Hydrogen absorption into aluminum alloy 2024-T3 during exfoliation and alternate immersion testing

Exfoliation and alternate immersion corrosion were investigated in Al alloy 2024-T3 (UNS A92024) uptake during exposure and to correlate it with corrosion characterization. Characterization involved determination of weight loss, pitting density, and maximum depth of attack. Hydrogen uptake was determined by subsequent hydrogen evolution during heating. In both accelerated corrosion tests, pitting developed into intergranular corrosion and intergranular attack. Hydrogen penetrated through Al 2024-T3. In the exfoliation test, hydrogen concentration correlated well with the increase in available surface area during intergranular attack. There was indirect evidence that the first portions of hydrogen absorbed were arrested chemically inside the specimen. Free hydrogen (which evolves with mild heating) started to build up only after all active sites were occupied.