The FactSage FSstel steel alloy database
With FactSage 5.3 & 5.4 there have been many changes, not only in the content of the databases, but in the way they are organized and used. Be sure to read the general documentation "How to use the databases with FactSage 5.4" on the previous menu.
TO OBTAIN :
- A LIST OF all the unary, binary, ternary and quaternary SYSTEMS WHICH HAVE BEEN ASSESSED
- A LIST OF ALL ASSESSED phases IN EACH OF THE SYSTEMS
- A CALCULATED PHASE DIAGRAM FOR EACH OF THE LISTED BINARY SYSTEMS
- ASSiSTANCE WITH PHASE SELECTION
- A LIST OF REFERENCES TO INDIVIDUAL SYSTEM ASSESSMENTS
CLICK ON "List of optimized systems and calculated binary phase diagrams."
The FactSage FSstel steel database is based on relevant steel sub-systems from the old SGTE SGSL Solution database, but now incorporating updates of those systems as well as new published assessments. “Tramp elements” have also been included to allow calculations relating to recycling and removal of unwanted impurities to be performed.
The model and data developed by Jung, Degterov and Pelton [1] for different liquid MeO and Me2O oxide associates have been incorporated in the liquid phase. These may be used in conjunction with the present FSstelBASE or the FS53BASE for calculations relating to equilibrium concentrations of oxygen resulting from particular processes such as deoxidation of steel. The data for the stoichiometric, solid oxides involved are identical in both databases. The liquid steel phase is also compatible with the data for oxide solutions (such as the molten slag) and stoichiometric oxides in the FToxid databases. A similar associate model [2] is used to take account of M-S interactions in the liquid phase. Data for stoichiometric solid sulphides are also available to allow desulphurization calculations. The liquid phase of the Fe-Mn-S system has been re-assessed by Hack and Jantzen [3] to agree with the phase diagram results of Mietinen and Hallsted [4]. Thus a full description of the Fe-Mn-S system is available in the present database.
The elements included in the FactSage FSstel steel database are:
Al, B, Bi, C, Ca, Ce, Co, Cr, Cu, Fe, La, Mg, Mn, Mo, N, O, Nb, Ni, P, Pb, S, Sb, Si, Sn, Ti, V, W, Zr
The database contains approximately 115 completely assessed binary alloy systems, together with 85 ternary and 17 quaternary systems for which assessed parameters are available for phases of practical relevance. As such, the database is intended to provide a sound basis for calculations covering a wide range of steelmaking processes, e.g.
- reduction of oxygen and sulphur concentration levels through deoxidation and desulphurization of the melt
- constitution of a wide range of steels, including austenitic, ferritic and duplex stainless steels and including carbide and nitride formation
- conditions for heat treatment operations to produce a desired constitution
- conditions for scrap remelting to maintain as low concentrations as possible of undesirable “tramp elements”
- melt-crucible interactions
- etc.
As its name implies, the database is intended to allow calculations primarily for Fe-rich composition ranges, but since many of the assessed parameters, particularly for the binary sub-systems, provide reliable descriptions over all ranges of composition, calculations may sometimes be extended to higher concentrations of alloying components in Fe.
Information on the possibility of calculating phase equilibria or thermodynamic properties for other composition ranges of multi-component alloys may be obtained by referring to the listing of systems and phases for which assessed parameters are available. (Click on "List of optimized systems and calculated binary phase diagrams.") This will allow the user to determine whether proposed calculations for a particular higher-order system will be based on a complete set of assessed binary and ternary parameters (at best) or summation of binary parameters only (at worst). Clearly the latter case, or use of incompletely assessed data sets, can lead to incorrect or unreliable results.
In a binary system, if no assessed mixing parameters are available for a particular phase, the phase will be treated as ideal. Correspondingly, the properties of a ternary or higher-order phase will be calculated applying the appropriate models used in the database. This procedure may give useable results if the alloy compositions in question are close to a pure component or to a binary edge for which assessed data are available. However, results of calculations for other composition ranges should be treated with extreme caution.
Specific information on each alloy system can be obtained from the list of references supplied with the documentation "List of compounds and solutions" on the present menu.
As mentioned above, the database is intended to allow calculations primarily for Fe-rich composition ranges, although the assessed data are also reliable for higher concentrations of alloying components in a number of cases.
The database is generally valid for the temperature range of approximately 400oC to 1800oC, although for some steels containing high melting point metals, calculations are reliable to still higher temperatures.
In the assessments, the liquid phase has been described using a simple substitutional solution approach based on the Redlich-Kister-Muggianu polynomial expression. The fcc(austenite) and bcc(ferrite) Fe-rich phases have been described using a sub-lattice model with carbon, nitrogen and vacancies on interstitial sites. Other non-stoichiometric intermetallic phases have also been described using sublattice models.
1. In-Ho Jung, Sergei A. Degterov, Arthur D. Pelton, A Thermodynamic Model for Deoxidation
Equilibria in Steel, Met. And Mat. Trans., 35B, 493-508 (2004).
2. In-Ho Jung, Private communication, 2004.
3. Klaus Hack, Tadjana Jantzen, GTT-Technologies, Private communication, 2004
4. J. Miettinen and B. Hallstedt, CALPHAD, Vol. 22, No.2 (1998), 257-273.