An Overview of Deformation Path Shapes on Equal Channel Angular Pressing
B. Ravisankar
Round 1
Reviewer 1 Report
I reviewed the review article entitled “An Overview of Deformation Path Shapes on Equal Channel 2 Angular Pressing”. The following points have come to my attention:
1- The author of a review article must be an expert in that field. In such a way that a large number of references in the article are related to the author, which is a proof of this fact. Of course, despite the fact that the authors had no experience in this field, they wrote relatively well. However, there are articles related to other alternatives of the ECAP process or its integration with other processes in the literature. Therefore, in order to make this article as comprehensive as possible, it is recommended that the authors study the following and similar articles:
 B Mani, M Jahedi, MH Paydar, “A modification on ECAP process by incorporating torsional deformation” Materials Science and Engineering: A 2011.
 Behtash Mani, Mohammad Jahedi, Mohammad Hossein Paydar, “Consolidation of commercial pure aluminum powder by torsional-equal channel angular pressing (T-ECAP) at room temperature”, Powder Technology, 2012.
 E Bagherpour, M Reihanian, N Pardis, R Ebrahimi, Terence G Langdon, “Ten years of severe plastic deformation (SPD) in Iran, part I: equal channel angular pressing (ECAP), Iranian Journal of Materials Forming, 2018.
 E Bagherpour, N Pardis, M Reihanian, R Ebrahimi, “An overview on severe plastic deformation: research status, techniques classification, microstructure evolution, and applications” The International Journal of Advanced Manufacturing Technology, 2019.
 M. Abdi , R. Ebrahimi, “Twin parallel channel angular extrusion as a development of ECAE in parallel channels” SN Applied Sciences, 2020.
2- In addition to the main item above, the following minor items must also be corrected:
2-1- In line 69, “shear stress” should be replaced by “shear strain”.
2-2- In line 130, “equivalent stress” should be replaced by “equivalent strain”.
2-3- The average grain size represents in figure 5 are related to how many passes?
2-4- In line 161, there is a scientific contradiction in this sentence. Room temperature or high temperature?
"Another advantage of heating the die it becomes possible to apply ECAP process at room temperature for metals and alloys such as magnesium. "
2-5- In line 200, “particle size” should be replaced by “grain size”.
2-6- In figure caption of figure 8, “strain-strain plot” should be replaced by “stress-strain plot”.
3- There is no section after discussion, generally a review article ends with a summary section.
Comments for author File: 
Comments.pdf
Author Response
Response to the Reviewer(s)' Comments:
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Dear Editors and Reviewers:
Thank you for your letter and for the reviewers and editors’ comments concerning our manuscript entitled “An Overview of Deformation Path Shapes on Equal Channel Angular Pressing” (metals-1906366). These comments were all valuable and very helpful for revising and improving our paper, as well as for providing important guidance for our research. We have studied the comments carefully and have made correction which we hope to meet with approval. The revised portions are marked in blue in the paper and given here in quotation marks. The main corrections in the paper and the responses to the reviewers and editors’ comments are as follows:
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Reviewer 1
I reviewed the review article entitled “An Overview of Deformation Path Shapes on Equal Channel 2 Angular Pressing”. The following points have come to my attention:
1- The author of a review article must be an expert in that field. In such a way that a large number of references in the article are related to the author, which is a proof of this fact. Of course, despite the fact that the authors had no experience in this field, they wrote relatively well. However, there are articles related to other alternatives of the ECAP process or its integration with other processes in the literature. Therefore, in order to make this article as comprehensive as possible, it is recommended that the authors study the following and similar articles:
- B Mani, M Jahedi, MH Paydar, “A modification on ECAP process by incorporating torsional deformation” Materials Science and Engineering: A 2011.
- Behtash Mani, Mohammad Jahedi, Mohammad Hossein Paydar, “Consolidation of commercial pure aluminum powder by torsional-equal channel angular pressing (T-ECAP) at room temperature”, Powder Technology, 2012.
- E Bagherpour, M Reihanian, N Pardis, R Ebrahimi, Terence G Langdon, “Ten years of severe plastic deformation (SPD) in Iran, part I: equal channel angular pressing (ECAP), Iranian Journal of Materials Forming, 2018.
- E Bagherpour, N Pardis, M Reihanian, R Ebrahimi, “An overview on severe plastic deformation: research status, techniques classification, microstructure evolution, and applications” The International Journal of Advanced Manufacturing Technology, 2019.
- Abdi , R. Ebrahimi, “Twin parallel channel angular extrusion as a development of ECAE in parallel channels” SN Applied Sciences, 2020.
