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Common Stick Welding Defects And How To Deal With Them
Stick welding is one of the oldest but most widely used welding methods in industries across the globe. This technique is known for its high welding speeds and low costs, which makes it an industry favorite, but it can also be used in various home applications.
Skill-wise, Stick welding is between easy MIG welding and challenging TIG welding. However, even the most experienced welders occasionally have to deal with spatter, electrode sticking, or holes.
In this article, we unravel the common stick welding defects and present helpful tips on how to deal with them.
Stick Welding And Welding Defects
As noted, Stick/Arc welding is one of the oldest welding methods that welders use even today. This technique uses the heat of an arc to melt the electrode and base metal, which is also known as arc welding.
Compared to methods such as TIG or MIG, Stick welding uses self-shielded electrodes. The core of the electrode is covered with a layer of flux, which melts alongside the electrode. The flux creates a layer of slag that protects the molten weld puddle from atmospheric contamination, so you don't need an external shielding gas.
Source: https://www.corrosionpedia.com/stick-welding-a-comprehensive-guide-to-a-very-popular-welding-process/2/6885
Stick welding is a fast and cheap welding technique. The ability to work outdoors is indispensable to various industries, such as pipeline welding, outdoor repair, farm, ranch, or any field work. However, this is not the cleanest method and various welding defects can occur during the process.
What Are The Welding Defects?
Welding defects are imperfections that occur during the weld, and these issues can appear on the surface or inside of the weld. Depending on the severity or location of the defect, it can compromise the structural integrity or mechanical properties of the weld and cause cracks or the entire weld failure.
We recognize the two primary types of welding defects:
- Surface irregularities
- Weld discontinuations
Surface irregularities are the welding defects that occur on the surface of the weld, and they can be easily observed during the visual inspection. Some of the most common surface irregularities are spatter, porosity, cracks, convex weld beads, concave beads, overlaps, undercuts, or uneven welds. Since most of these surface irregularities can easily be observed, they can be reworked and won't cause more significant damage.
Weld discontinuations are the welding defects that represent interruptions in the structure of the weld. These may include an absence of homogeneity of the physical, mechanical, and metallurgical characteristics of the weld. Common weld discontinuities include incomplete fusion, incomplete penetration, excessive burn-through, and slag inclusions.
The issue with internal welding defects is that you can miss them without proper testing, such as radiographic or ultrasonic testing. Meanwhile, they can cause severe damage to the structural integrity of the weld, so testing is crucial in any critical welding application.
Common Stick Welding Defects And How To Avert Them
There are over a dozen different welding defects that can occur in welding, but some are more common with specific welding processes than others. The most common Stick (Shielded Metal Arc) welding defects are:
- Spatter
- Porosity
- Poor arc starts
- Lack of fusion or penetration
- Undercutting
- Overwelding or overlapping
- Arc Blow
- Cracks
Understanding the nature of the defects is essential to avoiding them. So, let's explain how and why each stick welding defect occurs and what you can do to prevent it or deal with it.
Excessive Spatter In SMAW
Shielded Metal Arc Welding or Stick welding is not known as the cleanest welding method, so you should expect some amount of spatter. Spatter comes in the form of tiny droplets of molten metal that fly around the weld, and they can stick to the base metal.
While spatter won't affect the structural integrity of the weld, it affects the weld aesthetics. In addition, spending more time cleaning hard and excessive spatter can increase the overall welding costs, so many try to deal with it.
Why Does Spatter Occur in Stick Welding?
The spatter in Stick welding occurs due to long welding arc, high current, dirty or wet electrode, and dirty surface.
If your welding arc is too long (your electrode is too far from the welding joint), a ball forms on the electrode tip. As this ball drips into the welding joint, tiny droplets of molten metal can break around the joint and onto the base metal.
High current can also cause spatter in Stick welding. Too much heat can excessively heat the electrode and base pieces, causing the molten metal to start flying around the joint.
Finally, spatter often occurs when welding through contaminants such as rust, paint, or dirt. While Stick welding is one of the few methods that can weld dirty or rusty pieces, burning the contamination can also cause excessive spatter.
How To Deal With Spatter In Stick Welding
Understanding why spatter forms in Stick welding is the first step in dealing with this defect. Therefore, to avoid getting a lot of hard spatter in Stick welding, you should:
- Control the arc length: The arc length in stick welding shouldn't be larger than the diameter of the core of the electrode. For example, if you are using 1/8" electrodes, your arc length shouldn’t be higher than 1/8".
