TEM examination of the effect of post-irradiation annealing on 7.7 dpa AISI 304 stainless steel

Wade Karlsen, Mykola Ivanchenko, Janne Pakarinen, Torill Karlsen

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

    Abstract

    Analytical transmission electron microscopy (ATEM) was used to examine the effect of post-irradiation annealing (PIA) on radiation-induced segregation (RIS) at the grain boundaries of 7.7 dpa AISI 304 stainless steel. The grain boundary profiles and the irradiation damage were analysed in the as-irradiated state and after PIA of 6 hours at 500 °C and after 25 hours at 500°C and 550°C by using transmission electron microscopy (TEM). As a main conclusion from the TEM examinations, the effects of PIA were found to be relatively small after only 6 hours, while after 25 hours of PIA at both 500 and 550°C, RIS was almost recovered and only marginal deviation in chemical composition could be found near the GB. The as-irradiated state showed extreme RIS values of Si 4.9 wt%, Cr 14.7 wt%, Ni 23.4 wt%, and P 1.4 wt%., while upon PIA for 6 hours the extreme values for RIS were Si 3.9 wt%, Cr 16.0 wt%, Ni 21 wt%, and P 0.9 wt%. After 6 hours annealing at 500°C dislocation loops start to grow, while dislocation density remains of the same order of magnitude. After annealing for 25 hours at 500°C the average size of dislocation loops remains nearly the same, while dislocation density was reduced almost by one fold. In the areas where dislocation density was found to be the lowest some features, which can most likely be attributed to stacking fault tetrahedral (SFT) were found. Annealing at even higher temperature (550°C) affected the average size of the dislocation loops, making them almost twice as large as well as resulting in a very broad distribution of dislocation sizes. Density of dislocations is also reduced by one fold in comparison to the as irradiated condition and leads to formation of SFT's, which could be consistently found in the specimen. None of the applied PIA treatments had caused formation of voids.
    Original languageEnglish
    Title of host publicationProceedings of Fontevraud 8
    Number of pages11
    Publication statusPublished - 2014
    MoE publication typeA4 Article in a conference publication
    EventFontevraud 8: Conference on Contribution of Materials Investigations and Operating Experience to LWRs' Safety, Performance and Reliability - Avignon, France
    Duration: 15 Sep 201418 Sep 2014

    Conference

    ConferenceFontevraud 8
    CountryFrance
    CityAvignon
    Period15/09/1418/09/14

    Keywords

    • transmission electron microscopy
    • radiation induced segregation
    • post irradiation annealing

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