Microstructure and Wear Resistance of Hot-Work Tool Steels after Electron Beam Surface Alloying with B₄C and Al

Round 1

Reviewer 1 Report

The paper focuses on microstructure, microhardness, and wear resistance analysis of Hot‐Work Tool Steels after Electron Beam Surface Alloying. The topic is interesting and has an industrial potential. The results can contribute e.g., on mechanical engineering, automotive and aerospace engineering.

The paper is prepared clearly and comprehensively, the scientific quality of the text has a relatively good standard. The conclusions of the study correspond to the declared intention and fully fulfil the declared intention of the presented study.

I think it may be interest to readers in academic and industrial fields. The paper is very well written and interesting. I recommend this paper; however, some comments should be addressed.

From the description it is not obvious the experimental setup of the wear test. Please add a scheme of the measurement method. It will be good to clarify in the section "materials and methods" that the experimental conditions were under dry friction. Unfortunately, the reader will not get this information.

Both samples contained carbon particles in the layer contributing to high wear resistance as a lubricant. Then the self-lubrication process occurred during wear tests due to carbon particle development in the upper parts of the layer. In this case the article should be supplemented by Coefficient of Friction (COF) measurement. This measurement would confirm the hypothesis and show the evolution over the time, i.e., whether the self-lubricating process is present throughout all the experiment.

In the conclusion section, which is very important paragraph, the author(s) must more explicitly define what is the best combination regarding the wear resistance.

Author Response

The paper focuses on microstructure, microhardness, and wear resistance analysis of Hot‐Work Tool Steels after Electron Beam Surface Alloying. The topic is interesting and has an industrial potential. The results can contribute e.g., on mechanical engineering, automotive and aerospace engineering.

The paper is prepared clearly and comprehensively, the scientific quality of the text has a relatively good standard. The conclusions of the study correspond to the declared intention and fully fulfil the declared intention of the presented study.

I think it may be interest to readers in academic and industrial fields. The paper is very well written and interesting. I recommend this paper; however, some comments should be addressed.

1) From the description it is not obvious the experimental setup of the wear test. Please add a scheme of the measurement method. It will be good to clarify in the section "materials and methods" that the experimental conditions were under dry friction. Unfortunately, the reader will not get this information.

Reply: the block-on-ring scheme simulating dry sliding friction was added to the paper in the end of Materials and Methods section. It was clarified that the experimental conditions were under dry friction in the “materials and methods” section.

2) Both samples contained carbon particles in the layer contributing to high wear resistance as a lubricant. Then the self-lubrication process occurred during wear tests due to carbon particle development in the upper parts of the layer. In this case the article should be supplemented by Coefficient of Friction (COF) measurement. This measurement would confirm the hypothesis and show the evolution over the time, i.e., whether the self-lubricating process is present throughout all the experiment.

Reply: we agree with the reviewer that COF measurement should confirm the hypothesis of self-lubricating. However, the device to conduct the wear test with simultaneous COF measurement is not available at the moment. We plan to carry out such research later on and prepare separate publication. This intention were put in the end of discussion section 3.2.

3) In the conclusion section, which is very important paragraph, the author(s) must more explicitly define what is the best combination regarding the wear resistance.

Reply: the conclusion was updated. The most wear resistant combination was pointed out.  

Reviewer 2 Report

The need, surface modification procedure, test method and results are clearly presented. The results clearly agree with the measurements made and are satisfactory.

Author Response

the English was improved 

Reviewer 3 Report

The present researches are very interesting. It is well-organized and well-written. It can meet the requirements of the journal and can be accepted for publication after careful revision. 
1.    The abstract should be revised. The significances in engineering field should be highlighted.
2.    The authors are suggested to explain the novelty of the paper.
3.    For Section 3.2, further step analysis should be added. The authors are suggested to add comments as well as the references below. They are closely related with the present research. 
[1] Theoretical and experimental exploration into the fluid structure coupling dynamic behaviors towards water-lubricated bearing with axial asymmetric grooves[J]. Mechanical Systems and Signal Processing, 2022, 168: 108624.
[2] Analysis on the Lubrication Performances of Journal Bearing System Using Computational Fluid Dynamics and Fluid–Structure Interaction Considering Thermal Influence and Cavitation[J]. Tribology International, 2013, 64: 8-15.
4.    For the conclusions, it is a little long. Several brief points of conclusions are enough. The authors are suggested to rewrite the conclusions.
5.    The English should be improved considerately.

