Mobility for austenite grain growth

ripening phenomena, dislocations, grainboundary topology
nokkikku
Posts: 25
Joined: Wed Nov 25, 2009 1:07 pm
anti_bot: 333

Mobility for austenite grain growth

Post by nokkikku » Thu Apr 21, 2011 2:48 pm

Dear Bernd,

I come back with the question of austenite grain growth as I promised. We are making the simulation of austenite grain growth in 0.07%C 1.44%Mn 0.019%Cr 0.146%Mo 0.027%Si at 1100-1200 °C. Below you will see the necessary part of our driving file.


We put the mobility between 1/1 quite high, so that the grain growth fits our experimental data. (For reaction between 1/2 and 2/2, we put because we must give any other reaction between different phases. I understand that they don't affect the simulation because we have only austenite.)

This mobility is much higher than the data quoted in

Philippe Schaffnit, Charles Stallybrass, Joachim Konrad, Axel Kulgemeyer, Heike Meuser
Dual-scale phase-field simulation of grain growth upon reheating of a microalloyed line pipe steel,
International Journal of Materials Research 2010/04, Page 549-554


which is shown in the section 'MICRESS references'.


Figure 4 in this paper shows the product between mobility and interfacial energy in m^2/s. But the product of our mobility and interfacial energy in m^2/s will be in order of E-10 difference!!! This is weird! One argument can be that this publication simulatated the grain growth in 'microalloyed' steels. But I do not believe that only this will make such the difference.


My questions are:

1. Is there anything wrong in my simulation?
2. We noticed also that using this very high mobility makes the simulation much slower than using the low mobility. What's wrong?
3. Do you have any other reference for this kind of mobility in non-microalloyed steels? I am on my way of digging the information in the pile of literature.


