Formability Analysis and Oxidation Layer Effects in Dieless Drawing of Stainless Steel Wires
Round 1
Reviewer 1 Report
The paper presents interesting results, obtained in an experimental installation of its own design. It should be noted that continuous drawing is more important for the deformation of the wire, since the wire is used as a long product. However, this is difficult to implement, so the authors chose another scheme (backward non-continuous). The choice of material (stainless steel) is also not fully consistent with the task, because the steel is not intensively oxidized material. From the reviewer's point of view, copper would be the best choice. However, I do not require consideration of these comments in the paper.
However, it is necessary to make a number of changes.
1. In formula (1) the multiplication signs (points) should be removed.
2. In Fig. 4, the difference in the oxidized layer for the considered variants of drawing is not visible. If there is an opportunity, please submit pictures with high magnification to allow readers to see the layer of oxides and evaluate its properties.
3. The explanation of the authors of the reason for the increase in UTS after dieless drawing on the air seems doubtful to me (“Because the strength of the oxide layer is generally larger than that of stainless steel”). The fact is that oxides are very brittle and would have fractured at the initial stage of deformation. For this reason, it is so important to see the structure of oxides with high magnification (for example, SEM).
4. Phrase “Therefore, a finite element software DEFORM coupled with the induction heating mode was used, in which a boundary element technique is used to analyze the heat transfer during the dieless drawing process” from my point of view unsuccessful.
The boundary element method is the same numerical method as the finite element method. Therefore, writing something like this. “… a finite element software DEFORM … was used, in which a boundary element technique is used to analyze …” is not quite right, from my point of view.
It seems to me that it is better to write something like this „Therefore, a software DEFORM coupled with the induction heating mode was used, in which a boundary element method is used to analyze the heat transfer during the dieless drawing process.”
5. The units of measurement of the temperature problem parameters are best given in standard form.
Thermal conductivity (W·m−1·K−1)
convection coefficient W M-2 K-1
6. Was taken into account strain rate sensitivity of flow stress ? If so, it is necessary to give hardening curves for other strain rates, correlating this with the strain rate in this process.
Author Response
Replies to the comments from reviewer #1
The paper presents interesting results, obtained in an experimental installation of its own design. It should be noted that continuous drawing is more important for the deformation of the wire, since the wire is used as a long product. However, this is difficult to implement, so the authors chose another scheme (backward non-continuous). The choice of material (stainless steel) is also not fully consistent with the task, because the steel is not intensively oxidized material. From the reviewer's point of view, copper would be the best choice. However, I do not require consideration of these comments in the paper. However, it is necessary to make a number of changes.
Q1: In formula (1) the multiplication signs (points) should be removed.
A1: As suggested by the reviewer, “▪” has been removed. The revised equation is given on p.3, Eq.(1) of the revised manuscript.
Q2: In Fig. 4, the difference in the oxidized layer for the considered variants of drawing is not visible. If there is an opportunity, please submit pictures with high magnification to allow readers to see the layer of oxides and evaluate its properties.
A2: Generally the thickness of the oxide layer increases with the forming temperature and the surface color of the product becomes slightly darker as the forming temperature increases. The surface colors of the products at 700°C and 1100°C exhibit more vivid contrast. Thus, only the appearance of the products at temperatures of 700°C and 1100°C was shown in Fig.4. The thickness of the oxide layer exhibits some variation of about 1-7 µm, which is quite close to the results in Ref. [20].
The above statement has been given on p.5, lines 152-156 of the revised manuscript.
Q3: The explanation of the authors of the reason for the increase in UTS after dieless drawing on the air seems doubtful to me (“Because the strength of the oxide layer is generally larger than that of stainless steel”). The fact is that oxides are very brittle and would have fractured at the initial stage of deformation. For this reason, it is so important to see the structure of oxides with high magnification (for example, SEM).
A3: As pointed out by the reviewer, the oxides are very brittle and undergo fracture easily at the early stage of deformation, which usually results in the thickness variation of the oxide layer. According to ref. [20], the structures of the oxide layer are mainly Fe3O4 and FeCr2O4.
The above statement has been given on p.5, lines 148-150 of the revised manuscript.
