Welding, melting the formation of slag and gas, to protect the molten metal and metallurgical processing of the role of a substance. For submerged arc Welding Wire submerged arc welding agent. Used for brazing are: brazing flux and soldering flux. Flux is also called the Welding Flux, the definition should be broad, including molten salts, organic matter, reactive gases and metal vapor, remove the base metal and filler metal, refers to the third to reduce the interfacial tension of the base metal and filler metal substances. The nature of the filler metal and base metal wetting ability and solder of course a lot, but compared with the role of the flux is a secondary and more.