FeNbP in ultra-low carbon Nb-added steel containing high P

Ramos, Alfeu Saraiva; Sandim, Hugo Ricardo Zschommler; Hashimoto, Tomaz Manabu

doi:10.1016/s1044-5803(00)00070-x

Cited by 6 publications

(6 citation statements)

References 2 publications

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“…However, the retardation of recrystallization during annealing after cold rolling and the decrease in rvalue could be caused by the formation of the ternary phosphides, FeTiP 3) or possibly FeNbP. 5) In addition, the formation of the ternary phosphide also influences the recrystallization behavior during hot rolling in high-purity ferritic stainless steels with Nb and/or Ti addition, 6) in which P is present as a contaminant from the ferrochromium used as a raw material in stainless steelmaking. Therefore, it is useful to obtain information on the precipitation behavior of this ternary phosphide in these steels for microstructural control.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Analysis of Phase Equilibria in the Fe–Nb–P Ternary System

et al. 2009

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A thermodynamic analysis of the Fe-Nb-P ternary system has been carried out using the CALPHAD method. Among the three binary systems present in this ternary phase diagram, the phase equilibria in the Nb-P binary system, on which very few studies have been reported, were thermodynamically analysed. The thermodynamic properties of various phosphides and of a bcc solid solution obtained from first-principles calculations were utilized in this analysis to compensate for the lack of available experimental data. By applying these procedures, a highly plausible Nb-P binary phase diagram was established over the entire composition range. The thermodynamic descriptions of the Fe-Nb and Fe-P binary systems were taken from previous studies. The thermodynamic parameters of the Fe-Nb-P ternary system were evaluated based on experimental data for the phase boundaries and estimated thermodynamic properties of the ternary phosphides obtained using first-principles calculations. The calculated phase equilibria were in good agreement with the available experimental data. From the calculated results, we confirmed that the ternary phosphide, FeNbP, took part in equilibria with most of the binary phosphides.KEY WORDS: phase diagram; thermodynamic analysis; CALPHAD; first-principles calculations. 947© 2009 ISIJ appearing in the Nb-P binary system and the ternary phosphides was evaluated using the WIEN2k software package, 10) based on the Full Potential Linearized Augmented Plane Wave (FLAPW) method with a Generalized Gradient Approximation (GGA).11) We assumed Muffin radii of 2.0 au (0.106 nm) for Fe and Nb and 1.9 au (0.1005 nm) for P, and the plane wave basis set up to the cut-off energy of 20 Ry (270 eV) was utilized in our computations.2.1.2. Free Energy of the bcc Solid Solution in the Nb-P Binary System In addition to the formation energy of the various phosphides, the Gibbs energy of formation of the bcc solid solution (a) of the Nb-P binary system was evaluated using first-principles calculations. The procedure for obtaining the Gibbs free energy of formation is explained in this section.First, 36 types of bcc-based ordered superstructures, such as D0 3 , B2, and B32, were constructed by changing the stack of pure element planes along a given direction in the parent bcc structure lattice, [12][13][14] and the total energies of those structures were calculated using the WIEN2k software package.10) Then, the energy of formation of the bccbased ordered f phase, DE f form , was obtained from the total energy by subtracting the concentration-weighted averages from the total energy of the pure elements:.......... (1) where c i is the concentration of element i. The term E f total denotes the total energy of the f superstructure, whereas the terms E total bcc-Nb and E total bcc-P refer to the total energy of bcc Nb and hypothetical bcc P, respectively. The energy of formation, DE f form , can be also expressed as the sum of effective interaction energies for clusters, such as a point, nearest and second nearest neighbor pairs, a tri...

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Section: Introductionmentioning

confidence: 99%

Thermodynamic Analysis of Phase Equilibria in the Fe–Nb–P Ternary System

et al. 2009

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“…Low coiling temperature is not suitable for obtaining the desirable texture in case of IF steel. On the other hand, the appropriate coiling temperature, which is around 700 0 C, is also ideal for FeTiP type precipitation [18]. These precipitates consume substantial quantity of Ti, which can even lead to a situation where Ti would be insufficient for complete stabilization of carbon.…”

Section: Resultsmentioning

confidence: 99%

Improvement of Crystallographic Texture of High Strength Interstitial Free Steels by the Control of Steel Chemistry and Coiling Temperature

Bhattacharya

2011

MSF

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Effects of steel composition and coiling temperature on textures of a series of high strength IF steels were studied. An intermediate coiling temperature (6200C), instead of a high coiling temperature (7100C), was found most beneficial for the steels containing moderate to high phosphorus content. On the other hand, high coiling temperature was found beneficial for the steels containing low amount of phosphorus.

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“…25 Very large concentrations of phosphorus, approaching 0.8 wt-% in interstitial free steel alloyed with niobium, lead to the precipitation of FeNbP compounds, which embrittle the steel during cold rolling operations. 59 It has been argued 55 that when high strength interstitial free steels are not required, phosphorus and boron are best avoided since they cause a decrease in elongation, and the surface quality of the steel. 60,61 TRIP assisted steels There is a consensus that phosphorus can help increase the retained austenite content in TRIP assisted steels that have a microstructure of allotriomorphic ferrite, bainitic ferrite and retained austenite.…”

Section: Influence Of Strengthmentioning

confidence: 99%

Section: Influence Of Strengthmentioning

confidence: 99%

Is low phosphorus content in steel a product requirement?

Bhadeshia

Suh

2015

Ironmaking & Steelmaking

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An attempt is made, on the basis to published literature, to assess the amount of phosphorus that might be present in the steels without making it susceptible to grain boundary embrittlement. Embrittlement occurs when the general resistance to plastic flow is comparable to the stress required to separate crystals at their boundaries. A criterion is developed that enables a simple assessment to be made of the tendency to embrittle as a function of yield strength and the fraction of grain boundary sites that are covered by phosphorus. The latter is also sensitive to chemical composition, since some elements such as carbon segregate preferentially to phosphorus, giving rise to site competition that can permit a greater tolerance to the impurity. Other solutes affect the embrittling potency by different mechanisms, not all of which are clear.

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FeNbP in ultra-low carbon Nb-added steel containing high P

Cited by 6 publications

References 2 publications

Thermodynamic Analysis of Phase Equilibria in the Fe–Nb–P Ternary System

Thermodynamic Analysis of Phase Equilibria in the Fe–Nb–P Ternary System

Improvement of Crystallographic Texture of High Strength Interstitial Free Steels by the Control of Steel Chemistry and Coiling Temperature

Is low phosphorus content in steel a product requirement?

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