Embrittlement of laboratory and reactor aged CF3,CF8, and CF8M duplex stainless steels

Chung, H.M.; Leax, T.R.

doi:10.1179/026708390790191170

Cited by 29 publications

(62 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Particles were found to be a few nanometers in diameter and to precipitate preferentially on dislocations, and sometimes also homogeneously in the ferritic phase. Since, other workers corroborated this result for other duplex stainless steel grades [3][4][5][6]. It nevertheless appears that G-phase was observed for the first time in ferritic steels by ALLSOP and BROWN in 1960, even if not identified as "G" but as "S"-phase [7].…”

mentioning

confidence: 70%

“…In addition, literature data on the actual composition of these particles, as well as on their number density and volume fraction, exhibit a very large scatter (see for example [2][3][4][5][6][7]9] [5]. For samples aged 30 000 hours at 400 ° C, which are going to be analyzed in this paper, they revealed extensive spinodal decomposition of the ironchromium solid solution and a large amount of G-phase precipitates.…”

mentioning

confidence: 98%

See 1 more Smart Citation

A 3D study of G-phase precipitation in spinodally decomposed α-ferrite by tomographic atom-probe analysis

Danoix¹,

Auger²,

Chambreland³

et al. 1994

Microsc. Microanal. Microstruct.

View full text Add to dashboard Cite

Abstract. 2014 The capabilities of the newly developed Tomographic Atom-Probe have been used to study G-phase precipitates in the ferritic phase of duplex stainless steels aged 30 000 hours at 400 °C. It is shown, on three dimensional reconstructions in real space, that G-phase particles form at the interface between the domains produced by the Fe-Cr spinodal decomposition, namely 03B1 (Fe-rich) and 03B1' (Cr-rich). Furthermore, thanks to the instrument very high spatial resolution, the complex internal morphology of these particles can be studied, in particular the partitioning of the various chemical species.

show abstract

mentioning

confidence: 70%

mentioning

confidence: 98%

A 3D study of G-phase precipitation in spinodally decomposed α-ferrite by tomographic atom-probe analysis

Danoix¹,

Auger²,

Chambreland³

et al. 1994

Microsc. Microanal. Microstruct.

View full text Add to dashboard Cite

show abstract

“…[1][2][3][4][5][6][7][8][9] The CASSs are one of the most important alloy groups in light water reactor (LWR) systems as only the casting technologies, i.e., static and centrifugal castings, enable the fabrication of such large components with proper resistance to environmental attacks. Many primary components experience both reactor coolant and radiation environments exposing to elevated temperatures, internal pressures, and corrosive environments.…”

Section: Introductionmentioning

confidence: 99%

“…Further, numerous aging experiments in the past have been performed at or above 400°C to investigate microstructural evolution and mechanical behaviors and to predict long-term CASS behaviors. [2][3][4][5][6][7][10][11][12][13][14][15][16][17][18][19][20][21][22] However, such highly-accelerated aging treatment above the operation temperature range is yet to be thoroughly validated for simulation of the lower temperature (300°C) phenomena in the current fleet of nuclear power plants. 9 The current consensus might be that, although the vast majority of the current nuclear power plants are expected to be operational for extended lifetimes of 60 years or potentially longer, 1 the behaviors of CASS alloys during such prolonged periods have remained largely unknown.…”

Section: Introductionmentioning

confidence: 99%

Thermal Aging Phenomena in Cast Duplex Stainless Steels

Byun

Yang

Overman

et al. 2015

JOM

View full text Add to dashboard Cite

Cast stainless steels (CASSs) have been extensively used for the large components of light water reactor (LWR) power plants such as primary coolant piping and pump casing. The thermal embrittlement of CASS components is one of the most serious concerns related to the extended-term operation of nuclear power plants. Many past researches have concluded that the formation of Cr-rich a¢-phase by Spinodal decomposition of d-ferrite phase is the primary mechanism for the thermal embrittlement. Cracking mechanism in the thermally-embrittled duplex stainless steels consists of the formation of cleavage at ferrite and its propagation via separation of ferrite-austenite interphase. This article intends to provide an introductory overview on the thermal aging phenomena in LWR-relevant conditions. Firstly, the thermal aging effect on toughness is discussed in terms of the cause of embrittlement and influential parameters. An approximate analysis of thermal reaction using Arrhenius equation was carried out to scope the aging temperatures for the accelerated aging experiments to simulate the 60 and 80 years of services. Further, an equilibrium precipitation calculation was performed for model CASS alloys using the CALPHAD program, and the results are used to describe the precipitation behaviors in duplex stainless steels. These results are also to be used to guide an on-going research aiming to provide knowledgebased conclusive prediction for the integrity of the CASS components of LWR power plants during the service life extended up to and beyond 60 years.

