Loading...

An Investigation Into Microstructural Changes and Mechanical Properties During Friction Atir Welding of a Hardenable AA2017

Mirjalili, Abolfazl | 2011

587 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42267 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Kokabi, Amir hosein; Serajzadeh, Siamak
  7. Abstract:
  8. Friction stir welding (FSW) is considered a significant manufacturing process for joining of different metals and alloys and usage of this process has been developed in different industries. Accordingly, extensive works have been done on FSW of different engineering materials. However many ambiguous problems related to thermo-mechanical behavior of this process have not been solved yet. This research investigates FSW behavior of a hardenable aluminum alloy, AA2017. Firstly, thermo-mechanical response of the material has been predicted using a three-dimensional finite element analysis performed in ABAQUS software. Then, microstructural events such as grain size, distribution of second phase particles as well as mechanical properties of welded zone have been studied using experimental evaluation and simulation results. Also, effects of primary condition of the alloy, welding speed and rotational speed were studied. To evaluate mechanical properties of the joint and the predicted results, different tests were considered including microstructural studies, experimental measurement of temperature variations, determination of residual stresses, tensile and DIC tests and hardness test. To verify the predictions, experimentally recorded temperature variations and residual stresses were compared with predicted ones and reasonable consistency was observed. The predicted results show that with decreasing rotational speed from 800rpm to 700rpm at 4cm/min welding speed, the maximum temperature is reduced from about 16°C and also with decreasing welding speed from 6cm/min to 4cm/min at 800rpm rotational speed, the maximum predicted temperature rises to 510°C, while solidus temperature of AA2017 is about 515°C. In addition, residual stress experiments exhibit that the maximum longitudinal residual stress in T6 condition is about 45MPa more than of that in T4 condition. Also microstructural studies illustrate that notable grain refinement occurs during FSW in which the mean grain size within stir zone is less than 10μm
  9. Keywords:
  10. Friction Stir Welding ; Thermodynamic Model ; Finite Element Method ; Residual Stress ; Aluminum Alloy 2017

 Digital Object List

 Bookmark

No TOC