Strengthening Mechanisms in Vanadium Microalloyed Steels Intended for Long Products.

Zając, Stanisław; Siwecki, Tadeusz; Hutchinson, W. B.; Lagneborg, R.

doi:10.2355/isijinternational.38.1130

Cited by 72 publications

(49 citation statements)

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“…However, V-microalloyed steels also exhibit grain refinement through intragranular nucleation of ferrite on VN precipitates partly due to low lattice mismatch of VN with ferrite [11,12]. The addition of N in V microalloyed steel stimulates the precipitation of VN particles and increases their volume fraction [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

From heterogeneous to homogeneous nucleation for precipitation in austenite of microalloyed steels

Medina

2015

Acta Materialia

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This paper studies the influence of strain on precipitate nucleation in austenite for three is dependent not only on the strain magnitude but also on the driving force for precipitation. When the driving force is high, or low in absolute terms, the influence of the strain, i.e. the increase in the dislocation density, gives rise to a notable reduction in the t 0.05 value due to heterogeneous nucleation on the dislocation nodes. In contrast, when the driving force is low, or high in absolute terms, the influence of the strain on t 0.05 decreases considerably and the nucleation of precipitates becomes preponderantly homogeneous. Therefore, the driving force value is responsible for the transition from heterogeneous nucleation to homogenous nucleation.

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Section: Introductionmentioning

confidence: 99%

From heterogeneous to homogeneous nucleation for precipitation in austenite of microalloyed steels

Medina

2015

Acta Materialia

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“…However, it has been reported that when Ti is present in a steel which contains other microalloying elements such as V and Nb, the Ti addition changes the precipitation of V and Nb, and results in a lower yield strength. [12][13][14][15][16][17][18] Most of the work done so far in the development of the thin slab direct rolling technique has been concerned with the process parameters and there are no reports in the literature on a detailed study of the evolution of microstructure over the entire thin slab direct rolling process. The aim of this project was to investigate microstructural development in V-N and V-Ti-N microalloyed steels during the thin slab direct rolling process.…”

Section: Introductionmentioning

confidence: 99%

The Evolution of Microstructure during Thin Slab Direct Rolling Processing in Vanadium Microalloyed Steels.

Li¹,

Crowther

Mitchell³

et al. 2002

ISIJ International

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The evolution of microstructure during a simulation of the thin slab direct rolling process has been studied on two low carbon steels, microalloyed with V-N and V-Ti-N. The steels were examined using optical microscopy, analytical transmission electron microscopy (TEM) and energy dispersive X-ray (EDAX).After the 4th rolling pass, in a five pass schedule, the initial coarse austenite grain size (ഠ1 mm) was reduced to about 50 mm in Steel V-N and 22 mm in Steel V-Ti-N. The average ferrite grain size in the final strip was slightly smaller in Steel V-Ti-N (4.8-6.6 mm) than in Steel V-N (5.3-7.2 mm). For Steel V-N, VN was only observed after 1 050°C equalization, but it was not found after 1 200°C and 1 100°C equalisation. For Steel V-Ti-N, V-Ti(N) particles formed during casting and during equalization for all the equalization temperatures (1 200°C, 1 100°C and 1 050°C). AlN particles precipitated in Steel V-N only during 1 050°C equalization and were often associated with MnS or MnS and VN. No AlN was detected in Steel V-Ti-N. Fine V containing precipitates (Ͻ10 nm) were observed in the final strip for both of the steels, but the frequency of the fine particles was lower in Steel V-Ti-N than in Steel V-N. The fine precipitates in the final strip make a major contribution to dispersion strengthening. High strength (LYSഠ460-560 MPa) with good toughness and good ductility were achieved in the steels, which are competitive to similar products made by conventional controlled rolling. However, the addition of Ti to the V-N steel decreased the yield strength due to formation of V-Ti(N) particles in austenite, which reduced the amounts of V and N available for subsequent V rich fine particle precipitation in ferrite.KEY WORDS: vanadium and vanadium-titanium microalloyed steel; thin slab direct rolling; equalization temperature; microstructure, properties.rolling is generated at a temperature in excess of 1 450°C, while the equilibrium solubility of microalloy carbonitrides is very much greater than that at the soaking temperature used in the CCR process. Most TSDR processing chooses steels with carbon content less than 0.065 wt% to avoid the peritectic reaction and subsequent segregation. Also in the TSDR process, the as-cast austenite prior to rolling may be more highly supersaturated with respect to microalloying elements than the reheated austenite in the CCR process. This can affect subsequent microstructural development during processing.The addition of Nb to HSLA steel can give considerable strengthening, but when Nb is present in continuously cast HSLA steels, slab surface cracking, especially in the transverse direction, is a well documented observation.9) Attempts to produce acceptable surface finishes in Nb microalloyed steels have not been completely successful to date.7,10) This is associated with the precipitation of Nb compounds in a manner similar to that responsible for the ductility trough found during hot tensile testing of CCR processed steels in the temperature range from 750 to 925°C. 1,11) For this ...

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“…4, is principally due to precipitation strengthening by V-carbonitride second phase particles. 5,17) As the nitrogen content is increased the precipitation of V(C, N) in basically acicular ferrite and bainitic structure is enhanced and particles become more dispersed.…”

Section: Strengthmentioning

confidence: 99%

Influence of Reheating Temperature and Vanadium Content on Transformation Behavior and Mechanical Properties of Medium Carbon Forging Steels

et al. 2010

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Strengthening Mechanisms in Vanadium Microalloyed Steels Intended for Long Products.

Cited by 72 publications

References 0 publications

From heterogeneous to homogeneous nucleation for precipitation in austenite of microalloyed steels

From heterogeneous to homogeneous nucleation for precipitation in austenite of microalloyed steels

The Evolution of Microstructure during Thin Slab Direct Rolling Processing in Vanadium Microalloyed Steels.

Influence of Reheating Temperature and Vanadium Content on Transformation Behavior and Mechanical Properties of Medium Carbon Forging Steels

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