Loading...

Investigation of Semisolid Microstructure of Aluminum A356 Alloy Prepared by Electromagnetic Stirring and Gas Induction

Nafari, Nora | 2015

646 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47126 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Ashuri, Hossein
  7. Abstract:
  8. Diverse methods of producing semi-solid metal have been the subject of extensive study for the past 40 years. Among all these methods, electromagnetic stirring (EMS) and gas induced semi solid (GISS) have been used on a commercial scale. Considering the fact that in previous studies the intensity of electromagnetic field in the central part of the stirring chamber was negligible, a hollow cylinder with an almost pure iron core was utilized in the central part of the chamber in order to intensify the electromagnetic field in the center and to introduce gas bubbles into the melt. Aluminum A356 alloy was stirred by a three phase electromagnetic stirrer and introduction of gas bubbles under different conditions of stirring current and stirring time. The prepared semi-solid slurry was then transferred into a mold and was pounded by a drop device. Investigation of the results demonstrated that stirring by means of electromagnetic force and gas induction simultaneously, had no superiority in comparison with electromagnetic stirring solely. But when the two methods were separated, the results demonstrated a favorable shift in shape factor and aspect ratio. When the two methods were separated, while increasing gas induction time more than 30 seconds (half of the whole time interval), an increase in average diameter was observed. While 30 seconds of gas induction apparently had no effect on producing globular microstructure, when applied before electromagnetic stirring, resulted in a better microstructure in terms of shape factor and aspect ratio. Increasing current and time resulted in increased shape factor and decreased aspect ratio which means a more globular structure, while the average diameter of globules increased
  9. Keywords:
  10. Electromagnetic Stirring ; Semi-Solid Processing ; Globular Microstructure ; Aluminum Alloy A356 ; Gas Injection

 Digital Object List

 Bookmark

No TOC