aluminum material.
Increasing the wire extension and using a weaving technique while welding can also help minimize the potential for burn through.
4. Incomplete Penetration
Incomplete joint penetration (lack of penetration) happens when there is a shallow fusion between the base metal and filler metal, rather than full penetration of the joint. It results in a gap, cracks, or even joint failure.
• Causes of incomplete joint penetration:
Incomplete joint penetration could occur when the groove you are welding is too narrow, and the weld metal does not reach the bottom of the joint.
Improper joint preparation and insufficient heat input are the two primary causes of lack of penetration. Improper shielding gas mixture and welding wire diameter can also be a factor.
Also, if you leave too much space between the two metals you are welding, the metals will not melt together on the first pass and hence results in incomplete penetration.
• Remedies for incomplete penetration:
There are a number of remedies for incomplete joint penetration; this includes; using higher wire feed speed and voltage, reducing the travel pace to allow more weld metal penetrates through the joint, and proper joint design and preparation.
The joint should be prepared in such a way to allow the welder to maintain the proper wire extension and still access the bottom of the weld joint. Again, ensure that ‘the wire type and diameters’ and ‘the gas and the gas mixture’ are compatible.
Weld Cracks are the most serious type of welding defects. Weld Cracks are not acceptable in the welding industry.
However, a crack may occur just about everywhere in a weld; in the weld metal, on the plate next to the weld metal, or anyplace affected by intense heat.
The three major types of weld cracks are: Hot cracks, cold cracks, and crater cracks
• Causes of weld cracks:
Weld Crack could be caused by so many things such as base metal contamination, poor joint design, failure to preheat before welding, low welding current, high welding speed, using hydrogen when welding ferrous materials and welding at too high voltage.
• Remedies for weld cracks:
You can prevent this type of weld flaw by using the right metal. Proper joint design and preparation is also another way to prevent cracking. Crater cracking can be prevented by using a backfilling technique. Right Selection of filler metal and shielding gas can also help prevent cracking problems.
6. Incomplete Fusion
Incomplete fusion occurs when the weld metal fails to properly fuse with the base metal, or when the individual weld beads don’t fuse together. This type of weld defect is also referred to as cold lap.
• Causes of incomplete fusion
Incorrect gun angle is the most common cause of incomplete fusion. However, contaminants on the base metal and insufficient heat can also cause this weld defect.
In some instances, too short arc length, very high travel speed, too low welding amperage or when the electrode size is too small for the thickness of the metal you are welding, all could result to incomplete fusion.
• Remedies for incomplete fusion:
The very first thing to do to prevent this weld flaw is to properly clean the base metal before you start the welding; make sure that the base metal is free of oil, grease, dirt or other debris.
Make sure the weld angle is between 0 to 15 degrees; this will allow you to fully access the groove of the weld.
Also, for joints that require weaving technique, holding the arc on the sidewall for some time is very vital to help prevent this type of defect. Ensure that there is enough heat input to coalesce the base metal and the weld metal fully.
7. Slag Inclusions
Slag is the waste material that is usually formed while welding, bits of this solid waste material may accidentally be incorporated into the weld and causes contamination.
• Causes of slag inclusions:
Some of the common causes of slag inclusions include failure to properly clean a welding pass before applying the next pass, incorrect welding angle, incorporation of flux from stick welding electrode, and too low welding amperage.
Warpage is an unwanted distortion in the shape of a piece of metal. This occurs when the welder fails to properly control the expansion and contraction of the base material.
• Causes of warpage:
Warpage may arise when the welder clamps the welding joints too tightly, welding a piece of metal over and over again can also cause the metal to warp.
When welding a T-joint, the vertical part of the ‘T’ may sometimes pull itself towards the weld. Also, the more heat input you use, the more the chances you have to end up with a warpage.
• Remedies for warpage:
Warpage can be prevented by using only the required amount of heat. Opting for moderate travel speed and wire feed speed while welding can also help curtail the problem of warpage.
overlap occurs when the weld face extends far above the weld toe. In this case, the weld metal rollout and forms an angle less than 90 degrees.
• Causes of Overlap
Overlap welding defect can arise when using large electrodes greater than the metal size. High welding current and the use of improper welding technique can also cause this defect.
• Remedies for Overlap
Overlap welding defect can be avoided by employing the correct welding Technique, using small Welding electrode and less welding has.
Q. How Can Welding Defects Be Prevented?
The best way to prevent welding defects is by following proper welding procedures, using quality materials, and ensuring that your welder is set up properly. You should also be aware of the most common welding defects so that you can avoid them. By taking these precautions, you’ll be well on your way to producing quality welds every time.
Q. What Does Welding Defect Incomplete Fusion/Penetration Mean?
“Incomplete Fusion/Penetration” is another term for porosity. During the welding process, oxygen is introduced into the molten pool of metal, which causes gas to be trapped in the weld zone. This results in a weak joint and poor penetration (if not enough filler rod is used) or cracks (if too much filler rod is used). You can avoid this type of defect by keeping your work area clean, using the proper flux and gas mix for the welding material, and ensuring that all weld joints are free of contamination.
