The versatility and applicability of high-strength aluminum alloys with a good combination of low cost, lightweight and mechanical properties make them a
potential candidate to use in different automotive products and aerospace systems. However, these alloys are involved with a severe loss in ductility and premature fracture when exposed to hydrogen, leading to a limit in their usefulness. The interaction of the absorbed hydrogen with various microstructural features in the alloys significantly affects the trapping and mobility of hydrogen in aluminum alloys, determining the hydrogen susceptibility of the alloy. Hence, an understanding of the hydrogen interaction with the microstructure including different crystallographic defects and phases leads to introducing the involved mechanisms in hydrogen embrittlement.
In this study, the role of different trap sites affecting the hydrogen embrittlement behavior of the aluminum alloys was studied. It was presented that in different aluminum alloys, dislocations have a reversible nature. Higher dislocation density leads to higher amounts of hydrogen at grain boundaries leading to intergranular cracking. Also, the role of fine precipitates on hydrogen embrittlement of the aluminum alloys was introduced and explained. The hydrogen trapping at these traps leads to a good distribution of hydrogen inside the grains and a complete suppression of hydrogen embrittlement. Coarse soluble particles were also found as hydrogen trap sites with irreversible character, showing that the void formation and decohesion at the interface of the particles were detected as the hydrogen-assisted fracture mechanism.