Evolution of non-uniform grain structure during hot defornnation of a Nb-Ti microalloyed steel

Katajarinne, T.; Somani, Mahesh C.; Karjalainen, Pentti; Porter, David

doi:10.3989/revmetalm.2004.v40.i5.283

Cited by 2 publications

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“…The role of TiN particles in austenite grain size control is well known and the mechanism by which they exert their influence may be explained by Zener and Gladman expressions for pinning forces, [8][9][10][11] which relate the precipitate size, precipitated volume and austenite grain size. The results published to date agree that a Ti/N ratio below the stoichiometric ratio (3.42) yields good results in to control austenite grain size, especially when precipitation takes place in the solid state as finer precipitates are obtained.…”

Section: Introductionmentioning

confidence: 99%

Influence of the Size and Volume Fraction of TiN Particles on Hot Strength and Dynamic Recrystallisation in Structural Steels

Medina¹,

Vega²,

Gómez³

et al. 2005

ISIJ Int.

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The low solubility of titanium nitrides (TiN) in austenite is taken advantage of in structural steels to control the evolution of the microstructure in the hot rolling process and in the heat affected zone (HAZ) in processes involving the application of heat, such as welding. However, the quantitative influence of the precipitation state of these particles on hot strength and dynamic recrystallisation kinetics, given by the precipitate size distribution and the precipitated volume, is practically unknown. The present work studies the influence of various Ti and N compositions, which give rise to different precipitation states at the reheating temperatures, on the aforementioned phenomena. The influence of the precipitation state on hot strength has been quantified by changes in the peak stress and the activation energy. A maximum has been obtained for the activation energy which corresponds to a Ti/N ratio of approximately 1.3. The model used to predict the flow curve and dynamic recrystallisation kinetics has been improved, extending it to include microalloyed steels containing Ti.

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Section: Introductionmentioning

confidence: 99%

Influence of the Size and Volume Fraction of TiN Particles on Hot Strength and Dynamic Recrystallisation in Structural Steels

Medina¹,

Vega²,

Gómez³

et al. 2005

ISIJ Int.

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show abstract

“…Los precipitados formados en Estudio y modelización de la influencia de las partículas de segunda fase sobre el crecimiento de grano austenítico en un acero microaleado con niobio* el acero por elementos microaleantes, tales como vanadio, niobio y titanio, pinzan las fronteras de grano y las dislocaciones, inhibiendo su movimiento durante los procesos térmicos y termomecánicos [2] . La fuerza de pinzamiento depende de la propia existencia de los precipitados y, como consecuencia, de la estabilidad termodinámica de los mismos en la matriz de austenita [3][4][5][6][7] . La temperatura a la cual se rompe el equilibrio entre la fuerza motriz para el crecimiento de grano y la fuerza de pinzamiento se denomina temperatura de crecimiento libre (T CL ).…”

Section: Introductionunclassified

Study and modelling of the influence of second phase particles on the austenite grain growth in a niobium microalloyed steel

Martín¹,

Caballero

Capdevila

et al. 2006

Rev. metal.

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ResumenEn este trabajo se ha estudiado el crecimiento de grano austenítico producido durante el calentamiento continuo de un acero CMnNb. Se ha analizado la influencia de la velocidad de calentamiento sobre dicho proceso y se ha calculado la temperatura de crecimiento libre del grano austenítico, a la cual desaparece la influencia del pinzamiento provocado por los precipitados de carbonitruro de niobio. Finalmente, se propone un modelo del proceso de crecimiento de grano austenítico bajo pinzamiento que permite predecir el tamaño de grano austenítico (TGA) que se alcanza en el acero a una determinada temperatura por calentamiento continuo a velocidad conocida. Palabras ClaveCrecimiento de grano austenítico. Aceros microaleados con Niobio. Temperatura de crecimiento libre. Modelización. Calentamiento continuo.Study and modelling of the influence of second phase particles on the austenite grain growth in a niobium microalloyed steel AbstractThe austenite grain growth occurred during continuous heating in a niobium microalloyed steel has been investigated in this work. The effect of temperature and heating rate on the grain size is studied. The free grain coarsening temperature is determined as a function of the heating rate. It is found that unpinning by precipitates occurs around 40-70K below the temperature of complete dissolution of carbonitrides. Furthermore, a new model has been proposed to describe the austenite grain coarsening under the influence of niobium carbonitrides during continuous heating at different rates.

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Evolution of non-uniform grain structure during hot defornnation of a Nb-Ti microalloyed steel

Cited by 2 publications

References 0 publications

Influence of the Size and Volume Fraction of TiN Particles on Hot Strength and Dynamic Recrystallisation in Structural Steels

Influence of the Size and Volume Fraction of TiN Particles on Hot Strength and Dynamic Recrystallisation in Structural Steels

Study and modelling of the influence of second phase particles on the austenite grain growth in a niobium microalloyed steel

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