Q4: Phrase “Therefore, a finite element software DEFORM coupled with the induction heating mode was used, in which a boundary element technique is used to analyze the heat transfer during the dieless drawing process” from my point of view unsuccessful. The boundary element method is the same numerical method as the finite element method. Therefore, writing something like this. “… a finite element software DEFORM … was used, in which a boundary element technique is used to analyze …” is not quite right, from my point of view. It seems to me that it is better to write something like this „ Therefore, a software DEFORM coupled with the induction heating mode was used, in which a boundary element method is used to analyze the heat transfer during the dieless drawing process.”
A4: As suggested by the reviewer, the statement has been changed to “Therefore, a software DEFORM coupled with the induction heating mode was used, in which a boundary element method is used to analyze the heat transfer during the dieless drawing process.” which is given on p.7, line 188-190 in the revised manuscript.
Q5: The units of measurement of the temperature problem parameters are best given in standard form. Thermal conductivity (W·m−1·K−1), convection coefficient W·M-2 ·K-1
A5: As suggested by the reviewer, the unit of thermal conductivity has been changed to W·m−1·K−1 and that of convection coefficient has been changed to W·m-2 ·K-1. They are given on p.7, line 196-197 in the revised manuscript.
Q6: Was taken into account strain rate sensitivity of flow stress? If so, it is necessary to give hardening curves for other strain rates, correlating this with the strain rate in this process.
A6: The strain rate variation in the dieless drawing process was not so big. The average strain rate was about 0.25. Therefore the strain rate effect was not taken into account. The above statement has been added on p.7, line 191-193 in the revised manuscript.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The article describes an original research based on experimental and numerical simulation. Both the experimental work and the simulation Processes are sufficiently and clearly presented. Therefore, I recommend that this article be accepted for publication.
Few specific comments:
Line 27: the abbreviation MEMS is not fully defined.
Line 87/88: the definition of the areas is unnecessary. Just state as "?? and ?? are the cross-sectional areas of the wire before and after drawing, respectively."
The coverage of the reference list is relatively narrow since about 40% of the sources listed in the reference refer to a single research group.
Author Response
Replies to the comments from reviewer #2
The article describes an original research based on experimental and numerical simulation. Both the experimental work and the simulation Processes are sufficiently and clearly presented. Therefore, I recommend that this article be accepted for publication. Few specific comments:
Q1: Line 27: the abbreviation MEMS is not fully defined.
A1: MEMS denotes Micro-Electro-Mechanical-System, which has been added on p.1, line 27 in the revised manuscript
Q2: Line 87/88: the definition of the areas is unnecessary. Just state as "?? and ?? are the cross-sectional areas of the wire before and after drawing, respectively."
A2: As suggested by the reviewer, the statement has been changed to "?? and ?? are the cross-sectional areas of the wire before and after drawing, respectively." which is given on p.3, line 102-103 of the revised manuscript.
Q3: The coverage of the reference list is relatively narrow since about 40% of the sources listed in the reference refer to a single research group.
A3: Some more references from other researchers related to dieless drawing have been added and discussed in the “Introduction” section. (P. 2, L. 63 - 77) of the revised manuscript.
Author Response File: Author Response.pdf
Reviewer 3 Report
The present work deals with a topic already known to the scientific world for a decade. In fact, the first thing that catches one's eye is the small number of citations but above all the date of most of them, some of which date back to 1997. What emerges from the reading of the bibliography is also the repetition of an author who appears as first name in about half of the aforementioned publications, and this makes the topic rather niche for the small scientific sample that dealt with the subject. From this point of view, however, the topic could have some gaps that the few experts have not been able or have been able to investigate.
The article in the first part is well described, the introduction is quite exhaustive and the author leads the reader well towards the proposed research topic, motivating it in a detailed and clear way. In fact, the study of the influence that the oxidation layer formed during the process has on the mechanical properties of the material seems to be a relevant aspect for the quality of the final product.
The part of materials and methods is quite clear and well presented even though in Table 1 it is not clear why the atmosphere and the forming temperatures are considered at several levels while the other parameters are essentially finite values.
the present work deals with a topic already known to the scientific world already since the decade. In fact, the first thing that catches one's eye is the small number of quotations but above all the date of most of them, some of which date back as far back as 1997. What emerges from the reading of the bibliography is also the repetition of an author who appears as first name in about half of the aforementioned publications, and this makes the topic rather niche, given the small scientific sample that dealt with the subject. From this point of view, however, the topic could have some gaps that the few experts have not been able or have not enough time to investigate.
In figure 4 are shown the images relative only to 700 ° C and at 1100 ° C, while it would be interesting to have the images of the 5 temperature levels shown in table 1.
