What is Submerged Arc Welding (SAW)?
Definition: Submerged Arc Welding process (also known as SAW welding process) is a type of arc welding process in which the consumable electrode is fed continuously to the weld zone which is completely submerged under the large amount of granulated flux.
The Submerged Arc Welding process (SAW welding process) is generally used for doing faster welding jobs.
By using Sub Arc Welding process, a large deposition rate of metal can be achieved by using larger diameter electrodes and high current flow (around 4000 A).
By using Sub Arc Welding process, the metal deposition rate of upto 20 kg/hour can be achieved.
Submerged Arc Welding machine has a capacity to weld the metal having thickness upto 100 mm.
Having discussed the definition of submerged arc welding, now further I have explained this process with its diagram and procedure (i.e How Submerged Arc Welding works?)
So let’s begin with the process of submerged arc welding.
Submerged Arc Welding process (SAW welding process)
The Submerged Arc welding diagram is shown above in which you can see the labeled components and materials used in SAW welding process.
The consumable electrode wire is fed continuously in the weld zone as shown in the above diagram.
But do you know why submerged arc welding is referred to as “submerged”?
This is because in submerged arc welding process, the weld zone is completely covered with a large amount of granulated flux. This flux is delivered by the means of flux feed tube or flux hopper.
The arc produced between the electrode and workpiece is completely submerged under the granulated flux and we can’t see it from outside.
During the SAW welding process, some amount of flux melts and it forms slag which further covers the weld metal.
The flux which is not melted is collected back and it can be reused.
The Submerged Arc Welding power source can be either AC power source or DC power source. For this process, both constant current type and constant voltage type machines can be used.
If the electrode having larger diameter is used, then constant current type machines are preferred.
For Sub Arc Welding, the electrode wires having diameters 1.6 mm, 2 mm, 3.15 mm, 4.5 mm, 6.3 mm, and 8 mm are generally used.
These wires should be smooth, clean and free from any contamination.
In Submerged Arc welding process, a large amount of molten weld metal is produced. This fluid weld metal needs to be supported until it solidifies.
There are few ways to support the molten weld metal.
- Backing strips
- Backing weld
- Flux backing
- Gas backing
- Copper backing
In SAW process, the edge preparation of the workpiece is different from other arc welding process. The reason behind this is that the SAW process involves deeper penetration and large weld depositions.
What equipments are used in Submerged Arc Welding?
The equipment used in submerged arc welding are mentioned below along with their functions.
- Wire feeder: It is used to drive the electrode to the workpiece in the weld area.
- Welding power source: Welding power source (either AC or DC) is used to supply the electric current to the electrode.
- Flux hopper: The flux hopper stores the flux and it supplies it to the weld area.
Advantages of Submerged Arc Welding
The advantages of Submerged Arc Welding process are mentioned below.
- The weld spatter is not observed in the SAW welding process because the arc is completely submerged in the flux.
- The smoke and ash flash production during the welding operation is very less, so the welder needs less protective clothing.
- Smooth and uniform weld finishing is obtained by this type of welding.
- Metal deposition rate and welding speed is also higher compared to different other welding processes.
- Semi-skilled welder can operate the machine.
- This welding process is used for heavy fabrication work.
Disadvantages of Submerged Arc Welding
The disadvantages of Submerged Arc Welding process are mentioned below.
- Submerged arc welding is used for welding in flat or down hand positions only.
- This type of welding is not suitable for workpieces having less thickness.
- Welder cannot judge the accuracy of the weld during the welding operation as the weld area is submerged under the flux.
- The special edge preparation is required which is different from other welding processes.
- Not all the metals can be welded by using submerged arc welding process.
Applications of Submerged Arc Welding
The applications of Submerged Arc Welding process are mentioned below.
- SAW welding is used in the aviation industry, shipbuilding industry, nuclear industries, etc.
- Used for fabrication of pipes, railroads, bridges, railway coaches, etc.
- Welding of worn-out machines parts.