Effect of niobium on massive transformation in ultra low carbon steels: a solute drag treatment

Suehiro, Masayoshi; Liu, Zhe; Ågren, John

doi:10.1016/s1359-6454(96)00036-5

Cited by 87 publications

(49 citation statements)

References 13 publications

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“…Among them, the soluble Nb can decrease the temperature of the γ →α phase transformation by retarding the movement of phase interface by solute drag effect. [23][24][25] Moreover, the γ →α phase transformation temperature will also be decreased due to the greater degree of undercooling at a higher cooling rate.…”

Section: Microstructural Strengthening At Low Coilingmentioning

confidence: 99%

Effects of Coiling Temperature on Microstructure and Precipitation Behavior in Nb–Ti Microalloyed Steels

Tang

2018

ISIJ International

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This paper presents our latest studies on the effects of coiling temperature on the microstructure, precipitation behavior, and mechanical properties of an Nb-Ti microalloyed steel produced by endless strip processing (ESP) and coiled at different temperatures. The amounts of soluble elements were measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The microstructure and precipitates were analyzed using SEM, EBSD, TEM, and electrolytic dissolution and filtration tests. The results revealed that large amounts of microalloying elements were still in solution before coiling. As the coiling temperature decreased from 600°C to 560°C, the content of acicular ferrites (AF) increased and the average ferritic grain size was refined from 2.01 μm to 1.29 μm, the yield strength and tensile strength of the tested steel increased by 22 MPa and 20 MPa, respectively, under the effect of microstructural strengthening. As the coiling temperature increased from 600°C to 640°C, the mass fraction of precipitates increased from 0.083% to 0.110% and the percentage of fine precipitates (smaller than 18 nm) increased from 12.2% to 14.7%; the intense precipitation strengthening effect increased the yield strength and tensile strength by 35 MPa and 42 MPa, respectively. Therefore, as the coiling temperature decreased from 640°C to 560°C, the strength of the tested steel decreased first and then increased while the elongation decreased steadily from 18.9% to 14.1% due to the increasing content of AF.

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Section: Microstructural Strengthening At Low Coilingmentioning

confidence: 99%

Effects of Coiling Temperature on Microstructure and Precipitation Behavior in Nb–Ti Microalloyed Steels

Tang

2018

ISIJ International

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“…A number of alternative solute drag models have been proposed and applied to phase transformations in steels. [14][15][16] Recently, Fazeli and Militzer 17) used their solute drag model to describe the austenite-ferrite transformation in a 0.17 mass%C-0.74 mass%Mn steel. In their approach, in addition to M0, the binding energy of the solute to the interface as well as its diffusivity across the interface were further adjustable parameters.…”

Section: )mentioning

confidence: 99%

Modelling Phase Transformation Kinetics in Fe–Mn Alloys

Jia

Militzer

2012

ISIJ Int.

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A unified model is proposed for the austenite-to-ferrite transformation kinetics in binary Fe-Mn alloys that accounts for solute drag of Mn. To aid the model development, continuous cooling transformation (CCT) tests were conducted for an interstitial-free steel that can be considered as Fe-0.1%Mn alloy. The experimental transformation data are supplemented with literature data for Fe-1%Mn and Fe-2%Mn alloys to establish a CCT database for Fe-Mn alloys. The austenite-to-ferrite transformation kinetics is described from a fundamental perspective by assuming an interface-controlled reaction and including solute drag of Mn. Using the solute drag model of Fazeli and Militzer, intrinsic interface mobility, trans-interface diffusivity of Mn and its binding energy have been determined from the CCT data. The interfacial parameters are critically analyzed and compared with independent measurements of diffusion and grain boundary segregation.

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“…Since fine grain sizes bring benefits such as a high yield stress and a good formability, experimental and simulation research has been conducted. 7,8) The retardation in Nb microalloyed steel is derived from the pinning effect of NbC particles and the solute drag effect of dissolved Nb atoms in the g matrix or the grain boundaries, but it is difficult to separate the contribution of effects quantitatively. Concerning the pinning effect, Zener's model 9) is well-known.…”

Section: Introductionmentioning

confidence: 99%

Mobility Analysis of the Austenite to Ferrite Transformation in Nb Microalloyed Steel by Phase Field Modelling

Takahama

Sietsma

2008

ISIJ Int.

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It is well-known that the solute drag effect due to dissolved Nb and the pinning effect due to NbC in Nb microalloyed steel cause retardation of the grain growth during austenitisation and of the transformation during cooling. These effects strongly depend on the austenitisation-temperature. But there is little numerical research on both effects simultaneously so far. In this study the mobility behaviour during austenite (g) to ferrite (a) transformation was investigated by phase field modelling, showing that the a/g boundary velocity during cooling increases with increasing austenitisation-temperature. These phenomena are caused by both pinning and solute drag effects. The effect of pinning decreases as the austenitisation-temperature increases because NbC dissolves with austenitisation treatment at high temperature. On the other hand, the strength of the solute drag effect is the highest for intermediate austenitisation-temperature, where the a/g boundary velocity during cooling is in the intermediate range, and the strength is determined by the effects of both the concentration of dissolved Nb atoms and the a/g boundary velocity. These features are quantitatively discussed from the simulation results.

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Effect of niobium on massive transformation in ultra low carbon steels: a solute drag treatment

Cited by 87 publications

References 13 publications

Effects of Coiling Temperature on Microstructure and Precipitation Behavior in Nb–Ti Microalloyed Steels

Effects of Coiling Temperature on Microstructure and Precipitation Behavior in Nb–Ti Microalloyed Steels

Modelling Phase Transformation Kinetics in Fe–Mn Alloys

Mobility Analysis of the Austenite to Ferrite Transformation in Nb Microalloyed Steel by Phase Field Modelling

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