Source: https://www.wcwelding.com/arc-welding-tips.html
- Reduce the current: When selecting the current, make sure it fits the diameter and type of the electrode. Each manufacturer has its amperage requirements, so be sure to follow the recommendations.
- Check the electrode: The damp, wet, dirty, or damaged electrodes can cause excessive spatter, so avoid using old or burnt-out electrodes to reduce the spatter.
- Clean the base pieces: While Stick welding can burn through most dirt, rust, or paint, cleaning the surfaces and joints prior to welding will ensure you have less spatter to clean and worry about after the welding.
From: https://www.thefabricator.com/thefabricator/article/cuttingweldprep/5-steps-for-proper-weld-preparation
What Is Porosity?
The tiny holes on top of your weld are known as porosity, and this defect mainly occurs once the weld interacts with atmospheric or surface contamination. The trapped gasses or contaminants boil and escape the weld, leaving tiny holes on top of it.
Most porosity occurs on top of the weld, but it can also appear inside the weld. Out of the two, the internal porosity includes trapped contaminants that cannot be seen with a bare eye, so they can cause a lot of damage to the weld. Seeing holes in a weld bead is never a good sign, so you’ll want to avert this defect.
Why Does Porosity Occur in Stick Welding?
In Stick welding, the porosity occurs due to dirt on the base metal, incorrect arc length, current and/or welding speed, and wrong electrode type.
Similar to spatter, dirt, rust, or paint on top of the surface can also cause porosity. Suppose you don't burn all the contaminants; they can get trapped and create small holes that compromise the integrity of the weld.
An arc length that is too long or too short can also cause porosity. Improper welding techniques can mess up the slag formation, and this layer of flux is essential in protecting the weld puddle from contamination. Contaminants create tiny holes in the form of spatter.
The same rules apply to welding speed. Going too fast won't properly burn away the contaminants from the weld, and they will stay trapped as internal porosity. High current can cause fast weld puddle solidification, once again causing internal porosity.
To avoid porosity on the steel that has a low carbon or manganese content or a high sulfur (free-machining steel) or phosphorus content, use a low-hydrogen electrode. When using E6010 or E6011 electrodes, make sure that they are not too dry.
How To Avoid Porosity In Stick Welding
To avoid the porosity in stick welding, you should:
- Clean the base pieces: Like with a spatter, removing oil, grease, dirt, or paint from the surface can reduce the chances of porosity occurring on top of it.
- Adjust the welding technique: proper arc length, welding speed, and welding current are crucial in allowing the slag to form correctly and protect the molten weld puddle from contamination and porosity.
- Use proper and clean electrodes: Electrode selection is half the work, so make sure you use recommended electrodes for the given material and make sure they are clean and dry.
Poor Arc Starts In Stick Welding
As a beginner and new welder, you can have a lot of trouble starting an arc. In most cases, your electrode will either stick to the base metal (that's why it is called Stick welding in the first place) or you'll fail to start an arc.
While most of the arc starting issues are related to welding technique, they can also be caused by your machine settings or specific electrodes. Although poor arc start is not a typical defect, it is a common issue in Stick welding, so we'll see how you can deal with it.
How to Deal With Poor Arc Starts In Stick Welding
To deal with the poor arc starts in Stick welding, you should check your machine settings, check the electrode conditions and types, and practice the technique.
- Check Parameters: Using the correct current and enough OCV (Open Circuit Voltage) is crucial in getting a reliable arc start. However, some electrodes, such as the E7018, need a burst of amperage at the start. That’s why you can use a feature known as Hot Start, which increases the starting amperage to improve arc initiation.
- Check Electrodes: Once again, a faulty electrode can create unreliable arc starts. Moist or damaged electrodes can stick or have issues lighting up.
- Practice The Start Motion: The key to a successful arc starts in stick welding by scratching the surface and then lifting the electrode. However, you shouldn't lift it too high, or else it can extinguish an arc or stay too close since you can burn through the pieces or contaminate them.
Lack of Fusion or Penetration In Stick Welding
The lack of fusion or penetration is a severe defect in which the weld doesn't penetrate or fuse both pieces in the welding joint. Instead, the weld sits on top of the joint, and the weld failure is inevitable.
