Loading...

Friction Stir Welding of Aluminum to Magnesium Using Alumina and Zinc Powders

Alipour Masoumabad, Saeid | 2019

616 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51898 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Movahedi, Moshtaba; Pouranvari, Majid
  7. Abstract:
  8. In this work, friction stir welding of aluminum to magnesium sheets using alumina and zinc powders was investigated. A preliminary investigation has been carried out on the joining of aluminum 5052 to AZ61 magnesium alloys and finding the optimum welding parameters. The optimum parameters were found to be with the shoulder diameter, pin diameter, and pin height of 14 mm, 5 mm, and 2.7 mm, respectively, with the travel speed of 60 mm/min and rotating speed of 500 rpm. As regards the main purpose of the using zin and alumina powders are controlling of Al-Mg IMCs formation and benefiting from pinning effect of grain boundaries, hence by adopting preliminary investigations and fixing pervious variables, weight percent of zinc and alumina powders were determined. Finally, zinc/alumina weight percent ratio was selected as 0/100, 5/95, 15/85, 25/75, and 50/50. The purpose of this study was achieving maximum tensile and bending strengths. Scanning electron microscopy (SEM) and optical microscopy (OM) observations were employed for the investigation of joint microstructure and formed IMCs, as well as the mixing amount of powders and base metals in the weld interface. These investigations were consisting of shape and morphology of mixed zone, distribution of Zn and Al2O3 powders in the weld microstructure, and fracture surfaces. EDS analysis was conducted to determine the chemical composition of the existing phase in the weld region, and in order to further studies, X-ray diffraction were carried out on the welded surfaces. Mechanical testing results have shown that welded samples with zinc/alumina weight percent ratio of 25/75, exhibiting maximum tensile strength (182 MPa) and elongation (7.5%) in comparison with the other welded samples. Joint efficiency of this sample reached 73% of that of the Al 5052 base metal. In addition, the maximum bending angle with 28 degrees was obtained for this sample. Microstructural investigations of this sample revealed no existence of the Al-Mg IMCs, and formation of a continuous layer of melted zinc in the weld interface causes higher mechanical properties. Agglomeration of nanoparticles in the mixed zone of the sample containing 100 wt.% Al2O3, was revealed lowest mechanical properties in comparison with the other welded samples. Formation of a continuous layer of melted zinc incorporated with agglomerated Al2O3 nanoparticles in the 50 wt.% Al2O3 sample, causes lower mechanical properties in comparison with the 25 wt.% Al2O3 sample
  9. Keywords:
  10. Aluminum ; Magnesium ; Zinc Powder ; Alumina Powder ; Microstructure ; Mechanical Properties ; Friction Stir Welding

 Digital Object List

 Bookmark

No TOC