What Is a Weld Bead?
A weld bead is created by applying filler material to a joint between two pieces of metal. A deposit of filler metal from a single welding pass, also known as a welding bead.
Bead is deposited on and in the work surface when the wire or electrode is melted and fused into the steel. A stringer bead is a narrow bead with only a drag movement or slight vibration, while a web bead is wider with more vibration.
A good weld is easy to spot. It will be straight and even with no slag, cracks, or holes. There are no breaks in the weld. It should not be too thin and there should be no pits or craters in the bead.
When you melt a filler material into the workpiece, the movement of the torch affects how you advance the puddle and the type of bead you leave in the joint.
MORE: What is Welding?
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.
MORE: What is Stick Welding?
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.
MORE: What is MIG Welding?
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.
MORE: What is Flux-Cored Welding?
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
Stringer beads laid parallel to the joint, are used for welding stainless-steel pipe since there is less tendency toward carbide precipitation. Stringer beads are recommended for forwarding all carbon and low alloy pipe in the vertical-fixed position.
To make a stringer bead you drag your electrode straight across the seam. There is no weaving or motion other than dragging or pulling.
A stringer bead is opposed to a weaving bead. In surfacing, the weaving bead produces less dilution because the weld puddle is always in contact with the part of the bead produced on the previous oscillation rather than the base metal.
2. Weave Beads
Weave beads, produced by weaving the torch across the joint, can be used on carbon and low-alloy steel in the rolled or horizontal-fixed position. The advantage of using weave beads, in the rolled or horizontal-fixed position, is that it requires less time to complete the welds.
Weave bead welding is exactly as it sounds; you will make a weaving pattern in order to cover a larger area. You use this motion to make cover welds over stringer beads (multi-pass welding). In other words, you use this when you are layering welds. It’s used when you make two or more welds on the same seam.
The potential problem that can occur from poor weaving techniques is that you can undercut the weld bead edge as well as have bad fusion.
Limitation Of Weaving:
Weaving is generally allowed only three times the electrode diameter thickness, suppose if you are using a 3.2 mm electrode then you can move your electrode only 9.6 mm max, as per standard welding procedure specification.
In this case, how can we do something new in our welding operation is a question.
If done correctly, the weave, weave prevents slag from being trapped and reduces the possibility of pores by providing a little more time for the gases to exit the molten pool as it freezes. Weaving helps and also enables better fusion at the edges of the weld. The metal must be made or reinforced along any desired line according to the weave used.
The weaving volume is usually limited to 2.5 to 3 times the electrode core diameter. Extensive weaving can result in porous welds. weaving increases the weakening of the weld metal with the original metal and should be minimized when welding alloy steels.