中文摘要：

系统的研究了AZ31镁合金搅拌摩擦焊焊接接头在NaCl溶液中的腐蚀行为。结果表明,AZ31镁合金搅拌摩擦焊焊缝的腐蚀电位和母材相近,而母材的腐蚀电流密度为0.45 m A·cm^-2,焊缝的为1.63 m A·cm-2,后者是前者的近4倍。由于焊接接头的焊缝区受到晶粒尺寸及β相析出的影响,导致焊缝耐蚀性能比较差,腐蚀最先从焊缝区域产生。腐蚀初期母材的抗腐蚀能力比焊缝的抗腐蚀能力强,但当焊缝区域进入自保护状态时,母材腐蚀速率将大于焊缝区域。

英文摘要：

Weld joints of Mg-alloy AZ31 were prepared by friction stir welding, and then their corro- sion behavior was assessed in NaCI solution. The results show that the free corrosion potential of the friction stir weld joint of Mg-alloy AZ31 is like that of the base metal; however, the corrosion current density of the base metal was 0.45 mA-cm 2, while it was 1.63 mA.cm-2 for the joint. Moreover, the corrosion re- sistance in weld nugget zone was the worst because of the effect of the grain size and the distribution of ,8 phase, and the corrosion initialed in this region. In the initial corrosion stage, the corrosion resistance of the base metal was superior to that of the weld joint, but later the base metal exhibited faster corrosion rate rather than the weld joint, which may be ascribed to the occurrence of passivation of the weld joint.