An Investigation of the Fatigue Behavior and Dislocation Substructures of Friction-Stir-Welded SSM 6063 Aluminum Alloy
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors- The real image of the rotating tool should be given.
- Is there any reason to choose 1320 rpm as the rotating speed?
- Fig. 3 should be further enlarged. The microstructure can not be clearly observed in such figures.
- The fracture positions of the joints at different stress levels should be given.
This work is good after some minor revisions.
Author Response
Response to Reviewer 1 Comment
Point 1: The real image of the rotating tool should be given.
Response 1: Although the reviewer recommended, the author prefers to use this schematic because it can represent over all dimension from different angles leading to clearer illustrations and explanation.
Point 2: Is there any reason to choose 1320 rpm as the rotating speed?
Response 2: This was the optimum rotational speed from preliminary test which was not shown in this paper. Also, the author revise in the context mentioned in section 2.2
Point 3: Fig. 3 should be further enlarged. The microstructure can not be clearly observed in such figures.
Response 3: As the reviewer recommended, the Author adjust the image by enlarging and providing more explanation details.
Point 4: The fracture positions of the joints at different stress levels should be given.
Response 4: As the reviewer recommended, the author adds more explanation in section 3.2 about the 2 different stress levels shown in Figure 7e and 7f.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe phrase do not has verb “Cyclic loading induced recrystallization…” and therefore do not make sense
“sees extensive use in engineering applications” which application the authors refer here ?
It was difficult to understand which problem the authors aim to resolve – please be clear about this.
Table 1 was presented but no description was noted in the text
“The superior strength and corrosion resistance of SSM 6063 aluminum alloy can be attributed to its silicon and magnesium content” evidence for this claim is required
All the acronyms should be defined “OM” and many other
“globular α-primary aluminum matrix phase and β-eutectic phase” this should be pointed out in Figure 3 or appropriate figure
How many repetition were conducted for each trial ?
“*Failure not due to fatigue testing.” Ok but what else triggered the failure ?
“attributed to the dynamic loads” this is just an assumption without evidence. Other wise why the authors claim dynamic load. Cause in the fatigue process it is natural to be driven by crack initiation and propagation. Your focus is to describe mechanistical and microstructural this not just indicate the dynamic load as activation mechanism
“the fatigue failure of the samples is caused by defects” which kind of defect refer here ?
In figure 7 the authors claims different stage of fatigue which are concerning; for example the crack initiation is not evident from the presented image
The conclusion should avoid equation.
Comments on the Quality of English LanguageThe English could be improved to more clearly express the research.
Author Response
Response to Reviewer 2 Comment
Point 1: The phrase do not has verb “Cyclic loading induced recrystallization…” and therefore do not make sense
Response 1: As the reviewer recommended, the author has changed from “Cyclic loading induced recrystallization…” to “The cyclic loading has induced the recrystallization” which the author believes this would make more sense to the readers.
Point 2: “sees extensive use in engineering applications” which application the authors refer here ?
Response 2: The author has changed from “sees extensive use in engineering applications” to ““sees extensive use in many engineering applications in aerospace industry.” for clearer and specific applications.
Point 3: It was difficult to understand which problem the authors aim to resolve – please be clear about this.
Response 3: What the author is trying to solve is to understand the fatigue behavior of friction stir-welded SSM 6063 aluminum alloy. Therefore, the author has improved the last paragraph of the introduction section to “Therefore, this research focuses on understanding the fatigue behavior of friction stir-welded SSM 6063 aluminum alloy. The investigation's objectives are to conduct fatigue testing in the S-N curve, the endurance limit, and predict the fatigue life.” as the reviewer recommended.
Point 4: Table 1 was presented but no description was noted in the text
Response 4: As the reviewer recommended, the author adds a last sentence to the third paragraph of the introduction section to “In short, Table 1 shows the comparisons of all previous works studying the fatigue behaviour of FSW of aluminum alloys.”
Point 5: “The superior strength and corrosion resistance of SSM 6063 aluminum alloy can be attributed to its silicon and magnesium content” evidence for this claim is required
Response 5: The author makes adjustment according to reviewer recommendations by removing this sentence.
