搅拌摩擦焊接AA6061-AZ31B合金异质接头在搅拌区的电化学腐蚀行为

摘要

Joining of dissimilar metals will offer many advantages in transportation sectors such as fuel consumption, weight reduction and emission reduction. However, joining of aluminium (Al) alloys with magnesium (Mg) alloys by fusion welding process is very complicated. Friction stir welding (FSW) is a feasible method to join these two dissimilar alloys. Mixing these two metals together in stir zone (SZ) leads to poor corrosion resistance. In this investigation, an attempt has been made to understand the corrosion resistance of SZ of FSWed dissimilar joints of AA6061 Al alloy and AZ31B Mg alloy. Potentiodynamic polarization test was conducted by varying chloride ion concentration, pH value of the NaCl solution and exposure time. The corroded surfaces were analyzed using optical microscopy, scanning electron microscopy and XRD techniques. Of these three factors investigated, exposure time is found to be the most significant factor to influence the corrosion behaviour of SZ of friction stir welded dissimilar joints of Al/Mg alloys.%异质金属的连接在交通运输领域如燃料消耗降低、材料质量减轻、排放量减少等方面具有较多优越性.然而,采用熔焊工艺对铝、镁合金进行焊接是一个非常复杂的过程.搅拌摩擦焊接方法是一种对铝、镁合金进行连接的有效方法.在搅拌摩擦焊接过程中,铝、镁合金在搅拌区混合,致使合金在该区的耐蚀性能变差.本文作者研究搅拌摩擦焊AA6061-AZ31B合金异质接头的耐蚀性能,通过改变氯离子浓度、NaCl溶液的pH值和焊接时间对样品进行恒电位极化实验.采用光学显微镜、扫描电镜和X射线衍射技术对样品的腐蚀表面进行表征.结果表明,在所研究的3个参数中,焊接时间对搅拌摩擦焊AA6061-AZ31B合金异质接头耐蚀性能的影响最显著.