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An Investigation into the Kinetics of Dynamic Recrystallization of Fe-Ni Alloy

Dehghan, Hossein | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41889 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Karimi Taheri , Ali; Abbasi, Mehdi
  7. Abstract:
  8. The A-286 superalloy is an iron-nickel base alloy having properties such as oxidation resistance and high mechanical strength. In addition, good producibility and high workability are the important properties of this alloy. In the present work dynamic restoration mechanism of A-286 supper alloy during thermo-mechanical processing has been studied. The aim is to verify the dominant restoration mechanism in different deformation conditions and also to determine the desire deformation parameters for hot rolling. In this regard, utilizing compression test in the range of 950 to 1100ºC and strain rate of 0.001 to 1 per second, the strain-stress curve for this alloy was obtained. After correction of this curve for the friction effect and increase of the adiabatic temperature, calculation of the apparent activation energy of hot deformation as an indication of the kinetic was done, and constitutive equation proportional to the governing behavior model of material was determined. The increase of temperature was calculated by means of the mechanical-thermal simulation of compression test using the ABAQUS software. It was observed that for large strain rate the temperature of the sample increased significantly as a result of the adiabatic heating. Finally, hot-rolling experiment was conducted to investigate the effect of the thickness reduction and the rolling temperature on the mechanical properties of the alloy. These results in addition to the hot compression results revealed that increase of rolling temperature and reduction of thickness in each stage would cause to considerable improvement of the mechanical properties for this alloy after annealing. In other words, the maximum rolling temperature (1100ºC) and maximum thickness reduction (%45) in this temperature resulted in the most appropriate properties
  9. Keywords:
  10. A286 Superalloy ; Dynamic Recrystallization ; Dynamic Recovery ; Hot Compression ; Hot Rolling ; Mechanical Properties

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