Growth mode of austenite during reversion from martensite in Fe-2Mn-1.5Si-0.3C alloy: A transition in kinetics and morphology

Zhang, Xianguang; Miyamoto, Gorō; Kaneshita, Takeshi; Yoshida, Yoshitaka; Toji, Yuki; Furuhara, Tadashi

doi:10.1016/j.actamat.2018.05.035

Cited by 94 publications

(54 citation statements)

References 34 publications

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“…Microstructures were characterized using optical microscopy (OM, Nikon Instech Co., Ltd., Tokyo, Japan) and field emission scanning electron microscopy (FE-SEM; JEOL, JSM-7001F, JEOL Ltd., Tokyo, Japan) after etching in a 2% Nital solution. Volume fractions of the overall, globular, and acicular γ were quantified by point counting, and the details are described elsewhere [16]. The true thickness or true interspacing of acicular γ were estimated to be a half of the apparent average thickness or interspacing measured by random line intersections on SEM images, to take a stereographic effect into account [18].…”

Section: Methodsmentioning

confidence: 99%

“…The reversion of γ during isothermal holding has been well studied in previous works [10,16,17]. However, in the industry, steels are usually continuously heated.…”

Section: Introductionmentioning

confidence: 99%

“…The acicular γ grains hold near-Kurdjumov-Sachs (K-S) orientation relationships (OR) with all the surrounding tempered martensite (TM) [4,[10][11][12]15] and grow by migration of the α/γ interface with the near-K-S OR. The growth of acicular γ is accompanied by Mn and Si partitioning during isothermal holding, regardless of reversion temperatures [16]. On the other hand, the globular γ holds a near-K-S OR with a part of its surrounding TM variant, and growth is accompanied by Mn and Si partitioning at low temperatures and becomes partitionless at high temperatures [15,16].…”

Section: Introductionmentioning

confidence: 99%

“…The growth of acicular γ is accompanied by Mn and Si partitioning during isothermal holding, regardless of reversion temperatures [16]. On the other hand, the globular γ holds a near-K-S OR with a part of its surrounding TM variant, and growth is accompanied by Mn and Si partitioning at low temperatures and becomes partitionless at high temperatures [15,16].…”

Section: Introductionmentioning

confidence: 99%

“…In γ reversion from lath martensite, two types of reverted γ (acicular and globular γ) can be formed [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. These two types of γ have different crystallographic characters and growth kinetics [15,16]. The acicular γ grains hold near-Kurdjumov-Sachs (K-S) orientation relationships (OR) with all the surrounding tempered martensite (TM) [4,[10][11][12]15] and grow by migration of the α/γ interface with the near-K-S OR.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Heating Rate on Formation of Globular and Acicular Austenite during Reversion from Martensite

Zhang

Miyamoto

Toji³

2019

Metals

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The effects of heating rate on the formation of acicular and globular austenite during reversion from martensite in Fe–2Mn–1.5Si–0.3C alloy have been investigated. It was found that a low heating rate enhanced the formation of acicular austenite, while a high heating rate favored the formation of globular austenite. The growth of acicular γ was accompanied by the partitioning of Mn and Si, while the growth of globular γ was partitionless. DICTRA simulation revealed that there was a transition in growth mode from partitioning to partitionless for the globular austenite with an increase in temperature at high heating rate. High heating rates promoted a reversion that occurred at high temperatures, which made the partitionless growth of globular austenite occur more easily. On the other hand, the severer Mn enrichment into austenite at low heating rate caused Mn depletion in the martensite matrix, which decelerated the reversion kinetics in the later stage and suppressed the formation of globular austenite.

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Section: Methodsmentioning

confidence: 99%

“…The reversion of γ during isothermal holding has been well studied in previous works [10,16,17]. However, in the industry, steels are usually continuously heated.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effects of Heating Rate on Formation of Globular and Acicular Austenite during Reversion from Martensite

Zhang

Miyamoto

Toji³

2019

Metals

Self Cite

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In Situ Observations of the Microstructural Evolution during Heat Treatment of a PH 13‐8 Mo Maraging Steel

et al. 2023

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The standard heat treatment of PH 13‐8 Mo maraging steels consists of solution annealing and subsequent aging. Herein, it is investigated how an additional intercritical annealing step prior to aging affects the microstructure, and, consequently, the mechanical properties of a PH 13‐8 Mo maraging steel. In situ techniques by means of high‐temperature electron backscatter diffraction and high‐temperature X‐ray diffraction are applied to study the microstructural changes during intercritical annealing and subsequent aging. In addition, high‐resolution investigation methods, such as transmission electron microscopy and atom probe tomography supplemented by transmission Kikuchi diffraction, are used for an in‐depth characterization of the microstructure. The results reveal that a diffusion‐controlled martensite to austenite transformation accompanied by partitioning of the substitutional atoms Cr, Ni, and Mo takes place during intercritical annealing. As a result of partitioning during intercritical annealing, an inhomogeneous distribution of Ni remains in the microstructure after the martensitic transformation. Consequently, the formation of reverted austenite is facilitated during subsequent aging due to existing Ni‐enriched zones in martensite. Since the fracture toughness is significantly enhanced compared to the standard heat treatment, it is suggested that this improvement is related to the increased phase fraction of reverted austenite.

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Mechanism and Application of Reverse Austenitic Transformation in Medium Mn Steels: A Systematic Review

Guo

Luo

2022

steel research int.

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In this contribution, the nucleation and growth mechanism of austenite during the intercritical annealing (IA) of medium Mn steels (MMSs) are reviewed. The nucleation of austenite can be enhanced due to the introduction of (sub)grain boundaries, dislocations, and carbides before austenitization. Although martensite may transform to austenite in a displacive way during flash heating, austenitic nuclei usually grow with the diffusion and partitioning of solute C/Mn atoms. The latter, however, is still difficult to be modeled because the combined influence of interface dissipation energy, defects, and carbide particles is not well understood and quantified. Next, four recent emerging processing technologies, including prior deformation for generating dislocations, additional tempering for the precipitation of carbides, additional annealing before IA, and flash heating, are also analyzed according to the above-stated nucleation and growth mechanism. Finally, it is proposed that the targeted austenite grains for improving the mechanical properties of MMS shall be produced by enhancing both nucleation sites and growth kinetics of austenite via the deliberate design of processing routes.

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Growth mode of austenite during reversion from martensite in Fe-2Mn-1.5Si-0.3C alloy: A transition in kinetics and morphology

Cited by 94 publications

References 34 publications

Effects of Heating Rate on Formation of Globular and Acicular Austenite during Reversion from Martensite

Effects of Heating Rate on Formation of Globular and Acicular Austenite during Reversion from Martensite

In Situ Observations of the Microstructural Evolution during Heat Treatment of a PH 13‐8 Mo Maraging Steel

Mechanism and Application of Reverse Austenitic Transformation in Medium Mn Steels: A Systematic Review

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