Review Reports - Influence of Substrate on the Tribological Behavior of Inconel 625 GMAW Overlays

Round 1

Reviewer 1 Report

The authors have prepared two samples: one with an SS interlayer and one without. Upon careful examination, it appears that both samples exhibit nearly identical properties, with only slight differences. In fact, the authors themselves acknowledge in their conclusion that the samples possess the same properties. They have provided a discussion on what happened and why happened. my comments are as follows:

1. Figure 4: Please ensure that each subfigure includes a proper scale and clearly label the elements being mapped in the figure.

2. In the explanation for Figure 8, provide information regarding the depth of the wear track and the width of the wear track.

2. In section 3.3 and Figure 9, the authors have mentioned the wear rate with units of mm^3 N^-1 m^-1. Typically, these units are associated with specific wear rate rather than general wear rate. Please clarify if this refers to specific wear rate or provide the appropriate units for the general wear rate.

3. In Figures 13 and 14, it would be helpful to include the element composition percentage either in weight percent (wt%) or atomic percent (at%). This information would provide a clearer understanding of the composition analysis.

Author Response

Figure 4: Please ensure that each subfigure includes a proper scale and clearly label the elements being mapped in the figure.

It was done.

In the explanation for Figure 8, provide information regarding the depth of the wear track and the width of the wear track.

In the explanation for Figure 8, it was provided the information regarding the depth and the volume of the wear track.

In section 3.3 and Figure 9, the authors have mentioned the wear rate with units of mm^3 N^-1 m^-1. Typically, these units are associated with specific wear rate rather than general wear rate. Please clarify if this refers to specific wear rate or provide the appropriate units for the general wear rate.

The reviewer is right, the Figures and text were changed to “specific wear rate”.

In Figures 13 and 14, it would be helpful to include the element composition percentage either in weight percent (wt%)or atomic percent (at%). This information would provide a clearer understanding of the composition analysis.

It was corrected in Figures 13 and 14 the term in the composition percentage to weight percent (wt%). The chemical compositions of the samples were presented in Table 3.

Reviewer 2 Report

Review report on the topic ‘Mechanical Properties and Tribological Behavior of Alloy/Coatings’. The work is presented well. The comments to improve the quality of the manuscript are listed below:

Please omit the unnecessary information and add the key conclusion of the work at the end of the abstract section.
Please add a separate section to discuss the novelty of the work.
The introduction section is presented roughly. Add more references and try to make a bridge between current and previously published work. Add more discussion about the major problems associated with deposition and also about residual stresses: https://doi.org/10.3390/ma15207094.
Add scale in each figure.
How was the composition and base metal properties measured?
Discuss the selction of the welding wire.
Provide complete detail of the experimental setup with good quality image.
Discuss the waviness obtained after deposition.
Discuss the detail characterization of the interface including the laing and area map. Also discuss about the dilution and unmixed zone formation at interface of susbtrate and deposited metal. Also about the segregation of the Cr and Mo particle in IN625 deposition: https://doi.org/10.3390/ma14216591.
Mark the element in Fig. 4 for better interpretation.
The Nb in such filler plays a major role and sometimes leads the formation of the laves phase. Discuss about it with EDS results: https://doi.org/10.1007/s11665-023-08363-w.
In Fig. 11 add scale in each image and technical discussion and wear mechanism in detail.

Author Response

Please omit the unnecessary information and add the key conclusion of the work at the end of the abstract section.

It was done.

Please add a separate section to discuss the novelty of the work.

The authors appreciate the reviewer's suggestion, but the separation of a discussion session was not performed, as the Coatings template was followed.

The introduction section is presented roughly. Add more references and try to make a bridge between current and previously published work. Add more discussion about the major problems associated with deposition and also about residual stresses: https://doi.org/10.3390/ma15207094.

The authors are grateful for the suggestion. In the introduction conducted by the authors, an effort was made to include key points from the literature concerning the main aspects of the research (application context, microstructure, microhardness, and wear). It is important to highlight that this article did not delve into residual stress analysis; therefore, no discussion on this topic is provided in the introduction.

Add scale in each figure.

It was done.

How was the composition and base metal properties measured?

The information was extracted from standards or catalogs, as indicated by the citations referencing Table 2.

Discuss the selection of the welding wire.

It was done.

Provide complete detail of the experimental setup with good quality image.

The authors are grateful for the reviewer's suggestion but believe that the current description is sufficient, and including images of the experimental apparatus would not provide substantial additional information.

Discuss the waviness obtained after deposition.

It was done.

