New functionalities of TC-DICTRA - RWTH Aachen Universityweb.access.rwth-aachen.de/THERMOCALC/proceedings/anders.pdf · 2003. 6. 16. · Thermo-Calc Software Aachen 12th of June 2003

Thermo-Calc Software www.thermocalc.com

Aachen 12th of June 2003

New functionalities of TC-DICTRA

Thermo-Calc Anwendertreffen und SchulungAachen 11-13th of June 2003

Dr. Anders EngströmThermo-Calc Software

Stockholm Technology ParkSE-113 47 Stockholm, Sweden



Outline

Introduction

Thermo-Calc Classic, version P

Thermo-Calc for Windows, TCW2.2

DICTRA, version 22

Programming interfaces

Databases



History of Thermo-Calc

First version of Thermo-Calc was created in 1981. First sale was made in 1984. First sale of DICTRA somewhat later in 1994.

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.




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)




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:

”Thermo-Calc Software AB”

to take care of software maintenance, development and distribution.




Today Thermo-Calc Software 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.



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



DATABASE_RETRIEVAL (TDB)

New Command: SET_AUTO_APPENDFor conveniently appending a database with the same system definition

Automatic conversion of database files for compatibility between Unix and PC/Windows



GIBBS_ENEGRY_SYSTEM (GES5)

The maximum number of constituents in a non-ideal phase has been increased from 80 200. Ideal phases can have 1000 constituents.

Needed for solution phases with many associates or for aqueous solutions, in complex heterogeneous interaction systems.



POLY_3Improved convergence in the commands:

COMPUTE_EQUILIBRIUM

COMPUTE_EQUILIBRIUM *

MAP and STEP somewhat modified

Possibility to check internal stability of phases using:STABILITY_CHECKin the SPECIAL_OPTIONS command



POLY_3

Improvements in the command:COMPUTE_TRANSITION

Now possible to look for any new phase appearing when one conditions is varied



TCP Example

Calculation of phase transitions in the alloy Ti-10Al-2V using COMPUTE_TRANSITION

Exploring the new graphics

Dumping diagrams

Using C-E *



POLY_3Calculation of T0-temperatureThe temperature or composition where the two phases have the same Gibbs energy

γmGT

X

Gm

X

γ

α

T0-line

αmG

T=T0 for X=X1

X1This is usually regarded as the thermodynamic limit for a partitionless transformationImplemented in the SPECIAL_OPTIONS command and as an option in STEP



POLY_3Calculation of paraequilibrium

% M

% C

γ

α

T0 . Paraequilibrium or partial equilibrium occur when one component in an alloy diffuse much faster than the others.

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



POLY_3

γ

α

• •

% M

Iso-activity line for C in γ

Iso-activity line for C in α

Rapid transformation

Slow ν

fα fγ

% M

T0 .

Distance% C



TCP Example

Calculation of a T0-line and a phase diagram according to paraequilibrium conditions for γto α transformations in a Fe-1.5Mn-0.3Si-Calloy

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



POST

Conditions and database name are displayed in diagram when plotting

New command: CREATE_3D_PLOTFILECreates vrml-file (Virtual Reality Modelling Language) from tabulated data.

Makes it possible to view both squared, triangular and tetrahedral diagrams using one of many plug-ins freely available for web browsers.



Example of VRML viewers for Internet Explorer and Netscape Navigator

For Windows and Mac:Cortona WRML Client from Parallelgraphicswww.parallelgraphics.com

For Windows, Linux and SIG IRIX 6.2:VRMLview from Systems in Motion (SIM) www.sim.no

http://www.parallelgraphics.com/

http://www.parallelgraphics.com/

http://www.sim.no/



TCP Example

Calculate the “γ-volume” in the system Fe-Cr-C

Also, we will take a look at some liquidussurfaces as well as the “γ-volume” for the Fe-Cr-V-C system



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).



TCW2



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



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



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.



