New functionalities of TC-DICTRA

Transcription

1 New functionalities of TC-DICTRA Thermo-Calc Anwendertreffen und Schulung Aachen th of June 2003 Dr. Anders Engström Stockholm Technology Park SE Stockholm, Sweden

2 Outline Introduction Thermo-Calc Classic, version P Thermo-Calc for Windows, TCW2.2 DICTRA, version 22 Programming interfaces Databases

3 History of Thermo-Calc First version of Thermo-Calc was created in First sale was made in First sale of DICTRA somewhat later in The team of researchers behind the software worked at the department of Physical Metallurgy at the Royal Institute of Technology In the beginning the department was the base for development and distribution of the software packages.

4 History of Thermo-Calc To protect the software Thermo-Calc and DICTRA the researcher created a foundation and donated their software rights to: Stiftelsen för Tillämpad Termodynamik or Foundation of Computational Thermodynamics (Current chairman: Bo Jansson)

5 History of Thermo-Calc In 1997 it was realised that the department was not suited to be the base of a sizable software operation and the foundation created the company: AB to take care of software maintenance, development and distribution.

6 History of Thermo-Calc Today is the exclusive distributor of the software with agents in USA, Germany, Japan, China and South America. The foundation benefits from royalty payments which are used for grants to young researchers and to support of various projects in the filed of computational thermodynamics.

7 Thermo-Calc Classic, version P New features and commands in TDB, GES5, POLY3, POST, PARROT and ED_EXP modules Modifications to some special modules, i.e. BIN, SCHEIL and POURBAIX Improved documentation Increased example collection Improved graphics & 3D presentation Some bugs have been corrected

8 DATABASE_RETRIEVAL (TDB) New Command: SET_AUTO_APPEND For conveniently appending a database with the same system definition Automatic conversion of database files for compatibility between Unix and PC/Windows

9 GIBBS_ENEGRY_SYSTEM (GES5) The maximum number of constituents in a non-ideal phase has been increased from Ideal phases can have 1000 constituents. Needed for solution phases with many associates or for aqueous solutions, in complex heterogeneous interaction systems.

10 POLY_3 Improved convergence in the commands: COMPUTE_EQUILIBRIUM COMPUTE_EQUILIBRIUM * MAP and STEP somewhat modified Possibility to check internal stability of phases using: STABILITY_CHECK in the SPECIAL_OPTIONS command

11 POLY_3 Improvements in the command: COMPUTE_TRANSITION Now possible to look for any new phase appearing when one conditions is varied

12 TCP Example Calculation of phase transitions in the alloy Ti- 10Al-2V using COMPUTE_TRANSITION Exploring the new graphics Dumping diagrams Using C-E *

13 POLY_3 Calculation of T 0 -temperature The temperature or composition where the two phases have the same Gibbs energy T γ α T 0 -line G m γ G m T=T 0 for X=X 1 α G m X X 1 X This is usually regarded as the thermodynamic limit for a partitionless transformation Implemented in the SPECIAL_OPTIONS command and as an option in STEP

14 POLY_3 Calculation of paraequilibrium % M T 0. α γ Paraequilibrium or partial equilibrium occur when one component in an alloy diffuse much faster than the others. % C Conditions allow a partly partitionless transformation, where the new phase can form with different content of the mobile component, but with the same composition of the slow diffusing components. Implemented in the SPECIAL_OPTIONS command and as an option in STEP

15 POLY_3 % M T 0. Slow γ Iso-activity line for C in γ % M ν α f α f γ Rapid transformation Iso-activity line for C in α % C Distance

16 TCP Example Calculation of a T 0 -line and a phase diagram according to paraequilibrium conditions for γ to α transformations in a Fe-1.5Mn-0.3Si-C alloy Also, we will calculate an isothermal section of a phase diagram for Fe-Mn-0.3Si-C and append a calculated diagram according to Paraequilibrium conditions

17 POST Conditions and database name are displayed in diagram when plotting New command: CREATE_3D_PLOTFILE Creates vrml-file (Virtual Reality Modelling Language) from tabulated data. Makes it possible to view both squared, triangular and tetrahedral diagrams using one of many plugins freely available for web browsers.

18 Example of VRML viewers for Internet Explorer and Netscape Navigator For Windows and Mac: Cortona WRML Client from Parallelgraphics For Windows, Linux and SIG IRIX 6.2: VRMLview from Systems in Motion (SIM)

19 TCP Example Calculate the γ-volume in the system Fe-Cr-C Also, we will take a look at some liquidus surfaces as well as the γ-volume for the Fe-Cr-V-C system

20 Edit-Experiments (ED_EXP) Now possible to store and restore a weight set that records all the weights given to different experimental points in an assessment, using the new commands STORE_ALL_WEIGHTS and RESTORE_ALL_WEIGHTS. It is also possible to list out all the calculated equilibrium points (using the LIST_ALL_EQUILIBRIA command) and to immediately calculate property diagrams with selective stepping options in which the calculations and the set stepping variable are based on a specific experimental point (using the GRAPHICS_PLOT command, which is identical to the STEP_WITH_OPTIONS command in the POLY module).

21 TCW2

22 TCW2.2 TCC version P DLL engine Database information displayed on request Possibility to append databases Possibility to use functions in the post module Improved show value feature Improved MACRO management Some other small improvements, e.g. re-entrant function

23 TCW2.2 Example Calculation of Pitting Resistance Equivalence (PRE) in a duplex stainless steel: How to view database information How to Append a database How to change phase status How to enter functions and tables Exploring the show value feature

24 Example: PRE in a duplex stainless steel PRE (Pitting Resistance Equivalence) is a empirical measure for corrosion resistance in stainless steels. One definition of PRE is: PRE=w%Cr+3,3*w%Mo+16*w%N For duplex stainless steels, it is desirable to have a high and balanced PRE-numbers in ferrite and austenite.

