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Joining of AA5052 Aluminum to C30S Polypropylene Sheets Using Friction Stir Welding

Shahmiri, Hamid Reza | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47746 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Movahhedi, Mojtaba; Kokabi, Amir Hossein
  7. Abstract:
  8. Joining metals to polymers is an increasing demand in industry mainly due to weight savings. Polymer-metal hybrid structures are widely used in aerospace and automotive industries. However, dissimilar joining of polymer to metal is very difficult due to large mechanical and physical properties differences. Since conventional methods for joining polymers to metals have various limitations, it is necessary to employ new practical and environmental friendly joining processes. In this study, the feasibility of joining an aluminum alloy (AA5052) to polypropylene (C30S) sheets via friction stir welding was examined. Lap joint configuration was determined as the optimized configuration by analyzing preliminary samples. Investigated parameters include tool rotational speed (800, 1000 and 1200 rpm), tool transverse speed (50, 70 and 100 mm/min), pin plunge depth (0.5 and 1.5 mm) and polymer covering plate. For assessing shear strength and local hardness of the joints, lap shear and microhardness tests were conducted. Optical microscopy and FEM-EDS were utilized for microstuctural studies as well as determining joining mechanism. The maximum shear strength of 5.1 MPa (approximately 20% of polymer shear strength) was obtained at tool rotational and transverse speeds of 800 rpm and 70 mm/min, respectively. As a general trend, the shear strength of the joints decreased with increasing the heat input. FE-SEM images showed a distinctive, interaction layer at polymer/aluminum interface consisted of C, O and Al, according to EDS analysis. The adhesion of this layer to the matrix was weak. Joint samples with polymer covering plate had superior strength than those without covering plate. Results showed that the main joining mechanism is mechanical interlocking
  9. Keywords:
  10. Friction Stir Welding ; Polypropylene ; Polymers ; Aluminum ; Tensile-shear Strength ; Tensile Test ; Dissimilar Joint

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