Critical Comparison of Spherical Microindentation, Small Punch Test, and Uniaxial Tensile Testing for Selective Laser Melted Inconel 718
Round 1
Reviewer 1 Report
Comment 1
The paper deals with the Critical Comparison of Spherical Microindentation,
Small Punch Test, and Uniaxial Tensile Testing for Selective Laser
Melted Inconel 718.
The paper, in the opinion of the reviewer, is worth publishing
at the MDPI journal in the present form
but consequently the paper needs revision for publishing.
While the authors have made considerable research effort,
the presentation of the paper and the results are must be improved.
The reviewer suggested corrections to the authors,
which of accepted and inserted in the paper,
then the paper can be accepted for publication
in the journal.
Comment 2
Line 13
additive manufacturing (AM).
Replace
Additive Manufacturing (AM).
Comment 3
Line 17
by selective laser melting (SLM).
Replace
by Selective Laser Melting (SLM).
Comment 4
Line 25
Metal additive manufacturing (AM) has
Replace
Metal Additive Manufacturing (AM) has
Comment 5
Lines 35 - 36
[3] studied non
destructive evaluation (NDE) techniques
Replace
[3] studied Non
Destructive Evaluation (NDE) techniques
Comment 6
Line 55
uniaxial tensile test (UTT)
Replace
Uniaxial Tensile Test (UTT)
Comment 7
Line 111
finite element (FE)
Replace
Finite Element (FE)
Comment 8
Line 124
by Patel and Kalidindi to compare nanoindentation
Replace
by Patel and Kalidindi [15] to compare nanoindentation
Comment 9
Lines 149 - 150
It's not so good to start the section at the bottom of the page without using text
Comment 10
Line 155
computer aided design (CAD)
Replace
Computer Aided Design (CAD)
Comment 11
Line 196
machining (EDM) to ensure
Replace
machining (WEDM) to ensure
Comment 12
Line 197
EDM was performed at low heat
Replace
WEDM was performed at low heat
Comment 13
Line 198
The thickness of the EDM recast layer was measured to be approximately 15 m
15 m is typographical mistake/error.
Check and insert the right value or unit.
Comment 14
Line 207
After grinding, the samples were subsequently polished on a 3 m
3 m is typographical mistake/error.
Check and insert the right value or unit.
Comment 15
Line 208
and 1 m polishing pad using appropriate diamond pastes and alcohol-based lubricant.
1 m is typographical mistake/error.
Check and insert the right value or unit.
Comment 16
Line 209
Next, a polishing pad with 0.04 m colloidal silica polishing suspension was applied.
0.04 m is typographical mistake/error.
Check and insert the right value or unit.
Comment 17
Line 216
ied between 30 m and 50 m, so the residual indent covered no less than 10 grains. An
30 m (and 50 m) is typographical mistake/error.
Check and insert the right value or unit.
Comment 18
Figure 2
Extremely big font text size (especially: Projected area of contqact, πa2)
Comment 19
The numbering of all equations (1 - 12) should be at the end of the row on the right side of the text.
Comment 20
Line 329
of the as-EDM
Replace
of the as - WEDM
Comment 21
Figure 3 + line 332
Displacement (um) + (maintained below 15 µm.)
Is the same unit (um - μm)?
Comment 22
Line 362
total displacement in the SPT. This
Delete the extra space between the . and the word This
Comment 23
Line 384
where ?????is the elastic strain
Insert a space between ????? and the word is
Comment 24
Line 385
?????is the total strain from MSS analysis,
Insert a space between ????? and the word is
Comment 25
Lines 238 - 240
Τhe text must be corrected according to the instructions of the Journal.
Acconding to the instructions for authors, the figure 3 (with 3a and 3b) title
must be with a different format limits.
Comment 26
Lines 326 - 327
Τhe text must be corrected according to the instructions of the Journal.
Acconding to the instructions for authors, the figure 4 (with 4a and 4b) title
must be with a different format limits.
Comment 27
Line 413
Delete the space in the page end (move text).
Comment 28
Lines 486 - 493
Full text alignment
Comment 29
Line 495 - 499
Τhe text must be corrected according to the instructions of the Journal.
Acconding to the instructions for authors, the figure 8 (with 8a and 8b) title
must be with a different format limits.
Comment 30
Figure 8a
What is the difference between the three simulations curves?
The authors must insert more details.
Comment 31
Figure 8b
Average SPT is denoted by x (figure 8b Bottom Right),
while in figure 8b a blue continuous line is drawn.
Comment 32
Add a figure with the FEM simulation.
In the text add details such as the number of the elements.
Comment 33
Figure 9 (Bottom Right)
ActualTensileYield
ActualTensileUltimate
Replace (insert space between words)
Actual Tensile Yield
Actual Tensile Ultimate
Comment 34
Line 625
Insert a line
Comment 35
Line 649
SPT. SPT samples are essentially slices of material no greater than 500 m so 3-5 SPT
500 m is typographical mistake/error.
Check and insert the right value or unit.
Comment 36
Τhe references must be corrected according to the instructions of the Journal.
1. Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range.
Comment 37
Increase the number of the reference papers including (primarily) from MDPI journals.
