A Method for Determining the Workability Diagram by Varying Friction Conditions in the Upsetting of a Cylinder between Flat Dies
, Mladomir Milutinovic 1, Marko Vilotic 1, Sergei Alexandrov 2,3 and Lihui Lang 2,*Round 1
Reviewer 1 Report
The authors have reported a study devoted to model of workability diagram by varying frictional conditions in the cylinder upsetting test according to new fracture criterion based on equation (3) of the text. Owing to a potential impact of the study to the applied crystallography it can be of interest in teh readers of 'Crystals.'
Author Response
Please check the file attached.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This paper develops a method for determining the workability diagram by varying frictional conditions in the cylinder upsetting test. However, this article exaggerates the experimental results but lacks a sufficient verification and analysis in general. Many formulas and conclusions are derived without detailed procedures. This paper cannot be considered for publication in Crystal in its current form. The major revision should be made, and the comments are listed as follows:
1) What equipment was adopted for the upsetting? The author should give detailed information for the strain rate and the testing temperature.
2) The author should explain the workability diagram in the paper.
3) What is the difference between the turned friction surface and the ground friction surface? Author should add the pictures of the friction surfaces turned and ground in Table 1.
4) What are the differences in friction represented by the tribological conditions of the five series in Table 1?
5) The author should explain the selection lubricants in Table 1.
6) How to determine the instant of fracture initiation?
7) The schematic of series 5 has a problem and needs to be redrawn in Table 1.
8) In Figure 3, the author should explain why the number of points varies greatly for different series. Moreover, the size of Equation should be uniform.
9) The author should provide detailed explanation for “It is seen from this figure that series 4 can replace the torsion test.”
10) Please provide detailed explanation in the article for conclusion 3.
Author Response
The corrections in the revised manuscript are shown in red.
“This paper develops a method for determining the workability diagram by varying frictional conditions in the cylinder upsetting test. However, this article exaggerates the experimental results but lacks a sufficient verification and analysis in general. Many formulas and conclusions are derived without detailed procedures. This paper cannot be considered for publication in Crystal in its current form. The major revision should be made, and the comments are listed as follows:”
General answer: The key point of the theoretical analysis has already been published in [22]. It is valid for any strain-hardening material and any process. There is no need to develop it further. Please be more specific. Which part of the method proposed requires a theoretical analysis?
The reviewer correctly notes that the paper proposes a method for determining the workability diagram. Figure 5 verifies the method.
Specific points.
- What equipment was adopted for the upsetting? The author should give detailed information for the strain rate and the testing temperature.
We have added this information.
- The author should explain the workability diagram in the paper.
The workability diagram is the term used for the expression in equation (1). The original manuscript states it.
3) What is the difference between the turned friction surface and the ground friction surface? Author should add the pictures of the friction surfaces turned and ground in Table 1.
4) What are the differences in friction represented by the tribological conditions of the five series in Table 1?
5) The author should explain the selection lubricants in Table 1.
Answer to 3 to 5. The key idea throughout this paper is that all these issues are not important. The paper provides a method to ride off the description of friction conditions for determining the workability diagram. Any surface treatment and any lubricant can be used. These choices have no effect on the general method. We cannot explain it here because the entire paper is an explanation of this approach. This paper is concerned with ductile fracture; friction is just a tool.
6) How to determine the instant of fracture initiation?
We use a conventional method accepted in most studies that use continuum mechanics methods for describing ductile fracture. The surface of specimens is examined for the presence of cracks by the naked eye. Taking into account the scatter of experimental data in ductile fracture studies, higher accuracy is not required.
Reviewer 3 Report
This manuscript proposes a new method for determining the workability diagram and verifies its reliability by the comparison with literature. The methods are clearly presented, and the results are well discussed. I can recommend the publication of this manuscript, provided that the authors address the following issues:
- For the introduction part, I do not understand the logic between the 5th paragraph (line 76 to 80) with the 4th one.
- Load conditions need to be provided in section 3.
- Table 2 and corresponding descriptions should be placed in section 3 rather than results parts.
- Line 179: equation should be numbered as (10) rather than [10].
Author Response
The corrections in the revised manuscript are shown in red.
1. For the introduction part, I do not understand the logic between the 5th paragraph (line 76 to 80) with the 4th one.
The 5th paragraph emphasizes that the method proposed does not rely on numerical simulations. We consider that it is its great advantage. It is also noted in the 4th paragraph. The 5th paragraph provides references.
2. Load conditions need to be provided in section 3.
We have added a new figure (Fig. 1 in the revised manuscript) to describe the loading conditions.
3. Table 2 and corresponding descriptions should be placed in section 3 rather than results parts.
We agree.
4. Line 179: equation should be numbered as (10) rather than [10].
It is reference number 10. We have clarified it in the text.
