Development of Hot Working Process Maps for Incompressible TRIP Steel and Zirconia Composites Using Crystal Plasticity-Based Numerical Simulations

Round 1

Reviewer 1 Report

The current paper draft introduced a study used CP-based numerical simulations to simulate the deformation behavior of the material to develop hot working process maps for incompressible TRIP steel composites with zirconia particles. The reviewer found this is a good paper but there is certain points need to clarify.

(1) Constitutive model of trip steel is missing. At least, flow equations, hardening equations, or maybe austenite-martensite phase transformation equations are necessary for people to understand the current simulation work.

(2) In Figure 2, clear description of the  color bar is needed.

(3) In Figure 4, the colors of curves should be reset. Yellow color is difficult for many people to read.

(4) In Figure 6, the simulated stress strain curves of global RVE fit well to the experiment. But the stress strain curve of zirconia particles did not fit experiment so well. At high temperature the fit is good, but at low temperature simulation it is far away from experiment. Could the authors explain why there is such kind of temperature influence.

(5) Equation (1) has mistake. Deformation gradient does not have a unit [s^{-1}]. 

(6) Calculation of "efficiency of power dissipation" is the key contribution of this paper draft. However, the definition of this value is missing. The authors have to give clear descript of this parameter either by equation or by text.

(7) The conclusion part could be rewritten to reflect the their main contributions.   

As a conclusion, a revised manuscript is necessary.

Author Response

We are thankful to the reviewers for taking the time to review the article and providing valuable feedback, which helped us improve the article's clarity and outlook. All the reviewer comments have been appropriately addressed in the main article body, and the modified text is highlighted yellow for easier comparison. The article was read thoroughly to check for any grammatical or punctuation mistakes and improvement in the clarity of language professionally. The article's methods, results, and conclusion sections have been coherently revised to improve understanding and clarity.

A point-by-point response to each reviewer's comment with reason and subsequent modification in the article body is provided in the attached PDF document.

Author Response File: Author Response.pdf

Reviewer 2 Report

At present, the development of technological regimes for the  metals and alloys forming by pressure is almost always carried out using mathematical modeling. The key element of mathematical models are constitutive relations. Since the properties of materials are largely determined by their meso- and microstructure, multilevel models based on the plasticity of crystals have become the most popular in recent decades. At the same time, constitutive models are of particular interest for describing the thermomechanical processing of multiphase alloys, particle reinforced metal matrix composites. An important issue in the construction of constitutive relations is the determination of the representative volume of the material. These issues are considered in the proposed article, which indicates the relevance of the chosen research topic.

There are some questions and comments on the content of the article.

1. It seems necessary from the very beginning to indicate for the solution of which practically important problems the developed model can be used. Satisfactory results of model verification for simple loading (uniaxial compression) do not guarantee satisfactory accuracy when it is used to study complex loading processes implemented in real technological processes of alloy processing.

2. Page 2, 3rd paragraph (lines 64-72). Of course, the choice of a representative volume (RVE) is a very important point in modeling, but the choice of RVE is also determined by the detail of the analysis prescribed by the researcher, and it may be necessary to introduce different RVEs at different structural-scale levels. In connection with the foregoing, it seems appropriate to note for what purposes RVE is introduced.

The requirement for the isotropy of the RVE properties is not clear; in the supply status, the samples may have texture and anisotropy; in this case, even during annealing, the anisotropy that arose at the stage of sample preparation can be preserved due to texture inheritance during recrystallization.

3. The question also arises of the correctness of using identical RVEs for the material located in the bulk of the samples and at their free boundaries, where there are facilitated conditions for the emergence of dislocations on the surface.

4. Section 2 (p. 3). The use of well-known software packages (including DAMASK) for research does not mean the absence of basic information about the model used. Boundary conditions at interphase boundaries are of particular importance. Does the formulation of the model take into account the possibility of violation of the ideal contact at the grain boundaries (especially zirconium dioxide and the metal matrix), including the appearance of cavities, slippage of the material? Is grain boundary strengthening taken into account? Since the response of the material significantly depends on these factors, it is necessary to provide the data necessary for the analysis of the results obtained.

If ideal contact conditions are used at the phase boundaries, in the matrix grains adjacent to the zirconium dioxide crystallites, extremely large displacement gradients can occur, and in this case the applicability of the first-order constitutive relations is questionable (K. Truesdell).

5. Section 2.2. Was model identification carried out separately for each test temperature and strain rate? What data should be used in this case under the changed test conditions? What are the predictive capabilities of the model? Has the model been verified under other types of loading (for example, under tension at various temperatures and strain rates)?

It is not clear whether the modeling takes into account the processes of recovery and recrystallization; according to the results of the calculation, it is impossible to unequivocally confirm or refute the inclusion of this mechanism in the model. Of course, by determining the material parameters for each deformation mode, these processes can be implicitly taken into account in the model. However, since the driving force of recrystallization is not only temperature, but also the difference between the accumulated internal energy (on lattice defects) in neighboring grains, it is doubtful whether the model can describe deformation with sufficient accuracy at low strain rates and high temperatures, even for samples with a different grain structure, different from the model adopted at the stage of identification.

6. Section 3.1.2, pp. 9-10. It is not clear what the authors mean by "the process maps", this term has an ambiguous meaning. Isolines of what quantity are shown in Fig. 8, what is its dimension? It is desirable to explain more clearly how the statistical data shown in Figs. 10-12 were obtained, whether they were obtained on one sample or on a series of samples with different grain structures. In the text on pages 11-12, it seems appropriate to use the term "equivalent" instead of the term "true (stress, strain)".

 

There are some typos in the text of the article.

• Page 2, line 89: TRIp should be replaced with TRIP.

• Page 4, line 122, line 133; p.5, line 146: You must specify the dimension of the given RVE data (60x60x60, 20x20x20, 200x200x1).

• Page 5, line 146: Replace “gains” with “grains”.

Author Response

We are thankful to the reviewers for taking the time to review the article and providing valuable feedback, which helped us improve the article's clarity and outlook. All the reviewer comments have been appropriately addressed in the main article body, and the modified text is highlighted yellow for easier comparison. The article was read thoroughly to check for any grammatical or punctuation mistakes and improvement in the clarity of language professionally. The article's methods, results, and conclusion sections have been coherently revised to improve understanding and clarity.

A point-by-point response to each reviewer's comment with reason and subsequent modification in the article body is provided in the attached PDF document.

Author Response File: Author Response.pdf