Q. What Does Welding Defects Concave And Convex Welds Mean?
“Welding Defects Concave and Convex Welds” is not a term you will typically find in the welding industry. However, it is worth mentioning because it is a common question. In short, concave welds are created when the weld material bows inward, and convex welds are made when the weld material bows outward. These defects can cause the weld to be weaker and less durable than an adequately executed weld. They can be caused by many factors, such as incorrect welding procedures, incorrect welder settings, or poor weld joint design. If you are experiencing problems with your concave or convex welds, it is best to consult with a professional welder to diagnose the issue and recommend a solution.
Q. What Is Lamellar Tearing In Welding Defects?
Lamellar tearing is a welding defect that several factors can cause. It occurs when the thin layers of metal are moved apart in an uncontrolled manner along planes parallel to the material’s surface. The thin layers of metals appear as thin black lines on the finished product. A simple way to think about it is if you peel back pieces of thin aluminum foil, this would be similar to what lamellar tearing looks like. Lamellar tearing is often caused by too little heat input, which causes not enough fusion between layered materials, or too much heat, which causes welding with no filler rod and creating rough/sharp welds, perhaps causing metal blow-throughs on one side both sides. You can avoid this defect by using the correct welding procedure, welder settings, and filler rod.
Q. What Is Welding Defects Spatter?
“Welding Defects Spatter” is a type of porosity that can be caused by several factors, including insufficient shielding gas, incorrect welding procedures, or weld joint design. Spatter is tiny droplets of metal that are ejected from the weld zone and trapped in the weld. This defect can cause the weld to be weaker and less durable than an adequately executed weld. It can be remedied by ensuring that your work area is clean and free of contamination, using the proper flux and gas mix for the material you are welding, and ensuring that all weld joints are free of defects.
Q. What Does Remaining Groove Type Welding Defect Mean?
“Remaining Groove Type Welding Defect” is a type of weld defect that occurs when the weld material accumulates in the heat-affected zone (HAZ) and causes porosity, poor fusion, or lack of penetration. This welding defect occurs most often when an incorrect arc length is used on the welder, causing abnormal heating and melting of base metal around the electrode, which can accumulate into a ridge along with the final product. The remaining groove-type welding defects can be avoided by following proper welding procedures and ensuring that you are using the correct arc length for your particular application.
Q. What Does Welding Defect Distortion Mean?
“Welding Defect Distortion” is a welding defect that occurs when the weld fails to properly cool and contract at the same rate as its surrounding base metal, causing it to shrink and distort. This can happen for several reasons, such as using too much heat input or rapidly cooling the weld with water. It can be remedied by following proper welding procedures and ensuring that your work area is clean and contamination-free.
Q. What Are Craters In Welding Defects?
Craters are caused when the weld material cannot flow into the weld joint, creating a hole or depression in the finished product. This welding defect can be caused by several factors, such as incorrect welding procedures, incorrect welder settings, or poor weld joint design. If you are experiencing problems with your craters, it is best to consult with a professional welder to diagnose the issue and recommend a solution.
Q. What Is Welding Defect Pitting?
“Welding Defect Pitting” is a type of weld defect that can be caused by several factors, including insufficient shielding gas, incorrect welding procedures, or weld joint design. Pitting is small holes or indentations on the surface of the weld. This defect can cause the weld to be weaker and less durable than an adequately executed weld. It can be remedied by ensuring that your work area is clean and free of contamination, using the proper flux and gas mix for the material you are welding, and ensuring that all weld joints are free of defects.
Q. What Does Welding Defect Insufficient Reinforcement Mean?
“Welding Defect Insufficient Reinforcement” is a type of welding defect that can be caused by several factors, including poor shielding gas coverage or carbon contamination. This type of weld defect occurs when too little filler rod material is used on the weld joint, causing the finished product to be weaker and less durable than a properly executed weld. This can often occur if you are not following proper welding procedures or do not have enough practice. To avoid insufficient reinforcement type defects, follow your welder settings and make sure you are using the correct filler rod for your application.
Q. How Do You Identify Welding Defects?
Welding defects can be challenging to identify, especially if unfamiliar with the different types. It is best to consult with a professional welder to diagnose the issue and recommend a solution. However, there are some general tips you can follow to help you identify common welding defects:
- Look for signs of poor weld fusion, such as gaps, cracks, or porosity in the weld joint
- Check for evidence of poor weld penetration, such as lack of root fusion or excessive heat tint on the base metal
- Inspect the weld for signs of distortion, such as warping or cracking
- Look for craters or pits in the surface of the weld
- Check for insufficient reinforcement in the weld joint, which is caused when too little filler rod material is used
- Check the weld bead for signs of gas coverage issues, such as porosity or lack of fusion at the toes of the weld
The welding equipment needed to inspect your finished product is readily available at most home improvement stores. Once you have identified the type of defect you are dealing with, take your equipment to a professional welder who will diagnose and remedy the issue.
While welding defects and discontinuities may arise due to the welder’s poor welding skills, however, even the most skilled and experienced welders may in one way or another experience weld defects.
But the only way to stop these welding irregularities from negatively affecting productivity and increasing the cost of operations is by identifying and rectifying the problems as quickly as possible.
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