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The Effect of Direct and Cross Rolling on Mechanical Properties and Microstructure of Severely Deformed Aluminium

Rahimi Mamaghani, Kaveh | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43359 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Kazeminezhad, Mohsen
  7. Abstract:
  8. Recently, the severe plastic deformation (SPD) is known as one of the most used methods in decreasing the grain size and increasing the strength of metals. In this study, aluminum 1100was subjected toconstrained groove pressing (CGP) at room temperature. The CGPed samples in nanoscale structure, with different CGPed passes were direct rolled and cross-rolled in different rolling strains. Finally, all of the samples were annealed at temperatures of 100, 200 and 300 ° C for 30 min. It was observed that with increasing number of CGP passes and rolling strain the structure became more laminate and finer. With increasing rolling strain, the cross-rolling had greater effect on the microstructure and mechanical properties of CGPed aluminum. In cross-rolling of two passes CGPed aluminum, the UTS was increased to 223 MPa that which was 3.3 times greater than UTS of the starting annealed aluminum. By direct rolling or cross-rolling of annealed sheet the maximum intensity remains on (200) like annealed aluminum but direct rolling or cross-rolling of CGPed sheets changes the maximum intensity from (111) to (220). The minimum crystallite size of 600 nm is achieved in cross-rolled two passes CGPed aluminum with 2.07 rolling strain. The cross-rolling of CGPed aluminum led to better thermal instability in comparison with that of direct rolling. Annealing of rolled CGPed sheets at temperature of 300 ◦C led to the equaxied structure. The cross-rolling, increasing of initial CGP pass and rolling strain caused to the finer structure after annealing.

  9. Keywords:
  10. Severe Plastic Deformation ; Anneal ; Cross Rolling ; Direct Rolling ; Aluminum Alloy Series 1xxx

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