Materials Algorithms Project
Program Library

Program MAP_STEEL_FINITE

1. Provenance of code.
2. Purpose of code.
3. Specification.
4. Description of subroutine's operation.
5. References.
6. Parameter descriptions.
7. Error indicators.
8. Accuracy estimate.
9. Any additional information.
10. Example of code
11. Auxiliary subroutines required.
12. Keywords.
13. Download source code.
14. Links.

Provenance of Source Code

H.K.D.H. Bhadeshia,
Phase Transformations Group,
Department of Materials Science and Metallurgy,
University of Cambridge,
Cambridge, U.K.

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Purpose

Uses a finite difference method for the solution of the problem of X enrichment during the ageing of bainitic steels.

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Specification

Complete program.

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Description

When cementite first forms in bainite or martensite, it grows by a paraequilibrium transformation mechanism, so substitutional solutes (such as chromium or manganese) do not partition during growth. The cementite therefore has a non-equilibrium composition when it first forms. In fact, the ratio of iron to X (substitutional solute) in the cementite is the same as that in the parent phase.

Since the cementite is not at equilibrium due to the slow diffusivity of X at low temperatures, there will be a tendency for solute to partition between the the cementite and matrix over time. MAP_STEEL_FINITE calculates this redistribution by diffusion.

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References

1. H.K.D.H. Bhadeshia, Materials Science and Technology, 5, (1989), 131-137.

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Parameters

Input parameters

KTEMP - real

KTEMP is the absolute temperature (in kelvin).

EQFER - real

EQFER is the equilibrium weight percent of X in ferrite at the ageing temperature.

EQCEM - real

EQCEM is the equilibrium weight percent of X in cementite at the ageing temperature.

EBAR - real

EBAR is the average weight percent of X in the alloy.

TCEM - real

TCEM is the thickness of cementite (in metres).

TFER - real

TFER is the thickness of ferrite (in metres).

ICEM, IFER - integers

ICEM and IFER are the number of finite dimension slices for cementite and ferrite respectively.

J1 - integer

J1 is the number finite time slices

SETIME - real

SETIME is the time (in hours) that the experiment is to run.

A3 - real

A3 controls the amount of output written out. Data is written out during the finite difference analysis when the number of the time step is a multiple of A3.

FREQ - real

FREQ is the pre-exponential factor for the diffusion coefficient.

Q - real

Q is the activation free energy for the diffusion coefficient.

JTEST - integer

JTEST is to adjust the mass balance condition once cementite has achieved its equilibrium condition at its surface.

Output parameters

None

All output is to STDOUT (usually the screen).

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Error Indicators

None.

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Accuracy

No information supplied.

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Further Comments

None.

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Example

1. Program text

       Complete program

2. Program data

838.15       0.5D-03   39.0D+00   2.5D+00   1.0D-07   2.0D-06   1000   5
0.0003D+00   2.0D+00   43.2       6         5         2         2
2.53D-04     240580    0 
       1    0.7012D+01    (Cementite)
       2    0.6998D+01
       3    0.6988D+01
       4    0.6983D+01               Slice number, normalised conc.
       5    0.6982D+01
       1    0.2205D-01    (Ferrite)
       2    0.4387D-01
       3    0.6565D-01
       4    0.8737D-01
       5    0.1090D+00
       6    0.1306D+00

3. Program results

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Auxiliary Routines

None.

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Keywords

finite differences, enrichment, bainite ageing

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Download

Download source code

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