What Is a Weld Bead?
A welding bead is a seam deposit of molten metal that forms during welding in a single pass. At its core, a welding bead forms once the filler metal and base metal are heated to their melting point.
As the filler melts, it creates a molten weld pool that penetrates and fuses the pieces. Once everything solidifies, you get a welding bead or, simply put, a weld.
Even though weld beads are the structural and straightforward pieces of the weld, they greatly vary depending on the welding machine settings and technique. The final goal is to create a uniform weld bead that properly fills the joint and penetrates the two pieces.
However, that is often the most challenging task for most beginner welders. So, let’s discuss the properties of a weld bead and the differences between good and bad welding beads.
How Do You Create A Welding Bead?
Creating a weld bead involves preparing the metal surfaces, securing them in place, selecting the correct welding method, adjusting power settings, igniting the welding torch, and feeding filler material into the weld pool at a steady rate.
While this is enough to create a weld bead, its appearance and properties will significantly vary depending on your torch movement and dialed-in settings. Welding in harsh conditions and uncomfortable positions where you battle gravity will also impact the strength and properties of the weld bead.
Types of Welding Bead
1. TIG Welding Beads
TIG welding beads generally look like a “stack of dimes “. This is because the welder adds evenly spaced “dabs” of filler metal with the other hand as the TIG arc moves. Each of these blobs forms a circular shape when stacked on top of the other.
The timing of the dabs can greatly affect the appearance of the weld. A faster feed of the filler metal results in closer dime spacing and vice versa. TIG welds can be some of the most beautiful welds because of their appearance.
TIG welds don’t always have that “stack of dimes” look. Sometimes welders go “with the cup”. This is where the cored wire rests on the part to be welded is held. The welder moves the TIG cup back and forth as it moves forward in his weld.
This will melt the filler rod and spread it over the weld – think of putting cream cheese on a bagel! This technique is particularly popular with pipe welders.
Sometimes 2 or 3 spatula sticks are used at the same time to increase the amount of spatula applied. Imagine running the cup as a “weave” instead of a straight weld.
2. Stick Welding Beads
Stick welds can have multiple seam properties. The low hydrogen rod family is very versatile. A low hydrogen 7018 rod can be drawn as a straight bead. These are known as “stringer” beads because they are regular and narrow.
This is popular for flat, horizontal, and overhead stick welding. Vertical 7018 welds can benefit from using a weave pattern.
Uphill, the welder can use a variety of patterns to disperse the filler metal in the gouge. Weaving is much easier on vertical tests, but sometimes CWIs only allow stringer passes.
Below is our favorite welding symbols reference chart. Icons indicate what type of weld is required – which determines your bead size and style.
Sticks made of cellulose, i.e., 6010s and 7010s must be performed using a special “whip and pause” technique. The end result resembles a nice TIG weld. These welds generally don’t look as good as a proper TIG weld – but the dime effect is still visible.
In this technique, the welder strikes an arc and holds the rod in place to create a dime. They will then whip out and come back to deposit the next penny. For open roots on pipe and plate, 6010 cellulose sticks can be pulled like a 7018 and work great.
3. MIG beads
Hardwire MIG is very versatile as there are so many techniques to create a good weld. Some prefer to push the puddle and others prefer to pull the puddle.
There has always been a debate about whether pushing or pulling is stronger. Because hardwire MIG does not require flux coating, the user does not need to draw their puddle.
When it comes to welding, there’s a saying, “If there’s slag, you gotta drag”. This is because in most cases when you slide a stick rod or flux-cored MIG gun, the slag gets trapped in the weld.
This creates porosity. With flux-coated welding techniques, the drag technique allows the slag to form on the back of your puddle and harden as you continue to forward.
Many MIG welders do not weave or use a pattern. You simply perform a straight stringer bead. Although this can create a solid weld, using a weave pattern can be beneficial for wider joints and vertical welds. It spreads out the filler metal more, resulting in a flatter bead.
