Welding is a technological process for receiving undetachable welded joints of metals and their alloys or   dissimilar materials.

Joint which received after welding is defined of continuous structural connection and monolithic nature which are reached due to formation of atom-molecule connections between elementary particles of joined details.

Undetachable monolithic joint which produced due to welding is called welded joint.  At welding of melting the welded joints includes joint proper (1), metal of thermal influence zone (2) and basic metal (3).  Joint is cast allow of basic and doped metals; zone of thermal influence is piece of basic metal with changed properties as a result of welding