Computational thermodynamics and slag modelling applied to steel elaboration

Gaye, Henri; Lehmann, J.; Rocabois, Philippe; Ruby-Meyer, Fabienne

doi:10.1002/srin.200100150

Cited by 13 publications

(7 citation statements)

References 15 publications

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“…Thermodynamic data were obtained and assessed from the studies of the following systems: (1) Fe-Al-O, [16,17] (2) Fe-Ti-O, [18][19][20][21][22][23][24][25] and (3) Fe-Al-Ti-O. [26][27][28][29][30][31] The ranges of aluminum and titanium compositions generally encountered in IF steels are represented by a dashed circle. The star indicates the experimental conditions investigated in this study; this will be discussed later.…”

Section: B Deoxidation Simulation and Experimental Conditionsmentioning

confidence: 99%

Transient Behavior of Inclusion Chemistry, Shape, and Structure in Fe-Al-Ti-O Melts: Effect of Titanium Source and Laboratory Deoxidation Simulation

Wang

Nuhfer

Sridhar

2009

Metall Mater Trans B

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In the present study, laboratory-scale deoxidation experiments in a vacuum-induction furnace (VIF) were carried out to elucidate the evolution of inclusions during transient stages after a titanium addition. Three different titanium sources (Fe-70 wt pct Ti, Fe-30 wt pct Ti, and titanium granules) were employed and the results were compared in terms of the inclusion chemistry, structure, and morphology. It was found that, immediately after titanium additions to an aluminum-killed melt, titanium-containing inclusions, which are either single-phase or dual-phase particles having a certain amount of titanium and are contrary to melt equilibrium predictions, were formed. Analysis by transmission electron microscope (TEM) suggested that these inclusions could be Al 2 TiO 5 . The change in the inclusion chemistry was accompanied by a shift in the inclusion morphology from spherical to irregular. With time, the inclusion chemistry shifted back toward the thermodynamically stable Al 2 O 3 , but the change in morphology remained. The temporary Al 2 TiO 5 inclusions were formed as a result of local high content of titanium immediately after and at the vicinity of the titanium addition. When comparing the different titanium sources, it was found that they can be ranked as Ti > Fe-70 pct Ti > Fe-30 pct Ti, in terms of the amount of titanium-containing inclusions produced during the transient stage.

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Section: B Deoxidation Simulation and Experimental Conditionsmentioning

confidence: 99%

Transient Behavior of Inclusion Chemistry, Shape, and Structure in Fe-Al-Ti-O Melts: Effect of Titanium Source and Laboratory Deoxidation Simulation

Wang

Nuhfer

Sridhar

2009

Metall Mater Trans B

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“…Equilibrium thermodynamic calculations using the CEQSCI model 14) were used to determine the optimum reheating conditions to ensure the complete dissolution of V(C, N) precipitates in the as-cast ingots 8) and the hot rolling and coiling parameters were chosen in order to minimise the amount of V precipitation in the hot strip:…”

Section: Hot and Cold Rolling Simulationsmentioning

confidence: 99%

Vanadium Precipitation During Intercritical Annealing in Cold Rolled TRIP Steels

Perrard

Scott

2007

ISIJ Int.

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Flat carbon steel manufacturers are currently developing new TRansformation Induced Plasticity (TRIP) steels as a response to strong demands for vehicle lightening and security reinforcement from the automobile sector. Compared to conventional high strength steels these advanced grades exhibit a very favourable compromise between strength and ductility and can therefore be produced in thinner, lighter gauge strips with equivalent functional properties. The excellent mechanical properties of TRIP steels are attributed to the high strain hardening coefficient generated by the progressive transformation of metastable retained austenite to martensite during plastic deformation. Further improvements in mechanical properties can be obtained by microalloying, especially with vanadium and nitrogen additions. In this paper we discuss the rather complex evolution of vanadium carbonitride V(C, N) precipitation during continuous annealing of cold rolled strip. Transmission electron microscopy (TEM) and selective chemical dissolution are used to characterise the precipitation state during interrupted intercritical annealing cycles. The experimental results are compared with calculations made using a recent kinetic precipitation model. We show that reasonable agreement can be achieved using a simple uncoupled model, however a complete description of the precipitation sequence during continuous annealing will require fully coupled kinetic models describing the interactions between cementite dissolution, the ferrite to austenite transformation and V(C, N) precipitation.KEY WORDS: cold rolled TRIP; microalloying; V(C, N) precipitation; kinetics modelling. ISIJ International, Vol. 47 (2007), No. 8, pp. 1168-1177 Points 1-4 and 6 require that the precipitating species should be highly soluble in austenite. Points 5, 7 and 8 require the maximum possible precipitation driving force to generate a high particle nucleation density. Concerning point 7, intragranular precipitation will dominate if the precipitation step occurs in a deformed matrix, for example during annealing after cold rolling. Finally, point 9 would seem to favour the precipitation of nitrides or carbonitrides rather than pure carbides, which would tend to reduce the amount of carbon available to stabilise the residual austenite during the bainitic transformation. Taking into account all of the above criteria, the microalloying element which best satisfies these criteria is vanadium. Precipitation of VanadiumThe equilibrium solubility products for microalloy carbides and nitrides in austenite show that VN is the nitride which has the greatest solubility in austenite and that VC is even more soluble in austenite and in ferrite.10) For the purposes of precipitation strengthening in TRIP grades, it is the precipitates formed in the soft ferrite phase that are the most effective. It is therefore desirable to maintain the V in solution in the hot coil and to precipitate during continuous annealing after cold rolling. Due to the short holding times available in commercial c...

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“…By comparison with other major silicate melt components (i.e., Si, Ca, Fe), alkali metal oxide activity-composition models are only partly at hand to describe complex molten silicates belonging to natural or anthropogenic systems, although great efforts have been made in the thermodynamic modeling of alkalibearing liquids (Ghiorso and Sack, 1995;Pelton and Wu, 1999;Gaye et al, 2001;Romero-Serrano et al, 2005). A main reason for this dichotomy is the difficulty of performing experiments with alkali-bearing systems since alkalis are highly volatile at high temperature and/or reducing conditions (Tsuchiyama et al, 1981;Tissandier et al, 1998;Hewins et al, 2005).…”

Section: Introductionmentioning

confidence: 97%