A more recent trend is the “MIG like TIG” craze. This is where certain MIG settings can result in a bead that looks like the TIG dimes mentioned above. This is also largely due to a special technology with a low wire speed.
These beads are not as strong because the low heat penetrates the metal much less than normal. However, they’ve become standard in off-road culture because they’re such clean-looking welds.
4. Flux Cored MIG Beads
Flux core MIG (especially dual shield) can deposit a ton of filler in a short amount of time. Most’s flux-cored beads are run by simple stringers. Vertical Flux-cored welds will usually require a weave to manage the puddle.
Weaving a flux-cored bead will prevent you from getting a “drip” halfway through your weld. This is when the weld gets too hot and the molten metal drips off of your piece of material onto the floor.
Types Of Weld Beads Techniques
In general, torch manipulation is pretty much the same whether you are feeding the weld pool with a separate filler rod, mechanically fed wire, or stick electrode. But there are some techniques that are mostly used with a process. Main welding bead techniques:
- Stringer beads
- Weave beads
1. Stringer beads
To create a stringer bead, you push (or “drag”) the torch across the joint in a straight line with little side-to-side movement. Dragging refers to the electrode’s angle in the “forward” direction of the weld, which directs the puddle. This allows for the most penetration and solid welds.
Welders “push” the torch tip when working with thin, heat-sensitive metals or welding vertically. It would help if you did this by angling your welding torch away from the puddle and welding while doing so.
Molten metal falls downhill when welding up a vertical joint. However, pressing the weld causes it to solidify faster by keeping the heat away from the puddle.
Pushing has several disadvantages, including penetrating the base metal less than drawing (“dragging”) the molten pool. Stringer beads can be used in any welding position and are typically not wide.
Even though you are driving straight forward, it is still critical to “tie in” the weld toe on both sides of the joint. Keep in mind that welding goes beyond adding fresh metal to a joint. Fusion between the weld and the base metal is essential.
When the torch is moved slowly enough, the welding puddle can occasionally run over both sides of the joint. It might only take this to fuse successfully. Sometimes, a minor side-to-side adjustment is required.
Keep side-to-side movement minimal. You will make a weaving bead if you sway too much from side to side. Hard facing also uses string beads.
This surfacing procedure helps industrial equipment’s scoops, fenders, plows, and other outside metal elements last longer. The beads are used here to form a protective coating rather than fusing with the base metal.
2. Weave Beads
You can weave side to side along the joint for comprehensive welding. The quickest way for a fat joint to weld is weaving.
This is especially true for groove welds on thick stock. Fillet welds often contain weaves.
Of course, there are other weave types, and each welder has a favorite. Your hand might move in a zigzag, crescent, or curly shape.
Weaving manages the heat in your weld puddle and fills the beads. To establish a proper tie-in to the metal parts and avoid undercutting the edges, you can pause on each side of the weld.
You’ll want to move quickly over the joint’s center, though. You risk a high crown (a bulge in the middle) if you don’t. Therefore, it is preferable to have a flat or hardly convex weld face during weaving.
A triangle weave is helpful when you need to fill a steep pocket. This weaving method, for instance, enables you to create a shelf beneath the puddle in vertical-up welding, preventing molten metal from falling downhill.
You can try a semi-circle weave with the center point or your stroke across the front of the puddle (or just ahead of it) to prevent overheating or growing. As in the last illustration, weave the semi-circle (or crescent) back through the puddle to increase heat.
It can be challenging to weave overhead since gravity tends to draw the molten metal out of the weld. Laying down an overhead weave bead half an inch wide or wider can be tricky, even with practice. However, welders pick up the skill since weaving takes less time than running several string beads.
3. Whip Motion (Stick)
On the root pass, the first weld operation, a stick welder usually whips their wrist in a circular motion on open groove welds.
