Welding Beads are lines of welded metals created by introducing filler metal into the joint between two metal pieces. These beads create strong bonds that hold the pieces together.
As an engineer, you probably had to deal with weld bead defects created by wrong torch techniques.
In this article, we will cover anything you need to know to prevent that from happening ever again, from actually making the bead up to the weld quality control process.
Table of Contents
What Is a Welding Bead?
A welding bead forms when you deposit weld metal (in a line) from one pass of your torch.
You create it by melting filler material into the joint between two metal pieces. This process fuses the metals together and builds the strength of the connection.
Based on how you create it (movement you actually make during the process), the bead can look different and have different properties from an engineer point of view.
Your torch movement shapes the bead’s form, size, and depth:
- A steady drag gives deep penetration for strong bonds,
- A quick weave spreads the metal wider to cover more area.
That’s just 2 exemples out of many that we will cover later but, the technique impact the weld properties.
Controlling your speed and angle to avoid issues like uneven width or shallow ties to the base metal.
Think about stringer beads for straight runs that keep things simple and precise. When you weave, you handle heat better in bigger joints.
These choices help you match the bead to the job, whether it’s a thin sheet or a heavy pipe.
Poor control can lead to weld bead defects such as cracks or holes.
For bead appearance control, aim for legs that reach at least 80 percent of the thinner metal’s thickness, as KEYENCE notes in their 2024 measurement guide.
This ensures the bead holds up under stress.
Welding Beads Importance
Beads ensure strong bonds that hold structures together under pressure. They create solid connections between multiple metal pieces.
This allows even distribution of loads across the joint.
A well formed bead acts as a bridge for load transfer. This design helps avoid stress concentrations that lead to potential problems.
Beads also offer sealing properties.
They block gases or fluids from passing through the joint. Choose the right filler metal to boost corrosion resistance.
As little as 1% air entrainment in shielding gas causes distributed porosity in welds. Levels over 1.5% create gross surface breaking pores, per TWI Global in 2024.
Proper bead formation cuts these risks and supports good performances over time.
Good control over bead appearance prevents weld bead defects (like undercuts).
Why Use Different Torch Movements?
You face different challenges when welding based on the position of your work:
First, gravity pulls at the molten metal, so you adjust your torch path to keep it in place.
Then, for thin or heat sensitive materials (aluminum, titanium, etc.), you choose motions that limit excess warmth to avoid warping.
Overhead welding is also a very complexe operation exemple.
You move the torch quicker here to stop drips from falling onto your shield or face. Slower speeds let gravity win, leading to un even beads.
Those are the basic exemples, but you probably have your own exemples in your daily tasks.
That’s why before you start any torch work, get the basics right and think about “How am I going to achieve it? What can possibly go wrong?”.
Design the joint for good access and fusion :
- Pick filler material that matches your metals, like rods or wire for the job,
- Set your machine amps and voltage to fit the thickness and type,
- Anticipate the mouvements based on the position of the weld.
Welding is not as easy as it might seems. It requires proper preparation.
Types of Beads
You know how the way you hold and move your torch shapes the final weld. Torch manipulation stays similar no matter if you use stick, MIG, or TIG welding.
Definitions:
- Stick welding (SMAW) uses a consumable (flux coated electrode) to generate an arc for manual welding of heavy duty metals like steel, producing protective slag.
- MIG welding (GMAW) feeds a continuous wire electrode through a gun with inert gas shielding for fast, clean welds on thin to medium thick metals.
- TIG welding (GTAW) uses a non consumable tungsten electrode and inert gas for precise, high-quality manual welds on thin or exotic materials.
Small changes fit each process.
The main ways to create welding beads include stringer beads and weave beads.
Stringer Beads
A stringer bead uses a straight line drag or push with your torch.
Little side to side action happens.
Drag points the electrode forward to lead the puddle. This gives deep penetration and strong welds.
You push the torch tip for thin or heat sensitive metals. Or use it in vertical spots.
Push leans the torch away from the puddle. Heat stays back, so the weld sets fast.
Push cuts penetration compared to drag mouvement.
Stringer beads work in all positions. They stay narrow.
Always tie in the weld toe on both sides for good fusion with the base metal. Slow torch speed lets the puddle cover the joint edges. A tiny side move helps if needed.
Too much side action turns it into a weave bead.
Weave Beads
The weave bead technique swings your torch side to side along the joint, almost like a “zigzag” pattern.
There is a lot of possible patterns you can use:
- Zigzags: (convex or concave, curclicue weave),
- Triangle weave,
- Ladder weave,
- Jagged weave.
Weaving is primarily used for heat control:
- Pause at the sides to ensure proper fusion and prevent undercut.
- Move quickly across the center to maintain a flat bead profile and avoid excessive crown.
Specific patterns have specific uses:
- Triangle Weave: Best for vertical up welding. It builds a shelf to support the puddle against gravity.
- Semi Circle Weave: Used to adjust heat. Weave in front of the puddle to cool it. weave through the back of the puddle to increase heat.
In the overhead position, weaving is difficult but efficient, saving time over running multiple stringer beads.
Stick Welding Motion
For an open root groove weld with a stick welder, the technique is a “whipping” motion.
Most of the type, using an E6010 or E6011 electrode.
The goal is to achieve a complete penetration. As you push the rod through the gap, a keyhole will open up at the front of the weld puddle.
