NDT plays a key role in verifying weld quality for marine aluminium. Visual inspection checks for surface porosity and discoloration, which can indicate magnesium loss. Radiographic testing (RT) reveals internal porosity and lack of fusion. But neither method directly measures magnesium content.
For critical marine structures, chemical analysis of the weld metal, such as optical emission spectrometry (OES), is recommended to confirm magnesium levels remain within specification. This is especially important for components exposed to aggressive seawater environments, where even a small reduction in magnesium can accelerate pitting corrosion.
Per AWS D1.2, filler metals for 5083 should match the base metal composition. Using ER5356 or ER5183 filler helps maintain magnesium content. Controlling interpass temperature and using low heat input also minimize vaporization.
Source: AWS D1.2
How do you verify that your marine aluminium welds retain their corrosion resistance?