SOURCES OF POROSITY IN ALUMINIUM MIG WELDS.

The effect of variations in the water vapor level of the air surrounding the inert gas column and in the parent metal internal hydrogen level on the porosity content of single-pass, full-penetration 5083/5356 automatic MIG butt welds has been quantitatively evaluated. A fourfold increase in ambient water vapor level was found to have negligible influence on weld porosity content provided a continuous, undisturbed flow of argon shielding gas was maintained and contact between moisture-laden air and the filler wire surface was avoided. Although a similar variation in parent metal internal hydrogen level produced an increase in weld porosity content, welds with minimal porosity were formed using commercially-available 5083 parent metal.