The friction stir welded dissimilar aluminium alloy joints were friction stir processed under air (normal) and underwater (submerged) with room temperature conditions. The joints produced through these two distinct conditions were studied comparatively. The microstructural analysis revealed that due to the water rapid cooling system the grain sizes received were finer compared to the normal friction stir processing ones. The microstructural grain refinement contributed immensely toward the joint tensile properties. The submerged friction stir processed joints were found to be more ductile compared to the normal friction stir processed ones. The positioning of the harder alloy (AA6082) on the advancing side and the soft alloy (AA8011) on the retreating side yielded better results for both normal and submerged conditions. The sampling position was also found to have an impact on the results. This was observed when the specimens cut in the beginning of the joint were studied comparatively with those cut from other locations of the joint.

搅拌摩擦焊接的异种铝合金接头在室温（空气）（水下）和水下（浸没）下进行搅拌。通过这两个不同的条件产生的关节进行了比较研究。显微组织分析表明，由于采用了水快速冷却系统，因此与常规的搅拌摩擦加工相比，晶粒尺寸更小。显微组织的细化对接头的拉伸性能有很大的贡献。与普通的搅拌摩擦加工接头相比，浸没搅拌摩擦加工接头具有更大的延展性。在正常和浸没条件下，将较硬的合金（AA6082）放在前进侧，将软合金（AA8011）放在后退侧，可以得到更好的结果。还发现采样位置对结果有影响。当在关节开始处切割的标本与从关节其他位置切割的标本进行比较研究时，可以观察到这一点。