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 determinati on of weight loss, pitting density, and maximum depth of attack. Hydro gen uptake was determined by subsequent hydrogen evolution during heat ing. In both accelerated corrosion tests, pitting developed into inter granular corrosion and intergranular attack. Hydrogen penetrated throu gh Al 2024-T3. In the exfoliation test, hydrogen concentration correla ted well with the increase in available surface area during intergranu lar attack. There was indirect evidence that the first portions of hyd rogen absorbed were arrested chemically inside the specimen. Free hydr ogen (which evolves with mild heating) started to build up only after all active sites were occupied.