Ti6Al4V-0.72H on the Establishment of Flow Behavior and the Analysis of Hot Processing Maps

Round 1

Reviewer 1 Report

1. Line no.16 spelling. what does the word "ture" conveys? 

2. Line no.98 what is the meaning of 00mm/min kindly confirm. 

3. Line no.99 here reported powder feeding rate of 1.0 r/min kindly confirm. 

4. Table 1, how was the chemical composition of the sample measured? 

5. What is the reason behind different deformation temperature for Ti6Al4V and Ti6Al4V-0.72H.

6. Line no.141 check s-1 should be s -1

7. Fig 2.b the microstructure appears to be martensitic; what could be the difference of microstructure of 2 a & b. 

8. Kindly avoid using equation in conclusion section.

Author Response

1.Line no.16 spelling. what does the word "ture" conveys?

Thank you for your valuable comments. This is a misrepresentation that has been corrected and highlighted in the manuscript.

2.Line no.98 what is the meaning of 00mm/min kindly confirm.

Thank you for your valuable comments. The parameters have been checked again and the correct parameters have been modified in the manuscript.

3. Line no.99 here reported powder feeding rate of 1.0 r/min kindly confirm.

Thank you for your valuable comments. The parameters have been checked again and the correct parameters have been modified in the manuscript.

4. Table 1, how was the chemical composition of the sample measured?

Thank you for your valuable comments. The chemical composition of the sample was derived from relevant scientific data of other researchers in the research team, and references were added to the manuscript.

5. What is the reason behind different deformation temperature for Ti6Al4V and Ti6AI4V-0.72H.

Thank you for your valuable comments. Hydrogen is a stable element of the β phase and can reduce the β transition temperature. Therefore, the deformation temperatures of Ti6Al4V and Ti6AI4V-0.72H alloys are different.

6.Line no.141 check s-1 should be s -1

Thank you for your valuable comments. It was corrected and highlighted in the manuscript.

7. Fig 2.b the microstructure appears to be martensitic, what could be the difference of microstructure of 2 a & b

Thank you for your valuable comments. the difference of microstructure of 2 a & b was added and highlighted in the manuscript.

8.Kindly avoid using equation in conclusion section

Thank you for your valuable comments. It was corrected and highlighted in the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Managing the formation of crystalline grains during the additive manufacturing process for titanium alloys represents one of the major practical challenges for this type of technology. The authors have developed an interesting method to predict and manage this phenomenon. The method certainly has several points that can be improved with greater detail and more relevance to the specific case of production. The paper can be considered for publication after providing further details on some points listed below:

• In the "Materials and Methods" section, line 92, the authors should specify the supplier of the raw material to provide specific starting characteristics and essential information for the replicability of the experimentation.
• In the "Materials and Methods" section, line 94, the authors should provide the parameters adopted for the sandblasting process;
• In the "Materials and Methods" section, line 98, a null velocity is indicated, is this an error? Please clarify this parameter;
• In the "Materials and Methods" section, line 114, the unit of measure related to liters should be written in lowercase;
• In the "Materials and Methods" section, line 115, the cooling curve should be specified as the rapidity of the process can alter the final properties;
• The authors should provide indications on the potential practical applications of this experimentation to give more foundation to real-world cases of using this methodology.
• Otherwise, the method is well described and is interesting in terms of theoretical aspects.

The quality of general English should be checked in a moderate manner.

Author Response

1. In the "Materials and Methods" section, line 92, the authors should specify the supplier of the raw material to provide specific starting characteristics and essential information for the replicability of the experimentation.

Thank you for your valuable comments. The supplier of the raw material was added to the manuscript.

2. In the "Materials and Methods" section, line 94, the authors should provide the parameters adopted for the sandblasting process,

    Thank you for your valuable comments. the parameters for the sandblasting process was added to the manuscript.

3. In the "Materials and Methods" section, line 98, a null velocity is indicated, is this an error? Please clarify this parameter,

Thank you for your valuable comments. The parameters have been checked again and the correct parameters have been modified in the manuscript.

4. In the "Materials and Methods" section, line 114, the unit of measure related to liters should be written in lowercase,

Thank you for your valuable comments. The “1 L/min” have been checked again, It is right.

