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Semisolid Stir Joining of As-Cast Silicon-Aluminum Bronze

Ferasat, Keyvan | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45292 (07)
  4. University: Sharif University of Technology
  5. Department: Materials science and Engineering
  6. Advisor(s): Kokabi, Amir Hossein; Ashuri, Hossein
  7. Abstract:
  8. Aluminum Bronzes have many applications in marine environments. These alloys suffer from both hot cracking and cold cracking. In order to overcome the hot cracking and cold cracking, Semisolid Stir Joining method and a proper thermal cycle was used respectively. Effects of temperature, stirring rate, and tool type were investigated in Semisolid Stir joining method. In this method, butt joint design was used in order to place specimens, and the specimens were heated up to specific temperatures (920, 925, 930°C). A stirrer (Cylindrical and Grooved tool) with three rotational speeds (800, 1200, 1600 RPM) was introduced into the stir weld seam. Welded specimens were cooled to the 900°C temperature in the furnace, after that were quenched in cold water. Weld appearance (face and root of welds), Macrostructure, Microstructure, and mechanical properties were carried out to assess the joint properties. In a view of microstructure, globules with low Shape factor (0.69±0.05) were seen. In this alloy globules were introduced as porous globules. When the stirrer was not introduced to the weld seam, no joint was made. When Grooved tool was used, Ultimate Shear Strength was increased 14 percentage in comparison with Base metal (cast alloy) , and Bending Strength was decreased 0.27 percentage in comparison with Base metal. When Cylindrical tool was used, Ultimate Shear Strength was increased 20 percentage in comparison with Base metal (cast alloy) , and Bending Strength was increased 17.6 percentage in comparison with Base metal
  9. Keywords:
  10. Aluminum Bronze ; Shear Punch Test ; Three Point Bending Test ; Semisolid Stir Goining ; Weld Seam Stirring ; Rotational Speed Stirrer ; Stirrer Shape

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