Abstract:The post-weld heat treatment(PWHT) is carried out to Al-Li alloy joints welded by electron beam welding(EBW), and the behaviour of intergranular corrosion(IGC), exfoliation corrosion(EXCO) and electrochemical corrosion of different zones of welded joint before and after PWHT are investigated. Results show that the quantity of phase T1(Al2CuLi) in grain boundry of weldment increased after solution and aging treatment, and the obvious precipitate free zone(PFZ) generated to grain boundry. The IGC does not occur to joint in as-welded(AW) condition, while the pitting corrosion occurs to both heat-affected zone(HAZ) and base metal of welded joint. The susceptibility to IGC of joint increased after aging treatment, both the pitting corrosion and IGC occurred to HAZ, and the severe IGC produced to base metal. It has excellent EXCO resistance for both weld metal and HAZ in AW condition, while the susceptibility to EXCO is higher for base metal. The EXCO resistance can be improved to base metal after aging treatment, however the susceptibility to EXCO will increase to HAZ. Results of electrochemical corrosion measurement show that, compared to the weldment after aging treatment, the self-corrosion potential of weldment is a little higher in AW condition, and its density of self-corrosion current is lower, consequently, it has the relatively better corrosion resistance.