Thermal ageing and short-range ordering of Alloy 690 between 350 and 550 °C

Roman Mouginot, Teemu Sarikka, Mikko Heikkilä, Mykola Ivanchenko, Ulla Ehrnstén, Young Suk Kim, Soo Kimsung, Hannu Hänninen

    Research output: Contribution to journalArticleScientificpeer-review

    23 Citations (Scopus)


    Thermal ageing of Alloy 690 triggers an intergranular (IG) carbide precipitation and is known to promote an ordering reaction causing lattice contraction. It may affect the long-term primary water stress corrosion cracking (PWSCC) resistance of pressurized water reactor (PWR) components. Four conditions of Alloy 690 (solution annealed, cold-rolled and/or heat-treated) were aged between 350 and 550 °C for 10 000 h and characterized. Although no direct observation of ordering was made, variations in hardness and lattice parameter were attributed to the formation of short-range ordering (SRO) in all conditions with a peak level at 420 °C, consistent with the literature. Prior heat treatment induced ordering before thermal ageing. At higher temperatures, stress relaxation, recrystallization and ?-Cr precipitation were observed in the cold-worked samples, while a disordering reaction was inferred in all samples based on a decrease in hardness. IG precipitation of M23C6 carbides increased with increasing ageing temperature in all conditions, as well as diffusion-induced grain boundary migration (DIGM).
    Original languageEnglish
    Pages (from-to)56-66
    JournalJournal of Nuclear Materials
    Publication statusPublished - 1 Mar 2017
    MoE publication typeA1 Journal article-refereed


    • Alloy 690
    • Thermal ageing
    • Short-range ordering
    • Ni2Cr
    • Carbide precipitation
    • Cold work
    • Strain localization
    • Ni Cr


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