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Thermal Simulation of Selective Laser Melting Process to Predict Microstructure

Dastbaz, Ehsan | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52496 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Tavakoli, Ruhollah; Ashuri, Hossein
  7. Abstract:
  8. In the process of Additive manufacturing for metals, the ability to predict and control the microstructure can reduce the need for subsequent heat treatment and accelerate the component quality assessment process. The ability to predict and control the microstructure of materials in the laser deposition method needs to understand the thermal conditions during the solidification process. For this purpose, the present study investigated the relationship between cooling rate and temperature gradient during local solidification, and control parameters of the laser deposition process such as power, beam radius, scanning speed and strategy of laser, ambient temperature and preheating temperature. Therefore, in the first part of the project, the cooling rate and the thermal gradient during solidification were calculated numerically by solving the corresponding heat transfer equation using the finite element method, and then the results were obtained, including the solidification parameters mapped on the Ti-6Al-4V alloy solidification map. The results showed that changes in power, radius and speed of laser scanning, depending on the process conditions, can have a significant effect on the cooling rate and temperature gradient during the solidification process, such that by decreasing power, increasing scan speed of laser and increasing radius of laser, grain morphology can be changed from columnar to mixed (column and equiaxed) and completely equiaxed. In the second part, by calculating the cooling rate at the initiation temperature of the transformation (575–800 ⁰C), the volume fraction of the available phases and the effect of different process parameters on the amount of each phase are obtained
  9. Keywords:
  10. Additive Manufacturing ; Microstructure ; Finite Element Method ; Solidification ; Simulation ; Selective Laser Melting (SLM)

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