Submerged arc welding

Submerged arc welding (SAW) is a common arc welding process. The process requires a continuously fed consumable solid or tubular (metal cored) electrode. 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.

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 (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, 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.

• high labor costs associated with the cost of the flux.
• difficulties in correcting the position of the arc relative to the edges of the workpiece being welded;
• environmental impact of gases on the operator;
• invisibility of the welding site located under a thick layer of flux;
• it is not possible to perform welding in all spatial positions without special equipment;
• increased fluidity of molten metal and flux;
• careful assembly of edges for welding is required. With an increased gap between the edges, molten metal and flux may flow into it and the formation of defects in the seam.

• increased productivity;
• minimal loss of electrode metal;
• no splashes;
• the most reliable protection of the welding zone;
• minimal sensitivity to the formation of oxides;
• protective devices from light radiation are not required, since the arc burns under a layer of flux;
• low metal cooling rate provides high mechanical properties of the weld metal.