Why Is It Called Submerged Arc Welding?

Submerged arc welding (SAW) is a widely used welding method in industrial manufacturing, known for its high efficiency and stable quality. For those new to welding technology, a common question arises: Why is it called "submerged arc welding"? This seemingly simple naming actually contains the core characteristics of the technology, reflecting the unique working principle and structural characteristics of this welding method.​
The Core Reason for the Name: The "Submerged" State of the Arc​
The key to answering this question lies in understanding the working process of submerged arc welding. Unlike other welding methods such as shielded metal arc welding (where the arc is visible to the naked eye) or gas metal arc welding (where the arc is partially exposed), the arc in submerged arc welding is in a completely hidden state during the welding process.​
Specifically, before welding starts, granular flux is pre-laid on the surface of the base metal to be welded, forming a flux layer with a thickness of usually 20–50mm. When the welding power is turned on, the welding wire (which continuously feeds into the welding area) and the base metal are ionized to generate an arc. At this time, the arc is not exposed to the air but is completely wrapped in the flux layer. The high temperature of the arc melts the welding wire, the surface of the base metal, and part of the flux at the same time: the molten metal of the welding wire and the base metal forms a molten pool, while the molten flux forms a slag layer, which continues to cover the arc and the molten pool.​
This "arc is wrapped by flux and slag" is the most intuitive manifestation of "submerged". Just like a diver being submerged in water, the arc in submerged arc welding is "submerged" in the medium (flux and slag), so it is named "submerged arc welding".​
The Function of "Submersion": Why the Arc Needs to Be Hidden​
The "submerged" state of the arc is not a random design but a key measure to ensure welding quality and efficiency, which is also the fundamental reason why this technology has been widely used.​
1. Perfect Protection Against Atmospheric Contamination​
The flux and the slag formed after melting form a dense barrier, completely isolating the arc, molten pool, and high-temperature weld metal from the air. This prevents harmful gases in the air (such as oxygen, nitrogen, and hydrogen) from entering the molten pool-oxygen and nitrogen will cause oxidation and nitridation of the weld, reducing its toughness; hydrogen is the main cause of welding cracks. In submerged arc welding, due to the "submerged" protection, the weld metal has a lower gas content, and the probability of pores and cracks is significantly reduced compared with exposed arc welding methods.​
2. Stable Arc Combustion and Heat Concentration​
The flux layer can stabilize the arc. Unlike the arc in open welding (which is easily disturbed by air flow), the arc "submerged" in the flux is less affected by external air flow or vibration, ensuring stable combustion. At the same time, the flux has a certain thermal insulation effect, reducing heat loss during the welding process. This allows the heat generated by the arc to be more concentrated in the welding area, which is conducive to melting thicker base metals and improving welding efficiency.​
3. Reduction of Spatter and Smoke​
In exposed arc welding, high-temperature metal droplets are easily sputtered around the arc, causing material waste and potential safety hazards. In submerged arc welding, the flux layer "traps" the spatter-most of the sputtered metal droplets are blocked by the flux and can even flow back into the molten pool under the action of gravity, reducing material loss. In addition, the flux absorbs most of the smoke and harmful gases generated during welding, making the working environment cleaner.​
The Difference From Other Welding Methods: Highlighting the Characteristics of "Submersion"​
To better understand the uniqueness of "submerged arc", we can compare it with other common welding methods, and the difference in the state of the arc is obvious.​
Shielded Metal Arc Welding (SMAW)​
In SMAW, the arc burns between the electrode and the base metal, and although the electrode coating generates gas and slag to protect the molten pool, the arc itself is partially exposed to the air. During the welding process, the arc can be directly observed with the naked eye, which is significantly different from the completely hidden arc in submerged arc welding.​
Gas Metal Arc Welding (GMAW)​
GMAW uses inert gas (such as argon) or mixed gas (such as argon + carbon dioxide) to protect the arc and molten pool. The arc is in a gas environment, and although it is not in direct contact with the air, it is still in an "exposed" state (the gas is transparent, and the arc can be seen). There is no solid flux layer to wrap the arc, so it does not have the "submerged" feature.​
Flux-Cored Arc Welding (FCAW)​
FCAW uses a flux-cored wire, and the flux inside the wire melts to form a protective slag. However, its arc is only partially covered by slag, and most of it is still exposed. Moreover, the flux in FCAW is inside the wire, and there is no pre-laid flux layer like in submerged arc welding, so the arc cannot be completely "submerged".​
It is precisely because of the unique "arc is completely wrapped by flux" that submerged arc welding is named differently from other methods, and this naming has become a sign to distinguish it from other welding technologies.​
The Significance of Naming: Spreading and Standardizing Welding Technology​
The naming of "submerged arc welding" not only describes the phenomenon intuitively but also has important significance for the popularization and standardization of the technology.​
For beginners in welding, this name can quickly establish a cognitive connection: "submerged" reminds them that the core feature of this method is the hidden arc, which helps to understand its working principle and protection mechanism. For engineers and technicians, the name is a concise technical label, which can accurately convey the type of welding method in technical exchanges, drawings, and process documents, avoiding ambiguity.​
In addition, this naming also reflects the logic of engineering technology naming-usually based on the most prominent technical characteristics. Just as "gas shielded welding" is named after the gas protection method, "submerged arc welding" takes the "submerged" state of the arc as the core label, making the technology easy to identify and remember.​
Conclusion: A Name That Condenses Technical Essence​
In summary, the name "submerged arc welding" comes from its most prominent feature: the arc is completely wrapped in the flux and slag layer during the welding process, showing a "submerged" state. This state is not only a visual characteristic but also the key to ensuring high quality, high efficiency, and low pollution of the technology.​
Understanding the origin of this name is not only a matter of terminology but also helps to deeply grasp the working principle and advantages of submerged arc welding. For industrial production, this "submerged" arc brings reliable welds and efficient production; for the welding industry, this name is a vivid symbol of technological characteristics. It can be said that "submerged arc welding" is a perfect combination of technical essence and naming art.