Effect of material positioning on Si-rich TIG welded joints of AA6082 and AA8011 by friction stir processing

Abstract

The TIG-welded specimens were friction stir processed (FSPed) to analyze the impact material positioning of the base metals AA8011 and AA6082. The tests included the energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction, microstructure, hardness, tensile test and fracture surface analysis. The mean grain size of 24.83 µm was obtained for the TIG welded joint, 8.68 µm for the FSPed joint with AA6082 alloy on the advancing side (A.S), while 11.14 µm was obtained when the AA8011 was positioned on the A.S. In the TIG + FSPed zone, an intricate vortex flow pattern could be seen. The extremely superplastic flow of plasticized material is seen in the mixed flow zone, which results in a tumultuous intercalation pattern. In situ extrusions of different alloys and severe plastic, deformation was induced by stirring tool action. Lamellae structure was generated by moving the plasticized material layer by layer. In this zone, vigorous mixing and penetration of A6082 and AA8011 were observed. The maximum tensile strength and strain rate of the TIG weldment showed a significant increase after friction stir processing from 83.83 MPa with a strain rate of 23.79% to 90.09 MPa with a tensile strain of 28.04. However, evaluating the FSPed joints, the AA8011-AA6082 specimen had better tensile properties. Moreover, the fracture surface analysis correlated with the tensile tests. The FSPed AA6082-AA8011 joint showed a higher hardness than the AA8011-AA6082 one.