Austenite stability and heterogeneous deformation in fine-grained transformation-induced plasticity-assisted steel

Ryu, Jungho; Kim, Jeong In; Kim, Hyoung Seop; Oh, Chang Woo; Bhadeshia, H. K. D. H.; Suh, Dong‐Woo

doi:10.1016/j.scriptamat.2013.02.026

Cited by 97 publications

(15 citation statements)

References 23 publications

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“…So far, the PLC effect in medium-manganese TRIP steels has not been characterized in detail. Only a few publications concerning plastic instability phenomenon in these steels are available in the literature [6,13,[40][41][42][43][44]. The explanation of the DSA mechanism in medium-manganese steels showing the Transformation-Induced-Plasticity effect is a complex issue because of their microstructure consisting of several phases, as well as the TRIP effect exhibited by these steels.…”

Section: Effect Of Transformation-induced Plasticity (Trip) On Plastimentioning

confidence: 99%

“…Ryu et al [42] found that the localized strain triggered by Lüders band may cause the austenite transformation into martensite. PLC bands are a form of strain localization, in which the metastable austenite grains have good conditions to martensitic transformation because of the severe strain [6,42,44]. However, strain-induced martensite acts as obstacles for propagation of PLC bands.…”

Section: Effect Of Transformation-induced Plasticity (Trip) On Plastimentioning

confidence: 99%

“…However, some processing factors could trigger the PLC effect in hot-rolled medium-manganese steels. It was reported [42] that the time and temperature of isothermal holding in an intercritical region affect the appearance of the plastic instability effect.…”

Section: Hot-rolled Medium-mn Steelsmentioning

confidence: 99%

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Explanation of the PLC Effect in Advanced High-Strength Medium-Mn Steels. A Review

et al. 2019

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The paper reviews the recent works concerning the Portevin-Le Chatelier (PLC) effect in Advanced High-Strength Steels (AHSSs) with a special attention to high-strength medium-manganese steels. Theories explaining the mechanism of the plastic instability phenomenon in steels with medium-and high-Mn contents were discussed. The relationships between microstructural effects such as TRIP (Transformation-Induced Plasticity), TWIP (Twinning-Induced Plasticity) and the PLC effect were characterized. The effects of processing conditions including a deformation state (hot-rolled and cold-rolled) and strain parameters (deformation temperature, strain rate) were addressed. Factors affecting the value of critical strain for the activation of serrated flow behavior in particular in medium-manganese steels were described.The explanation of the Portevin-Le Chatelier mechanism in medium-Mn steels showing the TRIP effect is a complicated issue because of their microstructure consisting of several phases, as well as the TRIP effect exhibited by these steels. The exact characteristics of the factors affecting the PLC effect in AHSS is very important, both from a research point of view and their industrial implementation. This overview concerns the PLC phenomenon in Advanced High Strength Steels (AHSSs), with particular emphasis on advanced medium-Mn TRIP steels. The Nature of PLC Effect in SteelsThe plastic instability phenomenon occurring during the deformation of metallic materials shows two most common forms of propagative bands: Lüders and Portevin-Le Chatelier bands. The Lüders bands refer to the regions of localized strain. They form immediately after the onset of plastic deformation from the yield point drop, followed to a dominant stage of the stress plateau stage. Lüders bands are commonly caused by static strain aging (SSA) [13]. Static strain aging is characterized by an increase in strength properties associated with a decrease in plasticity. The PLC bands are represented by characteristic serrations on stress-strain curves. PLC bands are usually related to the dynamic strain aging (DSA) effect. The occurrence of the PLC bands is much more erratic, and can be observed in various forms (serration types) in comparison to the Lüders bands.There are several theories which explain the PLC effect in metallic materials. However, none has been so far clearly confirmed. The first interpretation of this phenomenon was proposed by Cottrell [1]. From his point of view, the PLC effect is related to the interactions between solute atoms, such as C or N, and mobile dislocations. The presence of serrations on a tensile curve is associated with the rapid release of dislocations from the atmospheres of dissolved atoms, which block their movement. This model is based on the assumption that atmospheres are formed around dislocations due to volume diffusion. In the presence of substitution atoms, diffusion is facilitated by vacancies resulting from plastic deformation. The interstitial gaps located in the vicinity of the dislocation are enl...

