Abstract
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 language | English |
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Pages (from-to) | 56-66 |
Journal | Journal of Nuclear Materials |
Volume | 485 |
DOIs | |
Publication status | Published - 1 Mar 2017 |
MoE publication type | A1 Journal article-refereed |
Keywords
- Alloy 690
- Thermal ageing
- Short-range ordering
- Ni2Cr
- Carbide precipitation
- Cold work
- Strain localization
- Ni Cr