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Subroutine MAP_STEEL_GMAAX

Provenance of code.
Purpose of code.
Specification.
Description of subroutine's operation.
References.
Parameter descriptions.
Error indicators.
Accuracy estimate.
Any additional information.
Example of code
Auxiliary subroutines required.
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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

Calculates the optimum nucleus carbon content and the activity of carbon in ferrite.

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Specification

Language:	FORTRAN
Product form:	Source code

SUBROUTINE MAP_STEEL_GMAAX(A1,A,W1,F,R,T,X,AFE,H1,S1)

DOUBLE PRECISION A1,A,W1,F,R,T,X,AFE,H1,S1

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Description

MAP_STEEL_GMAAX uses Newton iteration to calculate the optimum nucleus carbon content and the activity of carbon in the ferrite nucleus.

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References

H.I. Aaronson, H.A. Domian and G.M. Pound, Trans. AIME, 236, (1966), 753.
G.J. Shiflet, J.R. Bradley and H.I. Aaronson, Metallurgical Transactions, 9A, (1978), 999.
J.A. Lobo and G.H. Geiger, Metallurgical Transactions, 7A, (1976), 1347 and 1359.
H.K.D.H. Bhadeshia, Metal Science, 14, (1980), 230.

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Parameters

Input parameters

A - real: A is the natural logarithm of the activity of carbon in austenite.
W1 - real: W1 is the carbon-carbon interaction energy in ferrite (in joules per mole, Jmol^-1).
F - real: F is the free energy change (in joules per mole) for the transformation from austenite to ferrite in pure iron, modified for the presence of substitutional solutes. The transformation is assumed to occur without composition change.
R - real: R is the universal gas constant (in joules per mole per kelvin, Jmol^-1K^-1).
T - real: T is the absolute temperature (in kelvin).
AFE - real: AFE is the natural logarithm of the activity of iron in austenite.
H1 - real: H1 is the excess partial molar enthalpy of solution of carbon in ferrite.; H1 is 105525.0 if T > 1000, 111918.0 if T <= 1000.
S1 - real: S1 is the excess partial molar entropy of solution of carbon in ferrite.; S1 is 45.34521 if T > 1000, 51.44 if T <= 1000.

Output parameters

A1 - real: A1 is the natural logarithm of the activity of carbon in ferrite.
X - real: X is the optimum carbon concentration (mole fraction) of the ferrite nucleus.

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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

       DOUBLE PRECISION A1,A,W1,F,R,T,X,AFE,H1,S1
       INCLUDE 'map_constants_gas.f'
       READ (5,*) A,W1,F,AFE
       READ (5,*) T
       IF (T .GT. 1000.0) THEN
          H1 = 105525.0
          S1 = 45.34521
       ELSE
          H1 = 111918.0
          S1 = 51.44
       END IF
       CALL MAP_STEEL_GMAAX(A1,A,W1,F,R,T,X,AFE,H1,S1)
       WRITE (6,10) A1, X
10     FORMAT ('Natural log of activity of carbon in ferrite = ',F10.5
&        'Optimum carbon concentration in ferrite nucleus = ',F10.5)
       STOP
       END