Response: We would like to thank you for your valuable comments. We improved the manuscript in light of your suggestions.
2- In addition to the main item above, the following minor items must also be corrected:
2-1- In line 69, “shear stress” should be replaced by “shear strain”.
Response: Thank you very much your careful review. We reviewed whole manuscript and necessary corrections have been made.
2-2- In line 130, “equivalent stress” should be replaced by “equivalent strain”.
Response: Thank you very much your careful review. We reviewed whole manuscript and necessary corrections have been made.
2-3- The average grain size represents in figure 5 are related to how many passes?
Response: The following sentence has been added to the manuscript.
“After two ECAP passes at a temperature of 489K”.
2-4- In line 161, there is a scientific contradiction in this sentence. Room temperature or high temperature?
"Another advantage of heating the die it becomes possible to apply ECAP process at room temperature for metals and alloys such as magnesium. "
Response: The sentence has been revised as follows.
Another advantage of heating the die is that it enables ECAP treatment of metals and their alloys such as magnesium [50, 51], titanium [52], steel [53] and tungsten [54] where ECAP treatment is not possible or difficult at room temperature.
2-5- In line 200, “particle size” should be replaced by “grain size”.
Response: Thank you very much your careful review. We reviewed whole manuscript and necessary corrections have been made.
2-6- In figure caption of figure 8, “strain-strain plot” should be replaced by “stress-strain plot”.
Response: Thank you very much your careful review. The change you suggested has been made.
3- There is no section after discussion, generally a review article ends with a summary section.
Response: The last section was rearranged and changed to "Summary and Conclusions".
Author Response File: Author Response.pdf
Reviewer 2 Report
The article on “An Overview of Deformation Path Shapes on Equal Channel Angular Pressing” deals with various methods of ECAP process. There is no discussion on the deformation path or the mechanism of grain refinement. It looks like a collection of data from the literature with respect to the methods and types of ECAP. Interpretation of authors are missing which is an essential requirement for a Review article. Hence the paper is rejected.
Author Response
Dear Reviewers
Thank you for your letter and for the reviewers and editors’ comments concerning our manuscript entitled “An Overview of Deformation Path Shapes on Equal Channel Angular Pressing” (metals-1906366). These comments were all valuable and very helpful for revising and improving our paper, as well as for providing important guidance for our research. We have studied the comments carefully and have made correction which we hope to meet with approval. The revised portions are marked in blue in the paper and given here in quotation marks. The main corrections in the paper and the responses to the reviewers and editors’ comments are as follows:
We would like to thank you for your valuable comments.
In this study, the process parameters used in the ECAP method are discussed. In addition, with the increase in the applications of the SPD method, improvements have been made continuously to increase its efficiency. Therefore, there are many variations of the method. In this study, the findings were examined by including different die designs used in the SPD method.
Round 2
Reviewer 1 Report
The manuscript has been improved. it is now ready to publish.
Author Response
Response to the Reviewer(s)' Comments:
-----------------------------------------------------------------------------------------------------------------
Dear Editors and Reviewers:
Thank you for your letter and for the reviewers and editors’ comments concerning our manuscript entitled “An Overview of Deformation Path Shapes on Equal Channel Angular Pressing” (metals-1906366). These comments were all valuable and very helpful for revising and improving our paper, as well as for providing important guidance for our research.
-----------------------------------------------------------------------------------------------------------------
Reviewer 1
The manuscript has been improved. it is now ready to publish.
Response: We would like to thank you for your valuable comments.
Reviewer 2 Report
The authors added few more types of ECAP process to their old manuscript but not addressed the query raised by the reviewer. For example authors stated that “The ECAP-FE method is the most striking feature of combining the two methods and eliminating additional equipment. The extrusion process applies a back pressure for the ECAP process, which removes surface cracks and improves microstructure and mechanical properties. It was stated that this was related to the increase in the self- diffusion coefficient of Al due to the induced shear deformation and applied back pressure during ECAP”.
The review article needs to address Why upon applying back pressure microstructure and mechanical properties is improved and related discussions. How self diffusion co efficient increases on increasing shear stress and related discussions. Such features are not mentioned in the paper and hence it is rejected.