5. In the "Materials and Methods" section, line 115, the cooling curve should be specified as the rapidity of the process can alter the final properties;

Thank you for your suggestions. The annealing process of this work was carried out with annealing followed by water cooling. The process is a traditional stress-relief annealing of the metal without special processing. As far as we know, the cooling rate of water cooling is around 100℃~600℃/s.

6. The authors should provide indications on the potential practical applications of this experimentation to give more foundation to real-world cases of using this methodology.

Thank you for your suggestions. We have added the potential applications and ideals of this work at the introduction section in the revised manuscript.

7. Otherwise, the method is well described and is interesting in terms of theoretical aspects.

Thank you for your valuable comments.

Author Response File: Author Response.pdf

Reviewer 3 Report

1) The text of the manuscript contains many misspellings, such as "the ture" in the abstract. In general, it reduces the readability of the article. English should be checked by the native speaker or grammar services and improved.

2) Lines 73-75, it can be presented in the form of a table or figure.

3) Figure 1 - Ф is not the sign for the diameter.

4) Materials and Methods section should contain at least 2 subsections: 1) related to the experiment and verification - initial materials and equipment, characterization tools; 2) modeling tools and methods, software.

5) In Table 3, the columns miss titles; measuring units should be out of the cell with the results.

6) All the axes in graphs should have titles and measuring units.

7) Equations 11-13 are false and can not be published. They have no physical sense: measuring units from both of the parts of the equations should be equal: there is no sense for the 8th polyminal since M, N, P are not a function of ε.

8) the results and discussion are mixed. Try to separate it into a Section on Results and a Section on Discussion. Results should contain no links to the literature.

9) Lines 224-225 are good for the Materials and Methods.

10) The M, N, and P meanings should be shown in the Materials and Methods.

11) "a good linear relationship" - what was your criterion of "good"?

12) what is the quantitative difference between 0.01 and ε^8? (Equation 13)

13) Conclusions should include the statement on achieving the aim of the study and results based on study tasks. In the end, the practical significance of the results and future outlook should be mentioned.

14) In lines 86-89, I did not find any scientific value or novelty formulated here. There are also no formulated study tasks and the aim of the study.

English should be improved. The article containes misspellings, such as "the ture" in the abstract..

Author Response

1) The text of the manuscript contains many misspellings, such as "the ture" in the abstract. In Suggestions for Authors general, it reduces the readability of the article. English should be checked by the native speaker or grammar services and improved

Thank you for your valuable comments. This is a misrepresentation that has been corrected and highlighted in the manuscript.

2) Lines 73-75, it can be presented in the form of a table or figure

Thank you for your valuable comments. The introduction is usually not presented graphically.

3) Figure 1 - Ф is not the sign for the diameter

Thank you for your valuable comments. The ”Φ” is an international academic symbol of diameter.

4) Materials and Methods section should contain at least 2 subsections: 1) related to the experiment and verification - initial materials and equipment, characterization tools; 2) modeling tools and methods, software.

Thank you for your valuable comments. It was corrected and highlighted in the manuscript.

5) In Table 3, the columns miss titles, measuring units should be out of the cell with the results.

Thank you for your valuable comments. It was corrected and highlighted in the manuscript.

6) All the axes in graphs should have titles and measuring units.

Thank you for your valuable comments. , ,  is represent rheological stress, strain rate, and logarithm of rheological stress, respectively. In order to keep the pictures simple and concise, they are all represented by the corresponding symbols in the manuscripts

7) Equations 11-13 are false and can not be published. They have no physical sense: measuring units from both of the parts of the equations should be equal there is no sense for the 8thpolyminal since M, N, P are not a function of ε.

Thank you for your suggestions. The equation       is a typical multiple linear regression equation of Thermal Processing Diagram. The M, N, P parameters are used to represent stress as a function of temperature, strain and strain rate. The equations for 11-13 are the equations for the parameters M, N, and P fitted from the experimental data points to the response variable.

This Multiple Linear Regression Model is typical isomorphic model in hot process^[1].

[1]   Sajadi S A, Toroghinejad M R, Rezaeian A, et al. A study of hot compression behavior of an as-cast FeCrCuNi2Mn2 high-entropy alloy [J]. 2022, 896: 162732.

8) the results and discussion are mixed. Try to separate it into a Section on Results and a Section on Discussion. Results should contain no links to the literature.

