Thesis supervisor: Ákos Meilinger
Location of studies (in Hungarian): Institute of Materials Sciences and Technology Abbreviation of location of studies: ATI
Description of the research topic:
Aluminium castings have the worst properties in terms of weldability, which is why they are extremely difficult to weld with conventional fusion welding processes. The presence of gas porosity in the casting causes serious problems, and the high Si content also raises weldability issues. In addition, the good thermal conductivity and the oxide layer present on the surface make more difficult to create welded joints.
Besides this, the use of aluminium castings can be found more and more frequently in many areas of the industry, for example as an element of the car body. The demand for the appropriate joining technology has increased with the increased use of these materials. As aluminium castings are typically made with a higher wall thickness, mechanical joining technologies are less likely to be considered. This results in a growing need to improve weldability, but currently this area gives serious challenges for researchers.
Weldability problems are basically due to the fact that during fusion welding, the base material is heated to a high temperature and melts. This problem can be eliminated by using a solid-phase pressure welding process, but these processes typically have geometric limitations. An exception to this is one of the modern pressure welding processes: friction stir welding. This process is relatively new, so this is one of the most researched area in the science of welding.
Besides to optimizing the welding parameters, a wide range of research activities can be carried out in the design of the applied welding tool, which can eliminate a significant part of the weldability problems in aluminium castings.
During welding, complex structural changes take place due to the effects of frictional heat and pressure force, so physical simulation can be used to gain a deeper understanding of these processes.
Research conditions: the required welding equipment and testing equipments (Gleeble 3500 physical simulator, material testing equipment) are available at the Institute of Materials Science and Technology, as well as at the cooperating institutes.
Industrial background: The Institute of Materials Science and Technology provide a wide cooperation network in the industrial area.
Part-time education abroad: the actuality and importance of the research work offer the possibility of part time research abroad.
Further requirements:
• Language: good English for literature overview
• Preliminary studies:
- mechanical engineer MSc diploma with good or excellent grade;
- basic knowledge about material technologies and welding.
Recommended literature:
• Mishra, R. S.: Friction Stir Welding and Processing, ASM International, 2007
• Kvackaj, T.; Bidulsky, R.: Aluminium alloys, theory and applications, Intech, 2011
• Meilinger, A.; Török I.: The importance of friction stir welding tool, Journal of Production Processes and Systems, volume 6, 2013
• Meilinger, A.; Török I.: Effect of temperature field and pressure force on the inhomogeneity of 5754-H22 and 6082-T6 FSW joints, Materials Science Forum, Vols 794-796, 2014
• Totten, G.; MacKenzie, S.: Handbook of aluminium, Marcell Dekkel Inc., 2003
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