Dynamic Plasticity and Fracture of Al 7075 and V95T1 Alloys: High-Velocity Impact Experiments

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article deals with an interesting and important issue. Dynamic plasticity is an important property for Al alloys and the conditions where the material will be used.

In the introduction, the authors elaborated and approached the issue in the given area with an extensive literary basis.

The materials and methodology of the experiments were chosen with an emphasis on the researched issue and the authors described them in detail. I have no comments on this part.

The research results are described in detail and processed - without comments.

In conclusion, the authors summarized and defined important results. I recommend stating these results in bullet points.

Comments:

- edit literature citation

Author Response

Reviewer 1

R1.G. The article deals with an interesting and important issue. Dynamic plasticity is an important property for Al alloys and the conditions where the material will be used. In the introduction, the authors elaborated and approached the issue in the given area with an extensive literary basis. The materials and methodology of the experiments were chosen with an emphasis on the researched issue and the authors described them in detail. I have no comments on this part. The research results are described in detail and processed - without comments. In conclusion, the authors summarized and defined important results. I recommend stating these results in bullet points.

A1.G. Thank you for your positive feedback!

 

R1.1. Edit literature citation.

A1.1. Done. The literature citation is formatted according to the journal requirements.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors investigated the dynamic plasticity and fracture behavior of Al 7075 and Al V95T1 alloys by high-speed impact experiments. The results may be useful to some readers. However, the following questions remain:

1. The originality of this study compared to past studies is unclear. Please add an explanation of the originality of this study around line 85 on page 3.

2. What is the actual amounts of elemental components in the samples used this experiment? (The authors only show the amounts of elemental components based on general aluminum standards in Table 1. However, there is a range of values. How much does this range of values ​​affect the experimental values?)

3. Are Fig. 4 d, e, and f from lines 329 to 335 (P12) incorrect ?

Author Response

Reviewer 2

R2.G. The authors investigated the dynamic plasticity and fracture behavior of Al 7075 and Al V95T1 alloys by high-speed impact experiments. The results may be useful to some readers. However, the following questions remain:

A2.G. Thank you for this kind evaluation of our research and for valuable comments motivating us to improve presentation of our results!

 

R2.1. The originality of this study compared to past studies is unclear. Please add an explanation of the originality of this study around line 85 on page 3.

A2.1.The following explanation is added at the beginning of this paragraph:

“This work has three objectives: (i) to collect experimental data for further parameterization of the dynamic plasticity and fracture models with the machine-learning approach similar to [Rodionov_2023, Rodionov_2024]; (ii) to apply the novel method of direct processing of the experimental data [Rodionov_2023a] and compare the obtained dynamic flow stress with the literature data; and (iii) to compare dynamic properties of two similar high-strength aluminum alloy (7075 and V95T1). These three points explain the novelty of the present study.”

 

R2.2. What is the actual amounts of elemental components in the samples used this experiment? (The authors only show the amounts of elemental components based on general aluminum standards in Table 1. However, there is a range of values. How much does this range of values affect the experimental values?)

A2.2. Table 1 was supplemented by the measured chemical composition, which corresponds to specification, but shows significant fluctuations in chemical composition from point to point (microsegregation). The following explanation is added to section 2.1:

“This table shows elemental composition according to both specification data and measurements for particular tested samples. The measurements are performed at five local points using Jeol 6590LA scanning electron microscope equipped with an energy dispersive spectrometer. Large scatter of the measured element concentrations correlate with the known issue of microsegregation for this type of aluminum alloys [Ohno_2019]. All measured average values of concentrations are within the ranges defined by the specifications except that for Si, which, besides, reveals exceptionally non-uniform distribution.”

Concerning the influence on mechanical properties, the following sentence is added to Conclusion:

“Because of close chemical composition of both alloys, see Table 1, we assume that the difference in dynamic properties relates to different thermo-mechanical treatment at production.”

 

R2.3. Are Fig. 4 d, e, and f from lines 329 to 335 (P12) incorrect?

A2.3. Thank you for pointing this out! The typos are corrected.

Reviewer 3 Report

Comments and Suggestions for Authors

Questions in the attached document.

