Stages of Damage Evolution for Al 2024-T3 Around Fasteners in Marine Atmosphere

Abstract

Corrosion at fasteners in aluminum presents a high risk and a challenge to corrosion mitigation strategies. The objective of this study was to determine the stages of damage evolution for 2024-T3 around fasteners when exposed at a marine atmospheric corrosion site. A comparison was made between fasteners made from stainless steel, cadmium-plated steel, and cadmium-plated steel with a portion of the plating ground to expose steel and simulate damage to the coating. Corrosion modes were identified over 24-month exposure, and a sequence of corrosion damage stages was developed. Several modes interacted and/or occurred in a sequential pattern. In addition to classic galvanic corrosion, galvanic action had a significant effect on crevice corrosion, intergranular corrosion, and stress corrosion cracking. The important roles of rust on steel fasteners and wedging from the formation of dense corrosion products were identified. Results are relevant to crucial concerns in modeling of damage evolution and developmen...