铝合金5083-6082搅拌摩擦焊焊缝的电化学腐蚀行为

Electrochemical Corrosion Behavior of Friction Stir Welding Dissimilar Weld of 5083 and 6082 Aluminum Alloy

首先,对铝合金5083-6082搅拌摩擦焊(FSW)焊缝与5083母材、6082母材的金相组织进行了研究,结果表明,焊缝的组织与两种母材相比,其晶粒明显细化。其次,通过室温静态挂片试验以及动电位极化曲线测试,电化学阻抗谱(EIS)试验,在室温0.2 mol/L NaHSO3+0.6 mol/L NaCl溶液中,对铝合金5083-6082搅拌摩擦焊的焊缝以及两种母材的电化学腐蚀行为进行了研究。结果表明:主轴转速800 r/min,焊接速度160 mm/min,搅拌头倾角3°时的焊缝与两种母材相比,腐蚀电位Ecorr正向移动,平均腐蚀速率和腐蚀电流密度Icorr变小,极化电阻Rp增大。同时使用扫描电子显微镜(SEM)对室温静态挂片试验试样的表面形貌进行了观察,发现焊缝表面上只出现少量较浅的点蚀坑,而两种母材表面的点蚀现象较为严重。

Firstly, the microstructure of the FSW dissimilar weld is characterized by its much finer grains as contrast with the grains of two parent materials. Then, in the ambient temperature 0.2M NaHSO3 and 0.6M NaCl solution, by static weight loss experiment （gravimetric test） and potentiodynamic polarization curve and electrochemical impedance spectroscopy （EIS） , the electrochemical corrosion behaviors of friction stir welding（FSW） dissimilar weld of 5083 and 6082 aluminum alloy and two parent materials were comparatively investigated . At the tool rotation rate of 800 r/min, the traverse speed of 160 mm/min and 3 tool tilt, the corrosion potentials of the dissimilar weld were more positive than those of two parent materials, meanwhile, the corrosion rate and the corrosion current density were less than those of two parent materials, Rp（polarization resistance） of the FSW weld was larger than that of the two parent materials. Scanning electron microscope（SEM） observation showed that a few shallow pits presented on the surface of the dissimilar weld, however, a large number of deeper pits emerged on the surfaces of two parent materials.