Point 6: All the acronyms should be defined “OM” and many other
Response 6: Actually all acronyms are clearly stated in the Abbreviations section of this manuscript before the reference section
Point 7: “globular α-primary aluminum matrix phase and β-eutectic phase” this should be pointed out in Figure 3 or appropriate figure
Response 7: As the reviewer recommended, the author has adjust the image on Figure 3 and point out the area where globular α-primary aluminum matrix phase and β-eutectic phase are.
Point 8: How many repetition were conducted for each trial ?
Response 8: For fatigue test, 7 repeats were tested for each stroke levels. The author also add more in information about report in section 2.3 .
Point 9: “*Failure not due to fatigue testing.” Ok but what else triggered the failure ?
Response 9 : The intention of the author mentioned about this is to show that the samples was not broken even though the very high number of stress cycle was introduced. So, the author believes that there was no point to further or continue testing and the author stop the test. Therefore, the author would like to revise this from “ *Failure not due to fatigue testing ( our limit of this testing ).” to “ the samples did not show the sign of broken piece from stress test; therefore, the author decided to stop the test.”
Point 10: “attributed to the dynamic loads” this is just an assumption without evidence. Other wise why the authors claim dynamic load. Cause in the fatigue process it is natural to be driven by crack initiation and propagation. Your focus is to describe mechanistical and microstructural this not just indicate the dynamic load as activation mechanism.
Response 10 : As the review recommended, the author add more explanation into the last sentence in section 3.1 above Table 5.
Point 11: “the fatigue failure of the samples is caused by defects” which kind of defect refer here ?
Response 11 : As the author recommended, the author edits this sentence to “the fatigue failure of the samples is caused by crack defects”
Point 12: In figure 7 the authors claims different stage of fatigue which are concerning; for example the crack initiation is not evident from the presented image
Response 12: The author prefers to keep those images to present.
Point 13: The conclusion should avoid equation.
Response 13: The author has removed the question as the reviewer recommended.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors1. Sentence 'SSM 6063 aluminum alloy was found to possess excellent mechanical properties, such as strong corrosion resistance and weldability [16].': is corrosion resistance part of mechanical properties?
2. 'The average grain size of the α-primary aluminum matrix phase was around 22–52 μm': how can the average grain size be a range? Please provide the grain size statistical distribution.
3. For table 4, it would be better to clarify more what each parameter means.
4. Mark the RS-TMAZ, AS-TMAZ and SZ boundary in Figure 3. Also clarify the direction of rotation and travel in Figure 3.
5. Any polishing/grinding of fatigue testing sample before the test?
6. What is 'The stroke parameters of stress amplitude' and why does it have a unit of mm?
7. Remove all 'thanking' statement in the manuscript, such as 'With the support of the Synchrotron Light Research Institute in Nakhon Ratchasima, the microstructure was analyzed within a 3-week period' or 'GISSCO Company Limited (Songkhla, Thailand) sponsored the FSW experiment.'. The authors are advised to put those in the acknowledgment section after the main part of the paper, but NOT in the main text.
8. Specify where/which direction exactly each fatigue sample was taken considering a anisotropic post-weld microstructure.
9. 'The stress amplitude and the number of cycles at all FSW and BM conditions were similar, as shown in Table 4.': check this sentence.
10. The S-N curve is poorly fitted. Clarify this point, explain possible reasons, and/or add more exp data points.
11. I do not understand this sentence 'These atoms can evolve with ongoing independent and dislocation substructures and the crystal lattice where the arrangement of atoms deviates from the ideal formation, as shown in Figure 8b'. Please rewrite it.
12. Figure 8: please clarify where precisely the TEM lamellae were taken. The authors can provide a figure with smaller magnification and label it, considering the melt pool size.
13. Rewrite the sentence starting from 'The characteristics of the T-phase are transformations of intermetallic compounds of Al5FeSi particles'
14. It would be better to draw an illustrative graph summarizing the phase transformation that occurred.
15. The link between observed microstructure and measured fatigue properties needs to be discussed more.
Comments on the Quality of English LanguageNeed to be much polished before publication.