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 A2B

Numerical integration/differentiation of curves in the post processor



Diffusion in stoichiometric phases

BCC

FCC +Al13Fe4

BCC +Al2Fe

Al2Fe

Al5Fe2

Al13Fe4

Fe-Al

Al 2F

e

Al 13

Fe4

FCCBCC

Al 5F

e 2

λ

µ∆∑ ><−==

jC

1j

'kjk LJ (Ågren)Model:



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



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

RTQCemC eMM /

0−⋅=



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



Solidification simulations

Alloy:Fe- 5%Cr – 1%C – 2%V -8%W

Lever ruleSCHEIC

SCHEIL



SCHEIC (SCHEil with Interstitial Carbon)

Basically a SCHEIL model for the substitutionalcomponents, 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



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 andsolid phases.



DICTRA ExampleMicrosegregation during solidification:

Liquid

LiquidBccυ

LiquidBccυ

Fccυ

LiquidFccυ

Bcc

Fcc



DICTRA Example cont.

Secondary dendrite arm spacing assumed to be 200 µm.

Cooling rate assumed to be 0.2 ºC/s.

λ/2

Temperature function:1780 – 0.2 • TIME

Liquidλ/2 =100 µm

Inactive phases

Bcc

Fcc



Thermo-Calc Programming InterfacesNew Versions of:

TC-API (Thermo-Calc Application Programming Interface) For Windows programmingWritten in CAvailable for Windows and Linux environments

TQ-I (Thermodynamic Calculation Interface)Written in FORTRANAvailable for all UNIX dialects and Windows.

TC-Toolbox in MATLAB® Available for Windows.

All new versions based on Thermo-Calc version P



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) Mobility coefficient where J=diffusing specie

DT(Phase,J) Tracer diffusion coefficient where J=diffusing specie

DC(Phase,J,K,N) Chemical diffusion coefficient whereK=gradient specie, and N=reference specie

DI(Phase,J,K,N) Intrinsic diffusion coefficient



TCFE3

Thermo-Calc Software 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



TCFE3Improvements:

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.



TCFE3Comparison to experimental liquidus data for low alloy steels, tool steels and stainless steels

Liquidus

1350

1375

1400

1425

1450

1475

1500

1525

1550

1350 1375 1400 1425 1450 1475 1500 1525 1550

Experimental value

Calc

ulat

ed v

alue

Data from: Jernkontoret ” A Guide to the Solidification of Steels”



TCFE3

Solidus

1100

1200

1300

1400

1500

1100 1200 1300 1400 1500

Experimenta l va lue

Cal

cula

ted

valu

e

Comparison to experimental solidus data for low alloy steels, tool steels and stainless steels

Data from:Jernkontoret ” A Guide to the Solidification of Steels”, where a cooling rate of 0.1°C/s was used



TCFE3

C h ro m iu m co n te n t in Au ste n ite (m ass-% )

0

5

10

15

20

25

30

0 5 10 15 20 25 30

Ex p e rim e n ta l va lu e

Cal

cula

ted

valu

e

Comparison to experimental equilibrium austenite composition in different multicomponent, multiphase stainless steels

Data from:S.M. Wessman et al., EC Report EUR20315 EN



TCFE3Comparison to experimental equilibrium austenite composition in different multicomponent, multiphase stainless steels

M olybde num conte nt in Fe rrite (mass-%)

0.00

1.00

2.00

3.00

4.00

5.00

6.00

0.00 1.00 2.00 3.00 4.00 5.00 6.00

Experimental value

Cal

cula

ted

valu

e

Data from:S.M. Wessman et al., EC Report EUR20315 EN



TCFE3Comparison to experimental equilibrium fractions of ferrite and sigma-phase for a duplex stainless steel as a function of temperature

α

σ

Data from:J.-O. Nilsson, P. Kangas, T. Karlsson and A. Wilson, Metall. Mater. Trans. A 31A, (2000), 35.

Documents

New functionalities of TC-DICTRA - RWTH Aachen Universityweb.access.rwth-aachen.de/THERMOCALC/proceedings/anders.pdf · 2003. 6. 16. · Thermo-Calc Software Aachen 12th of June 2003