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The Effect of Multi-Directional Forging on the Warm Compression Behavior of AA2024-O

Afzali, Samira | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53111 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Kazeminezhad, Mohsen
  7. Abstract:
  8. Aluminum alloys have many applications in various industries such as automotive and aerospace due to their high strength to weight ratio. Today, much research is being done on the strength of metals and alloys after severe plastic deformation. Among these studies, limited work has been done on the hot deformation behavior of alloys that have undergone a severe plastic deformation process. In this research, aluminum alloy 2024-O is subjected to various passes under a type of severe plastic deformation process called multi-directional forging. Samples were divided into zero passes (annealed), one pass, three passes and five passes. After preparing pressure samples from them, hot pressure with a speed of 100 mm/min is performed at ambient temperatures, 200℃, 300℃, 400℃ in non-isothermal conditions. The behavior of hot pressure is determined by microstructural changes and stress-strain curves. The effects of restoration phenomena such as recovery and recrystallization, hard work of samples and grain refinement are investigated in this study. The recrystallization temperature during the non-isothermal pressure test varies for different samples. In annealed and single-pass samples, most grains are flattened at ambient temperature, 200℃ and 300℃, indicating the predominance of the dynamic recovery phenomenon. At 400℃ the seeds are larger. It can be said that for annealed samples and one pass, the optimum temperature for recrystallization is between 300℃ and 400℃. However, in the five-sample specimens, the seeds continue to shrink to a temperature of 400℃ and can be said to have not yet reached the growth stage. The stress-strain diagram of the samples at different temperatures shows that the softening and hard work processes occur under pressure test conditions and the curves are all strictly ascending. At ambient temperature, the stress difference between the annealed sample and the forged samples is large, and with increasing temperature, their stress level gradually decreases. Hardness increases with increasing temperature for annealed and forged specimens
  9. Keywords:
  10. Severe Plastic Deformation ; Multidirectional Forging ; Nonisothermal ; Thermal Pressure ; Aluminum Alloy 2024 ; Microstructure Evolution

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