Thank you for your suggestions. We are sorry about this, and we are very clear about the results and the logic of the discussion, are described the results of the experiment and then discuss and explain the mechanism or reasons, did not add references to the results.

9) Lines 224-225 are good for the Materials and Methods.

Thank you for your valuable comments.

10) The M, N, and P meanings should be shown in the Materials and Methods

The M, N, P parameters are used to represent stress as a function of temperature, strain and strain rate. The equations for 11-13 are the equations for the parameters M, N, and P fitted from the experimental data points to the response variable.

11)"a good linear relationship" -what was your criterion of "good"? Lines 276

Thank you for your suggestion. “good” means the experimental data points are in good agreement with the fitted curves

12) what is the quantitative difference between 0.01 and ε^8? (Equation 13)

The M, N, P parameters are used to represent stress as a function of temperature, strain and strain rate. The equations for 11-13 are the equations for the parameters M, N, and P fitted from the experimental data points to the response variable.

13) Conclusions should include the statement on achieving the aim of the study and results based on study tasks. In the end, the practical significance of the results and future outlook should be mentioned.

Thank you for your valuable comments. It was corrected and highlighted in the manuscript.

14) In lines 86-89, did not find any scientific value or novelty formulated here. There are also no formulated study tasks and the aim of the study.

Thank you for your suggestion. We have added novelty and aim of the study and modified the introduction section in the revised manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

1) The English of the paper is still not at an adequate level and must be improved.

2) The valuable proposal on systematization of the presented data in the Introduction was declined. Meanwhile, many articles contain it: https://www.mdpi.com/2075-4701/13/12/1936, https://www.mdpi.com/2227-7080/12/1/1, https://www.mdpi.com/2227-7080/11/3/78

3) The 3rd comment was also ignored. Ф  is a Cyrillic letter, https://en.wikipedia.org/wiki/Ef_(Cyrillic), the international diameter symbol is ⌀ (Unicode character U+2300), similar to the lowercase letter ø, https://en.wikipedia.org/wiki/%C3%98.

4) What was your Optical microscope? It was not mentioned in the text.

5) Table 3 is still awkward. It should be redone. The temperature columns should have titles.

6) Comment 6, regarding the necessity of presenting all the graphs with titles and measuring units, was ignored.

7) Equations 11-13 can not be published since they have no physical sense. Both parts of the equation should have similar measuring units like F=ma, E=mc, etc. The M, N, and P parameters are temperature, strain, and strain rate, which are not similar measuring units and can not be equal to ε^8 (The true strain to the 8th power). Moreover, in these equations, the measureless parameter and the true strain to the 8th power are not comparable in numerical value; thus, one of them or even most of the members of this polynomial should be ignored in the calculation. I have checked the provided reference, the equations 25-28 are also not OK. I will write to the Journal. The rest of the article is more or less adequate from the view of physical dependencies.

8) Comment 8 on separation Results (what the authors achieved) and Discussion (working out data and comparing them with previously published works) was ignored.

9) Comment 9 on the position of "In this paper, peak stress values are used 239 for the curve fitting [40]." was ignored.

10) Comment 10 on the M, N, and P meanings was ignored.

11) Comment 11: the term "good" should be excluded from the scientific paper. It was mentioned 8 times when it has no scientific value. In science, nothing is good but suitable for certain applications or not suitable for numerical expression. Please replace "good" with a numerical expression.

12) Comment 12 on the quantitative difference between 0.01 and ε^8 was ignored. The authors didn't answer the question.

13) The conclusions were not reworked according to Comment 13. 

14) There is still no scientific novelty formulated by the authors and no study tasks.

The English of the paper is still not at an adequate level and must be improved.

Author Response

• The English of the paper is still not at an adequate level and must be improved

Thanks for your suggestions. We have modified the English language in the revised manuscript.

• The valuable proposal on systematization of the presented data in the Introduction was declined. Meanwhile, many articles contain it: https:/www.mdpi.com/2075-4701/13/12/1936, https://www.mdpi.com/2227-7080/12/1/1, https:/www.mdpi.com/2227-7080/11/3/78

Thank you for your valuable comments. It has been added.

• The 3rd comment was also ignored. Ф is a Cyrillic letter, https://en.wikipedia.org/wiki/Ef_(Cyrillic), the international diameter symbol is ø (Unicode character U+2300), similar to the lowercase letter ø, https://en.wikipedia.org/wiki/%C3%98

Thank you for your valuable comments. It was corrected and highlighted in the manuscript.

