Many welding processes come about to avoid flaws. In reality, a large part of welding is about avoiding faults, and the more meticulous you are, the finer the weld. It underlines the need of identifying different welding flaws and their treatments. This article concentrates on a frequent issue, welding overlap. The discussion below contains its explanation, effects, and remedies. So, kindly continue with us to understand further about overlap welding.
- What is a Weld Defect?
- Overlap Welding: What is it?
- What Causes Welding Overlap?
- How to Avoid Overlap Welding
- How to fix Overlap Welding
What is a Weld Defect?
A weld defect is, in essence, any fault or imperfection that precludes a weldment from being used as intended. These are categorized using ISO 6520.
This indicates that a fault or defect may not weaken the weld, and when this happens, the weld is considered to have a discontinuity. This means that a weld may have a gap and not be deemed faulty.
Overlap Welding: What is it?
Normally, the base material that comprises metals and filler material melts and merges into one another to generate a weld connection. Sometimes, however, the additional filler metal is poured into the weld pool, but it does not mix well with the base metal, enabling it to leak outside the weldment. This is called welding overlap.
Overlap welding is indeed the protrusion of welded metal far beyond the root. The overlap is a projection that develops further than the weld toe. While overlap is much more of a welding gap, it is still regarded as a problem. Usually, overlap happens in the butt as well as fillet welds. Whenever an overlap happens, it signifies that metal is not entirely bonded. Generally, an overlap depicts a circular area that expands into unwanted locations.
An overflowing swimming pool is a nice comparison as we are already discussing a pool. When excess water surpasses a pool’s limit, it spills out of the pool and onto areas where it should never be. Welding overlap is additional filler material that goes out around the bead. Technically defined, welding overlap is additional filler material that sticks far beyond the weld toe or root.
What Causes Welding Overlap?
Welding overlap is classed as a welding fault. Unlike other defects, it does not impair the quality of the weld too much. Instead, weld overlap severely impacts pricing and appearances. No welder desires a poor weld or to lose money, thus preventing it has to be a welder’s focus.
The four major causes and remedies are summarized below. Various factors may cause the occurrence of an overlap. It occurs after the overflow of the weld pool on the weld metal surface. When the molten metal does not fuse with the base of the metal, it results in an overlap. This overlap might extend to form an angle of fewer than 90 degrees.
Use of Excess Amperage
Amperage, or current, is just a crucial influence in overlaps. A lot of filler material is formed inside the weld zone if it has been fulfilled. If this quantity is greater than necessary, it naturally runs out too and solidifies elsewhere. To prevent this, check a table or an expert welder on amperage values for a particular substance, fillet measurements, and joint type. Once you have a decent starting amperage level, run a few experiments and fine-tune the parameters before destroying the workpiece. Test it out beforehand. If you detect overlap, keep reducing the value till you achieve good results.
Low flow velocity also creates overlap. The filler distribution rate is constant throughout the weld, thus if you’re too slow, the filler will collect in the weld pool and produce overlapping. The remedy is apparent. Go a little faster when you discover overlap. It is quite probable that you will observe better outcomes. Yet, equally bear in mind that moving too quickly is also harmful. Finding the correct equilibrium ought to be the objective.
Electrode Selection & Usage
Improper electrode placement and inadequate technique produce several welding errors, including overlap.
The electrode angle affects weld depth as well as how much filler is injected on each edge of the weld bead. So, if the angle is improper, it enables more filler to penetrate on one side. In this instance, overlapping is inevitable. To avoid it from occurring, adjust the electrode angle to guarantee equal distribution of filler metal.
From the explanation above, it is evident that the quantity of filler metal dictates whether or not overlap happens. The electrode is indeed the filler, so if you use a bigger electrode, there is much more filler. So, if you detect an overlap, it can be due to a big electrode. Make careful you choose the suitable electrode size. You may examine the guides/charts or consult an experienced welder.
Edge preparation, base material composition, and hygiene can help to overlap. If there are lumps or holes on the base material surfaces, and you do not line the joint correctly, faults will arise. Use as much attention as necessary in pre-weld preparations to prevent mistakes like overlaps.
How to Avoid Overlap Welding
The best way to avoid welding overlaps is to use an appropriate welding technique. As is clear, overlap happens as a result of preventable welding errors. -Overlap-welding-defects.
Utilizing Tiny Electrodes
You run a high risk of applying excessive weld substance to the surface when using large electrodes. The use of small electrodes is advised to prevent overlap. This is because using smaller electrodes reduces the gap because fewer w1elds are applied at each point. The likelihood of extra materials and overlaps is reduced by using small electrodes.
Utilizing the Appropriate Amount of Current
Based on what you are using, you should adjust your current. The oscillating or direct current levels used should be appropriate for the task at hand. An electrode that glows or becomes excessively bright indicates that you have been overusing current. An electrode should have a diameter of one inch and an amperage of one thousand. Accordingly, a 3/4 diameter will require roughly 250 amps.
Clean the Base Metal
Clean the metal first to get rid of any impurities to guarantee a solid weld. This is due to the fact that it may hinder welding, produce resistance, overlap, or even result in a weld spill. You must clean the metal before welding it if it contains corrosion, varnish, dirt, or mill dust. Cleaning your base metal may be done in a number of ways.
Keep a Moderate Speed of Travel
Verify that your traveling rate is not too sluggish. One of the primary causes of welding overlap is slow travel speed.
But that doesn’t imply that you should drive too quickly. If the travel speed is too high, penetration may be reduced and the surface of the bead may get damaged. Additionally, it may result in undercutting at the borders of the weld, making slag cleaning hard, and trapping gases (porosity) inside the weld metal.
If you maintain your journey pace either too sluggish or too fast, you will run into trouble. You must thus keep your journey speed at a reasonable level. Please remember that overlap is considerably more likely to occur at low transit speeds. Therefore, you must avoid welding at a slow travel speed.
Learn how to handle Electrodes Correctly
It is one of the elements you should learn on your own. Every welder manipulates in a different manner. As a consequence, every manipulator has its own style. Finding the approach which is most appropriate for you requires experience. You should study the techniques used by pros and adapt them to create your own style.
Additionally, you must be careful to choose the appropriate electrode manipulation methods depending on the thickness of the material. You can also check our article for more information: Bad Welding VS Good Welding-3 Welding Types
How to fix Overlap Welding
Overlap Weld defects can be fixed by following various precautionary measures. No matter how careful you are, there may sometimes be a weld flaw. Do not be alarmed if there is any overlap. It can be fixed with a little hard work. First, determine and indicate the weldment or weld toe borders. then remove the overlap up to the stage by grinding. Be careful not to damage the joint while doing this.
When all is said and done, the weld will seem more attractive and professional. Overlap is often more of a surplus disposition than a flaw. A noticeable overlap may be corrected, unlike other welding flaws, by grinding away extra weld metal. Overlays are eliminated by smooth surface polishing at the metal’s base.
You must watch this video for a better understanding of overlap welding.
Welding overlapping is a frequent flaw brought about by a variety of causes. However, with a little caution and experience, you can create welds without any flaws. You won’t have any overlap welding if you properly implement each piece of advice. When choosing your electrode and adjusting the amperage, be cautious. As usual, make sure you comprehend the applicable welding methods and techniques. If overlap does happen, it may easily be removed while being cautious not to harm the joint.