Submerged arc welding

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 (SiO2).

Submerged arc welding (SAW) is a common arc welding process. The first SAW patent was taken out in 1935. 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. When molten, the flux becomes conductive, and provides a current path between the electrode and the work. 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. The process is normally limited to the flat or horizontal-fillet welding positions[2] (although horizontal groove position welds have been done with a special arrangement to support the flux). 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. Although currents ranging from 300 to 2000 A are commonly utilized,[3] currents of up to 5000 A have also been used (multiple arcs).

Single or multiple (2 to 5) electrode wire variations of the process exist. SAW strip-cladding utilizes a flat strip electrode (e.g. 60 mm wide x 0.5 mm thick). DC or AC power can be used, and combinations of DC and AC are common on multiple electrode systems. Constant voltage welding power supplies are most commonly used; however, constant current systems in combination with a voltage sensing wire-feeder are available.

  1. ^ US 2043960, Jones, Lloyd Theodore; Kennedy, Harry Edward & Rothermund, Maynard Arthur, "Electric welding", published 1935-10-09, issued 1936-06-09 
  2. ^ a b Kedzi, Okah (2019). Cost Evaluation and Life Cycle Assessment of Thick Plates Using SAW and GMAW (PDF). Lappeenranta – Lahti university of technology. pp. 20–21.
  3. ^ Kalpakjian, Serope, and Steven Schmid. Manufacturing Engineering and Technology. '5th ed'. Upper Saddle River, NJ: Pearson Prentice Hall, 2006.