Welding Technology

Welding technology encompasses the broad range of techniques and methodologies employed to accomplish a successful weld--the joining of two or more formerly separate pieces of material into a single unit. Some welds, such as cosmetic welds, have relatively limited quality requirements.

Welding Commonalities

All welding aims to join two or more pieces of material into a conjoined unit. Usually the two objects are of identical chemical composition (e.g. two plates of steel), but welding can also be used to join distinct materials. The melted material then cools and forms the bond.

Arc Welding
In arc welding, an arc of electricity between a cathode (electron emitter) and an anode, or the objects to be welded, produces the heat necessary to join the materials. Arc welders often use specialized welding power supplies that employ sophisticated solid-state power electronics.
Gas-shielded Arc Welding
Gas-shielded welding methods (such as gas tungsten arc welding (GTAW) or shielded metal arc welding (SMAW)) employ an inert shielding gas such as argon or helium to surround the active welding point. Usually a "filler metal" is placed near or between the two objects being welded. During welding the high-temperature electric arc heats this filler, which then releases the protective gas. The shielding gas prevents oxidative damage to the metals, and can promote a stronger weld of higher quality.
Gas Flame Welding
Gas welding uses a very high-temperature flame from a welding torch to generate the heat necessary to weld two objects together. The most common form of gas welding employs oxygen and acetylene gas, and produces a flame temperature near 6,000 °F. There are other customized welding gases that include more common fuels such as propane and butane.
Laser and Particle-beam Welding
Laser welding delivers heat to the weld point via a visible or invisible laser beam. This allows extremely focused welds that can be highly customized by changing the laser wavelength or power output. Electron beam welding (EBW) generates welding heat through a focused stream of high-energy electrons.
Explosive and Magnetic Welding
Friction welding generates a weld by basic friction, sometimes involving high-speed rotation. This type of welding generally doesn't generate sufficient heat to cause full melting at the weld point. Instead the combination of elevated temperature and extreme pressure joins the materials together. Explosive welding utilizes actual high explosives to drive pieces of metal together with so much energy that they weld. Magnetic pulse welding (MPW) achieves a similar effect with extreme magnetic fields.
Underwater Welding
Electric-arc welding is the most common underwater welding method, though hydrogen/oxygen gas flames can also be used. Some underwater welding tasks can only be conducted by a robot.