Hydrogen Trapping: Deformation and Heat Treatment Effects in 2024 Alloy

Corrosion is a major concern to the structural integrity of aging aircraft structures. The effect of corrosion on the damage tolerance ability of advanced aluminum alloys calls for consideration of the problems associated with the combined effect of corrosion and embrittling mechanisms. In recent work [

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] the authors have shown evidence of corrosion-induced hydrogen embrittlement in aluminium alloy 2024. Hydrogen is produced during the corrosion process and is being trapped in distinct energy states, which correspond to different microstructural traps. These traps are activated and liberate hydrogen at different temperatures. In alloy 2024, four traps T1 to T4 were identified. Trap T1 is considered to be a reversible trap, which liberates hydrogen continuously at low temperatures. Traps T2, T3 and T4 saturate with exposure time and are considered to be irreversible with critical evolution temperatures of 200, 410 and 500°C respectively. The hydrogen front advances with the corrosion front, so hydrogen penetrates in the material through the intergranular paths generated by the corrosion process. Then hydrogen diffuses further in the material establishing a hydrogen affected zone beneath the corrosion zone.