The Changing Role of Metastable Austenite in the Design of Alloys

Zackay, V.F.; Parker, E.R.

doi:10.1146/annurev.ms.06.080176.001035

Cited by 11 publications

(3 citation statements)

References 7 publications

(7 reference statements)

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“…S1 ). The stacking fault energy at room temperature (RT) is in the range of 5–15 mJ/m 2 in the austenitic structure 19 . The RT deformation is characterized by the sequential presence of stacking faults, ε-martensites and α-martensites.…”

Section: Resultsmentioning

confidence: 99%

Dislocation Strengthening without Ductility Trade-off in Metastable Austenitic Steels

Liu

Jin

Fang

et al. 2016

Sci RepHas erratum 2018-1-29 Has correction 2018-1-29

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Strength and ductility are mutually exclusive if they are manifested as consequence of the coupling between strengthening and toughening mechanisms. One notable example is dislocation strengthening in metals, which invariably leads to reduced ductility. However, this trend is averted in metastable austenitic steels. A one-step thermal mechanical treatment (TMT), i.e. hot rolling, can effectively enhance the yielding strength of the metastable austenitic steel from 322 ± 18 MPa to 675 ± 15 MPa, while retaining both the formability and hardenability. It is noted that no boundaries are introduced in the optimized TMT process and all strengthening effect originates from dislocations with inherited thermal stability. The success of this method relies on the decoupled strengthening and toughening mechanisms in metastable austenitic steels, in which yield strength is controlled by initial dislocation density while ductility is retained by the capability to nucleate new dislocations to carry plastic deformation. Especially, the simplicity in processing enables scaling and industrial applications to meet the challenging requirements of emissions reduction. On the other hand, the complexity in the underlying mechanism of dislocation strengthening in this case may shed light on a different route of material strengthening by stimulating dislocation activities, rather than impeding motion of dislocations.

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Section: Resultsmentioning

confidence: 99%

Dislocation Strengthening without Ductility Trade-off in Metastable Austenitic Steels

Liu

Jin

Fang

et al. 2016

Sci RepHas erratum 2018-1-29 Has correction 2018-1-29

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“…6,7,[12][13][14]21,[33][34][35]55). This austenite phase is very tough and break the continuity of brittle martensite phase.…”

Section: B Summary Of the Correlation Of Mechanical Properties With mentioning

confidence: 99%

Alloying and heat treatment optimization of Fe/Cr/C steels for improved mechanical properties

Sarıkaya¹

1979

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“…Being thermodynamically metastable, austenite retained at room temperature could decompose via either thermally-or mechanically-induced phase transformations. Such metastability has played a key role in controlling the strength and toughness in hypoeutectoid steels with carbon content less than 0.6 wt.%, for instance ausformed steels [1,2,3,4] and TRIP-assisted steels [4,5,6], whilst less has been explored on hypereutectoid steels.…”

Section: Introductionmentioning

confidence: 99%

Stability of retained austenite in martensitic high carbon steels. Part I: Thermal stability

Cui

Gintalas

Rivera-Dı́az-del-Castillo

2018

Materials Science and Engineering: A

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Thermal stability of retained austenite in 1C-1.5Cr steels with two Si and Mn contents is studied. Time-resolved high resolution synchrotron X-ray radiation and dilatometry are employed. The threshold transformation temperatures, decomposition kinetics, associated transformation strain, as well as the influence of Si and Mn were investigated. The coefficients of linear thermal expansion for both the bulk materials and individual phases are also obtained. The results indicate that an increase in the Mn and Si contents show little influence on the onset of retained austenite decomposition, but result in more thermally stable austenite. The decomposition is accompanied by a simultaneous increase in ferrite content which causes an expansive strain in the order of 10 −4 , and subsequent cementite development from 300-350 • C which causes a contraction that helps to neutralise the expansive strain. During decomposition, a continuous increase in the carbon content of austenite, and a reduction in that of the tempered-martensite/ferrite phase was observed. This process continued at elevated temperatures until full decomposition was reached, which could take less than an hour at a heating rate of 0.05 • C/s. Additionally, the observation of austenite peak splitting on samples with high Mn and Si contents suggests the existence of austenite of different stabilities in such matrix.

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The Changing Role of Metastable Austenite in the Design of Alloys

Cited by 11 publications

References 7 publications

Dislocation Strengthening without Ductility Trade-off in Metastable Austenitic Steels

Dislocation Strengthening without Ductility Trade-off in Metastable Austenitic Steels

Alloying and heat treatment optimization of Fe/Cr/C steels for improved mechanical properties

Stability of retained austenite in martensitic high carbon steels. Part I: Thermal stability

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