Antichrist
Expedition Leader
It's not moisture in the weld metal.How is moisture in a weld, moisture in sheet metal, or moisture in a forged part any different?
If welds are only visually inspected it's possible to have a weld that visually meets spec, but grind off part of the weld and you find cold lap, which allows moisture in and works it's magic from the "inside".
Cold lap is a very common defect in MIG welding, though with robotic welding one would think the incidence of of that would be nill, once the jigs are set up and the robotics set. Of course, if something causes the parts to shift sligtly before welding, it could happen.