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The Effect of Strain Rate on Multi-directional Forged Aluminum

Khamsepour, Peyman | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50901 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Kazeminezhad, Mohsen
  7. Abstract:
  8. In this study, multi directional forging as a severe plastic deformation method is applied on pure aluminum at the different strain of 0.5, 1.5, 2.5, and 3.5. Annealing has been applied to samples at 150 C, 250 C, 350 C, and 450 C for one hour. In the next step, compressive test is carried out on MDFed and annealed MFDed pure aluminum through strain rate of 0.01 1/s, 0.001 1/s, and 0.0001 1/s. Based on experimental data, when the number of MDF is passes increased, because of increasing the dislocation density and grain boundary area, yield stress is increased. As an example, the yield stress of 7 passed MDFed aluminum is 2.25 times of that of 1 passes MDFed aluminum. Annealing would cause the decrease in dislocation density and grain boundary area. Thus, yield stress would also decrease that the most noticeable reduction happens when samples have been annealed in 350 C and 450 C. In each sample with the same number of passes of MDF process, with increasing the strain rate of compressive test, yield stress would increase. As the number of passes is increased, the effect of strain rate becomes more noticeable. As it was mentioned, the result of all three models, ETMB model for estimating the yield stress of MDFed aluminum, a model based on unrecovered volume fraction for examining the yield stress of annealed MDFed aluminum, and Johnson Cook for examining the effect of strain rate on flow stress, correspond with experimental results
  9. Keywords:
  10. Strain Rate ; Pure Aluminum ; Multidirectional Forging ; Johnson-Cook Model ; ETMB Model ; Unrecovered Fraction

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