Effect of heat treatment and cold work on the ordening of alloy 690 at 475 °C

Roman Mouginot, Sarikka, Mikko Heikkilä, Ulla Ehrnstén, Young Suk Kim, Soo Kim Sung, Hannu Hänninen

Research output: Contribution to conference › Conference article › Scientific

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 languageEnglish
Pages17
Publication statusPublished - 2015
Event17th 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

Conference17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015
Abbreviated titleENVDEG 2015
CountryCanada
CityOttawa
Period9/08/15 → 12/08/15

Fingerprint

heat treatment
contraction
hardness
pressurized water reactors
stress corrosion cracking
corrosion resistance
integrity
stoichiometry
lattice parameters
mechanical properties
heat
microstructure
scanning electron microscopy
diffraction
water
electrons
temperature

Keywords

  • alloy 690
  • thermal ageing
  • short-range ordering
  • Ni2Cr
  • cold work
  • thermal treatment

Cite this

Mouginot, R., Sarikka, Heikkilä, M., Ehrnstén, U., Kim, Y. S., Sung, S. K., & Hänninen, H. (2015). Effect of heat treatment and cold work on the ordening of alloy 690 at 475 °C. 17. Paper presented at 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015, Ottawa, Canada.
Mouginot, Roman ; Sarikka ; Heikkilä, Mikko ; Ehrnstén, Ulla ; Kim, Young Suk ; Sung, Soo Kim ; Hänninen, Hannu. / Effect of heat treatment and cold work on the ordening of alloy 690 at 475 °C. Paper presented at 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015, Ottawa, Canada.
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title = "Effect of heat treatment and cold work on the ordening of alloy 690 at 475 °C",
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.",
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author = "Roman Mouginot and Sarikka and Mikko Heikkil{\"a} and Ulla Ehrnst{\'e}n and Kim, {Young Suk} and Sung, {Soo Kim} and Hannu H{\"a}nninen",
note = "Project code: 102621 ; 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015, ENVDEG 2015 ; Conference date: 09-08-2015 Through 12-08-2015",
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Mouginot, R, Sarikka, Heikkilä, M, Ehrnstén, U, Kim, YS, Sung, SK & Hänninen, H 2015, 'Effect of heat treatment and cold work on the ordening of alloy 690 at 475 °C' Paper presented at 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015, Ottawa, Canada, 9/08/15 - 12/08/15, pp. 17.

Effect of heat treatment and cold work on the ordening of alloy 690 at 475 °C. / Mouginot, Roman; Sarikka; Heikkilä, Mikko; Ehrnstén, Ulla; Kim, Young Suk; Sung, Soo Kim; Hänninen, Hannu.

2015. 17 Paper presented at 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015, Ottawa, Canada.

Research output: Contribution to conference › Conference article › Scientific

TY - CONF

T1 - Effect of heat treatment and cold work on the ordening of alloy 690 at 475 °C

AU - Mouginot, Roman

AU - Sarikka, null

AU - Heikkilä, Mikko

AU - Ehrnstén, Ulla

AU - Kim, Young Suk

AU - Sung, Soo Kim

AU - Hänninen, Hannu

N1 - Project code: 102621

PY - 2015

Y1 - 2015

N2 - 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.

AB - 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.

KW - alloy 690

KW - thermal ageing

KW - short-range ordering

KW - Ni2Cr

KW - cold work

KW - thermal treatment

M3 - Conference article

SP - 17

ER -

Mouginot R, Sarikka, Heikkilä M, Ehrnstén U, Kim YS, Sung SK et al. Effect of heat treatment and cold work on the ordening of alloy 690 at 475 °C. 2015. Paper presented at 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015, Ottawa, Canada.