What is not clear is the use or not of an experimental plan.
Looking at figure 5, I disagree in what is said at line 130-132 because in my opinion a difference between the two atmospheres is evident and it is clear, for example, looking at the curves from 900 ° C onwards that the stress variation for all temperatures is in the order of 100MPa.
The simulation part, in my opinion, loses a bit in quality. What had been clarified as an objective in the introduction is lost in assessments that never really clarify the influence on the mechanical properties of the material of the oxidized layer.
Figure 10a lacks quotation in the text.
An accuracy of the simulator is declared with error in the order of 0.7% on line 171 except to find in figure 15 a simulation result in absolute disagreement with the real results.
The authors should go through the suggestions in order the improve the general quality of the paper.
Author Response
Replies to the comments from reviewer #3
Q1: The present work deals with a topic already known to the scientific world for a decade. In fact, the first thing that catches one's eye is the small number of citations but above all the date of most of them, some of which date back to 1997. What emerges from the reading of the bibliography is also the repetition of an author who appears as first name in about half of the aforementioned publications, and this makes the topic rather niche for the small scientific sample that dealt with the subject. From this point of view, however, the topic could have some gaps that the few experts have not been able or have been able to investigate.
A1: Some more references from other researchers related to dieless drawing have been added and discussed in the “Introduction” section. (P. 2, L. 63 - 77) of the revised manuscript.
Q2: The article in the first part is well described, the introduction is quite exhaustive and the author leads the reader well towards the proposed research topic, motivating it in a detailed and clear way. In fact, the study of the influence that the oxidation layer formed during the process has on the mechanical properties of the material seems to be a relevant aspect for the quality of the final product.
A2: As pointed out by the reviewer, the existence of oxide layer affects the quality of the final product. The effects of the oxide layer on the mechanical properties of the product were discussed in this paper.
Q3: The part of materials and methods is quite clear and well presented even though in Table 1 it is not clear why the atmosphere and the forming temperatures are considered at several levels while the other parameters are essentially finite values.
A3: The other parameters have relatively small effects on the oxide layers. Thus, only the forming temperature and the atmosphere were considered at several levels and the other parameters were fixed. The above statement is added on p. 4, line 137 - p. 5, line 139 of the revised manuscript.
Q4: The present work deals with a topic already known to the scientific world already since the decade. In fact, the first thing that catches one's eye is the small number of quotations but above all the date of most of them, some of which date back as far back as 1997. What emerges from the reading of the bibliography is also the repetition of an author who appears as first name in about half of the aforementioned publications, and this makes the topic rather niche, given the small scientific sample that dealt with the subject. From this point of view, however, the topic could have some gaps that the few experts have not been able or have not enough time to investigate.
A4: Some more references from other researchers related to dieless drawing have been added and discussed in the “Introduction” section. (P. 2, L. 63 - 77) of the revised manuscript.
Q5: In figure 4 are shown the images relative only to 700°C and at 1100°C, while it would be interesting to have the images of the 5 temperature levels shown in table 1.
A5: Generally the thickness of the oxide layer increases with the forming temperature and the surface color of the product becomes slightly darker as the forming temperature increases. The surface colors of the products at 700°C and 1100°C exhibit more vivid contrast. Thus, only the appearance of the products at temperatures of 700°C and 1100°C was shown in Fig.4.
The above statement has been added on p.5, lines 152-156 of the revised manuscript.
Q6: What is not clear is the use or not of an experimental plan.
A6: Among the forming conditions, only two parameters, the atmosphere and forming temperature have relatively big influence on the oxide layer, thus no experimental plan was used.
Q7: Looking at figure 5, I disagree in what is said at line 130-132 because in my opinion a difference between the two atmospheres is evident and it is clear, for example, looking at the curves from 900°C onwards that the stress variation for all temperatures is in the order of 100MPa.
A7: As suggested by the reviewer, the statement “there are no big differences in the stress-strain curves in air and argon gas” has been deleted in the revised manuscript.
Q8: The simulation part, in my opinion, loses a bit in quality. What had been clarified as an objective in the introduction is lost in assessments that never really clarify the influence on the mechanical properties of the material of the oxidized layer.
A8: The objective of the simulation part is to analyze the formabilily of a wire dieless drawing process using DEFORM software coupled with a high frequency induction mode, which is different from the traditional approach using a constant temperature zone moving with heating coil position during the drawing process.
