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Mechanical and Microstructural Behavior of 2024-O Aluminum Alloy in Non-Isothermal Hot Compression Test

Taheri, Javad | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54977 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): KazemiNezhad, Mohsen
  7. Abstract:
  8. So far, a lot of research has been done on the hot behavior of different alloys; These studies have generally been performed using tensile, compression and torsion tests and isothermal conditions, which have greatly contributed to the understanding of the mechanisms of deformation at high temperatures. Due to the fact that in real deformation processes, it is less common for the material to experience isothermal conditions during deformation, so in this project, the aim is to investigate the behavior of 2024 aluminum-alloy in non-isothermal hot compression test. In this regard, non-isothermal hot pressure test was performed from 300℃ to 600℃ و temperature range and at different deformation speeds of 0.01s-1, 0.05 s-1 and 0.1s-1 and up to strain 0.7. At constant strain rates, the temperature 500℃ has reached the highest stress level of about 500 MPa compared to other temperatures, which has a microstructure with non-uniform granulation compared to lower temperatures. The strain rate 0.1s-1 with a higher deformation temperature range than the lower strain rates, shows a significant behavioral difference in the stress level at different deformation temperatures, so that the amount of stress required for deformation in Temperature 600℃ and strain rate 0.1s-1 is higher than the two lower strain rates, and increasing the temperature to 600℃ indicates the occurrence of complete recrystallization with coaxial grains at all three strain rates. The strain aging phenomenon occurs at a strain rate of 0.01s-1 and the intensity of indentation of the graph increases with increasing temperature. At a constant temperature of 400℃, the stress level at the strain rate is 0.05 s-1 with the highest volume percentage of dynamic deposition (48%) higher than other strain rates. In the stiffness rate discussion, with increasing temperature, the hardening level (changes in stiffness rate relative to the stress for deformation) increases the strain rate 0.1s-1 and approaches the hardening level of the lower strain rates. At constant temperature, a good agreement was reached between the true stress-strain diagram and the strain-stress strain rate diagram, so that at all temperatures an increase in stress to deform leads to an increase in critical stress. Also, strain rate variations are higher than stress for the strain rate of 0.05 s-1 at constant temperatures than the other two strain rates.

  9. Keywords:
  10. Hot Compression ; Nonisothermal ; Microstructure ; Aluminum Alloy 2024 ; Mechanical Behavior ; High Strain Rate

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