View in EDS

Long-Term Stability and Resulting Viscoplastic Behavior of Alloy 625 at 700 °C.

Saved in:
Bibliographic Details
Title: Long-Term Stability and Resulting Viscoplastic Behavior of Alloy 625 at 700 °C.
Authors: Machado Alves da Fonseca, Fabio1 (AUTHOR) fabiofonseca.meta@gmail.com, Rame, Jérémy1 (AUTHOR) j.rame@naarea.fr, Rousseau, Camille1 (AUTHOR), Burlot, Guillaume2,3 (AUTHOR), Cormier, Jonathan2 (AUTHOR) jonathan.cormier@ensma.fr
Source: Metallurgical & Materials Transactions. Part A. May2026, Vol. 57 Issue 5, p1990-2000. 11p.
Subjects: Viscoplasticity, Microstructure, Stress relaxation tests, Durability, Heat treatment, Inconel, Strains & stresses (Mechanics), Nickel alloys
Abstract: Alloy 625 is a mature Ni-based superalloy widely used in the aerospace and chemical industries, but its qualification for nuclear applications requires a better understanding of its long-term stability and viscoplastic behavior (i.e., time-dependent deformation). This study investigates the effect of thermal aging at 700 °C (100, 1000, 2664, and 4107 hours) on the microstructural evolution and the resulting creep and stress relaxation behavior of Alloy 625. Microstructural analyses revealed an initial state without detectable precipitates; with increasing aging time at 700 °C, progressive precipitation of strengthening γ″ (Ni3Nb, D022) occurred. With further exposure (> 1000 hours), γ″ progressively transforms into δ phase (Ni3Nb, D0a), strongly influenced by Nb/Mo chemical segregation, while Nb/Mo-rich carbides slightly coarsened at grain boundaries. Mechanical testing (tensile, creep and stress relaxation) demonstrated that short-term aging (100 hours) improves viscoplastic resistance through γ″ hardening, whereas prolonged exposure leads to a two-order-of-magnitude increase in strain rate at 300 MPa, reflecting reduced viscoplastic resistance due to δ formation at the expanse of γ″ particles. Despite this degradation, Alloy 625 retained high creep ductility (> 40 pct) under all conditions, and segregation bands did not significantly affect monotonic creep performance. Stress relaxation tests provided consistent trends with creep once internal stresses were relieved, offering an efficient means to identify viscoplastic parameters. Overall, these results clarify the link between microstructural transformations and viscoplastic behavior in Alloy 625, support its assessment for nuclear service at 700 °C, and provide a basis for the development of microstructure-sensitive constitutive models. [ABSTRACT FROM AUTHOR]
Copyright of Metallurgical & Materials Transactions. Part A is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
FullText Text:
  Availability: 0
Header DbId: egs
DbLabel: Engineering Source
An: 193084947
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
PreciseRelevancyScore: 0
IllustrationInfo
Items – Name: Title
  Label: Title
  Group: Ti
  Data: Long-Term Stability and Resulting Viscoplastic Behavior of Alloy 625 at 700 °C.
– Name: Author
  Label: Authors
  Group: Au
  Data: <searchLink fieldCode="AR" term="%22Machado+Alves+da+Fonseca%2C+Fabio%22">Machado Alves da Fonseca, Fabio</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> fabiofonseca.meta@gmail.com</i><br /><searchLink fieldCode="AR" term="%22Rame%2C+Jérémy%22">Rame, Jérémy</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> j.rame@naarea.fr</i><br /><searchLink fieldCode="AR" term="%22Rousseau%2C+Camille%22">Rousseau, Camille</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Burlot%2C+Guillaume%22">Burlot, Guillaume</searchLink><relatesTo>2,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Cormier%2C+Jonathan%22">Cormier, Jonathan</searchLink><relatesTo>2</relatesTo> (AUTHOR)<i> jonathan.cormier@ensma.fr</i>
– Name: TitleSource
  Label: Source
  Group: Src
  Data: <searchLink fieldCode="JN" term="%22Metallurgical+%26+Materials+Transactions%2E+Part+A%22">Metallurgical & Materials Transactions. Part A</searchLink>. May2026, Vol. 57 Issue 5, p1990-2000. 11p.