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Section: Effect Of Transformation-induced Plasticity (Trip) On Plastimentioning

confidence: 99%

Section: Effect Of Transformation-induced Plasticity (Trip) On Plastimentioning

confidence: 99%

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Explanation of the PLC Effect in Advanced High-Strength Medium-Mn Steels. A Review

et al. 2019

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“…Apart from the poor thermal stability, the austenite possessed deteriorated mechanical stability as well. The stress-induced martensite transformation might take place during elastic deformation and austenite transforms into martensite rapidly during plastic deformation [27,54], which was indicated by the extremely high strain-hardening rate.…”

Section: Influence Of Intercritical Annealing Temperature On Microstrmentioning

confidence: 99%

Influence of Intercritical Annealing Temperature on Microstructure and Mechanical Properties of a Cold-Rolled Medium-Mn Steel

Song

Zhou

et al. 2018

Metals

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Medium-Mn steels are characterized by ultrafine-grained (UFG) duplex microstructure consisting of ferrite and a large amount of retained austenite. Intercritical annealing is of great importance to achieving the UFG duplex microstructure and adjusting amount as well as stability of retained austenite. In the present work, the influence of intercritical annealing temperature on the microstructure and mechanical properties was investigated in a cold-rolled medium-Mn steel Fe-12Mn-3Al-0.05C. Particularly, the dependence of microstructural morphology on intercritical annealing temperature was emphasized to reveal the genesis of the microstructural morphology in medium-Mn steels. The ferrite-austenite duplex microstructure manifested an elongated morphology in the specimen annealed at 555 • C, which inherited the lath structure of the cold-rolled state. The medium-Mn steel exhibited a continuous yielding behavior and a relatively low strain-hardening rate. With an increase in intercritical annealing temperature up to 650 • C, the amount of retained austenite increased and microstructure was partially recrystallized, showing a mixture of elongated and equiaxed grain morphologies. When the intercritical annealing was applied at 700 • C, the medium-Mn steel mainly exhibited recrystallized microstructure with equiaxed morphology. The optimal balance between the amount and the stability of retained austenite led to an enhancement of strain hardening and ductility. With a further increase in the intercritical annealing temperature to 750 • C, the medium-Mn steel possessed pronounced strain-hardening behavior at the beginning of the tensile deformation with deteriorated ductility.

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“…The PLC bands are a kind of strain localization, in which unstable austenite grains transform to martensite, due to the severe strain. However, the newly formed strain-induced martensite acts as obstacles for the propagation of PLC bands [29,30]. Sun et al [31] noticed the localized martensite transformation occurring in the PLC areas, which spread during deformation.…”

Section: -Mean Value Of the Strain Period Between Successive Oscillamentioning

confidence: 99%

Analysis of Plastic Deformation Instabilities at Elevated Temperatures in Hot-Rolled Medium-Mn Steel

et al. 2019

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The study addressed the microstructure and mechanical properties of hot-rolled advanced high-strength medium manganese steel. Some of the curves that were obtained in static tensile tests at deformation temperatures of 20–200 °C showed the occurrence of the heterogeneous plastic deformation phenomenon, called the Portevin-Le Chatelier (PLC) effect. The deformation temperature significantly influenced a serration character. The correlations between the deformation temperature, serration range, microstructural features, and fracture behavior were investigated. The curves showed no Lüders elongation as a result of the thermomechanical processing applied. The serrated flow phenomenon was observed at 60 and 140 °C. The serration type was different and the most enhanced at 140 °C, where the PLC effect was present in both uniform and post-uniform elongation ranges. The disappearance of serrations at 200 °C was related to the increased diffusion intensity.

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Austenite stability and heterogeneous deformation in fine-grained transformation-induced plasticity-assisted steel

Cited by 97 publications

References 23 publications

Explanation of the PLC Effect in Advanced High-Strength Medium-Mn Steels. A Review

Explanation of the PLC Effect in Advanced High-Strength Medium-Mn Steels. A Review

Influence of Intercritical Annealing Temperature on Microstructure and Mechanical Properties of a Cold-Rolled Medium-Mn Steel

Analysis of Plastic Deformation Instabilities at Elevated Temperatures in Hot-Rolled Medium-Mn Steel

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