Grain Growth in Additive Manufacturing

ripening phenomena, dislocations, grainboundary topology
CharMIC
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Grain Growth in Additive Manufacturing

Postby CharMIC » Tue Mar 06, 2018 10:00 am

Hej,

In additive manufacturing, its possible to change the solidification condition by varying the process parameters. As a result, the thermal gradients and solidification velocities will be change. This will result the microstructure to have different grain structures, columnar, equiaxed and mix grains, depend upon the solidification conditions.

Is it possible to use MICRESS to simulate this grain evolution behavior giving thermal gradient and cooling rate as the inputs. In these simulations, the element distribution can be neglected and only the grain orientation and nucleation will be the important aspects.

BR
Chamara

Bernd
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Re: Grain Growth in Additive Manufacturing

Postby Bernd » Tue Mar 06, 2018 5:31 pm

Hi Chamara,

what you describe is not the dominant mechanism of grain selection in addditive manufacturing. The question whether you get columnar or equiaxed structures, e.g., depends strongly on the composition of the alloy.

Thus, what you need to do is a solidification simulation using the full composition of the alloy. Whether new grains are formed by nucleation depends on the balance between nucleation undercooling and tip undercooling of the growing dendrites - which depends on composition.

Bernd

CharMIC
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Re: Grain Growth in Additive Manufacturing

Postby CharMIC » Wed Mar 07, 2018 2:09 pm

Hej Bernd,

Thanks for the input. I actually tried to do this solidification simulation that you described. But was not successful. I will take that discussion further in another topic that I have created under solidification.

BR
Chamara

CharMIC
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Re: Grain Growth in Additive Manufacturing

Postby CharMIC » Fri Aug 03, 2018 4:35 pm

Hi,

Is it possible to import EBSD data of a microstructure to MICRESS and simulate the grain growth up on heat treatment?

BR
Chamara

deepumaj1
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Re: Grain Growth in Additive Manufacturing

Postby deepumaj1 » Sat Aug 04, 2018 3:44 am

Hi Chamara,
What all data would you like to import from EBSD?

Coming through Dream3D is another route to bring the data to Micress. Set up your microstructure in Dream3D and import to Micress in VTK format. But this route will only support 3D microstructures I guess.. The new version of micress also comes with HDF5 format. I haven't tried any of these till now and hence, can't comment beyond this...

BR,
Deepu

CharMIC
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Re: Grain Growth in Additive Manufacturing

Postby CharMIC » Sun Aug 05, 2018 5:38 pm

Hi Deepu,

I thought of importing the grain orientation data through EBSD and creating a microstructure from that data.

Then use this created microstructure for the heat treatment simulations

BR
Chamara

ralph
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Re: Grain Growth in Additive Manufacturing

Postby ralph » Mon Aug 06, 2018 10:15 am

EBSD data is usually not a well preperad microstructure as needed in MICRESS, i.e. clear grain, resp. phase boundaries.
That is the reason why a direct import of EBSD data in MICRESS does not exist so far. It's too much pre-processing.

Dream3D has some capabilities to work with EBSD data and can export to an XDMF file. This can be read by Paraview and be exported as legacy VTK.
I guess it's possible to use pseudo 3D by setting one dimension to 1 at all tool steps. But you have to take care about different axis systems if you work with orientations.

I am sure that there are other tools around to cope with EBSD data. You can also use Matlab to do the preprocessing. To be honest, I have only played with Dream3D with mixed success so far.

Best,
Ralph

CharMIC
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Re: Grain Growth in Additive Manufacturing

Postby CharMIC » Mon Jan 14, 2019 10:40 am

Hi,

Just a curiosity question. Can we simulate the effect of grain boundary misorientation on the grain growth with MICRESS asuuming we know the relationship between misorientation vs grain boundary energy and mobility?

BR
Chamara

Bernd
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Re: Grain Growth in Additive Manufacturing

Postby Bernd » Mon Jan 14, 2019 6:56 pm

Yes, of course! This by the way gives much more realistic grain structures with prevailing low-angle boundaries...

CharMIC
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Re: Grain Growth in Additive Manufacturing

Postby CharMIC » Tue Jan 15, 2019 10:49 am

Any recommended example that I should look in the example library to start such a work? :)


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