Effect of thermal aging on microstructure and hardness of industrial heats of Alloy 690

Caitlin Huotilainen, Ulla Ehrnstén, Matias Ahonen, Hannu Hänninen

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

Alloy 690 is a high-chromium nickel-base alloy used in various primary coolant system components and for steam generator tubes in many nuclear power plants. A thermal treatment is typically applied for Alloy 690 components, giving the material a better resistance to stress corrosion cracking, compared to mill-annealed condition, due to fine grain boundary carbides of type M23C6. The effect of thermal aging at 400 C was investigated in four different heats of Alloy 690. After 5000 h and 10 000 h of aging, one of the materials showed a significant increase in hardness, whereas the three other heats did not show a measurable effect of aging. Microstructural and hardness characterizations were performed, on both initial and aged material, by applying optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, microhardness and nanoindentation measurements, in order to study the microstructural features causing the observed increase in hardness.

Original languageEnglish
Title of host publication19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors
PublisherAmerican Nuclear Society (ANS)
Pages156-164
Number of pages9
ISBN (Electronic)978-0-89448-765-1
Publication statusPublished - 2019
MoE publication typeA4 Article in a conference publication
Event19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, EnvDeg 2019 - Boston, United States
Duration: 18 Aug 201922 Aug 2019

Conference

Conference19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, EnvDeg 2019
Abbreviated titleENVDEG 2019
CountryUnited States
CityBoston
Period18/08/1922/08/19

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