Welding

Refers to the process of joining two pieces of metal by softening or melting both surfaces to be joined by the application of heat, with or without inserting filler metal and with or without the application of pressure. For the metal joining process that necessarily involves the insertion of solder but not necessarily the softening or melting of the surfaces to be joined, see "soldering" for the process carried out at temperatures below 750 degrees Celsius, or "brazing" for the similar process carried out at temperatures ranging between 750 and 900 degrees Celsius.