Kinetics of γ → α phase transformation in Fe-Mn alloys containing low manganese

In this work, a 6-pass hot-rolling process followed by air cooling is studied by means of a coupled multi-scale simulation approach. The finite element method (FEM) is utilized to obtain macroscale thermomechanical parameters including temperature and strain rate. The microstructure evolution during the recrystallization and austenite (γ) to ferrite (α) transformation is simulated by a mesoscale cellular automaton (CA) model. The solute drag effect is included in the CA model to take into account the influence of manganese on the γ/α interface migration. The driving force for α-phase nucleation and growth also involves the contribution of the deformation stored energy inherited from hot-rolling. The simulation renders a clear visualization of the evolving grain structure during a multi-pass hot-rolling process. The variations of the nonuniform, deformation-stored energy field and carbon concentration field are also reproduced. A detailed analysis demonstrates how the parameters, including strain rate, grain size, temperature, and inter-pass time, influence the different mechanisms of recrystallization. Grain refinement induced by recrystallization and the γα phase transformation is also quantified. The simulated final α-fraction and the average α-grain size agree reasonably well with the experimental microstructure.

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“…where P α/γ is the effective driving pressure; M α/γ is the interfacial mobility of the moving α/γ interface, which can be described as [55]…”

Section: Ferrite Growth and Coarseningmentioning

confidence: 99%

Multi-Scale Modeling of Microstructure Evolution during Multi-Pass Hot-Rolling and Cooling Process

Lin

Zou

et al. 2021

Materials

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“…A lot of effort has been placed to clarify the intrinsic mobility in various binary and ternary alloys. [4][5][6][7][8][9] It is clear that M int decreases with lowering temperature while the intrinsic mobilities reported in literature scatters by orders of magnitude. Recently intrinsic mobility is reported to be nearly independent on transformation direction, e.g.…”

Section: Intrinsic Mobilitymentioning

confidence: 92%

Interaction of Alloying Elements with Migrating Ferrite/Austenite Interface

Miyamoto

2020

ISIJ Int.

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Alloying elements greatly influence phase transformation kinetics in steel due to local partitioning and interfacial segregation to migrating interface and quantitative understanding of the alloying effects is a key for tailoring mechanical properties of modern high strength steels. Energy dissipation for interface migration is an important concept to understand the alloying effects and also to control carbon enrichment in untransformed austenite in multiphase high strength TRIP or DP steels. In this review, possible sources causing energy dissipation for interface migration are introduced and the energy dissipation for interface migration in formations of grain boundary ferrite (α), Widmanstatten α and bainitic α investigated in various systems are summarized.

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“…To take the finite interface mobility into account, the value of acicular γ/TM interface mobility is needed for the DICTRA calculation. Several α/γ interface mobilities were reported for fcc → bcc massive transformations [21][22][23]. The massive transformation occurs by migration of incoherent interface; therefore, the mobility of the acicular γ/TM interface with better coherency should be smaller than the reported mobilities.…”

Section: Dictra Simulation Of the Growth Of Austenitementioning

confidence: 92%

“…The massive transformation occurs by migration of incoherent interface; therefore, the mobility of the acicular γ/TM interface with better coherency should be smaller than the reported mobilities. Hence, in this study, in order to reduce the interface mobility, the reported interface mobility [21] (M 0 = −4 × 10 −7 exp(−140,000/RT) m 4 /Js) was multiplied by various small constants (1~0.001) to evaluate the growth of acicular γ, as simulated in the isothermal holding process [16].…”

Section: Dictra Simulation Of the Growth Of Austenitementioning

confidence: 99%

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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Kinetics of γ → α phase transformation in Fe-Mn alloys containing low manganese

Cited by 108 publications

References 27 publications

Multi-Scale Modeling of Microstructure Evolution during Multi-Pass Hot-Rolling and Cooling Process

Multi-Scale Modeling of Microstructure Evolution during Multi-Pass Hot-Rolling and Cooling Process

Interaction of Alloying Elements with Migrating Ferrite/Austenite Interface

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

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