Comparison of Nano-Mechanical Behavior between Selective Laser Melted SKD61 and H13 Tool Steels

Round  1

Reviewer 1 Report

Review for metals-394962

Comparison of Nano-mechanical Behavior between Selective Laser Melted SKD61 and H13 Tool Steels

This document is clearly written and well organized. It is an interesting research work but, in my opinion, it would be advisable as an article instead of a short communication. 

Then, authors should include a state-of-the-art with more references (20-30 references). In addition, to better understand the research work, more details of both steels are needed.

Minor changes

Please, include (a), (b) and (c) in Figure 1.

Please, add “s” in (Indentation strain rate) in horizontal axis

Author Response

First, thank you for the review. The suggestions are very general and consistent, and contribute to the improvement of the quality of the revised manuscript. In particular, we appreciate that the reviewers have given us the opportunity to conduct further investigation of the materials in metal 3D printing process. We also appreciate the suggestions to use more appropriate vocabulary, figures, and tables which we gladly changed based on their comments on our manuscript. As a result, we present our best response for this review, as shown in the letter below, and we hope that these changes will help to receive positive action regarding the publication of our paper.
With best regards,

1. Please, include (a), (b) and (c) in Figure 1.

  - We include (a), (b) and (c) in Figure 1.

2. Please, add "s" in (Indentation strain rate) in horizontal axis

  - We add "s" in horizontal axis in Figure 3.

Reviewer 2 Report

In this communication, the authors explore the use of nanoindentation under several strain rates to investigate SKD61 and H13. Overall, the letter is interesting and well-written. I look forward to seeing an expanded research paper on this topic, as it would be interesting to the community. 

Some minor suggestions that would serve to enhance the presentation: 

There are many variables and acronyms used - it would be beneficial to provide a table at the beginning or end of the letter defining them

If possible, it would be better to use fewer acronyms and less jargon in the abstract. It may not be possible in such a technical manuscript, but the authors should at least consider this in the final version. 

It would be beneficial to add a couple more references which explore the impact of the various important parameters of SLM (e.g. scan speed, laser power, etc.) on the microstructure and how this may affect the results you found. Since this is a letter and not a research article, just a short discussion (2-3 sentences) in the introduction will indicate that the authors at least considered this. If you wish, you could instead talk about this in your conclusions as potential future work in this area. 

Please add some more detail to your discussion comparing the two materials (Lines 125-126). Define what a "better" microstructure means more rigorously and talk about grain size, as well as the pores, in brief. 2-3 sentences would suffice. 

Please put (a), (b), (c) labels on your panels in Figure 1 and increase the size of Panel C to make it easier to read. 

Please give a more descriptive caption to Figure 2a and explain why you changed the color of the microstructure (I understand why but readers may not)

Author Response

First, thank you for the review. The suggestions are very general and consistent, and contribute to the improvement of the quality of the revised manuscript. In particular, we appreciate that the reviewers have given us the opportunity to conduct further investigation of the materials in metal 3D printing process. We also appreciate the suggestions to use more appropriate vocabulary, figures, and tables which we gladly changed based on their comments on our manuscript. As a result, we present our best response for this review, as shown in the letter below, and we hope that these changes will help to receive positive action regarding the publication of our paper.
With best regards,

About all comments of you, we tried to reflect your comments and then we changed the contents on this manuscript.

Reviewer 3 Report

This letter addresses the nonomechanical properties of two SLM-produced tool steels. It shows some interesting results and discussion. It can be considered for publication after addressing the following comments:  

 Please check the English language of the whole text. For example, please correct the horizontal axis in Fig. 3. It should be “strain” not “train”.

 Have you observed any indentation size effect? How you found out the best load? Please explain.

Please compare your hardness results with those of conventionally produced counterparts.  

Please extend the literature review and address the significance of nanoindentation testing on SLM-produced metallic materials. Please see and use these works: International Journal of Machine Tools and Manufacture 133 (2018) 85-102 and Materials Science and Engineering: A 688 (2017) 20-26.  

Author Response

First, thank you for the review. The suggestions are very general and consistent, and contribute to the improvement of the quality of the revised manuscript. In particular, we appreciate that the reviewers have given us the opportunity to conduct further investigation of the materials in metal 3D printing process. We also appreciate the suggestions to use more appropriate vocabulary, figures, and tables which we gladly changed based on their comments on our manuscript. As a result, we present our best response for this review, as shown in the letter below, and we hope that these changes will help to receive positive action regarding the publication of our paper.
With best regards,

Please check the English language of the whole text. For example, please correct the horizontal axis in Fig. 3. It should be “strain” not “train”.

We checked the English language of the manuscript and then we corrected the English languages. In particular, a wrong word in Fig. 3 was corrected.

 Have you observed any indentation size effect? How you found out the best load? Please explain.

We referred that the widely used Oliver and Pharr method is accurate only for nanoindents that do not show significant pile-up deformation, which is related to the ratio of the residual depth and the maximum depth in manuscript. Also, we considered the previous Rockwell’s hardness results. It did not mention at this manuscript.

 Please compare your hardness results with those of conventionally produced counterparts.  

In this manuscript is showed the indentation values of SLM SKD61 and H13. So we did not mention the hardness results compared with conventionally parts. But we know that Rockwell hardness of conventional parts is about 40 HRC but SLM parts fabricated by PBF type is about 50 HRC.

Please extend the literature review and address the significance of nanoindentation testing on SLM-produced metallic materials. Please see and use these works: International Journal of Machine Tools and Manufacture 133 (2018) 85-102 and Materials Science and Engineering: A 688 (2017) 20-26.  

We added the contents on this manuscript to make use for your comments.

Round  2

Reviewer 1 Report

Authors should include a state-of-the-art with more references (20-30 references).

In addition, to better understand the research work, more details of both steels are needed.

Author Response

Authors should include a state-of-the-art with more references (20-30 references).

Thank you so much for your comments. We included more references about 14 concerned with manuscript. Therefore, the references included on this manuscript are total 23.

In addition, to better understand the research work, more details of both steels are needed.

In this research, two steels are same steel. Difference of two steels is the nomenclature. Two steels are specify follows;

Also, we expressed to separate two steels because SKD61 was fabricated by our gas atomizing process and H13 was purchased from sandvik.

Reviewer 3 Report

The revised version is now suitable for publication.

Author Response

The revised version is now suitable for publication.

Thank you very much for your comments.