Author Response
Response to the Reviewer(s)' Comments:
-----------------------------------------------------------------------------------------------------------------
Dear Editors and Reviewers:
Thank you for your letter and for the reviewers and editors’ comments concerning our manuscript entitled “An Overview of Deformation Path Shapes on Equal Channel Angular Pressing” (metals-1906366). These comments were all valuable and very helpful for revising and improving our paper, as well as for providing important guidance for our research. We have studied the comments carefully and have made correction which we hope to meet with approval. The revised portions are marked in blue in the paper and given here in quotation marks. The main corrections in the paper and the responses to the reviewers and editors’ comments are as follows:
-----------------------------------------------------------------------------------------------------------------
Reviewer 1
The authors added few more types of ECAP process to their old manuscript but not addressed the query raised by the reviewer. For example authors stated that “The ECAP-FE method is the most striking feature of combining the two methods and eliminating additional equipment. The extrusion process applies a back pressure for the ECAP process, which removes surface cracks and improves microstructure and mechanical properties. It was stated that this was related to the increase in the self- diffusion coefficient of Al due to the induced shear deformation and applied back pressure during ECAP”.
The review article needs to address Why upon applying back pressure microstructure and mechanical properties is improved and related discussions. How self diffusion co efficient increases on increasing shear stress and related discussions. Such features are not mentioned in the paper and hence it is rejected.
Response: We would like to thank you for your valuable comments. We improved the manuscript in light of your suggestions. The following sections have been added in line with the reviewer's suggestion
Xia and Wu [87] conducted an experimental study on pure Al powder and solid Al ingot wrapped in Al foil in the back-pressure ECAP mold they designed. In the study, the die was heated up to 100 C. And the samples were passed through the mold. As a result, it was determined that PM Al particles had better bonding, full density and excellent mechanical properties.
Some studies demonstrate that excellent bonding is achieved between particles when subjected to severe shear deformation at low temperatures under an average pressure. The reason for this is that the cut surfaces of the particles are clean and fresh and they provide good contact between them due to the compressive stress. Under these conditions, bonding between particles occurs spontaneously without the need for high temperature and pressure. In contrast to the long time required for diffusion bonding in sintering, the particles bond quickly as they pass through the shear zone. In addition, thanks to the back pressure, full density is reached in the first pass [87, 89-92].
The common purpose of the presented methods is to improve the microstructure and improve the mechanical properties by subjecting the the material irreversibly to excessive plastic deformation. After different number of passes in the SPD process, grain refinement is associated with phase transformations [99]. During phase transformations, the formation of nano-clusters, segregations, nanotwins and dislocation substrate occur, which provides the hardening mechanism of the material. Studies show that UFG can control the deformation mechanism, which increases the strain-hardening rate. Thus, the material can show good properties in terms of both strength and ductility [10, 100-102].
- Xia K, Wu X. Back pressure equal channel angular consolidation of pure Al particles. Scripta Materialia. 2005;53(11):1225-9. doi: 10.1016/j.scriptamat.2005.08.012.
- Paydar M, Reihanian M, Bagherpour E, Sharifzadeh M, Zarinejad M, Dean T. Equal channel angular pressing–forward extrusion (ECAP–FE) consolidation of Al particles. Materials & Design. 2009;30(3):429-32.
- Paydar M, Reihanian M, Bagherpour E, Sharifzadeh M, Zarinejad M, Dean T. Consolidation of Al particles through forward extrusion-equal channel angular pressing (FE-ECAP). Materials letters. 2008;62(17-18):3266-8.
- Robertson J, Im JT, Karaman I, Hartwig KT, Anderson IE. Consolidation of amorphous copper based powder by equal channel angular extrusion. Journal of Non-Crystalline Solids. 2003;317(1-2):144-51. doi: 10.1016/s0022-3093(02)01995-6.
- Senkov ON, Senkova SV, Scott JM, Miracle DB. Compaction of amorphous aluminum alloy powder by direct extrusion and equal channel angular extrusion. Materials Science and Engineering: A. 2005;393(1-2):12-21. doi: 10.1016/j.msea.2004.09.061.
- Barenji AB, Eivani A, Hasheminiasari M, Jafarian H, Park N. Effects of hot forming cold die quenching and inter-pass solution treatment on the evolution of microstructure and mechanical properties of AA2024 aluminum alloy after equal channel angular pressing. Journal of Materials Research and Technology. 2020;9(2):1683-97.
- Wang Y, Ma E. Strain hardening, strain rate sensitivity, and ductility of nanostructured metals. Materials Science and Engineering: A. 2004;375:46-52.
- Maganti NR, Kumar KN. Effect of equal channel angular pressing process on the hardness and microstructure of copper and Al-6082 alloy: a preliminary investigation. Materials Today: Proceedings. 2017;4(8):8400-8.
- Kim HS, Seo MH, Hong SI. Plastic deformation analysis of metals during equal channel angular pressing. Journal of Materials Processing Technology. 2001;113(1-3):622-6.
Round 3
Reviewer 2 Report
The authors incorporated the suggestions and hence it can be accepted
