Analysis of mechanical properties between submerged and normal multiple-pass friction stir processing of the FSWed dissimilar aluminium joints

Abstract

The friction stir welded dissimilar aluminium alloy joints AA8011-AA6082 were subjected to multiplepass friction stir processing under different operating conditions. The processing conditions used included room temperature (normal) and underwater (submerged) friction stir processing. Microstructural analysis, hardness and tensile tests were conducted to analyze the impact of different multiple-pass friction stir processing conditions on the friction stir welded dissimilar aluminium alloy joints. The microstructural results showed that the multiple-pass submerged friction stir processed grain structure was 67.72% finer compare to those of the multiple-pass normal friction stir processed joints. The ultimate tensile strength obtained correlated the grain size behaviour resulting in the multiplepass submerged joint having a UTS with a 3.2% increase in comparison to that of the normal friction stir processed joints. The percentage elongation results correlated with the tensile and grain size results. The multiple-pass submerged friction stir processed joints had a maximum hardness of 65 HV and the normal multiple-pass friction stir processed joints had a hardness of 53 HV.