Effect of Addition of Nitrogen of Oxygen in Shielded Gas on Porosity of MIG Aluminum Weld Metal

Abstract

For the purpose of decreasing blowholes in aluminum weld metal, this experiment was carried out under the shielding gas of argon mixed with nitrogen and/or oxygen.
Results obtained are as follows:-
1) Blowholes in aluminum deposited metal by MIG welding can be decreased by adding nitrogen and/or oxygen to supplied argon gas. Minimum porosity is obtained respectively for mixing ratios of argon 50%+nitrogen 50%, argon 98.5%+oxygen 6.5% (bead on plate) and argon 98.5%+oxygen 1.5% (I-butt weld).
2) In case of argon and oxygen shielding gas, same spray transfer is observed by oscillogram as in the case of argon only, but under argon-nitrogen shielding gas metal transfer changes to short circuit type.