A Thermodynamic Study of a Constitutional Diagram for Duplex Stainless Steels

Brandi, Sérgio Duarte; Schön, Cláudio Geraldo

doi:10.1007/s11669-017-0537-8

Cited by 13 publications

(6 citation statements)

References 3 publications

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“…The phase-type prediction can then be accessed via the phase field boundary of a specific phase in a certain multi-element phase diagram. Schaeffler diagram is found to approximately agree with isothermal Fe-Cr-Ni phase diagrams covering austenite and ferrite zones 27 . This is why we interpreted the equivalent coefficient of certain alloying element as the slope of the phase field boundary line relative to that of the major alloying element, as exemplified in Mo equivalent for β-Ti alloys 28 .…”

Section: Referencesmentioning

confidence: 63%

“…The most important concept in prevailing equivalent method is that the contribution of a certain element is only related to its content (i.e., the slope of boundary line depends on its given composition) but independent of the presence of other alloying elements (i.e., the expansion and shrinkage of phase boundaries caused by any other alloying element are ignored). It is also the fundamental concept in our equivalent method and has been proved by Brandi 27 through thermodynamic calculation. This concept is justified for classical alloys which are mostly terminal solid solutions; it may not hold for high entropy alloys in which interactions among alloying elements cannot be ignored.…”

Section: Introductionmentioning

confidence: 91%

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Composition equivalents of stainless steels understood via gamma stabilizing efficiency

Zhang

Wang

Yang

et al. 2021

Sci Rep

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The phase-type of a stainless steel is generally predicted by equivalent equations in terms of a major austenitic (γ) or ferritic (α) stabilizer Ni or Cr. The present paper attempts to understand the equivalent methods in stainless steels via the slopes of the phase boundary lines separating γ and γ + α phase zones. The prevailing equivalent coefficients are well interpreted using the slope ratios of the alloying elements divided by that of Ni or Cr, after analyzing over one hundred common stainless steels. Different from traditional composition equivalents which evaluate γ stabilizers and α stabilizers separately; the new equivalent scheme provides a unified phase stabilizing parameter for all alloying elements in stainless steels. This parameter is defined as γ stabilizing efficiency. Its negative or positive sign indicates γ stabilizer or α stabilizer, and its value represents the stabilizing efficiency.

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Section: Referencesmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 91%

Composition equivalents of stainless steels understood via gamma stabilizing efficiency

Zhang

Wang

Yang

et al. 2021

Sci Rep

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“…A set of thermodynamic calculations with the software Thermo-calc R (TC) was performed using the SGTE 1 Solid Solution 2.0 database (SSOL2). As discussed in a previous work by one of the authors [70], this is an old database, but it still can be considered reliable for the application to stainless steels. In order to perform the calculations, the system was approximated by a subset of this database corresponding to system Fe -C -Cr -Ni -Mn -Si -Nb and the A1 FCC, A2 BCC, LIQUID, M 23 C 6 and SIGMA phases.…”

Section: Thermodynamic Calculationsmentioning

confidence: 99%

Thermodynamics of an austenitic stainless steel (AISI-348) under in situ TEM heavy ion irradiation

et al. 2019

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The stability of the face-centred cubic austenite (γ-Fe) phase in a commercial stainless steel (AISI-348) was investigated through in situ transmission electron microscopy (TEM) with heavy ion irradiation at 1073 K up to a fluence of 1.3×10 17 ions•cm −2 (corresponding to a dose of 46 dpa). The γ-Fe phase was observed to decompose at a fluence of around 7.8×10 15 ions•cm −2 (3 dpa) when a new phase nucleated and grew upon increasing irradiation dose. Scanning transmission electron microscopy (STEM) with energy dispersive X-ray (EDX) spectroscopy and multivariate statistical analysis (MVSA) were used to characterise the irradiated specimens. The combination of such experimental techniques with calculated equilibrium phase diagrams using the CALPHAD method led to the conclusion that the new phase formed upon irradiation is the body-centred cubic Cr-rich α phase. At the nanoscale, precipitation of M 23 C 6 (τ-carbide) was also observed. The results indicate that ion irradiation can assist the austenitic stainless steel to reach a non-equilibrium state similar to a calculated equilibrium state observed at lower temperatures in which, under conventional conditions, is suppressed due to kinetic restrictions.

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“…These diagrams do not include the effect of tungsten and nitrogen which is very important in terms of newly developed super duplex, hyper duplex DSS [21]. Brandi and Schön [22] recently calculated the effect of tungsten and nitrogen based on thermodynamic calculation and suggested that prefactor of 0.5 for tungsten and calculated nitrogen prefactor as high as 50 but due to inaccuracy of the calculation, they recommended the same prefactor to be 30. Also, they recommended that for intermetallic precipitation, the proper thermodynamic calculation needs to be done for better prediction of phase.…”

Section: Effect Of Chemical Composition In Dssmentioning

confidence: 99%

Characteristics and Manufacturability of Duplex Stainless Steel: A Review

Patra

Agrawal²,

Mandal

et al. 2021

Trans Indian Inst Met

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Duplex stainless steels (DSS) have been growing continuously as they are cost effective alternative to austenitic stainless steel with better mechanical and corrosion resistance. Duplex stainless steel compositions are expanding in both directions towards leaner and richer chemistry for popular as well as very critical applications. The strength of DSS is its high yield strength compared to popular austenitic series and corrosion resistance particularly pitting and chloride stress corrosion cracking. Challenges of DSS remain in the embrittlement phase formation during the manufacturing of highly alloyed DSS, hot cracking and formability of the steel. Super duplex and hyper duplex steels are finding extremely critical application due to their good mechanical properties and corrosion resistance even replacing Nickel based alloys and Ti alloys in few applications. The paper reviews the characteristics and manufacturability of duplex stainless steel including recent developments.

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A Thermodynamic Study of a Constitutional Diagram for Duplex Stainless Steels

Cited by 13 publications

References 3 publications

Composition equivalents of stainless steels understood via gamma stabilizing efficiency

Composition equivalents of stainless steels understood via gamma stabilizing efficiency

Thermodynamics of an austenitic stainless steel (AISI-348) under in situ TEM heavy ion irradiation

Characteristics and Manufacturability of Duplex Stainless Steel: A Review

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