• What was your Optical microscope? It was not mentioned in the text.

Thank you for your valuable comments. Optical microscope models have been added and highlighted in the manuscript.

• Table 3 is still awkward. It should be redone. The temperature columns should have titles

Thank you for your valuable comments. It has been redone.

• Comment 6, regarding the necessity of presenting all the graphs with titles and measuring units, was ignored.

Thank you for your valuable comments. It has been redone.

• Equations 11-13 can not be published since they have no physical sense. Both parts of the equation should have similar measuring units like F=ma, E=mc, etc. The M, N, and P parameters are temperature, strain, and strain rate, which are not similar measuring units and can not be equal to s^8 (The true strain to the 8th power). Moreover, in these equations, the measureless parameter and the true strain to the 8th power are not comparable in numerical value, thus, one of them or even most of the members of this polynomial should be ignored in the calculation. I have checked the provided reference, the equations 25-28 are also not OK. l will write to the Journal. The rest of the article is more or less adequate from the view of physical dependencies

Thanks for your suggestions. In this study, we utilized the widely recognized Zener-Hollomon parametric equation, a part of the Arrhenius model, to analyze the changes in strain variables. However, the existing eigenfactorial equation only considers the deformation temperature and strain rate. Through observing real stress-strain curves, we noticed significant variations in rheological stress values under different strain conditions. These variations impact the parameter values in the eigen equation, highlighting the need to incorporate both strain amount and the eigenequation through a new phenomenological multiple regression model.

Our analysis revealed a strong linear relationship between certain variables, leading to the derivation and simplification of Equations 3-8 and 3-9. For the calculation of M, N, and P, we selected true stress values at true strains ranging from 0.1 to 0.9 at intervals of 0.1. Utilizing scatter plots, we applied polynomial fitting to determine the parameters of the intrinsic equation under various strain conditions. The relationship between alloy parameters and strain variables was established, with the degree of fit depicted in Fig. 8. By utilizing the finalized multivariate linear regression equations, we can now predict and simulate the rheological stress behavior of alloys under different deformation conditions more accurately.

• Comment 8 on separation Results (what the authors achieved) and Discussion (working out data and comparing them with previously published works) was ignored.

Thank you for your valuable suggestions. It has been corrected in the manuscript.

• Comment 9 on the position of "In this paper, peak stress values are used 239 for the curve fitting [40]." was ignored.

Thank you for your valuable suggestions. We have replaced the position of ‘In this paper, peak stress values are used 239 for the curve fitting’ and modified the sentence in the revised manuscript.

• Comment 10 on the M, N, and P meanings was ignored.

Thank you for your suggestions. The equation         is a typical multiple linear regression equation of Thermal Processing Diagram. The M, N, P parameters are used to represent stress as a function of temperature, strain and strain rate. The equations for 11-13 are the equations for the parameters M, N, and P fitted from the experimental data points to the response variable. M, N, and P are the parameters associated with the response variable.

• Comment 11: the term "good" should be excluded from the scientific paper. It was mentioned 8 times when it has no scientific value. In science, nothing is good but suitable for certain applications or not suitable for numerical expression. Please replace "good" with a numerical expression.

We apologize for using inappropriate words in an academic paper. We have checked and revised some vocabulary throughout the text that is not suitable for scientific paper expression.

• Comment 12 on the quantitative difference between 0.01 and e^8 was ignored. The authors didn't answer the question.

The parameter MNP is a polynomial fit function on the strain ε, which can be Taylor-expanded, where the larger the order of higher infinitesimals, the better the fit curve matches the experimental result curve. When we set the order to 8, all the fitted curves match the experimental result curves. 0.01 is the 0th order of the polynomial, and the fitted curve differs greatly from the experimental result curve, and the fitted curve matches the experimental result curve only when the order is 8.

• The conclusions were not reworked according to Comment 13

Thank you for your valuable comments. It was corrected and highlighted in the manuscript.

• There is still no scientific novelty formulated by the authors and no study tasks

Thank you for your suggestion. We have added novelty and aim of the study and modified the introduction section in the revised manuscript.

Author Response File: Author Response.pdf

Round 3

Reviewer 3 Report

1) English still requires corrections. For example, in the sentence "This indicates that the increase of moderate amount of hydrogen will reduce the flow instability region of the alloy, thus leading to an improved rate high-quality product output." - I see 2 grammars.

