Gas shielded welding is the use of shielding gas to cover and contain the arc generated by the welding process. This shield, along with the welding arc, is effective in protecting the welding zone from outside contaminants such as oxygen and nitrogen that can affect the weld quality. This process involves the use of a welding wire and shielding gas, which are then fed through the welding torch.
Shielded metal arc welding (SMAW), also referred to as stick welding, is the most popular gas shielded welding process. In SMAW, an electric arc is established between an electrode and the base metal. The electric arc is generated and sustained by the voltage, while a slag formation occurs, providing a protective shield of metal vapors to the weld puddle. The electricity passing through the length of the electrodes provides the energy necessary for the joining of the metal components in the SMAW process.
Gas-shielded welding process also involves a consumable metal coated with a flux. Rather than having the flux coating on the electrodes, these electrodes come pre-coated with a flux in the form of a welding wire. This welding wire is fed through the contact tip of the welding gun, which is connected to a gas source. The gas source is usually a regulated tank or pressurized cylinder which provide the shielding gas.
The choice of shielding gas used in gas shielded welding depends on the application and metal being welded. The three most commonly used shielding gases are Oxygen, Argon, and Carbon Dioxide. Oxygen is commonly used in SMAW since it improves the molten metals slag characteristics while providing good weld penetration. Argon and Carbon Dioxide are used more often in Gas Tungsten Arc Welding (GTAW) processes since they form a shielding atmosphere that induces better welds.
In addition to the welding process and choice of shielding gas, welders must also consider the appropriate gas shielded welding wire to use for the job. These welding wires are usually composed of a ferrous or non-ferrous metal with a flux or coating added as well as filler material.
The welders will choose a type and grade of wire according to the application, with the type being matched to the base metal being worked with. Examples of different wire types may be stainless steel, copper, aluminum, nickel, and cobalt. The carbon content of the wire determines the grade, while the size of the wire is often determined by the thickness of the base metals.
Welding professionals must use the right cables, shielding gas, and welding wire for the job in order for the gas shielded welding process to work properly. Proper maintenance of the equipment used in gas shielded welding is also necessary to ensure optimal weld quality. Finally, the proper welding techniques must be employed when performing a gas shielded weld in order to create a strong and defect-free welded joint.