The goal is to employ a flat bead of welding metal to join the work plates at the bottom. E6010 and 6011 “fast-freeze” rods are the most commonly used stick electrodes for root passes on low-carbon steel.
The electrode is raised through the gap and moved along by the welder. To achieve thorough penetration, this is crucial. As a result, you will notice a keyhole developing in the puddle’s head opening.
One of the most challenging strokes for welders to learn is this one. You need to keep the keyhole size constant while observing the puddle. You cannot fuse the two sides if it becomes too large (i.e., double the rod diameter).
Heat management is, therefore, essential during a root pass. You may regulate the size of the keyhole using the frequency of your whip strokes. In addition, you may use suitable joint designs and welder settings.
You’ll whip the rod upward and ahead of the weld before the keyhole size swells too much. This procedure keeps the keyhole size constant while cooling everything down. It also enables the puddle’s back bead to harden.
When the beads are set, you return to the molten pool. If you’re stuck welding, another drop of weld metal should drop off your rod, producing your next shot. Everything happens quickly.
Therefore, you must pay close attention; the amount of heat you see in the weld will influence the whipping rate.
Due to insufficient heat, you could not whip when you started welding. Due to the intense heat moving through the base metal, you can flick your wrist steadily by the time you reach the weld conclusion.
- J-WEAVE – WHIP VARIATION
A “J-weave” is a version of the whip motion. A V-groove joint’s second (or “hot”) pass often uses this combination of crescent and whip strokes.
In this position, slide your E6010 or other fast-freeze electrodes from one toe to the other, pausing briefly on either side and whipping the rod ahead and upward along the joint’s side.
The work benefits from a longer arc. Then, after whipping ahead like you would on a root pass, you’ll switch back to the adjacent clear space on the left (or right) side of the weld and repeat the stroke.
4. Walking the Cup (For TIG)
Welders use a TIG torch when doing a root pass on the pipe. Compared to stick or MIG welding, it produces a cleaner and more exact bead.
The procedure involves a hand motion called “walking the cup.” The ceramic insulator enclosing the tungsten tip is the cup in this instance. The cup is rocked back and forth along the weld joint by the welder.
The knotted wire cup brushes are used for deburring and removing welding scales. They are also employed for carbon cleaning, scale, and slag removal.
Characteristics of a Quality Weld Bead
How do you recognize a good weld bead? The following list details what to look for:
- Straightness: The bead should follow the edges being joined without wandering from side to side.
- Uniformity: A good bead will have a consistent width along its length, and there won’t be any gaps. A fillet weld will be centered between the pieces of metal rather than covering more of one and less of the other. (This type of flaw is called “asymmetry.)
- Smooth toe transition: This is the line where the sides of the bead meet the workpiece material. The bead should flow into the workpiece and not have steep, even near vertical, sides. (This would mean the weld bead is higher than it needs to be.)
- Smooth contour: The profile will be slightly convex, with minimal variation along the bead length. (Note that a weave pattern is acceptable, and even desired in some applications.)
- Minimal spatter: The area around the weld should be clean and free from droplets of weld material. This shows the welder had the wire feed and voltage settings in the optimal range.
- No defects: If cracks or pinholes are visible on the surface it’s almost certain there will be more inside the weld.
- Proper penetration: In the case of a butt weld, the weld should extend completely through the material, but not beyond. (When welding pipe this would disrupt the fluid flow.) In a fillet weld penetration can’t be assessed without sectioning the workpiece.
- No undercutting: If present, this will be seen along the toe or bead edges. It’s where the bead does not fill the groove formed during weld preparation and fit-up, and suggests a lack of strength.
- Even ripple pattern: When bridging gaps or creating a satisfying aesthetic appearance, many welders like to “weave” the torch from side to side while traversing the length of the weld. This produces a series of ripples along the bead that may, depending on how the torch was moved, even look like a line of overlapping coins. If the weld was made this way the ripple should be consistent along the bead.