Author Response
Response to Reviewer 3 Comment
Point 1: Sentence 'SSM 6063 aluminum alloy was found to possess excellent mechanical properties, such as strong corrosion resistance and weldability [16].': is corrosion resistance part of mechanical properties?
Response 1: the author had changed to “SSM 6063 aluminum alloy was found to possess excellent mechanical properties, weldability, and chemical properties (e.g., strong corrosion resistance) [16].”
Point 2: 'The average grain size of the α-primary aluminum matrix phase was around 22–52 μm': how can the average grain size be a range? Please provide the grain size statistical distribution.
Response 2: The author edit the sentence of this statement to “The average grain size of the α-primary aluminum matrix phase was around 37 µm. Meanwhile, in the β-eutectic phase involving the intermetallic compounds of Al5FeSi, the grain size was approximately 19 µm, with the base microstructure shown in Figure 1.”
Point 3: For table 4, it would be better to clarify more what each parameter means.
Response 3: As the reviewer recommended, the Author adds more details of effects from each parameters in the next column of Table 4.
Point 4: Mark the RS-TMAZ, AS-TMAZ and SZ boundary in Figure 3. Also clarify the direction of rotation and travel in Figure 3.
Response 4: As the reviewer recommended, the Author adds more details in the figure 3
Point 5: Any polishing/grinding of fatigue testing sample before the test?
Response 5: Yes, the samples were polished before the fatigue testing. The author add more details in section 2.3. to “(Samples were polished 1200 grit sandpapers on the cut surface to smoothen)
Point 6: What is 'The stroke parameters of stress amplitude' and why does it have a unit of mm?
Response 6: This is because the machine that the author used allows to set the stroke value instead of stress value. So, stroke is the length of up and down value in milli meters unit. (Amplitude height) during stress testing (R-1) which our machine was set instead.
Point 7: Remove all 'thanking' statement in the manuscript, such as 'With the support of the Synchrotron Light Research Institute in Nakhon Ratchasima, the microstructure was analyzed within a 3-week period' or 'GISSCO Company Limited (Songkhla, Thailand) sponsored the FSW experiment.'. The authors are advised to put those in the acknowledgment section after the main part of the paper, but NOT in the main text.
Response 7: As the reviewer recommended, the author has moved those parts to the acknowledgment section after the main part.
Point 8: Specify where/which direction exactly each fatigue sample was taken considering a anisotropic post-weld microstructure.
Response 8: Actually, the structure of our material we use the Aluminium SSM 6063 material is formed as a globular structure from gas-induced semi-solid (GISS) technique which does not show a property of anisotropic or isotropic (unlike in regular steel materials).
Point 9: 'The stress amplitude and the number of cycles at all FSW and BM conditions were similar, as shown in Table 4.': check this sentence.
Response 9: As the reviewer recommended, the author has edited and changed the sentence based on the reviewer recommendations
Point 10: The S-N curve is poorly fitted. Clarify this point, explain possible reasons, and/or add more exp data points.
Response 10: This graph (Figure 6) was plotted from 7 repeated tests (7 samples were tested in each stroke level) and among the 7 repeated samples the readout value is very consistent. Therefore, when looking at the chart the reader may not see any differences.
Point 11: I do not understand this sentence 'These atoms can evolve with ongoing independent and dislocation substructures and the crystal lattice where the arrangement of atoms deviates from the ideal formation, as shown in Figure 8b'. Please rewrite it.
Response 11: In order to make it more clear, the author edited to “These atoms can form independently at the dislocation substructures and the crystal lattice where the arrangement of atoms deviates from the original formation, as shown in Figure 8b.”
Point 12: Figure 8: please clarify where precisely the TEM lamellae were taken. The authors can provide a figure with smaller magnification and label it, considering the melt pool size.
