Odd way of dendrite growth in a Cr, Mn and B alloyed tool steel

dendritic solidification, eutectics, peritectics,....
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vamsi
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Odd way of dendrite growth in a Cr, Mn and B alloyed tool steel

Post by vamsi » Mon Mar 26, 2018 2:25 pm

Hello,

I'm running a simulation for Solidification in Cr, Mn and B alloyed tool steel. Grid spacing is 0.5µm and cell dimension is 150 X 150. As you can see in the image file below, initial dendrite growth is looking odd. I feel the interface energies are not the problem. Because higher interface energies are not allowing the liquid to solidify, and lower numbers are resulting 'trying hard phases errors'. So I'm sticking with current interface energy values. I'm thinking about modifying the resolution.

Kindly brief me with your feedback on the possible reasons?
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Bernd
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Re: Odd way of dendrite growth in a Cr, Mn and B alloyed tool steel

Post by Bernd » Mon Mar 26, 2018 3:56 pm

Dear Vamsi,

you give little information, but I assume that you used a 45° orientation so that you would expect the dendrite to form arms in the direction along the diagonal rather than along the x and z axis. If this is true, I would guess it could be due to unstable interfaces which in turn amplify the numerical anisotropy along the grid directions. Changing the interface energy would help, but change physics (as you explained).
In this scenario, whether you need to increase resolution to cope with that, depends on whether you already optimized numerical parameters. Therefore, I would like to know

1.) whether you use "mob_corr" to obtain diffusion limited kinetics or, if not, how you have chosen the interface mobility

2.) whether you already use interface stabilisation (2nd optional parameter in the same line with the interface energy, the value can be up to about 10x the value of the interface energy)

3.) whether you use averaging of the driving force ("avg").

4.) how big is the initial undercooling.

Bernd

vamsi
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Re: Odd way of dendrite growth in a Cr, Mn and B alloyed tool steel

Post by vamsi » Mon Mar 26, 2018 4:39 pm

Dear Bernd,

Thank you for the quick response. Yes, I used 45° orientation.

1) I did not use the mob_corr option for this. I started this simulation by using the mobility numbers for each phase interaction from another successfully completed simulation (which has no Mn. I added Mn for this current one but the phases of interest remains same and I changed all the input data accordingly). Later, I optimized those numbers with help of errors from output log data.

2) I use 'constant' interface energy. I don't seen any 'interface stabilization' option. How to choose that ?. For Ex., the phase interaction data looks like
# Data for phase interaction 0 / 1:
# ---------------------------------
# Simulation of interaction between phases 0 and 1?
# Options: phase_interaction no_phase_interaction
# [standard|particle_pinning[_temperature]|solute_drag]
# | [redistribution_control] or [no_junction_force|junction_force]
phase_interaction
# 'DeltaG' options: default
# avg ...[] max ...[J/cm^3] smooth ...[°] noise ...[J/cm^3] offset ...[J/cm^3]
avg 0.5 max 100
# I.e.: avg +0.50 smooth +0.0 max +1.00000E+02
# Type of interfacial energy definition between phases 0 and 1?
# Options: constant temp_dependent
constant
# Interfacial energy between phases 0 and 1? [J/cm**2]
# [max. value for num. interface stabilisation [J/cm**2]]
5.00000E-05
# Type of mobility definition between phases 0 and 1?
# Options: constant temp_dependent dg_dependent [fixed_minimum]
constant
# Kinetic coefficient mu between phases 0 and 1 [ min. value ] [cm**4/(Js)] ?
1.00000E-2
# Is interaction isotropic?
# Optionen: isotropic anisotropic [harmonic_expansion]
anisotropic
# Anisotropy of interfacial stiffness? (cubic)
# 1 - delta * cos(4*phi), (delta =delta_stiffness =15*delta_energy)
# Coefficient delta (<1.) ?
0.30000
# Anisotropy of interfacial mobility? (cubic)
# 1 + delta * cos(4*phi)
# Coefficient delta (<1.) ?
0.50000
#

3)Yes. I'm using 'avg'

4) For many seed types (9/11), I used 'min. undercooling' of 5.0 K and for other few, I used 1.0 K.

Do you think using mob_corr or interface stabilization options can influence this?

Thank you

Bernd
Posts: 1084
Joined: Mon Jun 23, 2008 9:29 pm

Re: Odd way of dendrite growth in a Cr, Mn and B alloyed tool steel

Post by Bernd » Mon Mar 26, 2018 10:59 pm

Dear Vamsi,

yes, using mob_corr makes life easier, because you need not calibrate the interface mobility. I strongly recommend to use it.

