Defence of dissertation in the field of materials science and engineering, Roman Mouginot, M.Sc.
Effect of thermal ageing on Alloys 690 and 52 in pressurized water reactor applications.
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The public examination of the doctoral dissertation of Roman Mouginot, M.Sc., will be held on 15 May 2017 at 12.15 at the Aalto University School of Engineering. The title of the dissertation is Effect of thermal ageing on Alloys 690 and 52 in pressurized water reactor applications.
The use of nickel-base alloys in modern nuclear power plants has greatly improved the structural integrity of key components as compared to stainless steels. However, long-term exposure to relatively high temperatures promotes changes in the microstructure of the materials that can increase their susceptibility to cracking and decrease the structural integrity of components. This phenomenon is known as thermal ageing of materials.
This study was focused on the effect of thermal ageing on nickel-base Alloys 690 and 52, which are key materials for critical components and welds. The work presented in the dissertation is part of a major research effort to characterize the long-term behavior of nickel-base alloys in nuclear power plants. Results showed that thermal ageing is susceptible to decrease the mechanical properties of Alloy 690 by triggering an atomic ordering reaction or by changing locally its microstructure. However, thermal ageing had a more beneficial effect on highly susceptible weld interfaces with Alloy 52 weld metal.
These results can help focus ongoing research on Alloy 690 on new potential degradation mechanisms, and they provide data on the long-term behavior of Alloy 52 welds that is directly beneficial to the Finnish nuclear industry.
Field of the dissertation is Materials Science and Engineering
Opponents: Professor Kai Nordlund, Helsinki University, Finland and Professor George A. Young, Dominion Engineering, USA
Supervisor: Professor Hannu Hänninen, Aalto University School of Engineering, Department of Mechanical Engineering
Electronic dissertation thesis: https://aaltodoc.aalto.fi/handle/123456789/25405
Contact information: Roman Mouginot, roman.mouginot@aalto.fi