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开展了2A12-T4铝合金平板试验件、螺栓干涉试验件和冷挤压后螺栓干涉试验件在海南万宁大气环境下暴露腐蚀7年、12年和20年后的疲劳试验,进行了试验件腐蚀形貌分析、断口形貌分析和断口附近的侧边损伤形貌分析,并讨论了结构裂纹萌生位置、结构断裂部位和寿命变化规律等疲劳特征的形成原因和机理。研究结果表明:平板试验件和冷挤压后螺栓干涉试验件在腐蚀20年后的疲劳寿命与腐蚀12年相比基本持平,而螺栓干涉试验件的疲劳寿命持续下降;在长期大气腐蚀环境下结构局部强度的衰减速度排序是:螺栓干涉强化部位>未强化部位>冷挤压后螺栓干涉强化部位;2A12-T4铝合金材料在L-S面中部的腐蚀敏感性与L-S面侧边和L-T面相比更弱;L-S面发生的沿晶腐蚀是疲劳开裂的主要萌生源,长期腐蚀后侧面密集损伤导致的能量分散是使腐蚀20年后平板试验件寿命与腐蚀12年相比无明显下降的主要原因。
The 2A12-T4 aluminum alloy flat plate test piece, the bolt interference test piece and the cold extrusion bolt interference test piece were subjected to the fatigue test after being exposed to corrosion for 7 years, 12 years and 20 years in the atmospheric environment of Wanning, Hainan Province, and the test pieces The analysis of the corrosion morphology, the analysis of the fracture morphology and the damage morphology of the side near the fracture surface are also discussed. The formation causes and mechanism of the fatigue characteristics such as the position of initiation of structural cracks, the fracture site of the structure and the law of change of life are discussed. The results show that the fatigue life of flat test pieces and the cold-pressed bolt interference test pieces after 20 years of corrosion is basically the same as that of the 12-year corrosion tests, while the fatigue life of the bolt interference test pieces continues to decline. In the long-term atmospheric corrosion environment The order of the decay speed of the local strength of the structure is: Bolt interference reinforced area> Un-strengthened area> Bolt interference reinforced area after cold extrusion; Corrosion sensitivity of 2A12-T4 aluminum alloy in the middle of LS surface is lower than that of LS surface and LT surface Weakened. The intergranular corrosion occurred on the LS surface is the main source of fatigue cracking. The energy dispersion caused by the intensive side damage after long-term corrosion is the main reason that the life of the flat test piece after 20 years of corrosion is not significantly reduced compared with that of 12 years of corrosion .