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Theoretical and Experimental Investigation of Warm Rolling of Al Alloy 2017

Khalili, Leila | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43760 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Serajzadeh, Siamak
  7. Abstract:
  8. A mathematical model was developed to assess thermomechanical behavior of work rolls during warm rolling processes of AA2017. A combined finite element analysis-slab method was first developed to determine thermal and mechanical responses of the strip being rolled under steady-state conditions; Then, the calculated roll pressure and temperature field were utilized as the governing boundary conditions for the thermomechanical problem of the work roll. Finally, the thermomechanical stresses within the work rolls were predicted by a thermoelastic finite element approach. The results indicate that, in warm strip rolling, thermal and mechanical stresses developed in the work rolls are comparable. Besides, the model is capable of determining the effects of various rolling parameters on the thermomechanical behavior of the work rolls. Furthermore, since warm rolling can affect final properties of the rolled strips through some metallurgical phenomena such as static strain aging (SSA) and static recrystallization (SRX), the effect of deformation path, rolling parameters including reduction, rolling speed and cooling media on final mechanical properties of AA2017 have studied. First, samples were rolled under different rolling conditions. Then, rolled strips were aged at room temperature for 57 days and meanwhile through hardness and tensile tests mechanical properties of the rolled samples were measured. Furthermore, a physically based internal state variable microstructure model has been incorporated to predict SRX. The results indicate that the occurrence of SRX can significantly affect the kinetic of subsequent SSA which is completely obvious in the comparison of single and multi-pass rolled samples. Moreover, a change in rolling parameter or cooling media results in a notable change in final properties of the sheets through changes in SRX and SSA kinetics. For example an increase in cooling rate not only increases yield stress and maximum hardness, but the time required to reach maximum hardness decreases considerably
  9. Keywords:
  10. Warm Rolling ; Thermal-Mechanical Stress ; Finite Element Method ; Static Recrystallization ; Static Aging

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