【摘要】 针对Al-Mg合金焊接接头敏化行为及修复技术研究滞后于基材，而实际服役过程中焊接接头是失效高发区的突出问题，本工作以5A06合金钨极惰性气体保护(TIG)焊接头为研究对象，系统研究了焊接态、敏化态(175℃等温处理100 h)及还原态(310℃等温处理1和24 h)下，接头母材(BM)、热影响区(HAZ)和焊缝区(WZ)的显微组织及腐蚀行为。采用多种微观表征方法与硝酸失重法(NAMLT)，旨在探究焊接接头各区域的敏化析出特性及还原处理对腐蚀性能的调控作用。结果表明，焊接态BM为完全退火形成的均匀再结晶晶粒，HAZ晶粒在焊接热循环作用下略有粗化，而WZ为等轴树枝晶组织且存在明显的Mg枝晶间偏析；敏化后BM与HAZ沿晶析出连续β’相并在NAMLT测试时发生强烈晶间腐蚀，WZ额外形成的枝晶间针状β’相则进一步诱发枝晶间腐蚀，腐蚀敏感性更高；310℃、1 h还原处理可溶解晶界β’相，而枝晶间针状β’相的回溶需更长时间。为保障接头整体的抗晶间腐蚀能力，应以WZ枝晶间针状β’相完全回溶作为还原处理工艺的制定依据。更多还原

【Abstract】 Owing to their excellent corrosion resistance and weldability, 5 xxx series Al-Mg alloys are widely used in marine and offshore structures. However, research on the sensitization behavior and reversion treatment of Al-Mg alloy welded joints remains underdeveloped with regard to base materials, despite welded joints being critical zones for failure. To address this limitation, the present study systematically investigated the microstructure and corrosion behavior of the base metal(BM), heat-affected zone(HAZ), and weld zone(WZ) of 5A06 alloy tungsten inert gas(TIG) welded joints under as-welded, sensitized(isothermal treatment at 175 ℃ for 100 h), and reversion-treated(isothermal treatment at 310 ℃ for 1 and 24 h) conditions. Various microstructural characterization techniques, along with the nitric acid mass loss test(NAMLT), were employed to clarify the sensitization-induced precipitation characteristics in different regions of the welded joints, as well as the effect of reversion treatment on corrosion performance. The results indicated that the as-welded BM consists of uniform, recrystallized grains formed by annealing. Due to welding thermal cycle, the grains in the HAZ were slightly coarsened, whereas the WZ exhibited equiaxed dendritic structures with notable Mg interdendritic segregation. After sensitization, continuous β’ phase precipitates formed along the grain boundaries in the BM and HAZ, leading to severe intergranular corrosion during the NAMLT. In the WZ, additional acicular β’ phase formed within the interdendritic regions, further inducing interdendritic corrosion and resulting in higher corrosion susceptibility. Reversion treatment at 310 ℃ for 1 h successfully dissolved the grain boundary β’ phase; however, complete dissolution of the interdendritic acicular β’ phase required a longer duration. Thus, to ensure the overall intergranular corrosion resistance of the joint, the reversion treatment parameters should be established based on the complete dissolution of the interdendritic acicular β’ phase in the WZ.更多还原