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Based on the previous background regarding the prevention and control of intergranular corrosion in 6-series aluminum alloys, the typical failure cases that are currently available in public can be categorized as follows: failure cases of high-speed train body profiles. For the extruded profiles made of 6005A-T6 and 6082-T6 aluminum alloys used in domestic rail vehicles, the lack of clear testing standards for intergranular corrosion in 6-series alloys led to abnormal distributions of precipitates at the grain boundaries in some weak areas of these profiles; as a result, intergranular corrosion occurred over time, posing a threat to the safety of train operations. This situation prompted the development of specialized evaluation techniques for intergranular corrosion in rail vehicle materials. Case of failure in battery trays for new energy vehicles: A 6061 aluminum alloy battery tray developed grain boundary cracking during salt spray testing. Tests showed that its reactivation rate Ra value was 8.7%, well above the acceptable threshold; the root cause was an improper solution treatment process. By optimizing the solution treatment parameters, the Ra value was reduced to 2.1%, thereby resolving the intergranular corrosion issue. Failure cases of 6008 aluminum alloy in high-temperature and high-humidity environments: When 6008 aluminum alloy with a high Si content is used in such environments, the Si element accumulates in large amounts at the grain boundaries, leading to an increase in intergranular precipitates. After 480 hours of salt spray corrosion, the corrosion rate reaches 0.034 mm/a, which is much higher than 0.018 mm/a for 6-series aluminum alloys with low Si content; obvious signs of intergranular corrosion appear. 6082-T6/6005A-T6: Cases of coupled failure in marine environments. When these two commercial 6-series aluminum alloys were exposed to a 3.5% NaCl solution, a combination of pitting corrosion, intergranular corrosion, and exfoliation corrosion occurred. The corrosion spread rapidly along the direction of extrusion, ultimately leading to the failure of certain grains due to their detachment. International academic research.