2) The presented table doesn't present any systematization of the knowledge.

3) The third comment was taken into account.

4) The fourth comment was taken into account.

5) Table 3 was revised.

6) The measurement units were added.

7) The presented equations are very far from the Zener–Hollomon model, where both parts of the equation are exactly in accordance. For the tasks and presented parameters, the polynomial is not suitable and misleads the inexperienced reader. Look for another expression for M, N, P parameters or other parameters. The units on both sides of the function expression must be equal. One meter is not equal to the sum of a dimensionless constant, a kilogram, a kilogram squared, a kilogram cubed, etc., up to the 8th power. Equation 3-7 will also not be published since the "5.89266" power has no sense. Equation 3-10 is also not OK. If the P parameter represents stress as a function of temperature, it should have a temperature inside the expression. Equations 3-8, 3-9 have the same problem. Any "ln" should be dimensionless.

8) Thank you for separating the results and discussion. However, according to the research plan, the results should have subtitles, and in the Discussion, there should be no lines without subtitles (lines 193-199). The discussion can also continue the research plan, including the study's analytical tasks, and it should also contain a subsection related to comparing the results with similar works (placing the study in the world knowledge base). All the parameters and models used in the study should be explained in the Materials and Methods section.

9) I didn't find the expression related to line 239 in the manuscript mentioned in Point 9 of the previous reviews.

10) Comment 10 was once again partly ignored. Those parameters appear only in the discussion. They should be explained in Section 2, where all the used methodologies should be listed, along with the measuring units of those parameters.

11) Comment 11 was taken into account.

12) Some parameters in a polynomial function can be neglected since the strain ε has a range of values. The comment was not answered. What is the range of values for the strain ε?

13) The conclusions are revised. However, the practical usage of the obtained data for the industry, specifically in the thermal processing of additively manufactured titanium and hydrogen-producing titanium alloys, is still unclear.

14) Please write exactly: 1 - the aim of the study, in numerical expression. What do you want to improve or reduce for practical reasons? 2 - what is newly proposed that was never proposed before? New method, new approach. 3 - the study's tasks.

15) The article is not well-structured and doesn't present a completed study with a scientific aim. It is very difficult to understand what is new and proposed by the authors and how the obtained data can influence the industry.

English should be lightly revised.

Author Response

1) English still requires corrections. For example, in the sentence "This indicates that the increase of moderate amount of hydrogen will reduce the flow instability region of the alloy, thus leading to an improved rate high-quality product output." - I see 2 grammars.

Thanks for your suggestions. All modifications have been highlighted. We have modified the English language and grammar in the manuscript again. This sentence we have changed to “The findings suggest that the introduction of a moderate amount of hydrogen can effectively mitigate flow instability in the alloy, thereby enhancing the production rate and quality of the output.”

In other places, such as in the conclusion 3, The original sentence was: Based on the stress-strain curves obtained from the high temperature deformation, the hot processing maps were calculated and drawn. By comparing the two hot processing maps, it was found that the flow instability zone of the alloy became larger when the hydrogen content was 0.72wt%. Finally, a reasonable processing interval temperature of 940 °C–980 °C and strain rate of 0.01 s^-1–0.1 s^-1 was finally determined for Ti6Al4V, and a reasonable processing interval temperature of 725 °C–760 °C and strain rate of 0.01 s^-1–1.5 s^-1 was determined for Ti6Al4V-0.72H. This will provide the theoretical basis and processing parameters for the thermal processing of additively manufactured titanium and hydrogen-producing titanium alloys.

We have changed to “The hot processing maps were calculated and plotted based on the stress-strain curves obtained from high temperature deformation. A comparion of the two hot processing maps revealed an increased size in the flow instability zone of the alloy when the hydrogen content was 0.72wt%. Finally, the optimal processing temperature range for Ti6Al4V was determined to be 940 °C-980 °C, with strain rate of 0.01 s^-1-0.1 s^-1 while for Ti6Al4V-0.72H, the recommended processing temperature range is 725 °C-760 °C, with a strain rate of 0.01 s^-1-1.5 s^-1. This study will establish the theoretical foundation and optimize the processing parameters for thermal treament of additively manufactured titanium and generating titanium alloys.” In this sentence, we have made an ordering and grammatical modification.

