Relationship between microstructure, microhardness and corrosion sensitivity of an AA 2024-T3 friction stir welded joint

Corrosion sensitivity of a friction stir welded (FSW) AA2024-T3 aluminum alloy has been investigated using both normalized intergranular corrosion test (ASTM-G110) and local electrochemical open circuit potential measurements. In addition, Vickers microhardness and microstructural analysis have been performed.The HAZ close to the TMAZ is the most sensitive to intergranular corrosion because of the presence of continuous lines of S′(S) intergranular precipitates at grain boundaries. Pitting corrosion is due to the intermetallic particles. Their fragmentation produced by stirring effect modifies the pitting corrosion behavior. Microhardness variations depend on the relative volume fraction of GPB zones and S′(S) intragranular precipitates.

► Intergranular corrosion test (ASTM-G110) to reveal rapidly the most corrosion sensitive zones of the weld.
► Local OCP profile to study the electrochemical behavior of each weld zone.
► Vickers microhardness profile along the weld.
► Study of intermetallic compound and precipitate distribution to explain corrosion sensitivity and microhardness variations.