C. N. Hulme-Smith
Phase Transformations Group,
Department of Materials Science and Metallurgy,
University of Cambridge,
27 Charles Babbage Road,
Cambridge, CB3 0FS, U.K.
E-mail: C. N. Hulme-Smith
Added to MAP: July 2019.
This program simulates the rapid cooling of alloys from the molten state and calculates the amount of austenite and ferrite during cooling. It also calculates the temperature as a function of time, which may be used for separate solid-state transformation modelling. It is to be used with MTDATA which provides thermodynamic modelling at each step of the program, to determine whether phase changes will occur and the identities and composition of newly-forming phases.
DROPCOOL was originally written under the name TeRRaCoTtA (Temporally-resolved rapid cooling of test alloys) for the InnovateUK project Series production of Lightweight parts by Isostatic pressing of Metal powders to give Material and Energy Reduction (SLIMMER).
Language: | FORTRAN 77 |
Product form: | Source corde and Linux-compatible executable |
Platform: | Linux - tested on Debian 8.0 (Jessie) and 9.0 (Stretch) |
Complete program.
DROPCOOL is a simulation of rapid cooling, designed to be used with small droplets, as found in the gas atomisation of liquid metals to form powders. It uses physical laws to simulate radiative and convective heat flow from spherical particle and calculates a time-resolved temperature profile. Thermokinetic modelling is used to predict solidification and the phases that form from the melt.
At each timestep, the driving force for solidification is calculated, allowing for either austenite or ferrite to be the nucleating phase. The expected number of solid nuclei is calculated at each timestep and once this expected number exceeds one, solidification is assumed to have begun. There then follows a period of recalescence during which the temperature of the droplet increases and solidification is assumed to be rapid and of the nucleating phase only. Once the temperature reaches a peak, the Scheil-Guliver model is used to determine phase fraction and composition of any new solid. In the case of ferrite being the nucleating phase, the peritectic reaction is permitted and accounted for in terms of heat flow and solid fraction. The Scheil-Guliver model is then restarted to allow any remaining liquid to solidify. Once solidification is complete, the temperature profile is calculated down to some specified end temperature, which provides a cooling profile that can be used, for example, in modelling solid-state precipitation of secondary phases.
All physical processes are modelled using physical parameters (e.g. heat capacity, thermal conductivity, etc.), which are specified in an editable input file. These may be changed without recompiling the program. These parameters are calculated for each time step by taking a weighted average of the values for the solid and liquid phases.
The as-provided executable accepts inputs from a file called input1.txt. The script simit.sh copies any nominated input file to input1.txt and executes the program, writing results to a second designated file. This script should be called using the following syntax:
./simit.sh input_example.dat output_example.txt
Alternatively, the program may be launched directly as long as the inputs are saved to a file in the same directory as the executable and named input1.txt. In this case, the results are written to the terminal unless they are redirected to a file using the standard Unix command:
./DROPCOOL > [results file name]
Files:
input_example.dat | Input data file, containing physical parameters and composition. |
DIRUSRAP.FOR | Definitions used by MTData, provided by the National Physical Laboratory (NPL). |
standard-plus.mpi | Contains the definitions of the system and lists of allowed phases and components used in MTDATA. Created using the NPL's PLUS database, version 4.02. |
DROPCOOL.f | FORTRAN 77 source code. |
DROPCOOL | Linux-compatible executable compiled using the source code DROPCOOL.f. |
compile | Shell script capable of compiling the source code into the executable and interfacing with MTData in Debian 8.0 (Jessie). |
simit.sh | Shell script that executes the program, specifies an input file from which data are read and a results file to which data are written. |
output_example | A results file containing the output obtained when the contents of input_example.dat is used as input data. |
Follow the steps listed below to use the module:
gunzip -c TeRRaCaTtA.tar.gz | tar xvf -
./compile DROPCOOL [output_executable_file_name]
File output_example.dat
The program will print out descriptive error indicators should the program execute abnormally. Each error message is unique and will provide a quick way to find the affected part of the source code.
No information supplied, although some data may be available in MTData technical manuals and documentation associated with the NPL PLUS database, version 4.02.
None.
Complete program.