– Name: Subject
  Label: Subjects
  Group: Su
  Data: <searchLink fieldCode="DE" term="%22Viscoplasticity%22">Viscoplasticity</searchLink><br /><searchLink fieldCode="DE" term="%22Microstructure%22">Microstructure</searchLink><br /><searchLink fieldCode="DE" term="%22Stress+relaxation+tests%22">Stress relaxation tests</searchLink><br /><searchLink fieldCode="DE" term="%22Durability%22">Durability</searchLink><br /><searchLink fieldCode="DE" term="%22Heat+treatment%22">Heat treatment</searchLink><br /><searchLink fieldCode="DE" term="%22Inconel%22">Inconel</searchLink><br /><searchLink fieldCode="DE" term="%22Strains+%26+stresses+%28Mechanics%29%22">Strains & stresses (Mechanics)</searchLink><br /><searchLink fieldCode="DE" term="%22Nickel+alloys%22">Nickel alloys</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Alloy 625 is a mature Ni-based superalloy widely used in the aerospace and chemical industries, but its qualification for nuclear applications requires a better understanding of its long-term stability and viscoplastic behavior (i.e., time-dependent deformation). This study investigates the effect of thermal aging at 700 °C (100, 1000, 2664, and 4107 hours) on the microstructural evolution and the resulting creep and stress relaxation behavior of Alloy 625. Microstructural analyses revealed an initial state without detectable precipitates; with increasing aging time at 700 °C, progressive precipitation of strengthening γ″ (Ni3Nb, D022) occurred. With further exposure (> 1000 hours), γ″ progressively transforms into δ phase (Ni3Nb, D0a), strongly influenced by Nb/Mo chemical segregation, while Nb/Mo-rich carbides slightly coarsened at grain boundaries. Mechanical testing (tensile, creep and stress relaxation) demonstrated that short-term aging (100 hours) improves viscoplastic resistance through γ″ hardening, whereas prolonged exposure leads to a two-order-of-magnitude increase in strain rate at 300 MPa, reflecting reduced viscoplastic resistance due to δ formation at the expanse of γ″ particles. Despite this degradation, Alloy 625 retained high creep ductility (> 40 pct) under all conditions, and segregation bands did not significantly affect monotonic creep performance. Stress relaxation tests provided consistent trends with creep once internal stresses were relieved, offering an efficient means to identify viscoplastic parameters. Overall, these results clarify the link between microstructural transformations and viscoplastic behavior in Alloy 625, support its assessment for nuclear service at 700 °C, and provide a basis for the development of microstructure-sensitive constitutive models. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Metallurgical & Materials Transactions. Part A is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
PLink https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=egs&AN=193084947
RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.1007/s11661-025-08043-5
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 11
        StartPage: 1990
    Subjects:
      – SubjectFull: Viscoplasticity
        Type: general
      – SubjectFull: Microstructure
        Type: general
      – SubjectFull: Stress relaxation tests
        Type: general
      – SubjectFull: Durability
        Type: general
      – SubjectFull: Heat treatment
        Type: general
      – SubjectFull: Inconel
        Type: general
      – SubjectFull: Strains & stresses (Mechanics)
        Type: general
      – SubjectFull: Nickel alloys
        Type: general
    Titles:
      – TitleFull: Long-Term Stability and Resulting Viscoplastic Behavior of Alloy 625 at 700 °C.
        Type: main
  BibRelationships:
    HasContributorRelationships:
      – PersonEntity:
          Name:
            NameFull: Machado Alves da Fonseca, Fabio
      – PersonEntity:
          Name:
            NameFull: Rame, Jérémy
      – PersonEntity:
          Name:
            NameFull: Rousseau, Camille
      – PersonEntity:
          Name:
            NameFull: Burlot, Guillaume
      – PersonEntity:
          Name:
            NameFull: Cormier, Jonathan
    IsPartOfRelationships:
      – BibEntity:
          Dates:
            – D: 01
              M: 05
              Text: May2026
              Type: published
              Y: 2026
          Identifiers:
            – Type: issn-print
              Value: 10735623
          Numbering:
            – Type: volume
              Value: 57
            – Type: issue
              Value: 5
          Titles:
            – TitleFull: Metallurgical & Materials Transactions. Part A
              Type: main
ResultId 1