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选取高速列车用A7N01P-T4铝合金及其焊接接头进行中性盐雾实验,研究了其在实际应用中未去包铝层情况下的盐雾腐蚀失效行为。结果表明,盐雾腐蚀过程中焊缝腐蚀最严重,其次是热影响区,母材腐蚀最轻;腐蚀过程起源于包铝层的点蚀,随实验时间的延长腐蚀坑变密并扩大,甚至相互交错连结成片。A7N01-T4焊接接头的腐蚀产物主要有O,Al和C;比较带有包铝层的母材、焊缝区以及去除包铝层的母材三者的极化曲线,其自腐蚀电位负向依次增加,腐蚀电流密度依次增大,从极化曲线也可得出三者的耐腐蚀性能依次降低,包铝层对于铝合金基体以及焊接接头的热影响区起到了较好的防护作用。
The A7N01P-T4 aluminum alloy for high-speed train and its welded joints were selected for neutral salt spray experiment. The corrosion failure behavior of salt spray without aluminum coating was studied. The results show that the weld corrosion is the most serious in the process of salt spray corrosion, followed by the heat affected zone, and the base metal corrosion is the lightest. The corrosion process originates from the pitting corrosion of the clad aluminum layer. As the experimental time prolongs, the corrosion pits become denser and wider, Interlaced into pieces. The corrosion products of A7N01-T4 welded joints mainly include O, Al and C. The polarization curves of the base metal with the alumite layer, the weld zone and the base metal with the alumite layer removed are compared. The corrosion curves of the A7N01- In turn, the corrosion current density increases in turn. It can be concluded from the polarization curves that the corrosion resistance of the three components decreases in turn, and the aluminum clad layer plays a good protective role in the heat affected zone of the aluminum alloy base and the welded joint.