Welding is becoming popular in every field, whether it’s the automotive, oil and gas industries, aerospace, and whatnot, welding is used at a significant scale. Several methods are currently used depending on the effectiveness and the nature of the metals for which it is used. We can say that this multivariate technique is a great invention, but at the same time, it is prone to several defects.
You know that every field demands expert techniques to give out the proper outcomes. So is the case with welding. You will never encounter any issues if you work with full attention and expertise. But if you are lagging in some aspect, then it is obvious that you will come across many other defects like slag inclusion in welding.
Here we will dig deeper into the causes and disadvantages of slag inclusion and see what we can do to avoid this issue in welding. Let’s take a running start.
What is Slag Inclusion?
In some cases, welders usually fail to select the proper welding technique and the side components or may lack expertise. In such a situation, a welding by-product may be seen at welding sites that are likely to reduce the performance or give different welding results from the expected ones. This whole condition is called slag in welding.
This type of defect is commonly seen with flux welding techniques, i.e., stick welding and arc welding.
What are its Disadvantages?
While welding any metal, the first step is to clean it properly and remove every contamination or roughness that may make the end results uneven. What do you think is the purpose behind this cleaning? It is done so that uniform welding results may be attained at the end.
A weld joint with perfect uniformity is said to be the perfect joint that is made to last. But when any deformity occurs on micro or macro, it is likely to give a long-term disadvantage.
Here are the consequences you may face due to slag inclusion in welding:
- Reduces durability of the metal
- Weakening the weld
- Corrosion-prone weld
- Sometimes there is a risk of development of crevices
- Provides more surface area for rust and corrosion
- Reduced mechanical integrity
- Disturbs natural interaction between individual grains
Ways to Identify Slag Inclusion
Identifying slag in welding may not be difficult for those who have been dealing with metals and welding for a long time. However, for a commoner, here are some points you need to identify if you feel like there is slag in welding.
- Slag inclusions are usually present in combination with flux
- Elongated or continuous lines can be seen on the welding junction
- Radiographic test results are also used for indication of slag in welding
- Low-density slag inclusions will look darker on the radiograph
- A glass-like appearance on the welds is also an indication of slags
- If you come across pinholes, then this is also a type of slag in welding
- The dye penetration technique is also a commonly used technique to identify such defects
How to avoid slag in welding?
Slag or any other defect in welding may cause problems for you in future, so avoiding it is the best thing you can do. Here are a few techniques used to prevent slag.
- Choose the best welding technique suited for the nature of metal
- Use accurate intensity of heat and current so that the filler may get a chance to flow equally and evenly.
- Avoid undercutting the side walls.
- Try to opt for the welding techniques that make tiny welding beads, i.e., reduced chances of welding flux and slag.
- Adjust the angle of the electrodes carefully
- Leave the least possible space for the puddle of metal
- Using high-intensity current and low temperature are the best techniques to get effective results
- Never skip the cleaning and clearing step before you start the welding procedure.
- Let the welded area cool down properly after you are done.
Are slag inclusion and welding flux two different things?
Slag is the modified form of flux. It is believed so because, at first, a combination of compounds enters and becomes part of the molten metal pool in welds.
When these compounds melt and become submerged in the metal pool, several chemical reactions take place. As a result, many non-metallic and metallic parts are formed.
The non-metallic part is classified as slag that you can see with your naked eye. Because of its low density, slag rises at the top and solidifies; after that, a layer is formed to prevent further reaction or contact between the two metal particles.
So, we can say that these terms are not the same or different but have a very close relationship.
Slag Inclusion Removal Techniques
After slag is identified in welds, multiple techniques exist to remove it. Different welders opt for distinct methods depending on ease and effectiveness. The most effective approach is using a simple wire brush or chipping hammer. But remember, this technique will only be effective if slags are near the surface of the metal.
But when the slags exceed in number or are present in the form of multiple clusters, redo the whole cavity or fill up the pinholes or slag completely. This is what professionals prefer to do.
A powered brush wheel is another tool most welders prefer to remove slag in welding. Similarly, angle grinders and angle discs are there to help you out in eliminating slag chunks and parts from the welding junction.
Remedies for Slag Inclusion in Welding
If you are a welder and want to excel in the future, then using these remedies will significantly help you.
- Increased current density
- Allow the weld to cool rapidly
- Remove slag immediately of you feel like it is present
- Welding speed should be adjusted
- Use low temperature
Frequently Asked Questions
1. Why is it essential to remove slag inclusion in welding?
If your welds include slags or hollow spaces in between, then the strength and durability of your weld are at risk. Also, the presence of slag means an increased risk of corrosion to the metal. That’s why once you are done with welding, make sure to remove slags with a slag hammer or the wire brush.
2. What are the tools used to remove slag inclusion?
Manual or power-operated tools are commonly used to remove slag in welds. Manual tools like chipping hammer and wire brush are used when the slag is seen close to the surface. A slag hammer usually has a pointed tip that is used to break the edges of slags in your welds.
Whereas power slag removal tools are used like angle grinders, grinder disks, and brushes to work on a bigger scale.
3. Which welding processes may cause slag inclusion commonly?
Slag can be seen in multiple welding methods, but most commonly, it is seen in flux-related methods. Here are a few examples of such methods that are likely to cause slag.
● Submerged arc welding
● Shielded arc welding
● Electro slag welding
● Flux-cored arc welding
● Gas shielded flux welding
● Flux arc welding
Welding seems like an easy business but only for the experts. If you are a beginner in this field, you may face a hard time. Many manufacturing companies are making good use of welding techniques to bring out outstanding products on a daily basis; that’s why having a sound knowledge of welding defects is also essential for them.
After reading this breakdown of slag inclusion in welding, we hope you are clear about this concept. So, if you are a welder or a manufacturing company owner, it’s your duty to keep a check on the welds so that you may not have to face the consequences in the near future.