Thanks and Happy Easter
nokkikku




# Flags and settings
# ==================
#
# Geometry
# --------
# Grid size?
# (for 2D calculations: AnzY=1, for 1D calculations: AnzX=1, AnzY=1)
# AnzX:
1000
# AnzY:
1
# AnzZ:
1000
# Cell dimension (grid spacing in micrometers):
# (optionally followed by rescaling factor for the output in the form of '3/4')
1
#
# Flags
# -----
# Type of coupling?
# Options: phase concentration temperature temp_cyl_coord
# [stress] [stress_coupled] [flow]
phase
# Type of potential?
# Options: double_obstacle multi_obstacle
double_obstacle
# Enable averaging of the driving force along the normal to the interface?
# Options: averaging no_averaging
no_averaging
#
# Phase field data structure
# --------------------------
# Coefficient for initial dimension of field iFace
# [minimum usage] [target usage]
0.10
# Coefficient for initial dimension of field nTupel
# [minimum usage] [target usage]
0.01
...
...
...
....
# Time input data
# ===============
# Finish input of output times (in seconds) with 'end_of_simulation'
# 'regularly-spaced' outputs can be set with 'linear_step'
# or 'logarithmic_step' and then specifying the increment
# and end value
# ('automatic_outputs' optionally followed by the number
# of outputs can be used in conjuction with 'linear_from_file')
linear_step 005.0 0020.0
linear_step 010.0 0250.0
linear_step 050.0 0600.0
end_of_simulation
# Time-step?
# Options: (real) automatic [0<factor_1<=1] [0<=factor_2] [max.] [min.]
# (Fix time steps: just input the value)
automatic
# Coefficient for phase-field criterion 1.00
# Number of iterations for initialisation?
5
#
#
# Phase data
# ==========
# Number of distinct solid phases?
2
#
# Data for phase 1:
# -----------------
# Simulation of recrystallisation in phase 1?
# Options: recrystall no_recrystall
no_recrystall
# Is phase 1 anisotrop?
# Options: isotropic anisotropic faceted antifaceted
isotropic
# Should grains of phase 1 be reduced to categories?
# Options: categorize no_categorize
no_categorize
#
# Data for phase 2:
# -----------------
# Simulation of recrystallisation in phase 2?
# Options: recrystall no_recrystall
no_recrystall
# Is phase 2 anisotrop?
# Options: isotropic anisotropic faceted antifaceted
isotropic
# Should grains of phase 2 be reduced to categories?
# Options: categorize no_categorize
no_categorize
#
# Grain input
# ===========
# Type of grain positioning?
# Options: deterministic random from_file
random
# Integer for randomization?
1000000
# Number of different types of grains?
1
# Number of grains of type 1?
230
# Input for grain type 1
# ----------------------
# Geometry of grain type 1
# Options: round rectangular elliptic
round
# Minimal value of x-coordinates? [micrometers]
0.00000
# Maximal value of x-coordinates? [micrometers]
1000.000
# Minimal value of z-coordinates? [micrometers]
0.00000
# Maximal value of z-coordinates? [micrometers]
1000.000
# Minimum grain radius? [micrometers]
100.000
# Maximum grain radius? [micrometers]
100.000
# Shall grain type 1 be stabilized or shall
# an analytical curvature description be applied?
# Options: stabilisation analytical_curvature
stabilisation
# Should the Voronoi criterion for grains of type 1 be applied?
# Options: voronoi no_voronoi
voronoi
# Phase number for grain type 1? (int)
1
# Minimal distance between grains (real) [micrometers]?
30.000
#
#
# Data for further nucleation
# ===========================
# Enable further nucleation?
# Options: nucleation no_nucleation [verbose|no_verbose]
no_nucleation
#
#
# 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]
no_phase_interaction
#
# Data for phase interaction 0 / 2:
# ---------------------------------
# Simulation of interaction between phase 0 and 2?
# Options: phase_interaction no_phase_interaction
# [standard|particle_pinning[_temperature]|solute_drag|redistribution_control]
no_phase_interaction
#
# Data for phase interaction 1 / 1:
# ---------------------------------
# Simulation of interaction between phase 1 and 1?
# Options: phase_interaction no_phase_interaction identical phases nb.
# [standard|particle_pinning[_temperature]|solute_drag|redistribution_control]
phase_interaction
# Type of surface energy definition between phases 1 and 1?
# Options: constant temp_dependent
constant
# Surface energy between phases 1 and 1? [J/cm**2]
7.00000E-05
# Type of mobility definition between phases 1 and 1?
# Options: constant temp_dependent dg_dependent
constant
# Kinetic coefficient mu between phases 1 and 1? [cm**4/(Js)]
0.22265E-02
#
# Data for phase interaction 2 / 2:
# ---------------------------------
# Simulation of interaction between phase 2 and 2?
# Options: phase_interaction no_phase_interaction identical phases nb.
# [standard|particle_pinning[_temperature]|solute_drag|redistribution_control]
phase_interaction
# Type of surface energy definition between phases 2 and 2?
# Options: constant temp_dependent
constant
# Surface energy between phases 2 and 2? [J/cm**2]
5.00000E-05
# Type of mobility definition between phases 2 and 2?
# Options: constant temp_dependent dg_dependent
constant
# Kinetic coefficient mu between phases 2 and 2? [cm**4/(Js)]
2.10125E-02
#
# Data for phase interaction 1 / 2:
# ---------------------------------
# Simulation of interaction between phase 1 and 2?
# Options: phase_interaction no_phase_interaction
# [standard|particle_pinning[_temperature]|solute_drag|redistribution_control]
phase_interaction
# Type of surface energy definition between phases 1 and 2?
# Options: constant temp_dependent
constant
# Surface energy between phases 1 and 2? [J/cm**2]
4.00000E-05
# Type of mobility definition between phases 1 and 2?
# Options: constant temp_dependent dg_dependent
constant
# Kinetic coefficient mu between phases 1 and 2? [cm**4/(Js)]
2.26841E-02
#
# Phase diagram - input data
# ==========================
# Equilibrium temperature (real) [K] between 1 and 2
1107.150
# Entropy of fusion between phase 1 and 2 ? (real) [J/(cm**3 K)]
1.000000
#
#
# Boundary conditions
# ===================
# Type of temperature trend?
# Options: linear linear_from_file profiles_from_file
linear
# Number of connecting points? (integer)
0
# Initial temperature at the bottom? (real) [K]
1373.150
# Temperature gradient in z-direction? [K/cm]
0.0000
# Cooling rate? [K/s]
0.0000
# Moving-frame system in z-direction?
# Options: moving_frame no_moving_frame
no_moving_frame
#
# Boundary conditions for phase field in each direction
# Options: i (insulation) s (symmetric) p (periodic/wrap-around) g (gradient) f (fixed)
# Sequence: E W (N S, if 3D) B T borders
pppp
# Unit-cell model symmetric with respect to the x/y diagonal plane?
# Options: unit_cell_symm no_unit_cell_symm
no_unit_cell_symm
#
#
# Other numerical parameters
# ==========================
# Phase minimum?
1.00E-05
# Interface thickness (in cells)?
5.00
#
#

zhubq
Posts: 84
Joined: Mon Jun 22, 2009 7:33 pm

Re: Mobility for austenite grain growth

Post by zhubq » Wed Apr 27, 2011 8:00 am

Hi, there.

I think mobility is quite undeterministic. The values from literature are in a large range. You'd better fit it with your own experimental data.
High mobility means high velocity of the interface. therefore, you have to decrease the time step (done by MICRESS automatically) thus more iterations are carried out, slowing down the simulation.

nokkikku
Posts: 25
Joined: Wed Nov 25, 2009 1:07 pm
anti_bot: 333

Re: Mobility for austenite grain growth

Post by nokkikku » Wed Apr 27, 2011 3:30 pm

Hi zhubq,

thanks a lot for your comments.