The above statement has been added in the introduction section on p.2, lines 87-90 of the revised manuscript.
Q9: Figure 10a lacks quotation in the text.
A9: As pointed out by the reviewer, Figure 10(a) was not quoted in the text. The missing part has been added on p. 8, line 200 in the revised manuscript.
Q10: An accuracy of the simulator is declared with error in the order of 0.7% on line 171 except to find in figure 15 a simulation result in absolute disagreement with the real results.
A10: The accuracy of 0.7% in the simulation results of wire diameters is convergence accuracy with different element numbers inside the wire, which means even though much more element numbers are set, the variations of the simulation results are within 1%.
The above statement has been added on p.8, lines 205-208 of the revised manuscript.
Q11: The authors should go through the suggestions in order to improve the general quality of the paper.
A11: All the suggestions have been considered and more explanations have been added in the revised manuscript
Author Response File: Author Response.pdf
Reviewer 4 Report
The paper presents the formability analysis and oxidation layer effects in dieless drawing of stainless steel wires. The work is relevant, and I suggest its publication after some revision.
- The novelty of the work should be highlighted at the end of the manuscript introduction.
- In chapter 2 the dieless drawing process should be improved.
- The appearance of the stainless steel wire is presented, is possible to quantify the roughness of the surface or the wire, or the thickness of the oxidation layer?
- The units N/sec/ºC and N/sec/mm/ºC should be improved in order to just have one /
- In Figure 9 the temperatures considered where obtained by the DEFORM database, why where not used the experimental ones presented in Figure 5 for the 2 conditions (with air and with argon gas)? This would give numerical results more accurate. The curves from Figure 9 and Figure 5 are very different.
- A direct comparison between the results from Figure 13 and 14 would help to understand the results discussion.
Author Response
Replies to the comments from reviewer #4
The paper presents the formability analysis and oxidation layer effects in dieless drawing of stainless steel wires. The work is relevant, and I suggest its publication after some revision.
Q1: The novelty of the work should be highlighted at the end of the manuscript introduction.
A1: " The novelty of this paper is that a high frequency induction heating theorem coupled with a software DEFORM is proposed to analyze the temperature distribution inside the workpiece wire and the formability of SUS304 wires in dieless drawing processes effected by the forming temperature and drawing speed are investigated.
The above statement has been added on p.2, lines 87-90 of the revised manuscript.
Q2: In chapter 2 the dieless drawing process should be improved.
A2: As pointed out by the reviewer, a more detailed description for the drawing machine and process has been added on p. 3, lines 105-116 of the revised manuscript.
Q3: The appearance of the stainless steel wire is presented, is possible to quantify the roughness of the surface or the wire, or the thickness of the oxidation layer?
A3: The diameter of the wire is so small that it is difficult to measure the surface roughness of the oxide layer. The thickness of the oxide layer exhibits some variation of about 1-7 µm, which is quite close to the results in Ref. [20].
The above statement has been added on p.5, lines 150-152 of the revised manuscript.
Q4: The units N/sec/ºC and N/sec/mm/ºC should be improved in order to just have one /
A4: As suggested by the reviewer, the unit of Thermal conductivity is changed to W·m−1·K−1 and that of convection coefficient is changed to W·m-2 ·K-1. They are given on p.7, lines 196-197 in the revised manuscript.
Q5: In Figure 9 the temperatures considered where obtained by the DEFORM database, why where not used the experimental ones presented in Figure 5 for the 2 conditions (with air and with argon gas)? This would give numerical results more accurate. The curves from Figure 9 and Figure 5 are very different.
A5: The curves in Fig.9 are the flow stresses of the wire before dieless drawing process, whereas, the curves in Fig.5 are the engineering stress-strain curves of the wire after drawing process. The flow stresses used in the simulations have to be the true stress-strain curves of the raw material.
Q6: A direct comparison between the results from Figure 13 and 14 would help to understand the results discussion.
A6: Because some forming conditions in Fig. 13 and Fig. 14 are not the same, the comparisons of the simulation and experimental results with the same forming conditions of VD=0.1 and 0.6 mm/s in argon atmosphere are summarized in Fig. 15.
I really appreciate the reviewer’s precious and helpful suggestions and comments.
Author Response File: Author Response.pdf
Round 2
Reviewer 4 Report
Thank you for including the reviewers' comments in the final version of the manuscript.