Response 12: The author changes to the explanation in Figure 8 to “Figure 8. TEM micrograph in BM of SSM 6063 aluminum alloy: (a) crystal lattice structure, (b) dislocation substructures in the grain boundary, and (c) T-phase.” This is because selection from any area of based metal are the same.
Point 13: Rewrite the sentence starting from 'The characteristics of the T-phase are transformations of intermetallic compounds of Al5FeSi particles'
Response 13: In order to make it more clear, the Author edited to “The characteristics of the T-phase are transformed from the intermetallic compounds of Al5FeSi particles,”
Point 14: It would be better to draw an illustrative graph summarizing the phase transformation that occurred.
Response 14: The author did not plan to have an illustrative graph to explain. However, the author intends to explain this transformation from TEM image record instead.
Point 15: The link between observed microstructure and measured fatigue properties needs to be discussed more.
Response 15: In order to make it more clear, the author have add more details to explain after the sentence with reference number 42 in section 3.3. “If the T-Phase and Guinier–Preston (GP) zone distribution are good, this will support a better microstructure which will increase the strength value.”
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors did not address the reviewer' comment (Comment 1, 2 and 4). Thus, this paper can not be accepted in its current version.
Comments on the Quality of English LanguageThe English should be improved.
Author Response
Response to Reviewer 1 Comment
Point 1: Comments and Suggestions for Authors
The authors did not address the reviewer' comment (Comment 1, 2 and 4). Thus, this paper can not be accepted in its current version.
Response 1: The author makes changes according to the previous comments 1, 2 and 4. The new version will be edited accordingly.
For comment 1: The author adds a real image of the machine onto Figure 2 as the reviewer recommended.
For comment 2: According to the author’s preliminary test and previous research reviews shown in Table 1, the author found that the optimum rotational speed was at 1320 rpm rotation speed (preliminary data was not shown in this manuscript). Therefore, the author edits some sentences in the paragraph in section 2.2 below Table 4 to clarify about this as the review suggested.
For comment 4: At first, the author intention is to show different types of fractures found on the samples in the optimum fatigue testing condition comparing to the original TEM micrograph in Figure 8 found in based metal in controlled condition, not try to compare the fracture patterns among different stress levels. Therefore, the author added some more explanation in the first few sentences in Section 3.2.
Point 2: Comments on the Quality of English Language
The English should be improve
Response 2: The author will review and use professional English editor to improve the quality of English language for this manuscript.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors.
Comments on the Quality of English LanguageThe English could be improved to more clearly express the research.
Author Response
Response to Reviewer 2 Comment
Point 1: Comments on the Quality of English Language
The English could be improved to more clearly express the research.
Response 1: The author will review and use professional English editor to improve the quality of English language for this manuscript.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe version is OK.
Author Response
Response to Reviewer 3 Comment
Point 1: Comments and Suggestions for Authors
The version is OK.
Response 1: Thank you for your time to review this manuscript. The author is very appreciated.
Author Response File: Author Response.pdf
Round 3
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors may not have understood the reviewer's question correctly.
The original comment 1. The tool image.
Comment 4. The fracture position of the joint.
It is very difficult?
Comments on the Quality of English LanguageEnglish should be improved.
Author Response
Response to Reviewer 1 Comment
Point 1: The authors may not have understood the reviewer's question correctly.
The original comment 1. The tool image.
Comment 4. The fracture position of the joint.
It is very difficult?.
Response 1:
For Comment 1, the author adds one more image of the tool in Figure 2 to show the shape of the tool. So, the reviewer can see the shape of the pin and shoulder of the tool. In addition, the author adds more explanations describing the shape of the tool in section 2.2.
For Comment 4, For clearer understanding, the author adds more explanations in the second sentence in the first paragraph in section 3.2 stating that “The position of fracture was only observed in AS-TMAZ.”
The author is very appreciated for all good comments from reviewers and feel free to feedback whether the above respond answering the comments of the reviewer clearly. The author is willing to provide all feedback accordingly.
Author Response File: Author Response.pdf
Round 4
Reviewer 1 Report
Comments and Suggestions for AuthorsThis work can be accepted in its current version.
