Segregation of manganese during intercritical annealing of dual phase steels

Pussegoda, N.; Tyson, W. R.; Wycliffe, P.; Purdy, G.R.

doi:10.1007/bf02648582

Cited by 20 publications

(9 citation statements)

References 3 publications

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“…Therefore, at the early stage of the α → γ transformation during annealing only with the partitioning of carbon, same as the previous studies with lower intercritical annealing temperatures. 8) As increasing the annealing time, substitutional alloying elements are partitioned between α and γ in order to decrease the total free energy toward the equilibrium states. From these results, it is clarified that the annealed steel under the typical annealing conditions in CAL (annealing temperature: 1 073 K, annealing time: less than 500 s) before cooling is in a metastable state where substitutional alloying elements are not fully partitioned even though the formation of γ during annealing is saturated.…”

Section: α →γ Transformation During Intercritical Annealingmentioning

confidence: 99%

“…[3][4][5][6][7][8][9][10][11][12] Some studies considered that the partitioning of substitutional alloying elements, such as Mn and Si, was important in the kinetics of the α → γ transformation. 5,6,8,11,12) They had mainly focused on microstructural changes at the annealing conditions with a low range of intercritical temperatures (around 973 K) and long annealing times (more than 1 hour) corresponding to the batch annealing conditions. 8) For example, Pussegoda et al 8) investigated the change in the volume fraction of γ and the Mn partitioning measured by TEM-EDX during annealing at 968 K, and compared the experimental results with a theoretical one-dimensional model developed by Wycliffe et al.…”

Section: Introductionmentioning

confidence: 99%

“…5,6,8,11,12) They had mainly focused on microstructural changes at the annealing conditions with a low range of intercritical temperatures (around 973 K) and long annealing times (more than 1 hour) corresponding to the batch annealing conditions. 8) For example, Pussegoda et al 8) investigated the change in the volume fraction of γ and the Mn partitioning measured by TEM-EDX during annealing at 968 K, and compared the experimental results with a theoretical one-dimensional model developed by Wycliffe et al. 6) The experimental results showed the volume fraction of γ saturated after 1 hour but it took approximately 50 hours to reach equilibrium volume fraction according to the calculation results, and the Mn content in γ were increasing © 2011 ISIJ even after 180 hours both in experimental and theoretical results.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Mn Partitioning during Intercritical Annealing on Following γ→α Transformation and Resultant Mechanical Properties of Cold-rolled Dual Phase Steels

Toji¹,

Yamashita²,

Nakajima³

et al. 2011

ISIJ Int.

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Sequential transformation phenomena of α → γ → α during intercritical annealing and subsequent cooling were investigated to achieve a more advanced control of mechanical properties in a low-carbon coldrolled DP steel sheet with a chemical composition of 0.13mass%C-1.4mass%Si-2.0mass%Mn. The steel was intercritically annealed at 1 073 K for 0-1 000 s, then air-cooled to 873-1 073 K (quenching start temperature: Tq), followed by water-quenching. The tensile strength increased with an extension of the annealing time, especially at the low Tq, corresponding to the increase in the volume fraction of martensite. This means the γ → α transformation during air-cooling was delayed by extending the annealing time. Microstructural observation and elemental analysis by EPMA indicated that the volume fraction of γ during annealing was almost saturated after annealing for 250 s, whereas the Mn content in γ was still increasing at that time. These results suggest that the retardation of the γ → α transformation during air-cooling by extending the annealing time results from the chemical stabilization of γ by the enrichment of Mn during intercritical annealing. In order to obtain the less scattering of mechanical properties in cold-rolled DP steel sheets, precise microstructural control considering the partitioning of substitutional alloying elements during intercritical annealing is quite important.

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Section: α →γ Transformation During Intercritical Annealingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Mn Partitioning during Intercritical Annealing on Following γ→α Transformation and Resultant Mechanical Properties of Cold-rolled Dual Phase Steels

Toji¹,

Yamashita²,

Nakajima³

et al. 2011

ISIJ Int.