Discuss the detail characterization of the interface including the laing and area map. Also discuss about the dilution and unmixed zone formation at interface of susbtrate and deposited metal. Also about the segregation of the Cr and Mo particle in IN625 deposition: https://doi.org/10.3390/ma14216591.

It was done.

Mark the element in Fig. 4 for better interpretation.

It was done.

The Nb in such filler plays a major role and sometimes leads the formation of the laves phase. Discuss about it with EDS results: https://doi.org/10.1007/s11665-023-08363-w.

It was done.

In Fig. 11 add scale in each image and technical discussion and wear mechanism in detail.

It was done.

Reviewer 3 Report

The article is devoted to a topic that is very relevant and popular among researchers, namely, the study of the wear resistance of a deposited layer from complex and expensive alloys to a cheaper base material.

In my opinion, the article should be published in the top-rated scientific journal Coatings. However, I have a few comments for the authors.

1. In figure 4, very small indicators of chemical elements and scales. They need to be increased.

2. To understand the thickness of the deposited layers, I recommend showing sketches of the cross-section of samples I and M. Indicate on these sketches the thickness of the deposited layers ERCrNiMo-3 and ER316LSi + ERCrNiMo-3. Or add this information to Figure 2.

3. Figure 5 shows the hardness on the surface of the sample? I recommend giving a graph of the results of measurements of hardness over the section of the sample. Show how hardness changes from the surface to the base metal.

4. Considering that in your conclusions you are talking about the difference in wear resistance of samples I and M, which depends on the morphology of the structure obtained during surfacing, I recommend that you provide a photo of the microstructures of the cross section of the samples. It will be interesting to see the transition zones and the difference in the microstructure of samples I and M.

5. When studying welded layers, most of the studies should be carried out on cross-sectional specimens. With an indication of the change in structure and microhardness when moving from surface to base metal. I recommend to get acquainted with the works:

https://doi.org/10.1007/s11015-021-01104-1

https://doi.org/10.3390/pr11041118

https://doi.org/10.1016/j.surfcoat.2022.128493

6. Line 118 says "Table II", but you need to write Table 2.

Author Response

In figure 4, very small indicators of chemical elements and scales. They need to be increased.

It was done.

To understand the thickness of the deposited layers, I recommend showing sketches of the cross-section of samples Iand M. Indicate on these sketches the thickness of the deposited layers ERCrNiMo-3 and ER316LSi + ERCrNiMo-3. Or add this information to Figure 2.

The thickness of the deposited layers was add in Figure 2.

Figure 5 shows the hardness on the surface of the sample? I recommend giving a graph of the results of measurements of hardness over the section of the sample. Show how hardness changes from the surface to the base metal.

We sincerely appreciate the suggestion and acknowledge that there might be an influence on hardness in the cross-section. However, it is essential to emphasize that the primary focus of this study was on the top of the coating. Therefore, we deliberately restricted our analyses solely to the top section.

Considering that in your conclusions you are talking about the difference in wear resistance of samples I and M, which depends on the morphology of the structure obtained during surfacing, I recommend that you provide a photo of the microstructures of the cross section of the samples. It will be interesting to see the transition zones and the difference in the microstructure of samples I and M.

We sincerely appreciate the suggestion and acknowledge that there might be an influence on the cross-section. However, it is essential to emphasize that the primary focus of this study was on the top of the coating. Therefore, we deliberately restricted our analyses solely to the top section.

When studying welded layers, most of the studies should be carried out on cross-sectional specimens. With an indication of the change in structure and microhardness when moving from surface to base metal. I recommend to get acquainted with the works:

https://doi.org/10.1007/s11015-021-01104-1

https://doi.org/10.3390/pr11041118

https://doi.org/10.1016/j.surfcoat.2022.128493

We appreciate the suggestions and have thoroughly reviewed the articles. Given the similarity of the research, we decided to include only one article (https://doi.org/10.3390/pr11041118) among the references cited in our paper.

Line 118 says "Table II", but you need to write Table 2.

It was corrected.

Reviewer 4 Report

Manuscript - coatings-2480728

Title: Influence of Substrate on Tribological Behavior of Inconel 625 2 GMAW Overlay

1. What is the main question addressed by the research?

This manuscript presented tribological results from Inconel 625 weld with and without 316LSi intermediate layer. The author proposed the differences in the wear rate is the results of thermal conductivity between stainless steel and carbon steel.

2. Do you consider the topic original or relevant in the field? Does it address a specific gap in the field?

This manuscript provided a possible explanation of different wear properties for specimens with and without an intermediate layer.

3. What does it add to the subject area compared with other published material?

Yes, it provides some possible mechanisms for the effect of the intermediate layer on the wear properties. However, the presentation is confusing due to incomplete information, such as the thickness of the layers and the color representation of different elements.