This keyhole is the indicator that you are fusing both sides of the joint at the root.
Your primary job is to control the size of this keyhole. If it gets too large you will burn through.
You control it by whipping the rod quickly up and away from the puddle.
This action cools the puddle, shrinks the keyhole, and allows the weld behind it to solidify. You then immediately bring the rod back into the puddle to deposit more metal.
The rate of your whip is dictated by the heat.
You may start with no whip at all and increase your speed as heat builds up in the plate.
Walking the Cup (TIG)
For high precision root passes on pipes, TIG welding is often used.
The technique is called “walking the cup.”
Instead of weaving with your wrist, you physically rock the torch’s ceramic cup back and forth along the beveled edges of the joint.
This creates a very consistent and clean weld bead.
Common Defects to be Aware of
As we’ve seen, the different techniques help build strong joints, but poor control often leads to weld bead defects that weaken your work.
Issues such as porosity, undercutting, and high crown can compromise safety and durability in mechanical projects.
We already made a complete overview of Welding quality testing which cover most of the defect you may face in real life.
While this is a complexe subject that require its own article about it, here is some important things to pay attention to, directly related to the techniques discussed:
Undercut: This is a groove melted into the base metal along the toes of the weld. It’s most often caused by excessive travel speed or failing to pause at the edges of a weave. The arc melts the parent metal, but you move on before filler metal can replace it.
Prevention: Pause briefly at each side of your weave. This allows the weld puddle to fill in completely, ensuring a smooth transition to the base plate.
Excessive Reinforcement (High Crown): This is too much weld metal built up in the center of the bead. It’s a direct result of moving too slowly across the middle of a weave. This concentrates filler metal in one area, creating a weak point due to stress concentration at the toes.
Prevention: Increase your travel speed as you cross the center of the joint. The goal is a flat or only slightly convex weld face.
Incomplete Penetration: This occurs when the weld fails to reach the root of the joint, leaving an unfilled gap. It’s often caused by insufficient amperage, too fast a travel speed, or incorrect technique on the root pass (like failing to establish and maintain a keyhole).
Prevention: Ensure your machine is set correctly and, on a root pass, focus on maintaining a consistent keyhole.
Porosity: These are gas pockets or voids trapped within the weld. Porosity is caused by contamination either from the atmosphere due to a long arc length or from impurities like oil, moisture, or rust on the base material.
Prevention: Keep a tight arc length and always work with clean, dry base metal and consumables.
Conclusion
Creating a quality welding bead requires a good technique, it is not just depositing some metal in the middle of two pieces to glue together.
We’ve covered that stringer beads provide straight, penetrating welds, while weave beads are used to control heat and fill wider joints.
The success of any weave depends your technique: pausing at the sides to prevent undercut and moving quickly across the center to avoid excessive crown.
Once you master this movement, most of your welds will be default proof!
Furthermore,
Specific processes require unique motions.
The whipping technique in stick welding is an important one for controlling the keyhole to ensure complete root penetration.
For work requiring very high precision, TIG welding’s “walking the cup” method offers the best consistency.
Each of these techniques is working great to prevent your welds from facing most of the common defects.
Frequently Asked Questions
When should I use a simple stringer bead instead of a more complex weave bead? You should use a stringer bead for narrow joints where a single, straight pass is sufficient. It’s ideal for root passes and situations where you need deep, focused penetration without adding excess heat to the surrounding metal. Use a weave bead when you need to fill a wider gap, bridge two pieces with a significant bevel, or manage heat on subsequent passes over a larger area.
What exactly happens if I don’t pause at the sides of a weave? If you don’t pause at the sides (the “toes”) of your weave, you will likely cause undercut. This is a defect where the arc melts a groove into the base metal, but you move away too quickly for the filler metal to fill it in. This creates a weak spot along the edge of your weld. The pause ensures complete fusion and a smooth transition from the weld to the base plate.
What is a “keyhole” in stick welding, and why is it so important for a root pass? A keyhole is the small hole that forms at the leading edge of the weld puddle when performing an open root pass. It is your visual confirmation that you are achieving complete penetration—fusing the two pieces of metal all the way through at the bottom of the joint. Controlling its size by “whipping” the electrode is critical; if it gets too large, you will burn through the metal entirely, and if it closes up, you’re not getting full penetration.
What’s the main difference between the “whipping” motion and the “walking the cup” technique? They are techniques for two different welding processes. Whipping is a wrist-and-arm motion used in stick welding (SMAW), primarily with E6010/E6011 rods, to control heat and penetration on a root pass. Walking the cup is a physical technique for TIG welding (GTAW) where you rock the torch’s ceramic cup back and forth along the joint. It uses the torch itself to create a highly consistent and precise weave, which is ideal for critical pipe welds.
I’m getting a high, rounded lump in the middle of my weave beads. What am I doing wrong? You are moving too slowly across the center of the joint. This defect is called excessive reinforcement or a “high crown.” When you linger in the middle, you deposit too much filler metal in one place. To fix this, maintain your pause at the sides, but increase your travel speed as you move across the center of the weld. The goal is a flat or only slightly convex bead profile.
What quality standards guide welding bead inspection? There is multiple standard that can apply to your application. The required code is specific to the industry and application. In the US, the most common are AWS D1.1 for structural steel, ASME Section IX for pressure vessels, and API 1104 for pipelines. Internationally, ISO 5817 is widely used.
