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Modeling of Mechanical Properties and Microstructure of Copper after Friction Stir Process

Sadeghi, Ehsan | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47878 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Kazeminezhad, Mohsen; Kokabi, Amir Hossein
  7. Abstract:
  8. In the present study, Friction Stir Process (FSP) was used to refine the microstructure of pure commercial copper in order to improve the mechanical properties. Since FSP can be considered as a hot deformation process, theoretical Models were utilized to simulate both thermal history and strain rate distribution. Zener-Hollomon parameter (Z) was then utilized to predict the microstructure of Stir Zone (SZ) which undergoes the Dynamic Recrystallization (DRX). Temperature distribution was formulated and solved by a commercial software COMSOL Multiphysics. Strain rate was analyzed using theoretical models and the codes were written by MATLAB. The predicted grain size was not in a good agreement with experimental observation and it has just anticipate the increase of grain size due to rotation speed enhancement. Microhardness test and tension test were carried out to investigate the mechanical properties of SZ. The results of experimental tests indicated the trivial influence of traverse speed on microstructural evolution and mechanical properties of SZ. Increasing the rotation speed lead to grain growth in SZ which consequently decreased the mechanical properties such as yield stress, ultimate strength and hardness. Measuring the dislocations density by microhardness method, showed that by increasing the rotation speed, dislocation density of SZ diminished
  9. Keywords:
  10. Mechanical Properties ; Thermal Modeling ; Friction Stir Welding ; Zener-Holomon Parameter ; Microstructure Evolution

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