Comments for author File: Comments.pdf

Author Response

Reviewer 3

R3.G. The authors report an experimental work investigating “Dynamic Plasticity and Fracture of Al 7075 and V95T1 Alloys: High-Velocity Impact Experiments”. The subject of the manuscript is interesting and represents an addition to the mechanical characterisation of the aluminium alloys studied and the techniques used. However, in order to increase the usefulness and quality of this work, the manuscript requires some revisions in order to be accepted for publication, as follows:

A3.G. Thank you very much for careful reading and useful comments! We have tried to improve the paper accordingly.

 

General considerations:

R3.1. Introduction needs to be improved;

A3.1. Introduction was reorganized and supplemented by additional explanations:

“Existing of a large number of metallic materials in various structural states and continuous development of new materials makes relevant development of robust, but simple and cheap methods for experimental dynamic testing.”

“Further simplification of the experimental procedure and data processing with extension of the strain rate range makes a sense.”

“Such experiments provide additional data for parameterization of the dynamic plasticity and fracture models with using of the machine-learning approach [Rodionov_2023, Rodionov_2024].”

“This work has three objectives: (i) to collect experimental data for further parameterization of the dynamic plasticity and fracture models with the machine-learning approach similar to [Rodionov_2023, Rodionov_2024]; (ii) to apply the novel method of direct processing of the experimental data [Rodionov_2023a] and compare the obtained dynamic flow stress with the literature data; and (iii) to compare dynamic properties of two similar high-strength aluminum alloy (7075 and V95T1). These three points explain the novelty of the present study.”

 

R3.2. The results obtained need to be analysed in depth and, whenever possible, justified with appropriate bibliographical references, rather than using the same works to justify everything (nothing against these references, but they are very limited);

A3.2. We disagree with this point, because a whole paragraph (the last paragraph of Section 4) of the initial text is devoted to the comparison with the literature data. At the same time, we have tried to further improve the level of analyses by addressing all other comments.

 

R3.3. Figure legends very confusing to read and interpret. Organise in alphabetical order (i.e. a), b), c), d), ...) and format according to the guidelines in the journal;

A3.3. Done.

 

R3.4. Format the references throughout the document according to the journal's guidelines.

A3.4. Done. The literature references are formatted according to the journal requirements.

 

Notes:

R3.5. Lines 21 to 23: “is somewhat” It's a very vague phrase. Rephrase the expression or, for example, specify the percentage of "is somewhat".

A3.5. The numerical comparison of flow stress and fracture strain is provided below. In this sentence we remain a qualitative conclusion, but remove the word “somewhat”:

“Thus, V95T1 aluminum alloy is less strength, but more ductile, while 7075 aluminum alloy is more strength, but, simultaneously, more brittle.”

The same is in the main text and in Conclusions.

 

R3.6. Lines 28 to 90: Very superficial introduction, not objective or concrete. The reader can't understand the reason for this study. What problems are these currently justifying this study? What is new about this work?

A3.6. Introduction was reorganized and supplemented, including the following statement of novelty of the present work:

“This work has three objectives: (i) to collect experimental data for further parameterization of the dynamic plasticity and fracture models with the machine-learning approach similar to [Rodionov_2023, Rodionov_2024]; (ii) to apply the novel method of direct processing of the experimental data [Rodionov_2023a] and compare the obtained dynamic flow stress with the literature data; and (iii) to compare dynamic properties of two similar high-strength aluminum alloy (7075 and V95T1). These three points explain the novelty of the present study.”

 

R3.7. Some historical concepts are touched on that add little or nothing to a scientific article that wants to be current and recent. Line 76: “large number of recent papers” it is necessary to give examples, it is not enough to mention them, otherwise the expression is not written.

A3.7. The examples are already included in the text just below this phrase. To make it clearer, the punctuation sign is changed from “.” to “:” as follows:

“large number of recent papers: Such aspects as the plasticity at increased temperatures [Liu_2023, Wu_2024, Ye_2024] and various previous heat treatments [Hua_2022], the properties of additively-manufactured samples [Fu_2023] and ballistic performance of 7075 aluminum alloy [Praveen_2022, Praveen_2023] are being actively studied.”

 

R3.8. Line 97: Table 1 is difficult to read and interpret. I suggest following the instructions and formatting the table accordingly. It would be interesting to point out and enlighten the reader, in addition to the composition, other physical and mechanical properties of the alloys under study.

A3.8. Tabel 1 was formatted according to the journal template; besides, the measured element concentrations were added. We did not measure other physical and mechanical properties of the alloys except the dynamic flow stress and fracture strain.

