In situ observation of austenite–ferrite interface migration in a lean Mn steel during cyclic partial phase transformations

Chen, Hao; Gamsjäger, Ernst; Schider, Siegfried; Khanbareh, Hamideh; Zwaag, Sybrand van der

doi:10.1016/j.actamat.2013.01.013

Cited by 55 publications

(32 citation statements)

References 43 publications

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“…A similar behavior was observed by in situ observation of cyclic partial phase transformations [17]. With the continuation of α→γ transformation, more small grains nucleated, and grain growth occurred via the impingement of grains until the transformation was complete.…”

Section: Austenite Grain Growth Behavior At High Temperaturessupporting

confidence: 51%

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In situ observation of austenite grain growth behavior in the simulated coarse-grained heat-affected zone of Ti-microalloyed steels

Wan

Huang

et al. 2014

Int J Miner Metall Mater

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Abstract:The austenite grain growth behavior in a simulated coarse-grained heat-affected zone during thermal cycling was investigated via in situ observation. Austenite grains nucleated at ferrite grain boundaries and then grew in different directions through movement of grain boundaries into the ferrite phase. Subsequently, the adjacent austenite grains impinged against each other during the α→γ transformation. After the α→γ transformation, austenite grains coarsened via the coalescence of small grains and via boundary migration between grains. The growth process of austenite grains was a continuous process during heating, isothermal holding, and cooling in simulated thermal cycling. Abundant finely dispersed nanoscale TiN particles in a steel specimen containing 0.012wt% Ti effectively retarded the grain boundary migration, which resulted in refined austenite grains. When the Ti concentration in the steel was increased, the number of TiN particles decreased and their size coarsened. The big particles were not effective in pinning the austenite grain boundary movement and resulted in coarse austenite grains.

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Section: Austenite Grain Growth Behavior At High Temperaturessupporting

confidence: 51%

“…(1) [17,20]: (1) and (2), we calculated the precipitated TiN for the three steels investigated in this work, as shown in Fig. 10(a).…”

Section: Pinning Effect Of Nanoscale Tin Particles On the Austenite Gmentioning

confidence: 99%

In situ observation of austenite grain growth behavior in the simulated coarse-grained heat-affected zone of Ti-microalloyed steels

Wan

Huang

et al. 2014

Int J Miner Metall Mater

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“…This temperature range is referred to as a stagnant stage in the literature. 7,32,33) The ferrite-austenite interface has to pass the manganese-rich region formed during prior austenite growth involving manganese partitioning. Manganese is an austenite stabilizer and the austenite near the interface is more stable than that with the nominal composition further away from the interface.…”

Section: Discussionmentioning

confidence: 99%

“…with the same crystallographic orientation. [2][3][4][5][6][7] Typically during epitaxial ferrite growth upon cooling, there is insufficient time for alloying elements including carbon to redistribute completely, which leads to the existence of concentration gradients in austenite: Higher carbon concentrations are found near the ferrite-austenite interface and lower concentrations in the centre of austenite islands. 8) Depending on chemical composition, at lower temperatures, e.g.…”

Section: Introductionmentioning

confidence: 99%

A Microstructure Evolution Model for Intercritical Annealing of a Low-carbon Dual-phase Steel

2014

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A model was developed to describe the microstructure evolution during intercritical annealing of a lowcarbon steel suitable for industrial production of DP600 grade dual-phase steel on a hot-dip galvanizing line. The microstructure evolution model consists of individual submodels for ferrite recrystallization, austenite formation and decomposition constructed using the Johnson-Mehl-Avrami-Kolmogorov approach and the additivity principle. The submodels for recrystallization and austenite formation are adopted from a previous study. The present paper provides a detailed analysis of the model development for the decomposition of intercritical austenite. The overall microstructure evolution model is validated using simulated industrial thermal paths for intercritical annealing. Model validation is expedited by in-situ measurements of the recrystallization completion temperature using laser ultrasonics and the intercritical austenite formation and decomposition using dilatometry.

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“…8) The Confocal Scanning Laser Microscope (CLSM) has recently provided a convenient possibility of making an "insitu" observation of the phase transformation on the surface of samples at high temperatures. Since the 1990's, Yin,9,10) Kimura, 11) Phelan, 12,13) Liu, 14) Chen, 15) and other researchers [16][17][18][19][20][21][22][23] have applied the CLSM to make in situ observations of the phase transformation of steels or alloys at special heating or cooling rates. For example, Yin 10) found that the incoherent δ/γ interphase boundaries (abbreviated as IBs hereafter) were always unstable with finger-like morphology during δ→γ transformation, which developed along δ/δ grain boundaries (abbreviated as GBs hereafter) at low supercoolings and even into the δ-ferrite matrix at higher supercoolings for the transformation.…”

Section: Introductionmentioning

confidence: 99%

In-situ Observation of δ↔γ Phase Transformations in Duplex Stainless Steel Containing Different Nitrogen Contents

Zhao

Sun

et al. 2017

ISIJ International

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The characteristics of the γ ↔δ phase transformations were observed on the surface of duplex stainless steels with different nitrogen concentrations by the Ultra High Temperature Confocal Laser Scanning Microscope (UHT-CSLM). The effects of the nitrogen content on the phase transformations are discussed based on the experimental results and thermodynamic calculations. It is found that the migration of the δ/γ IB is the main form of the phase transformation and leads to the continuous decline and final disappearance of the retained γ-phase during the γ→δ phase transformation in the high nitrogen steel (N1) and low nitrogen steel (N2). During the δ→γ phase transformation, the γ -cells prefer to precipitate along the δ/δ GBs and develop into the δ -ferrite matrix with finger-like or sword-like patterns. Then the γ-cells also nucleate in the δ -grains with a sword-like pattern and the growing speed in the longitudinal direction is much faster than that in the lateral direction. More importantly, the high nitrogen content can hinder the migration of δ/γ IBs during the γ→δ transformation and also promote the nucleation and growth of γ -phase during the δ→γ transformation by increasing both the starting and finishing temperatures of the phase transformation. Interestingly, the original δ/δ GB which is covered by the precipitation of γ -phase during the δ→γ transformation will reappear first at the same position by the moving of δ/γ IBs during the γ→δ transformation, but it is unstable and migrates fast with further heating.

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In situ observation of austenite–ferrite interface migration in a lean Mn steel during cyclic partial phase transformations

Cited by 55 publications

References 43 publications

In situ observation of austenite grain growth behavior in the simulated coarse-grained heat-affected zone of Ti-microalloyed steels

In situ observation of austenite grain growth behavior in the simulated coarse-grained heat-affected zone of Ti-microalloyed steels

A Microstructure Evolution Model for Intercritical Annealing of a Low-carbon Dual-phase Steel

<i>In-situ</i> Observation of <i>δ</i>↔<i>γ</i> Phase Transformations in Duplex Stainless Steel Containing Different Nitrogen Contents

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