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Production of Globular Structure of Al A356, Using Both Electromagnetic Stirrer and Gas induced Semi Solid (GISS) Process

yekani, Farnoush alsadaat | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51968 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Aashuri, Hossein
  7. Abstract:
  8. Production of semi solid slurry and creating the globular alloy structure is possible in the ways of Electromagnetic stirring and Gas induced semi solid, which are used widely in industrial scale. Because of the weak magnetic field in the middle part of stirrer, this part is being emptied of melt. As a result, The porous graphite cone is used in this part in order to inject the gas bubbles.In this research, the semi solid A356 Aluminum alloy, is produced under different durations and stirring flux using a three phase Electromagnetic stirrer and injection of the Argon gas. Consequently the slurry was transferred to a mold and compacted by a drop weight. By investigating and analyzing the metallographic images, it was concluded that in the simultaneous EMS and GISS processes for 120 seconds and 90 Amper, in comparison with electromagnetic solely, the shape factor and the aspect ratio improved considerably, but in the times less than 120 seconds, the improvement were not significant.In addition, the shape factor, aspect ratio and the mean diameter improved via the separation of EMS and GISS. GISS process didn’t affect the structure considerably in short periods of time (45 s), but by using EMS after 45 seconds injection of the gas, the structure improved considerable.Increasing the time of gas injection, up to 45 seconds, when the EMS and GISS used separately, the structural properties was improved and the finest structure was obtained using GISS for 45 second and EMS for 45 seconds but with increasing the gas injection time, the microstructural feature deteriorated. In general, the solid fraction increased with increasing the time and intensity of the stirring process
  9. Keywords:
  10. Semisolid Mixture ; Globular Structure ; Electromagnetic Stirrer ; Gas Induced Semi Solid (GISS) ; Aluminum Alloy A356

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