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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.

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.

Language: | FORTRAN |

Product form: | Source code |

SUBROUTINE MAP_STEEL_FPARAM(AGTX,AGT,AAT,VA,DL,A1)

DOUBLE PRECISION AGTX,AGT,AAT,VA,DL,A1

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, a_{1}, 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.

- H.K.D.H. Bhadeshia, S.A. David, J.M. Vitek, and R.W. Reed, 1991, Materials Science and Technology,
__7__, 686-698.

**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).

**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).

None.

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.

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

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

Difference in calculated and measured fractional change in volume = 0.01041

None.

enriched austenite, ferrite, lattice parameter, dilatation

**
MAP originated from a joint project of the National Physical Laboratory and the University of Cambridge.
**