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Investigation of the compression in Equal Channel Angular Extrusion with Forward Extrusion

Ghafarian Malmiri, Hadi | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41040 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Karimi Taheri, Ali
  7. Abstract:
  8. In recent years, more attention was devoted to ECAE process than any other Severe Plastic Deformation (SPD) process. Repeatability of the process and high mechanical properties of the exit profile are the reasons of this attention. ECAE process carried out with conventional extrusion process, provides more strain and back pressure. In this thesis an analytical model based on upper Bound analysis and Bezier interpolation functions is presented and the effects of process parameters were studied. According to the presented model, reduction of inner corner angle φ, increases strain, strain rate and press force. Reduction of the outer corner angle ψ, causes the same effect. Moreover, decreasing internal corner radius (r) increases strain and strain rate. Whereas, the maximum strain and strain rate in channel of ECAE occurs near the inner corner. Results showed that in channel of extrusion, increase of extrusion ratio and angle of extrusion and also decrease of length of extrusion die part, causes increase in strain and strain rate. In the linear extrusion dies, maximum of both strain and strain rate is observed to occur at die exit, while in nonlinear dies, maximum of strain rate occurs at the point with highest curvature. Finally, in order to compare modeling results with the experimental results, samples of pure aluminum and commercially pure lead, were extruded in ECAE-FE and ECAE dies and their property changes were investigated
  9. Keywords:
  10. Bezier Curve ; Upper Bound Method ; Equal Channel Angular Extrusion (ECAE)

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