Source: http://mechanicalinventions.blogspot.com/2014/10/different-types-of-welding-defects.html
The primary reason the lack of penetration transpires is the insufficient welding current. Still, it also appears due to fast travel speed or a combination of both these. Lack of heat in the welding joint deposits the weld metal on top of the joint instead of penetrating the pieces.
Although the weld can look pretty, unless it penetrates and fuses the pieces, it is worthless. In addition, lack of fusion in Stick welding can occur due to poor joint design, poor or large electrodes, wrong electrode type, and travel angle. That's why critical applications call for a rigorous test that inspects the strength and integrity of the weld.
How To Deal With Lack Of Penetration Or Fusion In Stick Welding
To avoid a lack of fusion in Stick welding, you should:
- Adjust welding current: Increasing the amperage will improve penetration. However, don't go too ham, as too high amperage can cause an opposite defect known as burn-through. Always try to follow the recommendations for the selected electrode, but if you feel you are running a bit cold, you can bump up the current for 5-10 more amps.
- Decrease welding speed: If your amperage is good enough, but your welds still lack penetration, you should move slower. High travel speed simply doesn't allow the weld to penetrate the base pieces properly, so moving slower can solve fusion issues.
Source: https://www.mig-welding.co.uk/arc-welding-faults.htm
- Pay attention to weld joint preparation and design: Besides porosity and spatter, preparing the pieces can also affect penetration and fusion. Joint design plays a crucial role, as you will need an even gap and clean joint to get the best results. If you are Stick welding thick metals, you will need to bevel them properly. Otherwise, a deep, narrow bead with an insufficient bevel may lack penetration. Root opening is also required for full penetration. Finally, a root face or a backup strip is necessary for fast welding and good quality.
- Choose the suitable electrode: Always choose an electrode type and diameter that is suitable for your job. For example, E6010 electrodes are known for their deep penetration, which is why they are used when welding a root opening. However, they can be challenging to run. Some electrodes, such as E6013, are better suited for low-amp applications. Diameter is also vital for penetration, especially in complex joint designs. Using a smaller diameter electrode can have a positive impact on complex joints.
- Practice the welding technique: Proper arc length, travel angle, and consistent travel speed are crucial in achieving proper fusion and penetration. Adjusting each welding parameter of your welding technique will greatly help.
Undercutting In Stick Welding
Undercutting is a weld defect that forms along the edge of the weld bead. It occurs once the base metal melts, but the filler metal does not adequately fill it. While this is primarily an aesthetic issue, it can also create a weak spot if the weld is loaded in tension or subjected to fatigue.
Common causes of undercuts in Stick welding are high current combined with high travel speed. It can also be caused by improper welding techniques, including travel angle and poor electrode condition or type.
How To Deal With Undercutting In Stick Welding
- Reduce current and welding speed: Reducing the current and welding speed will allow you to melt both the base metal and electrode. Spending more time on the edges will allow molten filler metal to fill the edges appropriately, eliminating the undercutting.
- Pause on sides when weaving: Larger gaps call for weave beads, which take time to perfect. Most beginners make mistakes when moving from side to side fast without allowing the electrode to fill the joint properly. To address this issue, you must pause on the sides or avoid weaving too much when that's not necessary.
- Reduce the puddle size: Reducing the current and speed, with modifications in arc length and angle, can help you reduce the puddle size. A smaller weld puddle is easier to control and direct into the sides, and with uniform welding speed, you can get excellent results.
Source: https://www.youtube.com/watch?v=7JgHzU66364&t=445s
Overwelding/Overlapping In Stick Welding
Overwelding is a weld defect that occurs once you deposit extensive or unnecessary amounts of filler metal into the weld. Most beginners make this mistake, thinking that adding some extra metal will make the weld stronger.
Source: https://www.youtube.com/watch?app=desktop&v=FyVrvNAde9U
In reality, depositing more metal into the weld joint will only slightly increase its strength. However, extra metal increases weight and increases the risk of distortion. In industrial applications, overwelding increases overall welding costs by increasing the material spent and time consumed during unnecessary welding.
How To Deal With Overwelding In SMAW?
