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C. Capdevila and H.K.D.H. Bhadeshia,
Phase Transformations Group,
Department of Materials Science and Metallurgy,
University of Cambridge,
Cambridge CB2 3QZ, U.K.
E-mail: cc226@cus.cam.ac.uk
Added to MAP: October 2000.A model incorporating nucleation and growth theory was used to describe the volume fraction of recrystallisation as a function of deformation and the heating rate. Observed variations in the recrystallisation temperature and the nucleation rate have been found to be consistent with the assumption that anything which introduces heterogeneity into the microstructure stimulates recrystallisation.
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Language: |
Fortran 77 |
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Product form: |
Source code |
Complete program.
Recrystallisation in commercial MA-ODS alloys occurs at very high temperatures close to melting, in spite of their large stored energy [1-3]. This is unlike conventional alloys which recrystallise at much lower homologous temperatures [4]. It could be argued that recrystallisation is inhibited by the fine yttria dispersoids. However, this is inconsistent with experimental observations which indicate an insensitivity of the recrystallisation temperature to variations in the overall pinning force [5]. Indeed, the limiting grain size in the presence of particles is far greater than the starting grain size.
There are indications that the activation energy for recrystallisation is very large, far greater than that for self diffusion [4,6] reported that recrystallisation happens at high temperatures and over a narrow temperature range during continuous heating. Cold-deformation of the consolidated produce has a dramatic effect on recrystallisation behaviour, as first recognised by Regle and Alamo [7]. The purpose of the present study was to analyse the effect of cold deformation on the nucleation of recrystallisation, and to formulate a model to explain the anisothermal recrystallisation behaviour in a commercial MA-ODS iron alloy designated PM2000.
Following the Johnson-Mehl-Avrami approach reviewed by Christian [8], the fraction z of recrystallisation, as a function of time t, is given by
where f is a shape factor, I is the nucleation rate and V is the grain-boundary velocity. Each unrecrystallised grain has a number of faces, which may bulge. Empirical expressions for I and V has been considered.
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No information supplied.
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Complete program.
|
CTEMP |
RECRYS |
NUCL |
VEL |
|
850. |
.000000E+00 |
.000000E+00 |
.315194E-13 |
|
860. |
.000000E+00 |
.000000E+00 |
.549784E-13 |
|
870. |
.000000E+00 |
.000000E+00 |
.949683E-13 |
|
880. |
.000000E+00 |
.000000E+00 |
.162498E-12 |
|
890. |
.000000E+00 |
.000000E+00 |
.275490E-12 |
|
900. |
.000000E+00 |
.130345E+23 |
.462867E-12 |
|
910. |
.000000E+00 |
.146652E+23 |
.770898E-12 |
|
920. |
.000000E+00 |
.164673E+23 |
.127299E-11 |
|
930. |
.669982E-03 |
.184553E+23 |
.208463E-11 |
|
940. |
.532497E-02 |
.206444E+23 |
.338613E-11 |
|
950. |
.345463E-01 |
.230509E+23 |
.545674E-11 |
|
960. |
.197643E+00 |
.256920E+23 |
.872574E-11 |
|
970. |
.103564E+01 |
.285857E+23 |
.138481E-10 |
|
980. |
.502177E+01 |
.317512E+23 |
.218162E-10 |
|
990. |
.215891E+02 |
.352087E+23 |
.341225E-10 |
|
1000. |
.668685E+02 |
.389794E+23 |
.529969E-10 |
|
1010. |
.992220E+02 |
.430854E+23 |
.817487E-10 |
|
1020. |
.999945E+02 |
.475503E+23 |
.125256E-09 |
|
1030. |
.999986E+02 |
.523985E+23 |
.190666E-09 |
|
1040. |
.999998E+02 |
.576557E+23 |
.288383E-09 |
|
1050. |
.100000E+03 |
.633488E+23 |
.433460E-09 |
|
1060. |
.100000E+03 |
.695057E+23 |
.647549E-09 |
|
1070. |
.100000E+03 |
.761558E+23 |
.961615E-09 |
|
1080. |
.100000E+03 |
.833296E+23 |
.141968E-08 |
|
1090. |
.100000E+03 |
.910587E+23 |
.208401E-08 |
|
1100. |
.100000E+03 |
.993763E+23 |
.304214E-08 |
none
ODS, Ferritic Steel, Steel, Recrystallisation
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