Structural steel fabrication is a complex metal structure product process that involves different kinds of sub-processes and techniques. From cutting and shaping to welding and assembly, all these constitute a single manufacturing process called structural steel fabrication. Structural welding is one of the critical procedures in structural steel fabrication as it is used to fuse two or more pieces of metal together to create a single structure. With no welding, no steel structure would be produced. In order to create a durable and strong steel structure, one needs to know what welding process is best used for the purpose.
In this blog, we will explore the different welding processes used in structural steel fabrication as well as advise on the most efficient one to use. Read on!
Common Welding Processes Used In Structural Steel Fabrication
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Stick welding
Stick (also known as SMAW among professional welders) is one of the oldest welding techniques. It is a manual welding process where a consumable electrode is fed into the weld pool. The electrode coating acts as a stabilizing agent, protecting the weld pool and weld seam from environmental contaminants. This process is known for extensive slag left behind on the surface of the weld seam, which can be removed by grinding or brushing. Stick welding may not be the most efficient welding process. However, it is best for beginner welders to learn the basics of welding. It is also the most cost-effective method as stick welding equipment is relatively inexpensive and easy to set up. For steel fabrication purposes, stick welding may not be the best fit, especially if time and maximum efficiency are of the utmost importance.
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Self-shielded flux-cored arc welding
In the self-shielded flux-cored welding technique, a hollow wire electrode is fed continuously into the weld pool through the welding gun. This method is fundamentally different from MIG welding in that the weld pool is not shielded from contamination by an outside gas, such as carbon dioxide or argon. Instead, a welding arc and a flux compound coating the wire combine to create a gas that shields the weld pool. Self-shielded flux cored arc welding is a very cost and process-efficient method as it does not require shielding gas, thus no need to get, fill up and transport the gas tank with the shielding gas. It is also a suitable welding method for outdoor welding as it is not affected by wind or other weather conditions.
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Gas-shielded flux-cored arc welding
In gas-shielded flux-cored arc welding, gas is required to protect the weld pool from environmental contaminants. It is often used in industrial and heavy-duty applications and thus is perfect for use in structural steel fabrication, especially if welding needs to be performed on-site and in remote areas. Gas-shielded flux-cored arc welding leaves a significant amount of slag on top of the weld which means there’s an additional step in the welding process to chip it off. Although, if visual appearance is not of high importance and does not affect the quality of the weld bead, this may not be an issue.
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Submerged arc welding
This type of welding process gets its name from the fact that the arc is submerged in the layer of flux covering the welding area. In submerged arc welding, there are two welding consumables involved, the electrode and the flux. The flux that covers the arc is molten and thus provides electrical conduction between the electrode and the workpiece. Flux also acts as a protective shield which prevents the weld area from oxidation and contamination from the air. Due to the fact that the weld gun is immersed in the layer of flux, minimal exposure to the arc and little fume generated, submerged arc welding is considered to be a safe welding method.
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Metal inert gas welding
Metal inert gas welding or MIG is one of the most common welding processes due to reasons such as ease of gun maneuvering and the welder’s ability to weld metals of different thicknesses. In MIG welding, a wire welding electrode is fed through a MIG gun, creating an arc that generates heat. The heat melts the metal being welded and thus fuses it together. MIG welding uses a shielding gas to protect the weld area from oxidation and contamination. Gas used in MIG welding varies from argon, carbon dioxide and helium to a mix of all these gasses. MIG welding is one of the most used welding methods in structural steel fabrication. Its ability to weld a variety of metals as well as efficiency and speed makes it a preferred welding method in structural steel fabrication.
Best Welding Process for Structural Steel Fabrication
Structural steel fabrication is a complex process, so welding involved in it has to be as easy as possible in order to not to further complicate the process. Stick welding and self-shielded flux-cored arc welding (FCAW-S) processes are most commonly used for welding structural steel in remote areas in applications subjected to adverse weather conditions. Gas-shielded flux-cored arc welding (FCAW-G) and submerged arc welding (SAW) are mostly used for structural steel welding carried out indoors.
Conclusion
Choosing the welding process for a particular application should primarily be guided by the metal type and its thickness. Other factors that influence the choice of the welding process such as the position in which welders will have to work, the type of welding equipment available for immediate use and the skill of the welder assigned to a particular project should also be taken into account when choosing the best welding process for structural steel fabrication.