2) The presented table doesn't present any systematization of the knowledge.

Thanks for your careful checks. We're sorry about that and we have added some specificities of the three models to the table.

3) The third comment was taken into account.

Thanks for your suggestions.

4) The fourth comment was taken into account.

Thanks for your suggestions.

5) Table 3 was revised.

Thanks for your suggestions.

6) The measurement units were added.

Thanks for your suggestions.

7) The presented equations are very far from the Zener–Hollomon model, where both parts of the equation are exactly in accordance. For the tasks and presented parameters, the polynomial is not suitable and misleads the inexperienced reader. Look for another expression for M, N, P parameters or other parameters. The units on both sides of the function expression must be equal. One meter is not equal to the sum of a dimensionless constant, a kilogram, a kilogram squared, a kilogram cubed, etc., up to the 8th power. Equation 3-7 will also not be published since the "5.89266" power has no sense. Equation 3-10 is also not OK. If the P parameter represents stress as a function of temperature, it should have a temperature inside the expression. Equations 3-8, 3-9 have the same problem. Any "ln" should be dimensionless.

Thank you for your valuable comments. Equation 3-7 has been modified and the powers have been rounded to integers. For 3-8 to 3-10, they are empirical models, which are also widely used to describe thermal deformation behaviors. They are designed to incorporate the effects of flow stresses.

The units on both sides of the equations are not the same, this is because such equations are designed to quantitatively describe the correlation between flow stresses, strains, strain rates and temperatures during thermal deformation, and thus are used to predict flow stresses under different deformation conditions. Therefore, it is not necessary to maintain the consistency of the units.

For example, Figs. 5 and 6 show plots of ln σ as a function of ln ε,  and 1000/T. It can be seen that the relationship between ln σ-ln ε and ln σ-1000/T is approximated as a quadratic relationship. These functional relationships also do not meet the equilibrium of the units. Therefore, such equations (3-8 to 3-10) are more for the purpose of expressing the relationship between them.

This empirical model is widely used and recognized[1-3]. In contrast, in this paper, the equation is optimized so as to make it more concise.

[1] Zhao J, Ding H, Zhao W, et al. Modelling of the hot deformation behaviour of a titanium alloy using constitutive equations and artificial neural network[J]. Computational Materials Science, 2014, 92: 47-56.

[2] Lin Y C, Huang J, Li H B, et al. Phase transformation and constitutive models of a hot compressed TC18 titanium alloy in the α+ β regime[J]. Vacuum, 2018, 157: 83-91.

[3] Lu C, Shi J, Wang J. Physically based constitutive modeling for Ti17 alloy with original basketweave microstructure in β forging: A comparison of three approaches[J]. Materials Characterization, 2021, 181: 111455.

8) Thank you for separating the results and discussion. However, according to the research plan, the results should have subtitles, and in the Discussion, there should be no lines without subtitles (lines 193-199). The discussion can also continue the research plan, including the study's analytical tasks, and it should also contain a subsection related to comparing the results with similar works (placing the study in the world knowledge base). All the parameters and models used in the study should be explained in the Materials and Methods section.

Thanks for the suggestion. We have separated the results into two parts, which are “Microstructure evolution” and “Analysis of deformation behaviour”. And that paragraphs without subtitles in the discussion had been placed in 2.2 of Materials and methods.

9) I didn't find the expression related to line 239 in the manuscript mentioned in Point 9 of the previous reviews.

Thanks for the question. The sentence “In this paper, peak stress values are used for the curve fitting [39].” was changed to “a constitutive equation is derived by fitting the peak stress in the stress-strain curve[40]”,and it was placed in line 158-159.

10) Comment 10 was once again partly ignored. Those parameters appear only in the discussion. They should be explained in Section 2, where all the used methodologies should be listed, along with the measuring units of those parameters.

Thank you for your suggestions. The equation  is a typical multiple linear regression constitutive equation. The M, N, P parameters are used to represent stress as a function of temperature, strain and strain rate. The equations for 11-13 are the equations for the parameters M, N, and P fitted from the experimental data points to the response variable. M, N, and P are the parameters associated with the response variable. Similarly, almost all articles about thermal deformation behavior have list the equations in the Results section or Discussion section [1-3], so I think it is reasonable.

