Stability of Retained Austenite in High-Al, Low-Si TRIP-Assisted Steels Processed via Continuous Galvanizing Heat Treatments

McDermid, Joseph R.; Zurob, Hatem S.; Bian, Yankui

doi:10.1007/s11661-011-0678-z

Cited by 36 publications

(26 citation statements)

References 35 publications

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“…Recently, McDermid et al [36] showed that while the strain-based model (Eq. 4, [12]) could successfully describe the kinetics of the RA to martensite transformation, a simple normalised plastic flow stress model (Eq.…”

Section: Factors Affecting the Retained Austenite Stabilitymentioning

confidence: 99%

Retained Austenite: Transformation-Induced Plasticity

Pereloma¹,

Gazder²,

Timokhina³

2016

Encyclopedia of Iron, Steel, and Their Alloys

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The deformation-induced phase transformation of metastable austenite to martensite is accompanied by macroscopic plastic strain and results in significant work hardening and the delayed onset of necking. Steels that exhibit such transformation-induced plasticity (TRIP) effect possess high strength-ductility ratios and improved toughness. Since the stability of the retained austenite (RA) phase is the rate controlling mechanism for the TRIP effect, the factors affecting the chemical and mechanical stability of RA in CMnSi TRIP steels are discussed. It was suggested that chemical stability plays a more important role at low strains, whereas other factors become responsible for RA behavior at higher strains. The importance of optimizing the processing parameters to achieve the desirable level of austenite stability is highlighted. Finally, the influence of mechanical testing conditions and the interaction between the phases during tensile testing are also detailed. ABSTRACTThe deformation-induced phase transformation of metastable austenite to martensite is accompanied by macroscopic plastic strain and results in significant work hardening and the delayed onset of necking. Steels that exhibit such transformation-induced plasticity (TRIP) effect possess high strength-ductility ratios and improved toughness. Since the stability of the retained austenite phase is the rate controlling mechanism for the TRIP effect, the factors affecting the chemical and mechanical stability of retained austenite in CMnSi TRIP steels are discussed. It was suggested that chemical stability plays a more important role at low strains, whereas other factors become responsible for the RA behavior at higher strains. The importance of optimising the processing parameters to achieve the desirable level of austenite stability was highlighted. Finally, the influence of mechanical testing conditions and the interaction between the phases during tensile testing are also detailed.Eds. R. Colás and G. E. Totten, chapter TRIP effect and retained austenite stability in steels 2

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Section: Factors Affecting the Retained Austenite Stabilitymentioning

confidence: 99%

Retained Austenite: Transformation-Induced Plasticity

Pereloma¹,

Gazder²,

Timokhina³

2016

Encyclopedia of Iron, Steel, and Their Alloys

View full text Add to dashboard Cite

show abstract

“…Two different forms of retained austenite are described in the literature. On the one hand, film‐like retained austenite between the martensite lathes (interlathe film), respectively, between the bainitic lathes, and, on the other, grains of retained austenite . After the employed heat treatments, retained austenite mainly exists as polygonal shaped grains.…”

Section: Discussionmentioning

confidence: 99%

“…Like in the work of Santofimia et al, the grains of retained austenite were particularly observed between primary martensite and ferrite or secondary martensite and ferrite. In TRIP steels, retained austenite occurs in a similar way, isolated or granular surrounded by ferrite or bainite or at their grain boundaries . A film‐like formation between the bainite lathes is also known.…”

Section: Discussionmentioning

confidence: 99%

“…Specifically, quenching‐and‐partitioning heat treatments (Q&P heat treatments) also enable certain fractions of retained austenite to be stabilized in the microstructure. Due to the transformation of retained austenite into martensite induced by subsequent plastic deformation, this heat treatment increases the ductility . Lately it has been pointed out that it is possible to combine the process of press‐hardening with that of the Q&P heat treatment routine .…”

Section: Introductionmentioning

confidence: 99%

“…Due to the transformation of retained austenite into martensite induced by subsequent plastic deformation, this heat treatment increases the ductility. [13,14] Lately it has been pointed out that it is possible to combine the process of press-hardening with that of the Q&P heat treatment routine. [15][16][17] For instance, heated press-hardening dies or the early removal of the hot component from the die can be employed together with overaging (partitioning stage) in a separate furnace.…”

Section: Introductionmentioning

confidence: 99%

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1‐Step “Quenching and Partitioning” of the Press‐Hardening Steel 22MnB5

Wolf¹,

Nürnberger²,

Rodman³

et al. 2016

steel research int.

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In recent years, high strength steels, particularly press‐hardening steel, have been more extensively employed for manufacturing safety‐relevant structural components in vehicle bodies. These applications require contrasting material properties such as extremely high strengths as well as high forming ductility. Owing to the purely martensitic microstructure, the residual ductility of the conventional press hardened steels is low. Quenching and partitioning heat treatments can fulfil the requirement of an increased residual ductility by stabilizing the retained austenite. Moreover, if the quenching and partitioning heat treatments are carried out after intercritical annealing treatment, then the steel's mechanical properties can be tailored by defining the volume fraction of ferrite in the microstructure. In order to determine the potential of an 1‐step quenching and partitioning heat treatment combined with intercritical annealing processes, elevated contents of retained austenite are produced in ferritic‐martensitic microstructures using the low‐alloyed 22MnB5 steel grade. In addition to a tempered martensitic microstructure, secondary martensite, and a low fraction of retained austenite, the microstructure consists of remaining fractions of ferrite; thus, providing an additional increase in ductility. For this optimized microstructure, a yield stress of 513 MPa and a tensile strength of 1045 MPa are measured with a total elongation of 10.8%.

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Dominating Role of Film‐Like Carbon‐Enriched Austenite for the Simultaneous Improvement of Strength and Toughness in Low‐Carbon Steel

Yang

Ding

Liu

et al. 2020

steel research int.

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Multiphase microstructures containing film‐like carbon‐enriched austenite and martensite matrix represent an ideal microstructure that can facilitate the breakthrough of the trade‐off between strength and toughness, as well as good low‐temperature toughness in high‐strength steels. In this study, to determine the impact of film‐like carbon‐enriched austenite on the toughness of low‐carbon high‐strength steel, quenching and low‐temperature partitioning process is applied to a newly designed alloy. The quenching step results in a mixed microstructure consisting of a martensite matrix with high dislocation density and film‐like retained austenite, which is stabilized via carbon enrichment during tempering at 200 ºC for 60 min. Thus, the produced high‐strength steel specimen shows excellent mechanical properties (yield strength = 1201 MPa and tensile strength = 1550 MPa) and superior toughness (68.8 J at −60 ºC). Its strength primarily results from dislocation strengthening, grain boundary strengthening, and solid solution strengthening, and its superior low‐temperature toughness is associated with the film‐like carbon‐enriched austenite, which relaxes local stress, dissipates the plastic energy at the microcrack tip, and delays the initiation and propagation of cracks. Finally, a schematic diagram is designed to elucidate the effect of the retained austenite stabilization on the ductile–brittle transition temperature.

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Stability of Retained Austenite in High-Al, Low-Si TRIP-Assisted Steels Processed via Continuous Galvanizing Heat Treatments

Cited by 36 publications

References 35 publications

Retained Austenite: Transformation-Induced Plasticity

Retained Austenite: Transformation-Induced Plasticity

1‐Step “Quenching and Partitioning” of the Press‐Hardening Steel 22MnB5

Dominating Role of Film‐Like Carbon‐Enriched Austenite for the Simultaneous Improvement of Strength and Toughness in Low‐Carbon Steel

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