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Modeling the Effect of Pressure on the Shrinkages Distribution

Ahmadian, Kasra | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46448 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Davami, Parviz; Abachi, Parvin
  7. Abstract:
  8. Due to the shrinkage defects, casting parts is sometimes unusable; as a result, researchers is tackling porosity removal problem, so that they would be able to cast parts in a way that have the least porosity. Nowadays, simulation is used to predict the location of the porosity. The design and the elimination of defects, which leads to additional costs, can reduce the overall costs in the projects.
    In this thesis, we focus on shrinkage defects. The main cause of porosity is the drop of pressure. As a matter of fact, the thermal agitation of the molecules is weaker than the strong intermolecular forces that would pull the molecules; therefore, the molten metals’ density will be increased when it is getting cooled. In this study, in order to relieve the pressure drop, we use variety of feeding height to diameter ratio(1 to 3) and safety factor (1 to 1.4) Simultaneously.
    For steel, cube with side length 8 cm pieces and feeding cylinder is used. According to the benchmark of the steel parts, which are available in Niyama[7] and Raoof parvaresh book’s[40] study the best result is the response of height to diameter ratio of 1.5 and a safety factor of 1.3. For A356 parts with a side length of 8 cm square piece, the results of the simulations were compared to the data from the actual casting of the practical results of the simulation results, and this experiment confirmed that the simulation is working well and specifically, the best result is the response of height to diameter ratio of 1 and a safety factor of 1.3. For plate A356 Parts, obtained fragment was never valid. On the other hand, as it was expected, the correct answer is achieved in all the cases by help of the exotherm
  9. Keywords:
  10. Modeling ; Pressure Effect ; Risering ; Shrinkage Defects Prediction ; Large Porosity

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