1. Welding arc properties

An arc is an electrical discharge established and maintained in a gas between two electrodes connected to the poles of a generator and giving off light and heat; it forms a conductive ionized column which essentially responds to physical laws:

• electrical, linking voltage and current, to which the characteristics and operation of generators are related;

• to which melting phenomena are linked.

The electric arc is the heat source behind a number of welding processes based on :

• its thermal effects on the electrodes: the welding arc is a short arc between an electrode, forming the tool, and the parts to be welded, which are heated locally to melting temperature;

• metal transfer phenomena which occur...