Submerged arc welding (SAW)
Today I will be discussing on what is submerged arc welding, its working principles applications. Previously, an article was published on Flux cored arc welding (FCAW). Check out!
What is submerged arc welding (SAW)
Submerged arc welding is another type of arc welding process that uses a continuously fed consumable tubular electrode. It can be operated in the automatic or mechanized mode. Is can also be operated on semi-automatic (hand-held) SAW guns with the delivery of pressurized or gravity flux fed. This process is not suitable for flat or horizontal filler welding position through the horizontal position have been done with a special arrangement in order to support the flux.
In this welding process, the arc zone and weld pool are protected from atmospheric contamination, due to the blanket of granular flux consisting of lime, silicon, manganese oxide, calcium fluoride, and some other compounds. The molten flux becomes conductive and create current between the electrodes and the base metal. The thick flux layer covers the metal completely, preventing sparks and spatters, and supporting the intense ultraviolet radiation and fumes which are part of the welding process.
SAW was first patent in the year 1935 and covered an electric arc beneath a bed of granulated flux. It was originally developed by Jones, Kennedy and Rothermund. The process has some distinct features that makes it differs from other arc welding process, which include:
- Welding head: this feeds the flux and the filler metal to the welding joint.
- Flux hopper: this helps to store the flux and controls the rate of flux deposition to the welding joint.
- Flux: the granulated flux protects the weld from atmospheric contamination. It also cleans the weld metal and modify its chemical contamination. Though some other arc welding process like MIG, SMAW offers this.
- Electrode: the filler material is a standard wire as well as other special forms. The thickness of these wire is normally 1.6mm to 6mm.
Just like other arc welding process, SAW also transferred current to the electrode from either AC or DC welding machine. It separately deposited flux to the weld zone before the joining takes place. This flux is a non-conductor of electricity when cold but becomes good conductor when melted with the arc heat. It also allows the current flow between the electrode and the workpiece. The flux which is visible to atmosphere, remains granular (unchanged), making it to be reused. The lower melted flux becomes slag, making it a waste material and must be removed after welding,
Using a predetermined speed, the electrode is continuously fed into the joint. Whilst in semi-automatic welding sets, the welding is done manually along the joint. In automatic, a separate drive moves either the welding head over the stationary job or the job rotates under the stationary welding head.
The followings are the applications of SAW process:
SAW process is suitable for welding carbon steels (structural and vessel construction). It is also used on low alloy steels, stainless steels, nickel-based alloys, and surfacing applications.
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And that is it for this article, what is submerged arc welding, its working principles and applications. I hope you enjoy it. If so, kindly comment and share. Thank for reading!