[1] Savaedi Z, Motallebi R, Mirzadeh H. A review of hot deformation behavior and constitutive models to predict flow stress of high-entropy alloys[J]. Journal of Alloys and Compounds, 2022, 903: 163964.

[2] Gao P F, Guo J, Zhan M, et al. Microstructure and damage based constitutive modelling of hot deformation of titanium alloys[J]. Journal of Alloys and Compounds, 2020, 831: 154851.

[3] Peng X, Guo H, Shi Z, et al. Constitutive equations for high temperature flow stress of TC4-DT alloy incorporating strain, strain rate and temperature[J]. Materials & Design, 2013, 50: 198-206.

[4] Azarbarmas M, Aghaie-Khafri M, Cabrera J M, et al. Microstructural evolution and constitutive equations of Inconel 718 alloy under quasi-static and quasi-dynamic conditions[J]. Materials & Design, 2016, 94: 28-38.

11) Comment 11 was taken into account.

Thanks for your suggestions.

12) Some parameters in a polynomial function can be neglected since the strain ε has a range of values. The comment was not answered. What is the range of values for the strain ε?

Thanks for the question. The range of values for ε is in line 345 of the manuscript and is 0.05-0.85.

13) The conclusions are revised. However, the practical usage of the obtained data for the industry, specifically in the thermal processing of additively manufactured titanium and hydrogen-producing titanium alloys, is still unclear.

The establishment of a flow model for titanium alloys with different hydrogen contents can accurately predict the flow behavior of the alloys at high temperatures, revealing the intrinsic law of the material. In the conclusion the Z-parameter flow model is obtained, which is a good reference for subsequent experiments. The Z-parameter flow model was used to obtain a multiple linear regression equation taking strain into account, and the accuracy of the equation was verified with experimental data, finding that the error is small and can be applied to the rheological behavior of titanium alloys at high temperatures, which can be used in industrial applications to reduce the amount of experiments, and be used to guide the design of the products as well as to improve the quality and reliability of the products. The conclusions we've reached so far may be superficial, but we're already continuing to delve deeper. flow behavior is of some significance in solidification, plastic deformation, metal processing, etc. Therefore, it is also important to establish the constitutive relationship so as to better predict the flow behavior.

14) Please write exactly: 1 - the aim of the study, in numerical expression. What do you want to improve or reduce for practical reasons? 2 - what is newly proposed that was never proposed before? New method, new approach. 3 - the study's tasks.

Aims of this research:

1. Addition of hydrogen to titanium alloys can reduce the deformation resistance, facilitate rolling and thus effectively refine the grain and microstructure, so that this phenomenon can be confirmed by high-temperature compression tests.
2. Through this paper, a suitable rheological model is build and its accuracy is verified in order to predict the flow behavior in different conditions during high-temperature deformation.
3. In this paper, the thermal processing maps of hydrogenated titanium alloy is established to determine the optimal deformation conditions.

Innovative:

1. The thermal deformation behavior of additively hydrogenated titanium alloys has not yet been investigated, and this thermal deformation behaviors needs to be investigated in order to better understand the thermal processing properties of additively hydrogenated titanium alloys, and therefore this work is innovative.
2. The variation of strain on stress is taken into account in the constitutive model and a multiple linear regression equation is proposed with high accuracy compared to experimental results.

15) The article is not well-structured and doesn't present a completed study with a scientific aim. It is very difficult to understand what is new and proposed by the authors and how the obtained data can influence the industry.

Currently, there are relatively few studies on the thermal deformation behavior of additive manufacturing hydrogenated titanium alloys, especially on the constitutive equations and thermal processing maps. As a bridge between the parameters of the material deformation process and the thermal deformation behavior, the constitutive equations of plastic deformation can predict the relationship between the parameters of the deformation process and the deformation behavior very well, and can describe the trend of its change more accurately on the basis of the constitutive equations. Therefore, through this paper, it is possible to predict the flow stress of additive manufacturing hydrogenated titanium alloys under different conditions, filter the optimal processing window, and guide the thermal processing of additive manufacturing hydrogenated titanium alloys in the actual production process.

Author Response File: Author Response.pdf

Round 4

Reviewer 3 Report

The authors have ignored most of the reviewer's comments.

The English is weak and requires revision by the Grammar editor or native speaker. Some of the sentences are difficult to understand and don't correspond to the journal's academic level.