show abstract

“…G-phase forms two type of particles: big TEM visible particles along dislocation lines or in the matrix after long annealing at temperature higher than 400°C and small (few nanometers) TEM invisible particles [6,7]. These latter were shown to appear at the α/α' interface by Atom Probe Tomography (APT) [3,5,6]. …”

mentioning

confidence: 99%

Influence of Ni, Mo and Mn Content on the G-Phase Precipitation and Spinodal Decomposition of Aged Duplex Stainless Steels.

Badyka

Pareige

Saillet³

et al. 2017

Microsc Microanal

View full text Add to dashboard Cite

Duplex stainless steels (DSS) used in primary circuit of 2 nd generation nuclear power plant endure thermal ageing at service temperature (285°C-325°C). It has been known for a very long time that these steels are prone to thermal ageing. The ageing impacts the mechanical properties (toughness decreases and hardness increases). The evolution of the mechanical properties depends on the DSS composition [1][2][3][4]. Mo-free grades which also contain a smaller amount of nickel than Mo-bearing ones were shown to age less [1][2][3]5]. The ageing of DSS steels is attributed to the decomposition of the ferrite: spinodal decomposition into regions enriched in iron (α) and regions enriched in chromium (α') and precipitation of G-phase particles enriched in Ni, Si, Mn and Mo. G-phase forms two type of particles: big TEM visible particles along dislocation lines or in the matrix after long annealing at temperature higher than 400°C and small (few nanometers) TEM invisible particles [6,7]. These latter were shown to appear at the α/α' interface by Atom Probe Tomography (APT) [3,5,6].The intensity of G-phase precipitation is much higher in Mo-bearing DSS than in Mo-free steels (with less G-forming elements) [5,[8][9][10]. Also, spinodal decomposition was also shown to develop more importantly in Mo-bearing steels [3,9]. The literature [5,6,10] reports that the effective time exponent of the spinodal decomposition in Mo-bearing steels is close to n=0.16 as expected for spinodal decomposition [11]. In Mo-free steel, the effective time exponent was shown to be lower and equal to 0.07. The effective time exponent of phase transformation is strongly related to the diffusion mechanism and to vacancy path ways. Indeed, both interface diffusion [12] or mechanisms involving the diffusion of n-mers (small clusters) instead of monomers [13,14] are known to decrease time exponents. These diffusion mechanisms do not only influence development of spinodal decomposition but also the evolution kinetics of small G-phase precipitates. Indeed, the same effective time exponents were found for the evolution of the G-phase particle radius and the wavelength of the spinodal decomposition because of a kinetic synergy [5,9,15] between spinodal decomposition and G-phase precipitation. If the origin of these different effective time exponents is not understood yet, for sure it originates from the affinity between vacancies and solute species. Ni has been shown to accelerate kinetics of spinodal decomposition in Fe-Cr-Ni model alloys [16,17]. In a lesser extent, Mn was also shown to have a similar effect in Fe-Cr-Mn alloys [17]. But in that respect, it is worth noting that:-No kinetic study has been undertaken on these model alloys. Comparison of the microstructure was done at one aging time, one temperature. It is thus not known if kinetic enhancement is linked to an increase in the time constant A of the relationship =At n or in the time exponent i.e. if Ni or Mn contents can explain the difference in effective time exponent. -Only ternary alloys we...

show abstract

Embrittlement of laboratory and reactor aged CF3,CF8, and CF8M duplex stainless steels

Cited by 29 publications

References 2 publications

A 3D study of G-phase precipitation in spinodally decomposed α-ferrite by tomographic atom-probe analysis

A 3D study of G-phase precipitation in spinodally decomposed α-ferrite by tomographic atom-probe analysis

Thermal Aging Phenomena in Cast Duplex Stainless Steels

Influence of Ni, Mo and Mn Content on the G-Phase Precipitation and Spinodal Decomposition of Aged Duplex Stainless Steels.

Contact Info

Product

Resources

About