Role of vanadium in dual-phase steels

Öström, Peter; Lönnberg, B.; Lindgren, Inga

doi:10.1179/030716981803275659

Cited by 17 publications

(2 citation statements)

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“…Recent findings also showed that vanadium alloying can refine the martensitic/retained austenite phase and demonstrate ductile fractures on heat-treated microalloyed steels [27,28]. In general, some reports advise that vanadium alloy enhances grain refinement, microstructure, strength and tempering stability [29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Short thermal cycle treatment with laser of vanadium microalloyed steels

Dewi

Volpp

Kaplan

2020

Journal of Manufacturing Processes

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Section: Introductionmentioning

confidence: 99%

Short thermal cycle treatment with laser of vanadium microalloyed steels

Dewi

Volpp

Kaplan

2020

Journal of Manufacturing Processes

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“…The microstructure of hot rolled and cold rolled TRIP steels contains, as major constituents, ferrite, bainite and austenite, see Ref. [3][4][5][6]. This latter constituent exhibits a mechanically induced transformation in martensite during forming.…”

Section: Introductionmentioning

confidence: 99%

Application of thermodynamics and diffusion in solids to the development of high strength steels for the Automotive Industry

Gouné¹,

Maugis²,

Jung³

2005

Mat.-wiss. u. Werkstofftech.

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This paper presents some applications of thermodynamics and diffusion in solids to the development of physical models applied to high strength steels production for the Automotive Industry. The scale of modeling is chosen to be the microstructural grain. The description of nucleation, interfacial conditions, diffusion controlled growth makes it possible to follow the process of microstructure formation, the evolution of each steel constituent and finally to describe the produced steel microstructure.In this paper, we propose a model that predicts the kinetics of cementite dissolution and austenite growth during heating and soaking. It is based on solving the mass balance and diffusion equations written with gradients of chemical potentials as driving forces. This model is applicable to multi component systems and a good agreement between the calculations and experimental data was obtained.Key words: Phase transformations, high strength steels, modelling, industrial application, automotive Im Rahmen dieser Arbeit wird die Anwendung der Thermodynamik und Diffusion in Festkörpern zur Entwicklung hochfester Stähle in der Automobilindustrie vorgestellt. Die Modellierung erfolgt auf der mikrostrukturellen Ebene der Körner. Die Beschreibung der Keimbildung, der Bedingungen an den Grenzflächen und des diffusionskontrollierten Wachstums ermöglicht dem Prozess der Mikrostrukturbildung und der Entwicklung jeder Stahlkomponente zu folgen und schließlich die entstandene Mikrostruktur des Stahls zu beschreiben.In dieser Arbeit wird ein Modell, zur Vorhersage der Zementitauflösung und des Austenitwachstums während des Erhitzens und des Abschreckens, vorgeschlagen. Es basiert auf der Lösung der Massenbilanz-und Diffusionsgleichungen, die mit Gradienten des chemischen Potenzials als treibende Kraft formuliert werden. Das Modell kann auf Multikomponentensysteme angewendet werden und eine gute Ü bereinstimmung zwischen Berechnung und Experiment wurde erzielt.

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Detailed study of the transformation mechanisms in ferrous TRIP aided steels

Iung¹,

Drillet²,

Couturier³

et al. 2002

Steel Research

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Development of TRIP aided ferrous alloys is one answer to the demand for weight decrease in the automotive industry. The microstructure of hot rolled and cold rolled TRIP steels is quite complex and the optimisation of such steel products requires a detailed understanding of the mechanisms of phase transformation, during thermomechanical treatment as well as during mechanical testing or metal forming. We present in this paper the results obtained at Irsid concerning the study of austenite stabilisation through bainitic transformation during thermal treatment and its transformation into martensite during mechanical testing. First of all, the characterisation methods are presented. An effort has to be put on this point due to the refinement of the microstructure of TRIP steels, especially the size of austenite and martensite islands. Carbon replicas for the observation by means of transmission electron microscopy (TEM) are used to analyse the morphological features of the microstructure ‐ nature of the constituents, size and shape ‐ and the composition of cementite particles present in the steels. The mean value for this carbon content in retained austenite is deduced from X‐ray diffraction measurements. Then the kinetics of bainitic transformation are discussed as well as cementite precipitation. The typical composition of the steel studied is 0.5 % C, 1.5 % Mn. The use of 0.5 % C steels facilitates the study of bainitic transformation by avoiding the ferrite formation usually occurring in TRIP steels. Cementite nucleation appears at the ferrite/austenite interface without any partitionning of substitutional elements. To satisfy thermodynamic equilibrium at the interface, the silicon content on the cementite side is very low and high on the austenite side. Then, carbon diffusion towards austenite is delayed and, as a consequence, cementite growth is also delayed. As the diffusion kinetics are low at 400 °C, cementite keeps this “non partitioned” composition, even after 3 hours holding. At 500 °C, diffusion kinetics are higher and cementite composition approaches that predicted by equilibrium. Finally, the stability of retained austenite during mechanical testing is studied. Before and after mechanical testing the morphological characteristics of the microstructure (austenite island size and elongation) are analysed by TEM replicas and image analysis. There is a high density of very small austenite islands but they represent only a small fraction of the total retained austenite. These results confirm and quantify the size effect on austenite stabilisation during deformation.

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Role of vanadium in dual-phase steels

Cited by 17 publications

References 1 publication

Short thermal cycle treatment with laser of vanadium microalloyed steels

Short thermal cycle treatment with laser of vanadium microalloyed steels

Application of thermodynamics and diffusion in solids to the development of high strength steels for the Automotive Industry

Detailed study of the transformation mechanisms in ferrous TRIP aided steels

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