MICRESS Forum

Dear Bernd,

I want to simulate the transformation of austenite to ferrite and bainite by Micress, so that ferrite can nucleate at the austenite grain boundary (nucleation temperature 1000K) and bainite can nucleate at the austenite grain boundary and inside the austenite grain (nucleation temperature 850K), but the results show that the bainite nucleus is very slow and needlelike bainite can hardly be seen. The specific simulation diagram is as follows, and my driver file is attached. I have referred to some of your explanations in the forum, but my problems have not been solved. Therefore, I hope you can put forward some modification suggestions for me.
Thank you.r

lv

Dear shaojielv,

I have no own experiences with bainite, but it seems you are trying to simulate acicular growth of cementite. For doing so you combine the antifaceted anisotropy type with tetragonal symmetry which is not very helpful (you also forgot to define the second parameter of the tetragonal anisotropy coefficients...). I would instead recommend to take the example T015_Gamma_Alpha_FeC_Acicular_dri (as of version 7.0) as reference for needle growth.

You may further face the problem that the cementite fraction in your alloy is quite low, which results in very small precipitates. It is well possible that you also will need a higher grid resolution for that reason.

Bernd

Dear Bernd,

Yes, you are right, I do want to simulate bainite transformation, but bainite cannot be represented in thermodynamics, so I want to represent bainite by cementite, which seems to be a wrong idea, can you tell me what phase I should use to represent bainite? I know from literature that bainite can be expressed as ferrite, but I already have ferrite here, so I don't know what else I can define bainite.

Dear shaojielv,

I am not the right person to ask that, but there are other people who have used MICRESS for simulation of Bainite, e.g. W. Song. I just shared some links here.

Bernd

Dear Bernd,

First of all, thank you for your reply. I will try to solve the problem by myself. I have the following error during the calculation process. Can you help me determine the reason?

shoajie lv

Dear Bernd,

I can send you the startup files if you want, thank you very much.

shaojie lv

Dear shaojielv,

The crash message does not contain any usable information. Can you please send me your input files (including .GES5)?

Bernd

Dear Bernd,

Ok, there will also be such an error, attach a picture together.

shaojie lv

Dear Bernd,

I'm sorry I misunderstood what you said. When I read the reply again today, I found out that I made a mistake due to carelessness. I have sent the documents you need to your private email. Please check and I will explain me The main main content, I'm the reference case simulates the transformation of austenite to ferrite and cementite (needle), where ferrite nucleates at austenite grain boundaries and triple points, cementite In the austenite grain boundary and intragranular nucleation, after my modification of the model in the past two days, I found that the formation of ferrite will undergo a sudden change (the formation speed is particularly fast), while the cementite does not change. The above is my main question.

shaojie lv

Dear shaojielv,

It seems that the .GES-file you are using is either corrupt or incompatible (too old?). If you use a more recent one, the results will be quite different. You will further need to reduce the nucleation undercooling values to get transformation to ferrite and then nucleation of cementite.

Another issue is that the amount of cementite is very small due to the low carbon content of the alloy.

Bernd