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Comparison of the Effect of Controlled Annealing on Accumulative Roll Bonded 5083 Aluminum Alloy and AZ31 Magnesium Alloy Sheets

Kalani, Amir Reza | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52813 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Akbarzadeh, Abbas
  7. Abstract:
  8. Lightweight aluminum and magnesium alloy sheets do not generally possess as much strength as steel sheets and their strength need to be increased by a suitable process such as Accumulative Roll Bonding (ARB). One of the most important limitations of ARB is the low ductility and formability of the sheets produced by this process. In the present research conducted on the 5083 aluminum and AZ31 magnesium alloy sheets efforts have beem made to overcome this limitation by heating up the sheets whether during metal forming process as hot deformation or as distinct controlled annealing process subsequent to the deformation, in order to develop the application domain of the sheets. Results demonstrate that conducting controlled intermediate annealing at 400 ˚C on aluminum sheets leads to an increase in ductility in expense of a fair fall of strength, in favor of the occurrence of dynamic recrystallization and avoiding the localization of deformation. On magnesium alloy sheets, ARB can only conducted at elevated temperatures which leads to the formation of shear bands. Hot cross accumulative roll bonding can cause much smaller grains and increase the strength compared to hot ARB. By applying this rolling route on magnesium alloy sheets the strength and anisotropy would be lowered because of more engagement of twinning and increasing of recrystallized grains’ fraction. In the other section of the research, investigation of the annealing behavior of these two alloy sheets at different temperatures and durations shows that in contrast to magnesium which is potent for the formation of bimodal microstructure, aluminum possesses a homogenous microstructure. Annealing behavior in recovery, recrystallization and grain growth stages of the two alloys are compared as well
  9. Keywords:
  10. Controlled Annealing ; Accumulative Roll Bonding (ARB) ; AZ31 Magnesium Alloy ; Aluminum Alloy 5083 ; Dynamic Recrystallization ; Hot Workability

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