25 DICTRA version 22 TCC version P thermodynamic engine Larger workspaces to handle simulations with >10 elements Possibility to simulate interfacial mobility controlled phase transformations. Achieved by adding a Gibbs-energy contribution to the growing phase Model for diffusion in stoichiometric phases without any freedom, such as A 2 B Numerical integration/differentiation of curves in the post processor

26 Diffusion in stoichiometric phases Fe-Al BCC BCC + Al 2 Fe Al 2 Fe Al 13 Fe 4 BCC Al 2 Fe Al 5 Fe 2 Al 13 Fe 4 FCC Al 5 Fe 2 FCC + Al 13 Fe 4 Model: C J k = < L ' kj > j= 1 µ λ j (Ågren)

27 Diffusion of C in Cementite (Fe3C) Experimental data from Ozturk et al. Experimental data from Schneider et al. (Höglund, 2002) Experimental information on the growth of cementite layers at different carbon activities Mobility of C in cementite evaluated from this data Aachen 12th of June 2003

28 Evaluation of mobility for C in Cementite Mobility of C evaluated for each activity The average mobility determined at each temperature The logarithm of the mobility assumed to have a linear temperature dependency Finally, the parameters M0 and Q in the expression below were assessed M Cem C = M 0 e Q / RT

29 Solidification simulations Equilibrium methods (lever-rule) Solute diffusion is rapid, i.e. complete solute back diffusion uniform composition in both solids and liquid Non equilibrium methods (SCHEIL) Negligible diffusion in solids, i.e. no solute back diffusion solids retain same composition through solidification Partial equilibrium methods (SCHEIC) Complete interstitial but negligible substitutional solute back diffusion Moving phase boundary methods (DICTRA) Full integration of thermodynamics and kinetics

30 Solidification simulations Lever rule Alloy: Fe- 5%Cr 1%C 2%V -8%W SCHEIC SCHEIL

31 SCHEIC (SCHEil with Interstitial Carbon) Basically a SCHEIL model for the substitutional components, with the addition that interstitial components are allowed to move freely among the liquid and all portions of the solid phases, so that their chemical potentials becomes equal everywhere throughout the whole system. Status TCS has developed an application program with the aid of the TQ interface. Future A separate module is planed to be available in TCQ and TCW 3.0

32 Solidification simulations using DICTRA Assumptions: Assuming that equilibrium hold locally at the phase interface. Assumption regarding the geometry and size of the system, e.g. the interdendritic spacing. Assumption regarding the cooling rate. However, Full consideration of diffusion in both the liquid and solid phases.

33 DICTRA Example Microsegregation during solidification: Bcc Fcc Bcc υ Liquid Liquid υ Bcc Fcc υ Liquid Fcc υ Liquid

34 DICTRA Example cont. Secondary dendrite arm spacing assumed to be 200 µm. Cooling rate assumed to be 0.2 ºC/s. Inactive phases Bcc Fcc Liquid λ/2 =100 µm Temperature function: TIME λ/2

35 Thermo-Calc Programming Interfaces New Versions of: TC-API (Thermo-Calc Application Programming Interface) For Windows programming Written in C Available for Windows and Linux environments TQ-I (Thermodynamic Calculation Interface) Written in FORTRAN Available for all UNIX dialects and Windows. TC-Toolbox in MATLAB Available for Windows. All new versions based on Thermo-Calc version P

36 TQ-I version 4.0 Now also possible to calculate kinetic coefficients, e.g. atomic mobilities, tracer diffusion, chemical diffusion and intrinsic diffusion coefficients All syntaxes the same as in DICTRA, e.g. M(Phase,J) DT(Phase,J) Mobility coefficient where J=diffusing specie Tracer diffusion coefficient where J=diffusing specie DC(Phase,J,K,N) Chemical diffusion coefficient where K=gradient specie, and N=reference specie DI(Phase,J,K,N) Intrinsic diffusion coefficient

37 TCFE3 Steel database version 3 Update of TC-FE2000 Released with TCC version P For Fe-rich alloys with the alloying elements: Al-B-C-Co-Cr-Cu-Mg-Mn-Mo-N-Nb-Ni-O-P-S-Si-Ti-V-W

38 Improvements: TCFE3 Improved data for sigma phase in stainless steel. Data added in the Nb-Ni, Fe-Cr-Mo and Cr-Mo-Ni systems. Improved data for the Ti(C,N) fcc-carbonitride. Improvements in starting values.

39 TCFE3 Comparison to experimental liquidus data for low alloy steels, tool steels and stainless steels Liquidus Calculated value Data from: Jernkontoret A Guide to the Solidification of Steels Experimental value

40 TCFE3 Comparison to experimental solidus data for low alloy steels, tool steels and stainless steels Solidus 1500 Calculated value Data from: Jernkontoret A Guide to the Solidification of Steels, where a cooling rate of 0.1 C/s was used Experimental value

41 TCFE3 Comparison to experimental equilibrium austenite composition in different multicomponent, multiphase stainless steels Chromium content in Austenite (mass-%) Calculated value Data from: S.M. Wessman et al., EC Report EUR20315 EN Experimental value

42 TCFE3 Comparison to experimental equilibrium austenite composition in different multicomponent, multiphase stainless steels Molybdenum content in Ferrite (mass-%) Calculated value Data from: S.M. Wessman et al., EC Report EUR20315 EN Experim ental value

43 TCFE3 Comparison to experimental equilibrium fractions of ferrite and sigma-phase for a duplex stainless steel as a function of temperature σ α Data from: J.-O. Nilsson, P. Kangas, T. Karlsson and A. Wilson, Metall. Mater. Trans. A 31A, (2000), 35.