Author Response
Attached is a document with my responses to your comments. Thank you for your interest in my paper. I appreciate the time that you've taken to review and comment on my work!
Figures within the manuscript were altered as needed and have been saved to a new zip file. I will upload the new zip file. I will also upload the updated manuscript with all changes tracked.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
1. The abstract section is too long, please shorten the content.
2 . The SLM samples pictures are not seen in the manuscript, please add.
Author Response
Attached is a document with my responses to your comments. Thank you for your interest in my paper. I appreciate the time that you've taken to review and comment on my work!
Figures within the manuscript were altered as needed and have been saved to a new zip file. I will upload the new zip file. I will also upload the manuscript with the tracked changes.
Author Response File: Author Response.pdf
Reviewer 3 Report
REVIEW
on article
Critical Comparison of Spherical Microindentation, Small Punch Test, and Uniaxial Tensile Testing for Selective Laser Melted Inconel 718
Zachary Courtright, Nicolas Leclerc, Hyung Nun Kim and Surya Kalidindi
SUMMARY.
The article deals with the interesting problem of comparing various methods for determining the mechanical characteristics of Inconel 718 by spherical microindentation, small punch testing and uniaxial tensile testing. The comparison was performed on Inconel 718 samples produced by selective laser melting. The techniques are known, standardized and tested on various steel grades.
As a novelty, it can be pointed out that in the conditions of additive manufacturing of parts from Inconel 718 produced by selective laser melting, it is advisable to choose inexpensive methods for determining mechanical properties. The accuracy of the methods in this case is important.
The authors made samples for testing according to the specified methods. The thoroughness of sample preparation and testing is commendable. Comparison of the results allowed the authors to point out the strengths and weaknesses of the studied methods in relation to the Inconel 718.
The article is well-structured and logical. The reference list contains 47 items. Also, the strong point of the article is that the authors in the Discussion compare their results with the data obtained by other authors. This will surely attract the attention of readers.
COMMENTS.
- The Abstract must be revised in accordance with the requirements of the journal. The last phrase in the Abstract is not the Result or the Conclusion. Editors strongly encourage authors to use the following style of structured abstracts, but without headings: (1) Background: Place the question addressed in a broad context and highlight the purpose of the study; (2) Methods: Describe briefly the main methods or treatments applied; (3) Results: Summarize the article's main findings; and (4) Conclusions: Indicate the main conclusions or interpretations. The abstract should be an objective representation of the article.
- Citations in the text must be in accordance with the Citations Style Guide for MDPI Journals https://mdpi-res.com/data/mdpi_references_guide_v5.pdf.
- The final part of the Introduction should contain the formulation of a scientific problem. Why is it so important? This will attract the readers' attention and strengthen the article.
- Line 213-214. "... a spherical indenter tip with a 6.35 mm radius". What kind of microhardness is this? This is Brinell hardness.
- Line 214-215 "... a residual indentation radius of approximately 180 mm". It's a typo?
- Line 231. It is better to name this average contact stresses.
- Line 232. "... the primary indentation zone »4a". H»2.4a this is a very strong idealization that can be used under certain constraints. This scheme has nothing to do with your methods. It is better to replace the cylinder with a half-space in Figure 2.
- Line 306. This method is not auto modeling and is effective for deep draw-forming or stamping problems.
- Figure 6. I understand that it would be desirable to get both Young's modulus and yield stress with one test. But there are more accurate methods for determining Young's modulus, for example, ultrasound oscillations or a method for determining resonant frequencies. These methods give an accuracy of 0.2%
- There are many common phrases in the Conclusion. It is necessary to reflect the specific results obtained by the authors
In general, the article solves interesting and relevant problems. However, there are many ambiguities in the article, so I recommend the article for publication after major corrections.
Author Response
Attached is a document with my responses to your comments. Thank you for your interest in my paper. I appreciate the time that you've taken to review and comment on my work!
Figures within the manuscript were altered as needed and have been saved to a new zip file. I will upload the new zip file. I will also upload the manuscript with the tracked changes.
Author Response File: Author Response.pdf
Reviewer 4 Report
Spherical indentation and small punch test were used to measure the tensile properties of selective laser melted Inconel 718. Both testing techniques have advantages in testing mechanical properties with a small amount of material. This paper shows that those two testing methods can be an alternative to the uniaxial tensile test. In my opinion, this manuscript should take into account the next considerations:
1、 Lot of approaches have been developed to extract stress-strain curve from indentation results or small punch test results. The methodologies adopted in this paper have been reported in previous publications. From this part, the novelty of this manuscript is limited, but I believe authors may find out other interesting results. Please clearly write in the manuscript.
2、The introduction about the indentation test on page 5 is not correct, please check all the units.
3、Experimental results (like the load-displacement curves) should be presented in the paper.
Author Response
Attached is a document with my responses to your comments. Thank you for your interest in my paper. I appreciate the time that you've taken to review and comment on my work!
Figures within the manuscript were altered as needed and have been saved to a new zip file. I will upload the new zip file. I will also upload the manuscript with the tracked changes.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
The article has been substantially revised. The authors have reviewed all my comments, and many have been corrected. Some comments have not been corrected, but the author has answered them. I recommend the article for publication.
Reviewer 4 Report
The paper can be accepted in present form.
