Abstract
Alloy 690 was developed to improve the corrosion
resistance of components in nuclear power systems since
the 90s. Its composition is close to the Ni2Cr
stoichiometry which promotes an ordering reaction upon
ageing at temperatures below 550 °C with a maximum effect
at 475 °C. Atomic ordering promotes lattice contraction
and brittle intergranular fracture and reduces the
mechanical properties. It is a concern for the structural
integrity of Alloy 690 in modern pressurized water
reactors (PWR), especially considering the primary water
stress corrosion cracking (PWSCC) behavior. To assess the
effect of ageing time, cold work and thermal treatment on
the level of ordering of Alloy 690, four original
conditions (solution annealed, solution annealed and cold
rolled and/or heat-treated) were aged for up to 10 000 h
at 475 °C. The microstructures were characterized by
scanning electron microscopy (SEM) and electron
backscatter diffraction (EBSD), and the ordering levels
were assessed by hardness and lattice parameter
measurements. All conditions showed evidence of
short-range ordering. As compared to the solution
annealed condition, thermal treatment decreased the level
of ordering. Cold worked samples showed contradictory
results with reduced hardness increase but stronger
lattice contraction.
Original language | English |
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Pages | 17 |
Publication status | Published - 2015 |
Event | 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015 - Ottawa, Canada Duration: 9 Aug 2015 → 12 Aug 2015 |
Conference
Conference | 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015 |
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Abbreviated title | ENVDEG 2015 |
Country/Territory | Canada |
City | Ottawa |
Period | 9/08/15 → 12/08/15 |
Keywords
- alloy 690
- thermal ageing
- short-range ordering
- Ni2Cr
- cold work
- thermal treatment