Submerged ARC welding
Submerged Arc Welding (SAW) is the preferred welding method for joining plate metal because it creates such strong welds.
Flux is poured directly into the weld pool where it becomes molten and conductive and acts as its own shield protecting the weld site from contamination. Excess flux gets recycled back into the hopper where it can be reused.
SAW is usually a fully automatic process, but it can also be semi-automatic so it must rely on machinery and parameter settings to manage bead shape, depth of penetration, and chemical composition of the weld metal.
SAW can be extremely effective in certain situations.
Extremely high deposition rates
Low skill required
Easily automated
High quality, sound, uniform welds
Deep weld penetration
Little to no fumes, arc light, spatter, or sparks are emitted
Suitable for indoor or outdoor applications
Single pass welds are possible
Little to no edge preparation is required
Flux is recoverable, recycled and reused
MIG (GMAW) welding with shielding gas and a solid wire electrode produces a clean, slag-free weld without the need to continually stop welding from replacing the electrode, as in Stick welding.
Carbon Dioxide (CO2) is the most common of the reactive gases used in MIG welding and the only one that can be used in its pure form without the addition of inert gas. Pure CO2 provides very deep weld penetration, which is useful for welding thick material.
Increased productivity and reduced clean up are just two of the benefits possible with this process.
The primary purpose of shielding gas is to prevent exposure of the molten weld pool to oxygen, nitrogen and hydrogen contained in the air atmosphere. The reaction of these elements with the weld pool can create a variety of problems, including porosity (holes within the weld bead) and excessive spatter.