Computer Modeling of Grain Structure Formation during Quenching including Algorithms with Pre- and Post-Solidification

Round 1

Reviewer 1 Report

The simulation is based on cellular automation. I think the results have been well presented. I suggest direct acceptance. 

Here are some minor suggestions:

1. The article is too long, figures are too many.
2. The methodology was not introduced at the beginning (it is mentioned somewhere later).
3. I do not see clearly how the model parameters are related to an actual process.

Cellular automation (the method used in the article) does not describe a physical process (i.e., thermodynamics is not involved); it only visualizes a physical process. Hence, I only hope the authors can be more straightward on the methodology.

Author Response

Dear Professor, in the revised manuscript, your fine observations and corrections were taken into consideration. For better reference, they are included in red color.

1. We apologize because the paper had to come a bit longer because other reviewers asked actual macrostructures of the cast billets.
2. Indeed, we agree the methodology comes first. In the new manuscript we corrected this aspect.
3. The link between the model and the process is now specified.

We give the thanks for your valuable time employed in the review of our paper. We know is a time-consuming activity.

 

Sincerely Yours,

The Authors

Reviewer 2 Report

The authors have studied the formation of particle structure by the computer simulation.  It is very important to understand the microstructure and composition of materials to understand the formation of mushy area. Therefore, it is necessary to establish a microscopic solidification model. In this work, the influence of the programmed algorithms and solidification speed over the dynamic evolution of the grain structure on the chill, columnar and equiaxed zones is presented. This work is well done and can be accepted with minor revision. 

There are a few grammatical errors in the manuscript, need to be revised.

Author Response

Dear Professor, in the revised manuscript, your fine observations and corrections were taken into consideration. For better reference, they are included in red color.

We have revised the grammatical errors and corrected them.

On behalf of my co-authors and myself I thank you for your valuable comments on our work. Thank you very much for your time.

Reviewer 3 Report

In this manuscript, computer simulation of the formation of grain structures during the solidification of metals is performed. The influence of the nodal solidification times and the computer algorithms on the dynamic formation of the chill, co-lumnar and equiaxed zones is discussed. The authors propose an algorithm/model, which incorporates pre-nucleation and pre-growth routines. However, the presented discussions are descriptive, while the obtained results are more from the field of computational mathematics and programming than from the field of physics. The authors do not compare their results (neither qualitatively nor quantitatively) with experimental data and existing theories of grain nucleation and growth. The work can be recommended for publication in the journal ''Metals'' only after major revision taking into account the following comments:

1. Authors should compare their results with available experimental data or other theoretical results. A correspond discussion should also be added to the work.
2. It is necessary to interpret the results in terms of physics and applicability to real systems (i.e. metals or alloys) with examples.
3. Line 132: the authors claim that “There are no models considering only nucleation to simulate grain formation”. This is too bold a statement. In fact, there are many theories and kinetic models that can be used to describe the processes of nucleation and growth of solid (crystalline) grains. For example, the classical nucleation theory, the models of Turnbull-Fisher, Kelton-Greer, etc., which are described in works [A.L. Greer et al., J. Cryst. Growth 99, 38 (1990); D. Turnbull et al., J. Chem. Phys. 17, 71 (1949); D. Kashchiev, Nucleation: Basic Theory with Applications, Butterworth Heinemann, Oxford, UK, 2000; A.V. Mokshin et al., Phys. Chem. Chem. Phys. 19, 11340 (2017)]. This point should be discussed in the context of these works.
4. The manuscript is overloaded with figures. Perhaps the block diagrams (figure 7) and related discussions should be moved to an appendix for optimize the structure of the work.
5. The word "cold" should be used instead of the word "chill".

Author Response

Dear Professor, in the revised manuscript, your fine observations and corrections were taken into consideration. For better reference, they are included in red color.

1. Authors should compare their results with available experimental data or other theoretical results. A correspond discussion should also be added to the work.

Re: Thanks we added new material including experimental data to complement the presentation of our results.

2. It is necessary to interpret the results in terms of physics and applicability to real systems (i.e. metals or alloys) with examples.

Re: In the new manuscript we apply the model to a specific industrial caster.

3. Line 132: the authors claim that “There are no models considering only nucleation to simulate grain formation”. This is too bold a statement. In fact, there are many theories and kinetic models that can be used to describe the processes of nucleation and growth of solid (crystalline) grains. For example, the classical nucleation theory, the models of Turnbull-Fisher, Kelton-Greer, etc., which are described in works [A.L. Greer et al., J. Cryst. Growth 99, 38 (1990); D. Turnbull et al., J. Chem. Phys. 17, 71 (1949); D. Kashchiev, Nucleation: Basic Theory with Applications, Butterworth Heinemann, Oxford, UK, 2000; A.V. Mokshin et al., Phys. Chem. Chem. Phys. 19, 11340 (2017)]. This point should be discussed in the context of these works.

Re: “There are no models considering only nucleation to simulate grain formation”. We did not really mean this phrase; you are right and corrected in the new manuscript.

4. The manuscript is overloaded with figures. Perhaps the block diagrams (figure 7) and related discussions should be moved to an appendix for optimize the structure of the work.

Re: We have passed Figure 7 to an appendix. Thanks for your suggestion.

5. The word "cold" should be used instead of the word "chill".

Re: Chill is used for the first solidified metal in contact with mold. You are right.

On behalf of my co-authors and myself I thank you for your valuable comments on our work. Thank you very much for your time.

Round 2

Reviewer 3 Report

The authors took into account the comments and made the corrections. This work can be accepted in the present form.