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show abstract

“…[9][10][11] (3) The phases present in the initial microstructure before heating (ferrite, pearlite, carbides, martensite, and bainite) also influence how the nucleation and growth of austenite takes place. [26,27] In steels with a ferrite + pearlite initial microstructure, similar to the steels studied in this work, austenite formation takes place via two main steps. First, preferential nucleation at the boundaries of pearlite colonies until pearlite is completely transformed to austenite; this is then followed by the ferrite to austenite transformation, which takes place at a much slower rate.…”

Section: Introductionmentioning

confidence: 97%

Influence of Aluminum Alloying and Heating Rate on Austenite Formation in Low Carbon-Manganese Steels

Martín

Palizdar

García‐Mateo

et al. 2011

Metall Mater Trans A

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This investigation focuses on the austenite formation process during continuous heating, over a wide range of heating rates (0.05 to 20 K/s), in three low carbon-manganese steels alloyed with different levels of aluminum (0.02, 0.48, and 0.94, wt pct Al). High resolution dilatometry, combined with metallographic observations, was used to determine the starting (Ac 1 ) and finishing (Ac 3 ) temperatures of this transformation. It is shown that both the aluminum content and the applied heating rate have a strong influence on this process. During fast heating (>1 K/s), the pearlite phase present in the initial microstructure remains almost unaffected up to temperature Ac 1 . On the contrary, during slow heating, cementite lamellas inside pearlite partially dissolve, this dissolution effect being more pronounced for the lower carbon and higher aluminum content steels. The changes in the initial microstructure during slow heating affect the austenite nucleation and growth processes. Furthermore, in the aluminum alloyed steels, slow heating conditions shift the Ac 3 temperature to higher values. This shift is suggested to be due to aluminum partitioning from austenite to ferrite, which stabilizes ferrite and delays its transformation to higher temperatures. Thermodynamic calculations carried out with MTDATA software seem to support some of the experimental observations carried out under very low heating conditions close to equilibrium (0.05 K/s).

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“…Many studies have revealed that alloying elements are partially partitioned during the intercritical annealing. 28,39,40) In the four-year research project from 2006 to 2009 called "Mathematical Models for Predicting Microstructures and Mechanical Properties of Steels" organized by the ISIJ, the partitioning behavior of Mn and Si during annealing at intercritical temperature and its influence on the transformation behavior was studied, and some of the results of this study are introduced here.…”

Section: Model For Predicting Microstructures Of Advanced High-strengmentioning

confidence: 99%

Present Status and Future Prospects of Simulation Models for Predicting the Microstructure of Cold-rolled Steel Sheets

Senuma

2012

ISIJ Int.

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Annealing treatment of cold-rolled steel sheets are mostly subjected to the continuous annealing line. In such process recovery, recrystallization, reverse transformation and dissolution or formation of precipitates occur during heating and homogenizing treatments, and the transformation and precipitation in the steel during the subsequent cooling and aging treatments. The required microstructure and mechanical properties are obtained by controlling these metallurgical phenomena appropriately. Because a simulation model that predicts the microstructure is a useful tool for the minute control of these phenomena, many models have been developed. In this review, the present status of these models is surveyed and their problems and future tasks are discussed.

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Segregation of manganese during intercritical annealing of dual phase steels

Cited by 20 publications

References 3 publications

Effect of Mn Partitioning during Intercritical Annealing on Following γ→α Transformation and Resultant Mechanical Properties of Cold-rolled Dual Phase Steels

Effect of Mn Partitioning during Intercritical Annealing on Following γ→α Transformation and Resultant Mechanical Properties of Cold-rolled Dual Phase Steels

Influence of Aluminum Alloying and Heating Rate on Austenite Formation in Low Carbon-Manganese Steels

Present Status and Future Prospects of Simulation Models for Predicting the Microstructure of Cold-rolled Steel Sheets

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