Correct Answer - Option 1 : High tendency of oxidation
Concept:
The high affinity of aluminium with atmospheric gases increases the tendency of formation of oxides and nitrides (having density similar to that of aluminium) especially when
- protection of weld pool is not enough,
- proper cleaning of filler and base metal has not been done,
-
shielding gases are not pure enough and therefore making oxygen and hydrogen available to molten weld pool during welding,
- gases are present in a dissolved state in aluminium itself and tungsten inclusion while using GTA welding.
Presence of these inclusions disrupts the metallic continuity in the weld, therefore, these provide a site for stress concentration and become a source of weakness leading to the deterioration in mechanical and corrosion performance of the weld joints
