flux-cored arc welding (fcaw or fca) is a semi-automatic or automatic arc welding process. fcaw requires a continuously-fed consumable tubular electrode containing a flux and a constant-voltage or, less commonly, a constant-current welding power supply. an externally supplied shielding gas is sometimes used, but often the flux itself is relied upon to generate the necessary protection from the atmosphere, producing both gaseous protection and liquid slag protecting the weld. the process is widely used in construction because of its high welding speed and portability.