150.0E-06 ! diameter in micrometres 1.60E+03 ! starting temperature in Celsius 3.0E+02 ! final temperature in Celsius 3.0E+02 ! temperature of the atomising gas in Celsius 4.0E+01 ! temperture of the atomiser wall in Celsius 8.0E+02 ! specific heat capacity of the molten droplet in J/(kg K) 8.0E+02 ! specific heat capacity of the enriched liquid in J/(kg K) 3.0E+02 ! specific heat capacity of the solid steel in J/(kg K) 1.0E-03 ! time step in seconds 7.0E+00 ! interfacial heat transfer coefficient between the droplet and the gas in W/(sq.m K) 2.0E-01 ! black-body emissivity of the droplet (dimensionless) 0.0147 ! wt% C 2.00 ! wt% Mn 10.78 ! wt% Ni 17.14 ! wt% Cr 0.00 ! wt% Al 0.75 ! wt% Si 2.50 ! wt% Mo 0.00 ! wt% Co 0.00 ! wt% W 0.00 ! wt% V 0.00 ! wt% not used standard-plus ! name of MPI (MultiPhase Input) file for MTData calculations standard-plus ! name of MPR (MultiPhase Results) file for MTData calculations
The first four lines of the output (beginning with the inverted question mark, ¿) are due to the launch of MTData and may be ignored.
¿[37;44;0m Time / s,Temperature / C,Atomic fraction of solid,Last solid phase to form 0.1000000E-02,1599.066 0.2000000E-02,1598.133 0.3000000E-02,1597.202 0.4000000E-02,1596.273 0.5000000E-02,1595.346 0.6000001E-02,1594.420 0.7000001E-02,1593.496 0.8000000E-02,1592.574 0.9000001E-02,1591.654 0.1000000E-01,1590.735 0.1100000E-01,1589.819 0.1200000E-01,1588.903 0.1300000E-01,1587.990 0.1400000E-01,1587.079 0.1500000E-01,1586.169 0.1600000E-01,1585.260 0.1700000E-01,1584.354 0.1800000E-01,1583.449 0.1900000E-01,1582.546 0.2000000E-01,1581.645 0.2100000E-01,1580.745 0.2200000E-01,1579.847 0.2300000E-01,1578.950 0.2400000E-01,1578.056 0.2500000E-01,1577.163 0.2600000E-01,1576.271 ⋮ 0.2570002E+00,1405.815 0.2580002E+00,1405.200 0.2590002E+00,1404.586 0.2600002E+00,1403.973 0.2610002E+00,1403.361 0.2620002E+00,1402.750 0.2630002E+00,1402.139 0.2640001E+00,1401.530 0.2650001E+00,1400.921 0.2660001E+00,1400.313 0.2660001E+00,1400.313, 0.1098E-07,BCC_A2 0.2660002E+00,1400.313, 0.1000E+01,FCC_A1 0.2660002E+00,1400.313, 0.1000E+01,FCC_A1 0.2670002E+00,1399.659 0.2680002E+00,1399.007 0.2690002E+00,1398.355 0.2700002E+00,1397.704 0.2710001E+00,1397.054 0.2720001E+00,1396.405 0.2730001E+00,1395.757 0.2740001E+00,1395.110 0.2750001E+00,1394.464 ⋮ 0.1976277E+02, 300.130 0.1976377E+02, 300.123 0.1976477E+02, 300.115 0.1976577E+02, 300.108 0.1976677E+02, 300.101 0.1976777E+02, 300.094 0.1976876E+02, 300.087 0.1976976E+02, 300.080 0.1977076E+02, 300.073 0.1977176E+02, 300.066 0.1977276E+02, 300.059 0.1977376E+02, 300.051 0.1977476E+02, 300.044 0.1977576E+02, 300.037 0.1977676E+02, 300.030 0.1977776E+02, 300.023 0.1977876E+02, 300.016 0.1977976E+02, 300.009 0.1978076E+02, 300.002 0.1978176E+02, 299.995 COOLING COMPLETE. PROGRAM ENDS SUCCESSFULLY.
None.
rapid solidification, undercooling, nucleation, powder metallurgy, net-shape manufacturing, atomisation, additive manufacturing, 3D-printing
MAP originated from a joint project of the National Physical Laboratory and the University of Cambridge.