Submerged arc welding

The process requires a continuously fed consumable solid or tubular (metal cored) electrode.

[1] The molten weld and the arc zone are protected from atmospheric contamination by being "submerged" under a blanket of granular fusible flux consisting of lime, silica, manganese oxide, calcium fluoride, and other compounds.

This thick layer of flux completely covers the molten metal thus preventing spatter and sparks as well as suppressing the intense ultraviolet radiation and fumes that are a part of the shielded metal arc welding (SMAW) process.

[2] SAW is normally operated in the automatic or mechanized mode, however, semi-automatic (hand-held) SAW guns with pressurized or gravity flux feed delivery are available.

Deposition rates approaching 45 kg/h (100 lb/h) have been reported — this compares to ~5 kg/h (10 lb/h) (max) for shielded metal arc welding.

Flux with fine and coarse particle sizes are recommended for welding heavier and smaller thickness respectively.

Electrodes are generally copper coated to prevent rusting and to increase their electrical conductivity.

Since the flux is not electrically conductive when cold, the arc may be struck either by touching the electrode with the work piece or by placing steel wool between electrode and job before switching on the welding current or by using a high frequency unit.

The upper portion of the flux, in contact with atmosphere, which is visible remains granular (unchanged) and can be reused.

[5] A backing plate of steel or copper may be used to control penetration and to support large amounts of molten metal associated with the process.

Submerged arc welding. The welding head moves from right to left. The flux powder is supplied by the hopper on the left hand side, then follow three filler wire guns and finally a vacuum cleaner.
A submerged arc welder used for training
Close-up view of the control panel
A schematic of submerged arc welding
Pieces of slag from submerged arc welding exhibiting glassy surface due to silica (SiO 2 ).