Simulation of delta-ferrite/austenite solidifcation sequence under SLM conditions
Posted: Fri Jul 29, 2022 6:27 pm
Dear Bernd,
I would like to construct a simulation to observe the solidification sequence in a low alloyed steel under SLM conditions. From Scheil simulations, delta-ferrite starts to form in the beginning of solidification (hypoperitectic composition) at around 1797 K and towards the end, austenite starts to form around 1765 K and solification proceeds as austenite till the end . I would like to monitor if the initial delta-ferrite will transform to austenite or somehow will surpressed during initial solidification under SLM conditions (and then maybe later in HAZ to see C redistribution if a re-construction is possible from a restart file). In parallel, I also would like to screen corresponding Mn and C segregation.
Although I set the interface nucleation of austenite on delta-ferrite boundaries and corresponding nucleation temperatures (1675 K) I dont see any austenite formation and growth along the simulation, independent from nucleation temperature and min. undercooling value (force automatic start value appears in .log file). My nucleation and phase interaction paramters are shared below (simple interface nucleation on delta-ferrite boundaries). I started my simulation with a flat bcc grain and set the bottom temperature to 1K below the liquidus temperature. I would appreciate your help to identify what is missing in my approach !
Thank you and kind regards,
Ahmet
# Enable further nucleation?
# Options: nucleation nucleation_symm no_nucleation [verbose|no_verbose]
nucleation
# Additional output for nucleation?
# Options: out_nucleation no_out_nucleation
no_out_nucleation
#
# Number of types of seeds?
1
#
# Input for seed type 1:
# ----------------------
# Type of 'position' of the seeds?
# Options: bulk region interface triple quadruple front [restrictive]
interface
# Phase of new grains (integer) [unresolved|add_to_grain|split_from_grain]?
1
# Reference phase (integer) [min. and max. fraction (real)]?
0
# Substrate phase [2nd phase in interface]?
# (set to 0 to disable the effect of substrate curvature)
2
# Maximum number of new nuclei of seed type 1?
# (set negative for unlimited number)
-1
# Grain radius [micrometers]?
0.000
# Choice of growth mode:
# Options: stabilisation analytical_curvature
stabilisation
# min. undercooling [K] (>0)?
20
# Determination of nuclei orientations?
# Options: random randomZ fix range parent_relation
random
# Shield effect:
# Shield time [s] [shield phase or group number] ?
5.E-5
# Shield distance [micrometers] [ nucleation distance [micrometers] ]?
0.9
# Shall categorization be applied to this seed type?
# Options: categorize {Number} no_categorize
no_categorize
# Nucleation range
# min. nucleation temperature for seed type 1 [K]
0
# max. nucleation temperature for seed type 1 [K]
1765
# Time between checks for nucleation? [s]
# Options: constant from_file
constant
# Time interval [s]
1.00000E-05
# Shall random noise be applied?
# Options: nucleation_noise no_nucleation_noise
no_nucleation_noise
The interaction between fcc and bcc also enabled in phase interactions:
# 1 (FCC_A1) / 2 (BCC_A2)
# -------------------------
# Simulation of interaction between 1 (FCC_A1) and 2 (BCC_A2) ?
# Options: phase_interaction no_phase_interaction identical phases nb
# [ standard | particle_pinning[_temperature] | solute_drag ]
# | [ redistribution_control ] or [ no_junction_force | junction_force ]
1 2 phase_interaction redistribution_control
# 'DeltaG' options: default
# avg ...[] max ...[J/cm^3] smooth ...[Deg] noise ...[J/cm^3] offset ...[J/cm^3]
avg 0.5 smooth +45.0 max 1000
# I.e.: avg +0.50 smooth +45.0 max +1.00000E+03
# Type of interfacial energy definition between 1 (FCC_A1) and 2 (BCC_A2) ?
# Options: constant temp_dependent
constant
# Interfacial energy between 1 (FCC_A1) and 2 (BCC_A2) ? [J/cm**2]
# [max. value for num. interface stabilisation [J/cm**2]]
5.0E-05 5.0E-04
# Type of mobility definition between FCC_A1 and BCC_A2?
# Options: constant temp_dependent dg_dependent [fixed_minimum]
constant
# Kinetic coefficient mu between FCC_A1 and BCC_A2 [cm**4/(Js)] ?
1.E-6
# Shall misorientation be considered?
# Options: misorientation no_misorientation
# [low_angle_limit <degrees (default=15)>] [special_orient <nb>]
no_misorientation
# Is interaction isotropic?
# Options: isotropic
# anisotropic [junction_force] [harmonic_expansion]
isotropic
# Which phase diagram is to be used?
# Options: database {local|global|interface|fragment}[<maximal distance>]
# | linear | linearTQ
database global 2
# Relinearisation interval for interface FCC_A1 / BCC_A2
# Options: automatic manual from_file none
manual 1.00000E-05
# Please specify the redistribution behaviour of each component:
# Format: forward [backward]
# Options: nple para paratq normal [mob_corr] atc [mob_corr] [verbose]
# Component C:
atc mob_corr
# Component MN:
atc mob_corr
I would like to construct a simulation to observe the solidification sequence in a low alloyed steel under SLM conditions. From Scheil simulations, delta-ferrite starts to form in the beginning of solidification (hypoperitectic composition) at around 1797 K and towards the end, austenite starts to form around 1765 K and solification proceeds as austenite till the end . I would like to monitor if the initial delta-ferrite will transform to austenite or somehow will surpressed during initial solidification under SLM conditions (and then maybe later in HAZ to see C redistribution if a re-construction is possible from a restart file). In parallel, I also would like to screen corresponding Mn and C segregation.