In the phase interaction input, there is the line

"# [max. value for num. interface stabilisation [J/cm**2]]"

which I meant. As I said, you can put a value ~10x the interfacial energy which helps keeping the interface together. Furthermore, increasing the avg value e.g. from 0.5 to 0.9 would also contribute to the interface stability.

Bernd

vamsi
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Re: Odd way of dendrite growth in a Cr, Mn and B alloyed tool steel

Post by vamsi » Sat Mar 31, 2018 6:34 pm

Dear Bernd,

Thank you for your inputs. By using mob_corr and altering avg driving force, I can be able to simulate dendrite with a regular growth unlike before. So I believe that the problem is solved. But now I'm facing another problem in the same simulation of Fe-C-B-Cr-Mn system. We have 5 elements and 5 phases. Other than liquid and Austenite, two other hard phases(phases 3 and 5, image of .TabF file is attached) precipitated during the solidification. When 5th phase is precipitating, the simulation started to show 'trying hard phases' errors.

trying hard phases 0 1 level: 4 zp= 277 error=30501
trying harder! Error = 30501
trying hard phases 0 3 level: 4 zp= 278 error=30501
trying harder! Error = 30501
trying hard phases 0 5 level: 4 zp= 277 error=30501
trying harder! Error = 30501
trying hard phases 1 3 level: 4 zp= 278 error=30501
trying harder! Error = 30501
trying hard phases 1 5 level: 4 zp= 278 error=30501
trying harder! Error = 30501

By looking at these errors, I understood that there is a need to change the numbers for phase interactions 0/1, 0/3, 0/5, 1/3 and 1/5. Why suddenly its showing errors only after phases 3 and 5 are nucleated?.

I increased interface mobility of all those above interactions twice by a factor of 100 and 10000 from the actual values used (have a look at phase interaction data below) but still, those errors are appearing. I think 'Max. Interface energies' are good because those values are taken from thermocalc and with a multiplication factor of 10.

