Väitös materiaalitekniikan alalta, Roman Mouginot, M.Sc.
Effect of thermal ageing on Alloys 690 and 52 in pressurized water reactor applications.
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Roman Mouginot, M.Sc., väittelee 15.5.2015 klo 12.15 Aalto-yliopiston insinööritieteiden laitoksella, aiheesta Effect of thermal ageing on Alloys 690 and 52 in pressurized water reactor applications. Väitöskirjan ala on materiaalitekniikka.
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.
Vastaväittäjät: Professori Kai Nordlund, Helsingin yliopisto ja professori George A. Young, Dominion Engineering, USA
Valvoja: Professori Hannu Hänninen, Aalto-yliopisto, konetekniikan laitos
Väitöskirjan verkko-osoite: https://aaltodoc.aalto.fi/handle/123456789/25405
Väittelijän yhteystiedot: Roman Mouginot, roman.mouginot@aalto.fi