Corrosion-induced mechanical properties degradation of Al-Cu-Li (2198-T351) aluminium alloy and the role of side-surface cracks


Corrosion-induced surface deterioration as well as mechanical properties degradation of AA2198-T351 were experimentally investigated and compared against AA2024-T3. Pre-corroded tensile and fatigue specimens were mechanically tested. Several degradation mechanisms were detected for different exposure times: a) pitting formation for short exposure times, where AA2198-T351 is superior to AA2024-T3 regarding corrosion resistance, b) exfoliation corrosion for higher exposure times (> 24 h), where almost the same corrosion resistance, regarding tensile elongation at fracture Af decrease, is evident for the two alloys and c) delamination between the grain layers on the side-surfaces. The fatigue endurance limit of AA2198-T351 was almost halved after 6 h corrosion exposure. Side-surfaces corrosion-induced cracks play a pivotal role on the Af decrease of AA2024-T3 due to delamination between the grain layers in the longitudinal rolling direction while this was not observed for AA2198-T351.
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