Although I set the interface nucleation of austenite on delta-ferrite boundaries and corresponding nucleation temperatures (1675 K) I dont see any austenite formation and growth along the simulation, independent from nucleation temperature and min. undercooling value (force automatic start value appears in .log file). My nucleation and phase interaction paramters are shared below (simple interface nucleation on delta-ferrite boundaries). I started my simulation with a flat bcc grain and set the bottom temperature to 1K below the liquidus temperature. I would appreciate your help to identify what is missing in my approach !
Thank you and kind regards,
Ahmet
# Enable further nucleation?
# Options: nucleation nucleation_symm no_nucleation [verbose|no_verbose]
nucleation
# Additional output for nucleation?
# Options: out_nucleation no_out_nucleation
no_out_nucleation
#
# Number of types of seeds?
1
#
# Input for seed type 1:
# ----------------------
# Type of 'position' of the seeds?
# Options: bulk region interface triple quadruple front [restrictive]
interface
# Phase of new grains (integer) [unresolved|add_to_grain|split_from_grain]?
1
# Reference phase (integer) [min. and max. fraction (real)]?
0
# Substrate phase [2nd phase in interface]?
# (set to 0 to disable the effect of substrate curvature)
2
# Maximum number of new nuclei of seed type 1?
# (set negative for unlimited number)
-1
# Grain radius [micrometers]?
0.000
# Choice of growth mode:
# Options: stabilisation analytical_curvature
stabilisation
# min. undercooling [K] (>0)?
20
# Determination of nuclei orientations?
# Options: random randomZ fix range parent_relation
random
# Shield effect:
# Shield time [s] [shield phase or group number] ?
5.E-5
# Shield distance [micrometers] [ nucleation distance [micrometers] ]?
0.9
# Shall categorization be applied to this seed type?
# Options: categorize {Number} no_categorize
no_categorize
# Nucleation range
# min. nucleation temperature for seed type 1 [K]
0
# max. nucleation temperature for seed type 1 [K]
1765
# Time between checks for nucleation? [s]
# Options: constant from_file
constant
# Time interval [s]
1.00000E-05
# Shall random noise be applied?
# Options: nucleation_noise no_nucleation_noise
no_nucleation_noise
The interaction between fcc and bcc also enabled in phase interactions:
# 1 (FCC_A1) / 2 (BCC_A2)
# -------------------------
# Simulation of interaction between 1 (FCC_A1) and 2 (BCC_A2) ?
# Options: phase_interaction no_phase_interaction identical phases nb
# [ standard | particle_pinning[_temperature] | solute_drag ]
# | [ redistribution_control ] or [ no_junction_force | junction_force ]
1 2 phase_interaction redistribution_control
# 'DeltaG' options: default
# avg ...[] max ...[J/cm^3] smooth ...[Deg] noise ...[J/cm^3] offset ...[J/cm^3]
avg 0.5 smooth +45.0 max 1000
# I.e.: avg +0.50 smooth +45.0 max +1.00000E+03
# Type of interfacial energy definition between 1 (FCC_A1) and 2 (BCC_A2) ?
# Options: constant temp_dependent
constant
# Interfacial energy between 1 (FCC_A1) and 2 (BCC_A2) ? [J/cm**2]
# [max. value for num. interface stabilisation [J/cm**2]]
5.0E-05 5.0E-04
# Type of mobility definition between FCC_A1 and BCC_A2?
# Options: constant temp_dependent dg_dependent [fixed_minimum]
constant
# Kinetic coefficient mu between FCC_A1 and BCC_A2 [cm**4/(Js)] ?
1.E-6
# Shall misorientation be considered?
# Options: misorientation no_misorientation
# [low_angle_limit <degrees (default=15)>] [special_orient <nb>]
no_misorientation
# Is interaction isotropic?
# Options: isotropic
# anisotropic [junction_force] [harmonic_expansion]
isotropic
# Which phase diagram is to be used?
# Options: database {local|global|interface|fragment}[<maximal distance>]
# | linear | linearTQ
database global 2
# Relinearisation interval for interface FCC_A1 / BCC_A2
# Options: automatic manual from_file none
manual 1.00000E-05
# Please specify the redistribution behaviour of each component:
# Format: forward [backward]
# Options: nple para paratq normal [mob_corr] atc [mob_corr] [verbose]
# Component C:
atc mob_corr
# Component MN:
atc mob_corr