 

R3.9. Lines 93 to 128: How many samples were manufactured to obtain valid results? What precautions and values were taken into account when turning the samples (e.g. cutting speed, thickness removed in each pass, type of cutting tool used, ...)?

A3.9. The following explanation is added to Section 2.1:

“A total of 12 samples of each type were prepared using a manual feed lathe; most of the samples were subjected to dynamically tests at different impact velocities, while some were used for preliminary tests and control purposes.”

 

R3.10. What test standards were used in this study? It is rather limiting to consider only 2 or 3 works by the same author.

A3.10. We are developing a new testing method allowing a cheap and fast examination of dynamic properties of metallic materials; therefore, there is no a test standard used. Several samples are applied to increase the precision of the results and to treat the statistical straggling of mechanical properties.

 

R3.11. Line 135: “consider a simple method previously proposed in [Rodionov_2023a]” Why? What is the justification?

A3.11. The method was verified in the previous paper for the case of cold-rolled copper. The following explanation is added in Section 2.2:

“This method was verified in [Rodionov_2023a] against 3D numerical simulations by an example of cold-rolled copper. It was shown that the estimates are valid under conditions of deformation of only the profiled part of the cylinder, while the non-profile part should not experience deformation.”

 

R3.12. Lines 194 to 206: Complete the text with values, e.g. how much the sample has shrunk, what the diameter is at different speeds, based on the results already collected for the construction of Figures 6.

A3.12. Now we presented all measured parameters in Appendix A. The following explanation is given in Section 3.1:

“Table A1 in Appendix A collects the measured geometric parameters of all deformed samples impacted without fracture, including the final lengths and diameters of impact edge.”

 

R3.13. Lines 213 to 225: Support text with values (e.g. dimensions, deformation percentages).

A3.13. All values are shown further in the text: graphically in Fig. 6 and now in new Table A1.

 

R3.14. Line 246: Insert the scales of the figures shown.

A3.14. Spatial scales were added to Fig. 5.

 

R3.15. Line 263: Looking at the graphs, you can see trends. Can these trends be justified with results from the literature? Or is it a novelty, in which case it should be highlighted.

A3.15. The following explanation was added to Section 3.1:

“Remarkably, similar trends of the final length depending on the impact velocity described by second-order polynomials for classical cylinders and third-order polynomials for profiled cylinders are reported in [Mayer_2025] for both MD data for nano-sized samples and experimental data for millimeter-sized samples in the case of copper.”

 

R3.16. Line 265: “Figure 6” Pay attention to formatting: In the vertical scales of the graphs, replace the , by . ; To emphasise differences and/or common points, equalise the speed scales (between 40 and 200 m/s); The vertical scale of graph (a) equals (c) and (b) equals (d); Equal number of decimal places.

A3.16. Done.

 

R3.17. Line 285: What is the relationship/influence of the type of fracture observed with the test speed? Again, the ideas put forward need to be explored further.

A3.17. The following analysis was added to Section 4:

“This conclusion is in line with the fracture pattern shown in Figure 4 and Figure 5: Stress concentrators near the transition between the reduced head part and the main part provokes broking-off of the head part in the brittle 7075 alloy, while in the ductile V95T1 alloy the fracture goes along the shear direction and stress concentrators are not so dangerous.”

 

R3.18. Lines 338 to 341: On the basis of what assumption or scientific evidence was it made “a constant dynamic flow stress in this range of strain rates”? If “we don’t have enough statistically-based information to be sure in this softening” to overcome and properly justify this issue, enlighten the reader on what needs to be done in a future study, for example.

A3.18. The following clarification was added:

“suppose a constant dynamic flow stress in this range of strain rates as the simplest hypotheses.”

As far as we do not have enough evidences about a complex behavior, it is the most reasonable to use the simplest possible model, a constant value in this case.

 

R3.19. Line 380: Table 2: Difficult to read, format according to the newspaper's instructions.

A3.19. Table 2 was formatted accordingly.

 

R3.20. Lines 427 to 429: Rewrite the paragraph or create a future work section. It's not a conclusion.

A3.20. Done: This sentence is removed.

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

All questions raised were taken into consideration by the authors and answered.

Corrections and improvements have been added to the article.

Congratulations on your work.

Comments on the Quality of English Language

no