Welding is a joining process that uses heat to fuse metals together.

There are many different types of welding, including MIG (GMAW) welding, TIG (GTAW) welding, Stick (SMA) welding, and Flux-Cored (FCAW) welding.

Gas Tungsten Arc Welding, commonly called TIG or Heliarc, is a welding process that uses a non-consumable tungsten electrode to heat the base metal and to create a molten weld puddle. An autogenous (no filler metal) weld can be created by melting two pieces of metal together. An external filler rod can be added into the molten puddle to create the weld bead and increase mechanical properties. Like the GMAW process, the molten weld puddle needs to be shielded by an external gas supply. The most commonly used shielding gas is argon, but argon/helium mixtures can be used on heavy aluminum. GTAW can be used to weld most alloys.

Flux-cored Arc Welding is a welding process similar to GMAW, in that it uses a continuously fed electrode, but uses a tubular wire filled with flux instead of a solid wire. There are two types of flux-cored wire, self-shielded and dual shield. Self-shielded is used without the aid of an external gas shield and uses the flux to shield the molten weld puddle. Dual shield uses the flux and an external shielding gas to protect the molten weld puddle. Typical shielding gases are carbon dioxide and argon/carbon dioxide mixes. Self-shielded wires are optimal for outdoor use, even in windy situations. Both wires produce a slag covering on the finished weld.

Gas Metal Arc Welding, commonly called MIG welding, is a process that uses a continuously fed, solid wire electrode through a welding “gun.” The operator pulls a trigger on the welding gun, which feeds the consumable electrode through. An electric arc forms between the electrode and the base material, which heats the base material, causing it to melt, and join. The molten weld metal is protected from oxides and nitrides in the atmosphere by an externally supplied shielding gas. The most commonly used gas is carbon dioxide or a mixture of argon and carbon dioxide.

Shielded Metal Arc Welding, commonly called Stick, is a welding process that uses an electrode (welding rod) to carry the electric current and provide the majority of the weld metal. The electrode consists of a core wire coated in flux. An electric arc is created across the gap when the energized circuit and the electrode tip touches the work piece. This heat melts both the base metal and the electrode creating the weld. During this process, the molten metal is protected from oxides and nitrides in the atmosphere by a gaseous shield created by the vaporizing of the flux coating. The electrode produces a slag covering on the finished weld.

Welding melts the base metal, while brazing and soldering use filler metals to create a bond without melting the base metal.

Most metals, including stainless steel, titanium, and various alloys, can be welded.

Not with traditional welding processes such as SMAW, FCAW, GMAW, or GTAW, the formation of brittle intermetallic compounds.