Materials Algorithms Project
Program Library

Subroutine MAP_STEEL_FPARAM

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.

Added to MAP: June 1999.

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Purpose

It is used in the analysis of volume changes occurring during the transformation from austenite to ferrite. This subroutine uses calculated values for the lattice parameters for a given volume fraction of ferrite to evaluate the expected fractional change in volume, and produces as output the difference in this calculated value and the experimentally measured fractional volume change.

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Specification

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Description

MAP_STEEL_FPARAM is used in the analysis of the transformation from austenite to ferrite using MAP_STEEL_DILAT. It uses calculated values for the lattice parameters for a given volume fraction of ferrite to evaluate the expected fractional change in volume, using equation (4) of reference 1. The output, a₁, is the difference in this calculated value (dV/V) from the experimentally measured fractional volume change:

The experimental fractional volume change is measured from the fractional change in length (dL/L) and taken to be approximately 3.dL/L. This subroutine is used as part of an iterative procedure to calculate the volume fraction of ferrite present.

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References

1. H.K.D.H. Bhadeshia, S.A. David, J.M. Vitek, and R.W. Reed, 1991, Materials Science and Technology, 7, 686-698.

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Parameters

Input parameters

AGTX - real

AGTX is the lattice parameter of carbon-enriched austenite.

AGT - real

AGT is the lattice parameter of carbon-free austenite.

AAT - real

AAT is the ferrite lattice parameter.

VA - real

VA is the volume fraction of ferrite present.

DL - real

DL is the fractional change in length (strain).

Output parameters

A1 - real

A1 is the difference between the expected fractional change in volume (as calculated from the given lattice parameters and volume fraction of ferrite using equ. (4) of reference 1) and the experimental fractional volume change (3 x strain = 3 DL).

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Error Indicators

None.

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Accuracy

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Further Comments

The lattice paramters may be specified in any units, provided the same units are used in all cases. Nanometres or Ångstroms are recommended. The specified values for the lattice parameters should be appropriate for the temperature of the material under examination.

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Example

1. Program text

      DOUBLE PRECISION AGTX,AGT,AAT,VA,DL,A1
      WRITE(*,*) 'Input lattice parameters for'
      WRITE(*,*) 'C enriched austenite, C free austenite, ferrite:'
      READ (*,*) AGTX,AGT,AAT
      WRITE(*,*) 'Input ferrite volume fraction, strain:'
      READ (*,*) VA,DL
      CALL MAP_STEEL_FPARAM(AGTX,AGT,AAT,VA,DL,A1)
      WRITE (*,1) A1
    1 FORMAT ('Difference in calculated and measured fractional '
     &        'change in volume = ',F9.5)
      STOP
      END

2. Program data

 Input lattice parameters for
 C enriched austenite, C free austenite, ferrite:
    3.62472   3.61547  2.88565
 Input ferrite volume fraction, strain:
    0.8  0.001463

3. Program results

Difference in calculated and measured fractional change in volume =   0.01041

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Auxiliary Routines

None.

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Keywords

enriched austenite, ferrite, lattice parameter, dilatation

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Download

Download source code

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