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Modelling of Pressure Effect on Metal/Mold Interface Resistance in the A356 Aluminium Alloy Casting Process

Fardi Ilkhchy, Ali | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39051 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Davami, Parviz; Varahram, Naser
  7. Abstract:
  8. The computer simulation of freezing patterns in castings has done much to broaden our understanding of casting and mold system design. The structural integrity of shaped castings is closely related to the time–temperature history during solidification, and the use of casting simulation could do much to increase this knowledge in the foundry industry. However, some uncertainties must be eradicated, particularly heat transfer at the metal/mold interface. The accurate knowledge of interfacial heat transfer coefficients is necessary for accurate modeling of castings. The present work focuses on the determination of transient mold–environment and metal–mold heat transfer coefficients during solidification. In this study the heat transfer coefficient, h, at the metal–chill (mould) interface for A356 alloy is measured. Different pressures (0.1,1.14 and 1.66 Mpa) are used to study the effect of the pressure on the heat transfer at the metal–chill interface. The experiments were carried out by positioning the five thermocouples in both metal and mold. The comparison between experimental and theoretical results is made by an automatic search of the best fitting among theoretical and experimental cooling curves simultaneously in metal and in mold. This has permitted the evaluation of the variation of heat transfer coefficients along the solidification process in unsteady state unidirectional heat flow of A356 alloy. The method uses the expedient of comparing theoretical and experimental thermal profiles and can be applied metallic alloys. A solidification model based on the finite difference technique has been used to provide the theoretical results. Finally, the heat transfer coefficients versus pressure were fixed. Aluminum alloys with silicon as a major alloying element consist of a class of alloys which provides the most significant part of all shaped castings manufactured. This is mainly due to the outstanding effect of silicon in the improvement of casting characteristics, combined with other physical properties such as mechanical properties and corrosion resistance
  9. Keywords:
  10. Modeling ; Contact Resistance ; Heat Transfer Coefficient ; Pressure ; Aluminum Alloy A356

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