Please guide me to finish this simulation. Thank you

# Phase interaction data
# ======================
#
# Data for phase interaction 0 / 1:
# ---------------------------------
# Simulation of interaction between phase 0 and 1?
# Options: phase_interaction no_phase_interaction
# [standard|particle_pinning[_temperature]|solute_drag]
# | [redistribution_control] or [no_junction_force|junction_force]
phase_interaction redistribution_control
# 'DeltaG' options: default
# avg ... [] max ... [J/cm**3] smooth ... [degrees] noise ... [J/cm**3]
avg 0.9 max 100
# I.e.: avg +0.50 smooth +0.0 max +1.00000E+02
# Type of surface energy definition between phases LIQUID and 1?
# Options: constant temp_dependent
constant
# Surface energy between phases LIQUID and 1? [J/cm**2]
# [max. value for num. interface stabilisation [J/cm**2]]
5.00000E-05
# Type of mobility definition between phases LIQUID and 1?
# Options: constant temp_dependent dg_dependent thin_interface_correction [fixed_minimum]
constant
# Kinetic coefficient mu between phases LIQUID and 1 [ min. value ] [cm**4/(Js)] ?
4.00000E-1
# Is interaction isotropic?
# Optionen: isotropic anisotropic [harmonic_expansion]
anisotropic
# Anisotropy of interfacial stiffness? (cubic)
# 1 - delta * cos(4*phi), (delta =delta_stiffness =15*delta_energy)
# Coefficient delta (<1.) ?
0.30000
# Anisotropy of interfacial mobility? (cubic)
# 1 + delta * cos(4*phi)
# Coefficient delta (<1.) ?
0.50000
#
# Data for phase interaction 0 / 3:
# ---------------------------------
# Simulation of interaction between phase 0 and 3?
# Options: phase_interaction no_phase_interaction identical phases nb
# [standard|particle_pinning[_temperature]|solute_drag]
# | [redistribution_control] or [no_junction_force|junction_force]
phase_interaction redistribution_control
# 'DeltaG' options: default
# avg ... [] max ... [J/cm**3] smooth ... [degrees] noise ... [J/cm**3]
avg 1 max 100
# I.e.: avg +1.00 smooth +0.0 max +1.00000E+02
# Type of surface energy definition between phases LIQUID and 3?
# Options: constant temp_dependent
constant
# Surface energy between phases LIQUID and 3? [J/cm**2]
# [max. value for num. interface stabilisation [J/cm**2]]
1.00000E-04
# Type of mobility definition between phases LIQUID and 3?
# Options: constant temp_dependent dg_dependent thin_interface_correction [fixed_minimum]
constant
# Kinetic coefficient mu between phases LIQUID and 3 [ min. value ] [cm**4/(Js)] ?
4.00000E-04
# Is interaction isotropic?
# Optionen: isotropic anisotropic [harmonic_expansion]
isotropic
#
# Data for phase interaction 0 / 5:
# ---------------------------------
# Simulation of interaction between phase 0 and 5?
# Options: phase_interaction no_phase_interaction identical phases nb
# [standard|particle_pinning[_temperature]|solute_drag]
# | [redistribution_control] or [no_junction_force|junction_force]
phase_interaction redistribution_control
# 'DeltaG' options: default
# avg ... [] max ... [J/cm**3] smooth ... [degrees] noise ... [J/cm**3]
avg 1 max 100
# I.e.: avg +1.00 smooth +0.0 max +1.00000E+02
# Type of surface energy definition between phases LIQUID and 5?
# Options: constant temp_dependent
constant
# Surface energy between phases LIQUID and 5? [J/cm**2]
# [max. value for num. interface stabilisation [J/cm**2]]
1.00000E-04
# Type of mobility definition between phases LIQUID and 5?
# Options: constant temp_dependent dg_dependent thin_interface_correction [fixed_minimum]
constant
# Kinetic coefficient mu between phases LIQUID and 5 [ min. value ] [cm**4/(Js)] ?
4.00000E-04
# Is interaction isotropic?
# Optionen: isotropic anisotropic [harmonic_expansion]
isotropic
#
# Data for phase interaction 1 / 3:
# ---------------------------------
# Simulation of interaction between phase 1 and 3?
# Options: phase_interaction no_phase_interaction identical phases nb
# [standard|particle_pinning[_temperature]|solute_drag]
# | [redistribution_control] or [no_junction_force|junction_force]
phase_interaction redistribution_control
# 'DeltaG' options: default
# avg ... [] max ... [J/cm**3] smooth ... [degrees] noise ... [J/cm**3]
avg 1 max 20
# I.e.: avg +1.00 smooth +0.0 max +2.00000E+01
# Type of surface energy definition between phases 1 and 3?
# Options: constant temp_dependent
constant
# Surface energy between phases 1 and 3? [J/cm**2]
# [max. value for num. interface stabilisation [J/cm**2]]
1E-4
# Type of mobility definition between phases 1 and 3?
# Options: constant temp_dependent dg_dependent thin_interface_correction [fixed_minimum]
constant
# Kinetic coefficient mu between phases 1 and 3 [ min. value ] [cm**4/(Js)] ?
1.00000E-11
# Shall misorientation be considered?
# Options: misorientation no_misorientation [transition LAB/HAB in degree]
no_misorientation
# Is interaction isotropic?
# Optionen: isotropic anisotropic [harmonic_expansion]
isotropic
#
# Data for phase interaction 1 / 5:
# ---------------------------------
# Simulation of interaction between phase 1 and 5?
# Options: phase_interaction no_phase_interaction identical phases nb
# [standard|particle_pinning[_temperature]|solute_drag]
# | [redistribution_control] or [no_junction_force|junction_force]
phase_interaction redistribution_control
# 'DeltaG' options: default
# avg ... [] max ... [J/cm**3] smooth ... [degrees] noise ... [J/cm**3]
avg 1 max 20
# I.e.: avg +1.00 smooth +0.0 max +2.00000E+01
# Type of surface energy definition between phases 1 and 5?
# Options: constant temp_dependent
constant
# Surface energy between phases 1 and 5? [J/cm**2]
# [max. value for num. interface stabilisation [J/cm**2]]
1E-4
# Type of mobility definition between phases 1 and 5?
# Options: constant temp_dependent dg_dependent thin_interface_correction [fixed_minimum]
constant
# Kinetic coefficient mu between phases 1 and 5 [ min. value ] [cm**4/(Js)] ?
1.00000E-11
# Shall misorientation be considered?
# Options: misorientation no_misorientation [transition LAB/HAB in degree]
no_misorientation
# Is interaction isotropic?
# Optionen: isotropic anisotropic [harmonic_expansion]
isotropic
#
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Bernd
Posts: 1084
Joined: Mon Jun 23, 2008 9:29 pm

Re: Odd way of dendrite growth in a Cr, Mn and B alloyed tool steel

Post by Bernd » Sun Apr 01, 2018 12:26 am

Dear vamsi,

What you cannot know is the meaning of the error number which is still not well-documented. 5-digit numbers beginning with 3 like "30501" mean that phases 05 and 01 assume exactly identical composition although they represent a different phase in the database phase listing. This error occurs, if both phases (1 and 5 in MICRESS user numbering) represent different composition sets of the same phase (like e.g. FCC_L12 and FCC_L12#3) which should have different compositions. However, in such a case, it can easily happen that one of the phases switches to the wrong composition which cannot be allowed. Therefore, this error is automatically created.

What to do in such a case I recently discussed in another thread:

Re: Error when linearisation!

My proposal in this thread should also work for you.

Best wishes
Bernd

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