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High Temperature Deformation and Creep-Aging Behavior of an Aluminum Alloy 5083

Khodamoradi, Zahra | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51461 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Serajzadeh, Siamak
  7. Abstract:
  8. Mechanical behavior of aluminum-magnesium alloy, AA5083, was studied at high temperatures using hot tensile testing together with uniaxial creep experiments. In the first place, the as-received AA5083 sheet was subjected to annealing heat treatment to remove the effect previous plastic straining. Then, creep experiments were conducted at temperatures in the range of 190°C to 300 ° C under constant the stress varied between 30 MPa to 100 MPa. The hot tensile testing was also carried out from room temperatures up to 400 °C under nominal constant strain rates of 0.0005, 0.005, 0.01 and, 0.05 (1/s). In addition to the mechanical testing, optical metallography and scanning electron microcopy were made to investigate the microstructures of the alloy after deformation as well as to evaluate the volume fraction and morphologies of the voids and cavitations produced during creep deformation. Accordingly, the activation energy and strain rate sensitivity was calculated as 140 kJ/mol and 0.19, respectively. This suggests that the governing mechanism of the creep might be dislocation climb controlled by bulk diffusion. Furthermore, microstructural observations have shown that the strain-controlled growth was operative during creep cavitation while the cavitations were mostly formed at trip junctions and the interface of Fe-rich particles. Both dynamic recovery and dynamic recrystallization were observed during hot tension testing and the apparent hot deformation activation energy was calculated as 154.4 kJ/mol. However, at lower temperatures i.e. 150 °C or less, the phenomenon of dynamic strain aging was detected leading to negative strain rate sensitivity. Finally, the results of the tensile tests were employed to develop processing maps which can be used as a guideline for a proper designing of hot working processes
  9. Keywords:
  10. Hot Deformation ; Creep ; Cavitation ; Processing Map ; Neural Network ; Aluminum Alloy 5083

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