Shielded metal arc welding (SMAW) is a fusion welding process that uses a consumable, flux-coated electrode to create an arc between the electrode and the work piece. Molten metal travels from the electrode via the electrical arc and is deposited into the work piece. The flux coating is also melted and it surfaces on top of the molten weld pool in the form of slag.
Shielded metal arc welding is one of the oldest arc welding processes and is one of the simplest and affordable welding processes that can be used to make quality weldments. This is due to the simplicity of the equipment needed for shielded metal arc welding. All the process requires is a constant current power source, an electrode, an electrode holder, a ground clamp and a work piece.
Shielded metal arc welding electrodes have a flux coating. This flux coating is used to protect the molten weld metal from the atmosphere and oxidation. This is necessary because no external shielding gas is used for this welding process. When the flux coating is deposited into the weld, it resurfaces as slag. This slag must be cleaned away prior to making another weld pass or it could result in a weld defect. Some shielded metal arc welding electrodes, such as low hydrogen electrodes, must be stored in a rod oven to prevent moisture from compromising the electrode's low hydrogen qualities.
Shielded metal arc welding does not produce welds as fast as gas metal arc welding (GMAW) and it is not as versatile as gas tungsten arc welding (GTAW). However, it is still used quite frequently because of its portability and simplicity. Shielded metal arc welding also does well in outdoor applications because the flux-coated electrodes make it less likely to be negatively impacted by windy conditions.