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H.K.D.H. Bhadeshia,

Phase Transformations Group,

Department of Materials Science and Metallurgy,

University of Cambridge,

Cambridge, U.K.

Calculates the effective diffusivity of carbon in austenite.

Language: | FORTRAN |

Product form: | Source code |

SUBROUTINE MAP_STEEL_PROGC(VMAX, T, XMAX, W, XBAR, HH,

& BOLTZ, R, PI, ANS)

DOUBLE PRECISION VMAX, T, XMAX, W, XBAR, HH, BOLTZ, R, PI, ANS

MAP_STEEL_PROGC calculates the effective diffusivity of carbon in austenite, taking
account of the concentration dependence of this diffusivity. The concentration dependence
uses the theory in [1], and is accounted for by evaluating the weighted
average diffusion coefficient __D__ for the range of carbon concentrations from
that of the bulk alloy to the equilibrium austenite composition at the
temperature concerned i.e.:

The effect due to substitutional alloying elements on the activity and interaction energy of carbon in austenite is calculated according to the theory in [2].

- R.H. Siller and R.B. McLellen, Trans. Metallurgical
Society of the American Institute of Mech. Engineers,
__245__, (1969), 697-700. - J.R. Lacher, Proc. Camb. Phil. Soc. Math. Phys. Sci.,
__33__, (1937), 518. - R.H. Fowler and E.A. Guggenhiem, Statistical Thermodynamics, Cambridge University Press, New York, 1939.

**T**- real- T is the temperature (in Kelvin).
**XMAX**- real- XMAX is the equilibrium mole fraction of carbon in austenite.
**W**- real- W is the carbon-carbon interaction energy in austenite.
**XBAR**- real- XBAR is the mole fraction of carbon in the alloy.
**HH**- real- HH is Planck's constant.
**BOLTZ**- real- BOLTZ is Boltzmann's constant.
**R**- real- R is the gas constant.
**PI**- real- PI is pi.

**ANS**- real- ANS is the weighted average diffusion coefficient of carbon in austenite (in cm
^{2}s^{-1}). **VMAX**- real- VMAX is the speed of diffusion of carbon in austenite.

None.

See [1] for details.

None.

DOUBLE PRECISION T, XMAX, W, XBAR, VMAX, HH, BOLTZ, R, ANS INCLUDE 'map_constants_planck.f' INCLUDE 'map_constants_gas.f' INCLUDE 'map_constants_boltz.f' READ (5,*) T, W, XMAX, XBAR CALL MAP_STEEL_PROGC(VMAX, T, XMAX, W, XBAR, HH, BOLTZ, R, PI, ANS) WRITE (6,10) VMAX 10 FORMAT('The speed of diffusion of carbon in austenite = ',D13.5) WRITE (6,20) ANS 20 FORMAT('Weighted average diffusion coefficient = ',D13.5) STOP END

961.15 8352.3 0.03023 0.0062

Weighted average diffusion coefficient = 0.32954D-08

**Subroutines**:

MAP_STEEL_RRAD

MAP_STEEL_VEL4

**Functions**:

MAP_STEEL_CG

MAP_STEEL_DCG

MAP_STEEL_XALPH

**Utility Subroutines**:

MAP_UTIL_TRAPE

diffusion, carbon, diffusivity, austenite

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