To prevent overwelding in SMAW, you should:
- Follow the weld specifications: The bead surface should be nearly flat, with a buildup that doesn't exceed 1/16". Fillets should have equal legs, and the entire weld should have a uniform appearance.
- Adjust welding technique: Modify the travel speed and electrode travel angle to avoid excessive buildup. Move just fast enough to get enough penetration and good deposition but not too steep, slow, or fast.
Arc Blow In Stick Welding
Stick welding has a unique defect known as an arc blow. In this defect, the arc stream does not follow the shortest path between the electrode and the workpiece. Instead, the arc is deflected forward or backward from the direction of travel. This uncontrollable arc can cause various issues, such as excessive spatter, incomplete fusion, and porosity, and interfere with the quality of the weld.
The arc blow is a phenomenon that occurs due to the thermal or magnetic properties of the weld metal. The magnetic field surrounding the arc is generated by the current flow in the plate. This field interacts with the magnetic field of the current that is running through a return cable, causing deflections. Arc blow can also occur due to the thermal resistance of some metals, but this is a rare case.
Source: https://www.youtube.com/watch?v=V8AFjzZHz5g
How To Deal With Arc Blow In Stick Welding?
To prevent arc blow in Stick welding, you should:
- Switch to AC current: While most stick welding is carried out in DC, dealing with arc blow will require you to switch to AC. While AC is not the most suitable current option for Stick, it will eliminate the magnetic interference. However, before you switch, make sure your electrode is designed to run on AC.
- Change the location of the earth clamp: Arc blow can happen when welding toward or away from the ground clamp due to magnetic interference of arc current and current in the ground. Changing the position of the clamp can sometimes solve the issue.
Source: https://www.youtube.com/watch?v=V8AFjzZHz5g
Cracks In Stick Welding
There is an entire science behind the cracking in welding, but this is a common issue that appears if you are not careful enough. The worst part about it is the fact cracks can occur due to different reasons.
In some cases, that's rapid cooling or thermal stress in the joint. There are also hydrogen cracks, cold cracks, distortion cracks, overwelding, forces, etc. Understanding the cause of the crack is the first step in eliminating the issues, but here are some helpful tips.
How To Deal With Cracks In Stick Welding
To reduce the chances of cracks in Stick welding, you should:
- Preheat the sensitive pieces before welding: Rapid heating or cooling of the metals with high carbon content can create cracks. To avoid it, preheat or postheat the high-carbon metals after the welding.
- Use low hydrogen electrodes: Excessive hydrogen content can create hydrogen embrittlement or hydrogen cracks. Hydrogen lowers the crack resistance of the metal, resulting in embrittlement.
Photo by @weldingandstuff (TikTok)
- Reduce the heat input: On thick pieces, a high current won't cause burn-through, but it can create hot cracks. To solve the issue, reduce the current to the optimal level and use smaller diameter electrodes.
- Pay attention to the root pass: In multi-pass welding, a root pass must have sufficient size and be flat or convex enough to resist cracking until the later beads can be added for support.
- Fill the crater: The crater is a small hole that appears at the end of the weld. This defect occurs once you don't let the weld correctly fill the end of the joint. This crater is prone to cracking, and it can create cracks across the entire weld bead.
Final Thoughts
Stick welding is a relatively simple, fast, and cheap welding method, but small mistakes can cause welding defects. While there are dozens of welding defects in Stick welding spatter, porosity, poor arc starts, lack of fusion or penetration, undercutting, overwelding, arc blow, and cracks occur.
Defects such as spatter or overwelding mainly affect the weld aesthetics, but cracks, undercutting, or lack of penetration can cause weld failure. That's why avoiding defects is crucial, and most of them can be prevented by choosing the right electrode, adjusting welding parameters, and practicing the welding technique.
🧐Common Stick Welding Defects And How To Deal With Them FAQ
1. What Are The Welding Defects?
Welding defects are imperfections that can appear on the surface or inside the weld, potentially compromising its structural integrity or mechanical properties, leading to cracks or weld failure. These defects are generally categorized into two types: surface irregularities and weld discontinuities.
2. How To Avoid Porosity In Stick Welding?
- Clean the base material: Remove oil, grease, dirt, or paint to prevent contamination.
- Optimize welding technique: Use the correct arc length, speed, and current for proper slag formation.
- Use clean, proper electrodes: Select recommended electrodes and keep them dry and clean.
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