[MAP Logo]

Materials Algorithms Project
Program Library


Subroutine MAP_STEEL_DISLOC

  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.

Subroutine added: April 1999.

Top | Next

Purpose

Calculates the dislocation density and the strengthening due to dislocations in steel.

Top | Next | Prev

Specification

Language:FORTRAN
Product form:Source code

SUBROUTINE MAP_STEEL_DISLOC(RTEMP,DEN,STR,IFAIL)

DOUBLE PRECISION RTEMP,DEN,STR
INTEGER IFAIL

Top | Next | Prev

Description

From experiments on acicular ferrite [1] it was found that a dislocation density of 3.9x1014m-2 (+/- 1.97x1014m-2) produced a strengthening of 145MPa. As the strengthening has been shown to depend on the square root of the dislocation density [2], the expected strengthening due to a given dislocation density can be calculated from the equation:

St = 145.sqrt(p)/sqrt(3.9 x 1014)

where p is the dislocation density and St the strengthening (MPa). The dislocation density, p, in bainitic ferrite and martensite has been measured as function of reaction temperature, T. An empirical formula relating these two parameters is [3]:

p = 10(9.2848 + 6880.73/T - 1780360/T2) .

MAP_STEEL_DISLOC uses these two equations to calculate the dislocation density and strengthening of a steel for a given reaction temperature.

Top | Next | Prev

References

  1. J. R. Yang and H. K. D. H. Bhadeshia, 1990, The Dislocation Density of Acicular Ferrite in Steel Welds, American Welding Journal, 69, 305.
  2. A.S. Keh and S. Weissmann, "Deformation structures in body-centered cubic metals", Electron Microscopy and the Strength of Crystals, eds. G. Thomas and J. Washburn, Interscience, New York, pp231-300.
  3. M. Takahashi and H. K. D. H. Bhadeshia, 1990, A Model for the Transition from Upper to Lower Bainite, Materials Science and Technology, 6, 592.

Top | Next | Prev

Parameters

Input parameters

RTEMP - real
RTEMP is the temperature (in Kelvin).

Output parameters

DEN - real
DEN is the dislocation density (m-2).

STR - real
STR is the strengthening due to dislocations (MPa).

IFAIL - integer
IFAIL = 1 if the temperature falls outside the empirical range for which the calculation is valid. The range used in MAP_STEEL_DISLOC is 523.15K to 923.15K.

Top | Next | Prev

Error Indicators

IFAIL = 1 if the temperature falls outside the empirical range for which the calculation is valid, IFAIL = 0 otherwise.

Top | Next | Prev

Accuracy

Error ~ 25% or more (see Description above).

Top | Next | Prev

Further Comments

None.

Top | Next | Prev

Example

1. Program text

     DOUBLE PRECISION RTEMP,DEN,STR
      INTEGER IFAIL
      WRITE(*,*) 'Input reaction temperature (Kelvin):'
      READ (*,*) RTEMP
      CALL MAP_STEEL_DISLOC(RTEMP,DEN,STR,IFAIL)
      IF (IFAIL.EQ.1) GOTO 100
      WRITE (*,1) DEN,STR
      GOTO 110
  100 WRITE (6,2) 
  110 STOP
    1 FORMAT ('Density =       ',D11.3,' per square metre'
     &       /'Strengthening = 'F10.3,' MPa')
    2 FORMAT ('Temperature falls outside valid range')
      END

2. Program data

 Input reaction temperature (Kelvin):
 700

3. Program results

Density =         0.303D+16 per square metre
Strengthening =    403.970 MPa

Top | Next | Prev

Auxiliary Routines

None.

Top | Next | Prev

Keywords

steel, dislocation density, strengthening

Top | Next | Prev

Download

Download source code

Top | Prev

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

MAP Website administration / map@msm.cam.ac.uk

Top | Index | MAP Homepage Valid HTML 3.2!