Submerged Arc Welding - SAW
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Subermed arc welding is a high productivity method for welding thick sections (typically 10 mm and upwards) in the flat position. It is also used for the overlay welding of mild and low-alloy steels.
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Submerged arc welding is used for heavy workpieces. Usually, one or two bottom weld beads are deposited first by some other welding process. The joint is then filled by submerged arc welding. In certain cases the bottom bead may also be submerged-arc welded. This is facilitated by using root backing.
The flux is supplied through a funnel located ahead of the filler wire which is fed continuously. The flux exercises a shielding function. During welding, part of it is converted into a readily removable slag. Superfluous flux is automatically recovered by the machine and reused. This process requires higher currents than in the case of manual arc welding. Due to the material thickness and the presence of residual flux and slag, cooling is relatively slow. The time during which the material is within the critical temperature range of 500-800°C often tends to be long, with the consequent risk of carbide precipitation. In submerged-arc welding, the parent metal should always have a lower carbon content than in the case of metal-arc welding with covered electrodes, if resistance to corrosion is to be the same.
A high quality welding flux suitable for stainless materials must be used.
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