Understanding sigma-phase precipitation in a stabilized austenitic stainless steel (316Nb) through complementary CALPHAD-based and experimental investigations

Perron, Aurélien; Toffolon-Masclet, Caroline; Ledoux, Xavier; Buy, Frédéric; Guilbert, Thomas; Urvoy, Stéphane; Bosonnet, Sophie; Marini, B.; Cortial, F.; Texier, G.; Harder, Claus; Vignal, V.; Petit, P.E.; Farre, J.; Suzon, E.

doi:10.1016/j.actamat.2014.06.066

Cited by 54 publications

(22 citation statements)

References 32 publications

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“…As an example, A. Perron et al [34] have studied the influence of σ phase in a 316Nb austenitic stainless steel. They observed two different mechanisms of precipitation of sigma phase.…”

Section: Introductionmentioning

confidence: 99%

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Effect of the Temperature in the Mechanical Properties of Austenite, Ferrite and Sigma Phases of Duplex Stainless Steels Using Hardness, Microhardness and Nanoindentation Techniques

Argandoña¹,

Palacio

Berlanga

et al. 2017

Metals

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Abstract:The aim of this work is to study the hardness of the ferrite, austenite and sigma phases of a UNS S32760 superduplex stainless steel submitted to different thermal treatments, thus leading to different percentages of the mentioned phases. A comparative study has been performed in order to evaluate the resulting mechanical properties of these phases by using hardness, microhardness and nanoindentation techniques. In addition, optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been also used to identify their presence and distribution. Finally, the experimental results have shown that the resulting hardness values were increased as a function of a longer heat treatment duration which it is associated to the formation of a higher percentage of the sigma phase. However, nanoindentation hardness measurements of this sigma phase showed lower values than expected, being a combination of two main factors, namely the complexity of the sigma phase structure as well as the surface finish (roughness).

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“…As an example, A. Perron et al [34] have studied the influence of σ phase in a 316Nb austenitic stainless steel. They observed two different mechanisms of precipitation of sigma phase.…”

Section: Introductionmentioning

confidence: 99%

“…Another important aspect is that the kinetics of sigma phase's nucleation is very fast at 850 • C due to the eutectoid decomposition of the ferrite into sigma phase and secondary austenitic phase [29][30][31][32][33][34]. As an example, A. Perron et al [34] have studied the influence of σ phase in a 316Nb austenitic stainless steel.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Temperature in the Mechanical Properties of Austenite, Ferrite and Sigma Phases of Duplex Stainless Steels Using Hardness, Microhardness and Nanoindentation Techniques

Argandoña¹,

Palacio

Berlanga

et al. 2017

Metals

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“…Since the Sigma phase is stable in all four constituent ternaries [8,10,17] and has been frequently reported in the austenitic stainless steels, [2,3,[5][6][7]23] the experimental phase equilibrium data in literature can reasonably constrain the modeling of these end-members and interaction terms. The Chi phase has a bcc unit cell (space group I 143 m) containing 58 atoms and having a reported lattice parameter varying between 0.8807 and 0.892 nm [3,24] phase.…”

Section: ðYþ: ½2mentioning

confidence: 99%

“…A good understanding of the solubilities of Cr, Ni, and Mo in the Fe-rich facecentered cubic (fcc) matrix phase and the intermetallic phases is essential for making robust choices regarding alloy compositions and heat treatment parameters, and to ensure better microstructures and mechanical properties. While the stability of Sigma phase in austenitic stainless steels has been studied in depth recently, [5][6][7] the Chi and Laves phases are less investigated. The composition and temperature regions of stable Chi and Laves phases have been studied in constituent ternaries of the Fe-Cr-Mo, Fe-Mo-Ni, Fe-Cr-Ni, and Cr-Mo-Ni systems, [8][9][10][11][12][13] but knowledge on their stability in the quaternary Fe-Cr-Ni-Mo space is still lacking.…”

Section: Introductionmentioning

confidence: 98%

Thermal Stability of Intermetallic Phases in Fe-rich Fe-Cr-Ni-Mo Alloys

Yang

Tan

Busby

2015

Metall Mater Trans A

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Understanding the thermal stability of intermetallic phases in Fe-rich Fe-Cr-Ni-Mo alloys is critical to alloy design and application of Mo-containing austenitic steels. Coupled with thermodynamic modeling, the thermal stability of intermetallic Chi and Laves phases in two Fe-CrNi-Mo alloys was investigated at 1273 K, 1123 K, and 973 K (1000°C, 850°C, and 700°C) for different annealing times. The morphologies, compositions, and crystal structures of the precipitates of the intermetallic phases were carefully examined by scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and transmission electron microscopy. Two key findings resulted from this study. First, the Chi phase is stable at high temperature, and with the decreasing temperature it transforms into the Laves phase that is stable at low temperature. Secondly, Cr, Mo, and Ni are soluble in both the Chi and Laves phases, with the solubility of Mo playing a major role in the relative stability of the intermetallic phases. The thermodynamic models that were developed were then applied to evaluating the effect of Mo on the thermal stability of intermetallic phases in type 316 and NF709 stainless steels.

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“…More precisely, precipitation of r phase has been reported after aging in the temperature range from 773 K to 1173 K (500°C to 900°C). [1][2][3][4] 1138 K (865°C) has been identified as the most critical temperature for r phase formation [5] and certainly corresponds to the nose of the Time-Temperature-Transformation curve. Secondary M 23 C 6 carbides start precipitating below 1323 K (1050°C).…”

Section: Introductionmentioning

confidence: 99%

Isothermal and Cyclic Aging of 310S Austenitic Stainless Steel

Parrens

Lacaze

Malard

et al. 2017

Metall Mater Trans A

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. Unusual damage and high creep strain rates have been observed on components made of 310S stainless steel subjected to thermal cycles between room temperature and 1143 K (870°C). Microstructural characterization of such components after service evidenced high contents in sigma phase which formed first from d-ferrite and then from c-austenite. To get some insight into this microstructural evolution, isothermal and cyclic aging of 310S stainless steel has been studied experimentally and discussed on the basis of numerical simulations. The higher contents of sigma phase observed after cyclic agings than after isothermal treatments are clearly associated with nucleation triggered by thermal cycling.

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Understanding sigma-phase precipitation in a stabilized austenitic stainless steel (316Nb) through complementary CALPHAD-based and experimental investigations

Cited by 54 publications

References 32 publications

Effect of the Temperature in the Mechanical Properties of Austenite, Ferrite and Sigma Phases of Duplex Stainless Steels Using Hardness, Microhardness and Nanoindentation Techniques

Effect of the Temperature in the Mechanical Properties of Austenite, Ferrite and Sigma Phases of Duplex Stainless Steels Using Hardness, Microhardness and Nanoindentation Techniques

Thermal Stability of Intermetallic Phases in Fe-rich Fe-Cr-Ni-Mo Alloys

Isothermal and Cyclic Aging of 310S Austenitic Stainless Steel

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