Figure 2 needs scale bars.

Figure 4 – what is the color representation for different elements?

4. What specific improvements should the authors consider regarding the methodology? What further controls should be considered?

It may be interesting to perform nanoindentation and nanoscratch tests on the cross-sectioned surfaces to verify the real cladding layer property changes.

5. Are the conclusions consistent with the evidence and arguments presented and do they address the main question posed?

Line 199 – “The results of hardness assessment, as shown in Figure 5, indicate that the substrate did not present a significant influence on the Inconel weld overlay.”

What is the depth or size of the indentation? Did the author consider the indentation hardness results may be influenced by the intermediate layer? This is commonly referred to as indentation substrate effects.

Line 215 – “As seen in Figure 6, according to the wear assessment, samples I and M did not display differences in the friction coefficient.” Figure 6 caption indicates data collected after 30 min of sliding. How many cycles is that? Results from Figure 7 are in terms of wear cycles not time.

Is it possible to show the cross-section view of the tracks in Figure 8? The depth of the tracks looks very similar. How is the wear rate in Figure 9 calculated? From the entire track or only the center portion of the track?

Line 246 – “The wear rate of the counterbodies was also measured and is shown in Figure 10. It is possible to observe that the counterbodies that slide against Inconel suffer a considerable wear rate and there is not a significant difference between the behavior for samples I and M.”

The meaning of these sentences is not clear.

Figure 11 – The reviewer does not see the differences between samples I and M. Please explain and highlight the characteristic differences.

Figure 12 – It is difficult to draw a conclusion from the chemical analysis of a single particle on each track. Is it possible the particles sampled are from the counterbodies? Did the authors sample other features on the track?

6. Are the references appropriate?

Yes

Author Response

What is the main question addressed by the research?

This manuscript presented tribological results from Inconel 625weld with and without 316LSi intermediate layer. The author proposed the differences in the wear rate is the results of thermal conductivity between stainless steel and carbon steel.

The authors are grateful for the comments and concur with the analysis performed.

Do you consider the topic original or relevant in the field? Does it address a specific gap in the field?

This manuscript provided a possible explanation of different wear properties for specimens with and without an intermediate layer.

The authors are grateful for the comments and concur with the analysis performed.

What does it add to the subject area compared with other published material?

Figure 2 needs scale bars.

It was done.

Figure 4 – what is the color representation for different elements?

It was done.

What specific improvements should the authors consider regarding the methodology? What further controls should be considered?

It may be interesting to perform nano indentation and nano scratch tests on the cross-sectioned surfaces to verify the real cladding layer property changes.

The authors acknowledge that conducting such an analysis would indeed be interesting. However, they lack sufficient resources and equipment to undertake it.

Are the conclusions consistent with the evidence and arguments presented and do they address the main question posed?

Line 199 – “The results of hardness assessment, as shown in Figure 5, indicate that the substrate did not present a significant influence on the Inconel weld overlay.”

The authors appreciate the analysis conducted, but they want to clarify that the layer thickness is 5.5 mm. Since the indentation was performed on the top of the coating, there is no influence from the intermediate layer.

As described in the method, a frequency of 2 Hz was utilized, resulting in a total of 216,000 cycles. Figure 7 was generated using a stability period of 7,000 cycles to improve the visualization of the map. This additional information has been included in the text.

The volume was obtained from the entire length of the wear track. This additional information has been included in the text. Unfortunately, due to the time constraints for delivering the revised article, it was not possible to include the requested image showing the cross-section.

Line 246 – “The wear rate of the counter bodies was also measured and is shown in Figure 10. It is possible to observe that the counter bodies that slide against Inconel suffer a considerable wear rate and there is not a significant difference between the behavior for samples I and M.”

The meaning of these sentences is not clear.

The text has been revised in an effort to enhance clarity.

Figure 11 – The reviewer does not see the differences between samples I and M. Please explain and highlight the characteristic differences.

An enhancement has been made to the explanation, and the wear mechanisms are illustrated in Figure 11.

Figure 12 – It is difficult to draw a conclusion from the chemical analysis of a single particle on each track. Is it possible the particles sampled are from the counter bodies? Did the authors sample other features on the track?

Analyses were performed in triplicates. It is not possible for the sampled particles to originate from the counterbodies as they have a different chemical composition compared to Inconel 625.

Are the references appropriate?

Yes

The authors are grateful for the comments and concur with the analysis performed.

Round 2

Reviewer 3 Report

The authors responded to my comments. Some of my comments were not taken into account by the authors, but nevertheless I recommend the article for publication.