Carbon arc welding (CAW) is an arc welding process which produces coalescence of metals by heating them with an arc between a non-consumable carbon (graphite) electrode and the work-piece. It was the first arc-welding process developed but is not used for many applications today, having been replaced by twin-carbon-arc welding and other variations. The purpose of arc welding is to form a bond between separate metal pieces. In carbon-arc welding a carbon electrode is used to produce an electric arc between the electrode and the materials being bonded. This arc produces temperatures in excess of 3,000 °C. At this temperature the separate metals form a bond and become welded together.

CAW could not have been created if not for the discovery of the electric arc by Humphry Davy in 1800, later repeated independently by a Russian physicist Vasily Vladimirovich Petrov in 1802. Petrov studied the electric arc and proposed its possible uses, including welding.

The inventors of carbon-arc welding were Nikolay Benardos and Stanisław Olszewski, who developed this method in 1881 and patented it later under the name Elektrogefest ("Electric Hephaestus").^[1][2]

• Twin carbon arc welding (TCAW) in which the arc is established between two carbon electrodes
• Gas carbon arc welding (CAW-G) no longer has commercial significance. Other processes that use shielding gases have also replaced carbon-arc welding such as tungsten-arc welding (GTAW, or TIG), plasma-arc welding (PAW), and atomic-hydrogen welding (AHAW). Each of these processes, including carbon-arc welding, use a nonconsumable electrode.^{[citation needed]} A filler metal is generally used to aid the bond in the workpieces.