Technological Advances in Inert Gas Shielded Arc Welding Processes

Inert-gas-shielded arc welding processes widely used for quality welds comprise MIG, TIG - and Plasma. The technological advances which have taken place since their introduction, can be broadly classified in terms of processdesign and process-parameters.

The general developments in process-design encompass the pulsification of the arc current and magnetic control of arc. The advances in MIG cover narrow gap welding, welding in thermally ionized gas, synergic pulse mode and spot welding. Hot-wire, orbital and multielectrode techniques are some of the processdesign developments in TIG. Another recent modification is the SERIES MIG-TIG welding. The above technological advancements contribute to the superiority of the welded structure from the view point of metallurgical and mechanical properties, higher degree of automation, ease of accessability, in-situ operation, reliability and economy.

The developments in process-parameters include combined effect of anode/cathode geometry and type of shielding gas on the penetration characteristics in TIG, and .high . deposition rate with electrode negative polarity in MIG. Arc stability and achievability of keyhole weld with intermediate plasma and potentiality of microplasma in the field of precision fabrication have been highlighted by the authors with due emphasis.