The Effect of Thickness and Heat Treatment on Residual Stress of Aluminum 356 Castings

Ganji Moqadam, Omid | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51998 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Ashuri, Hosein; Varahram, Naser
  7. Abstract:
  8. The purpose of this research is to investigate the residual stresses generates during solidification of a casting part and the effect of casting geometry and thermal treatment conditions on these stresses. The pattern was designed with to arms to ensure tensile tension. CO2 process was used for modeling and due to the high hardness of the mold, it also acts as a constraint and exacerbates the tension. To measure tensions in parts, two methods consist of Hole Drilling, and an innovative method based on heat treatment and dimension change have been used. The results of the two methods show the same values of stress. The Hole Drilling method is a verified and high-precision method, which is limited due to its high cost. This method is used to confirm the results of the innovative method. The innovative method is based on the measurement of changes in the sample size due to the release of stress due to heat treatment and calculates the one-dimensional strain and stress. The results of this study show that the presence of different cross sections in a casting unit, in the presence of geometric constraints that prevent the free contraction of the piece, exacerbates the residual stress. As the difference in the cross section is greater, the stress level is also increasing respectively. In this study, the effect of thermal treatment of T6 on residual stresses of parts has been investigated, and annealing thermal treatment has been used to reduce existing stresses. One of the most significant achievements of this research is the validation of the innovative method using the standard hole drilling technique
  9. Keywords:
  10. Residual Stress ; Casting ; Aluminum Alloy A356 ; Heat Treatment ; Hole-Drilling

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