I understand that when the mobility is increased, the grain growth happens more intensively. And MICRESS has to solved the equations more due to this interaction. That's why it takes much longer??

nokkikku

admin
Site Admin
Posts: 48
Joined: Fri Jun 13, 2008 4:03 pm

Re: Mobility for austenite grain growth

Post by admin » Wed Apr 27, 2011 3:43 pm

Hi,

Great to see that discussion is now starting between users of the MICRESS forum!

@zhubq: bottle of champaign next time we meet!

@all: use the "subsribe forum" button at the bottom of the page in each subforum to get email notice of new answers or threads!

admin

Bernd
Posts: 1148
Joined: Mon Jun 23, 2008 9:29 pm

Re: Mobility for austenite grain growth

Post by Bernd » Wed Apr 27, 2011 3:48 pm

Hi,

best would be to get a comment from Philippe who is also member of the MICRESS forum...


I have the feeling that the values he has given in the paper are too small. I would rather trust in the own calibration.


Bernd

zhubq
Posts: 84
Joined: Mon Jun 22, 2009 7:33 pm

Re: Mobility for austenite grain growth

Post by zhubq » Wed Apr 27, 2011 7:52 pm

nokkikku wrote:Hi zhubq,

thanks a lot for your comments.


I understand that when the mobility is increased, the grain growth happens more intensively. And MICRESS has to solved the equations more due to this interaction. That's why it takes much longer??

nokkikku

Yes, because for each time step, the interface can only move one cell.

zhubq
Posts: 84
Joined: Mon Jun 22, 2009 7:33 pm

Re: Mobility for austenite grain growth

Post by zhubq » Wed Apr 27, 2011 8:05 pm

admin wrote:Hi,

Great to see that discussion is now starting between users of the MICRESS forum!

@zhubq: bottle of champaign next time we meet!

@all: use the "subsribe forum" button at the bottom of the page in each subforum to get email notice of new answers or threads!

admin
@admin: I will do more and better in order to get more champagne. :lol:

Edit: Bottle of nice Moet Champagne was handed over on 29th of August 2014 at PFM2014 conference in State College ;)

Bernd
Posts: 1148
Joined: Mon Jun 23, 2008 9:29 pm

Re: Mobility for austenite grain growth

Post by Bernd » Thu Apr 28, 2011 2:24 pm

Hi, nokkikku

I think, for doing a reasonable simulation of grain growth which can be calibrated to experimental data, you should consider the following:

- you should use a high enough number of grains (>1000) to get reasonable statistics. It takes quite long ripening time until you get a realisic size distribution which corresponds to stationary growth - and at that time, the number of grains is already strongly reduced...

- you should consider to use the script "random_grid" for getting initial structures which are much closer to a stationary distribution. This script works better than the "normal" random grain setting in MICRESS, especially when using high grain numbers. If you don't have it already, I can send it to you.

- you should consider to do it in 3D

- please check whether there is some phase 0 left after initialisation - this could completely spoil the outputs on grain statistics and can easily be overlooked!

These changes of the inital structure could also have a strong influence on the mobility which you get by calibration to the experiment!

Bernd

nokkikku
Posts: 25
Joined: Wed Nov 25, 2009 1:07 pm
anti_bot: 333

Re: Mobility for austenite grain growth

Post by nokkikku » Fri Apr 29, 2011 10:38 am

Bernd wrote:Hi, nokkikku

I think, for doing a reasonable simulation of grain growth which can be calibrated to experimental data, you should consider the following:

- you should use a high enough number of grains (>1000) to get reasonable statistics. It takes quite long ripening time until you get a realisic size distribution which corresponds to stationary growth - and at that time, the number of grains is already strongly reduced...

- you should consider to use the script "random_grid" for getting initial structures which are much closer to a stationary distribution. This script works better than the "normal" random grain setting in MICRESS, especially when using high grain numbers. If you don't have it already, I can send it to you.

- you should consider to do it in 3D

- please check whether there is some phase 0 left after initialisation - this could completely spoil the outputs on grain statistics and can easily be overlooked!

These changes of the inital structure could also have a strong influence on the mobility which you get by calibration to the experiment!

Bernd

Hi Bernd,

I do not know if we do have the script 'random_grid'. I will be really appreciated if you send to me, but how? By email?

I am also trying to fit this mobility from different grain size distribution.

nokkikku

Bernd
Posts: 1148
Joined: Mon Jun 23, 2008 9:29 pm

Re: Mobility for austenite grain growth

Post by Bernd » Fri Apr 29, 2011 3:50 pm

Just sent you the script by e-mail!

Bernd

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