Author Response

The present researches are very interesting. It is well-organized and well-written. It can meet the requirements of the journal and can be accepted for publication after careful revision.

1. The abstract should be revised. The significances in engineering field should be highlighted.

Reply: The abstract was revised. 

2. The authors are suggested to explain the novelty of the paper.

Reply: the novelty of the paper was explained at the end of the Introduction.

3. For Section 3.2, further step analysis should be added. The authors are suggested to add comments as well as the references below. They are closely related with the present research.

[1] Theoretical and experimental exploration into the fluid structure coupling dynamic behaviors towards water-lubricated bearing with axial asymmetric grooves[J]. Mechanical Systems and Signal Processing, 2022, 168: 108624.

[2] Analysis on the Lubrication Performances of Journal Bearing System Using Computational Fluid Dynamics and Fluid–Structure Interaction Considering Thermal Influence and Cavitation[J]. Tribology International, 2013, 64: 8-15.

Reply: Section 3.2. was updated with the further plans of investigations and suggested reference.  

4. For the conclusions, it is a little long. Several brief points of conclusions are enough. The authors are suggested to rewrite the conclusions.

Reply: the conclusions were rewritten.

5. The English should be improved considerately.

Reply: the English was improved 

Reviewer 4 Report

In this manuscript, author reported an electron beam surface alloying method for improving the microstructure and wear resistance of Hot‐Work Tool Steels. The work was interesting and the result convincing. I recommend that this work can be published in lubricants after minor revision.

1. EDS analysis results of element composition are usually expressed by atomic ratio. Why use mass ratio in this work?

 

2. The background on surface alloying in this paper is insufficient. More description and scope of application will help readers understand the purpose of the article. Here are several articles that describe the application background in detail, such as: Carbon 191 (2022) 290-300; Acta materialia 231 (2022) 117893.

 

3. Important report (ACS Appl. Energy Mater. 2021, 4, 2, 1335–1345; Corrosion Science, (2022) 200 110231.) has pointed out that the alloying elements could lead to the change of interfacial bonding and separation energy, thus would exert obvious influence to the interfacial bonding behavior. Related introduction could be included for a more comprehensive background.

 

4. The fonts in figures are suggested to be unified for readability.

 

Author Response

In this manuscript, author reported an electron beam surface alloying method for improving the microstructure and wear resistance of Hot‐Work Tool Steels. The work was interesting and the result convincing. I recommend that this work can be published in lubricants after minor revision.

1) EDS analysis results of element composition are usually expressed by atomic ratio. Why use mass ratio in this work?

Reply: Mass ratio was chosen due to the accepted measurement unit given in the reference data [1-5].

2) The background on surface alloying in this paper is insufficient. More description and scope of application will help readers understand the purpose of the article. Here are several articles that describe the application background in detail, such as: Carbon 191 (2022) 290-300; Acta materialia 231 (2022) 117893.

Reply: We agree with the reviewer to update the background and main text with the proposed articles. The first article in Carbon 191 (2022) 290-300 was referred to at the end of 3.1 section to describe the positive effect of carbon barrier layer on the weakening of the interfacial reaction. The second article in Acta materialia 231 (2022) 117893 was referred to in the Introduction.

3) Important report (ACS Appl. Energy Mater. 2021, 4, 2, 1335–1345; Corrosion Science, (2022) 200 110231.) has pointed out that the alloying elements could lead to the change of interfacial bonding and separation energy, thus would exert obvious influence to the interfacial bonding behavior. Related introduction could be included for a more comprehensive background.

Reply: We think, the suggested reports in Appl. Energy Mater and Corrosion Science are not directly related to the present research. The research on the effect of the alloying elements on the interfacial bonding and separation energy of AgCu based alloy during corrosion test is quite different to the area of the current research. At the same time, we plan to push our research in this direction. Boron/aluminum containing layers are resistant to corrosion and oxidation at high temperature. Such laboratory tests will be conducted in the following research.

4) The fonts in figures are suggested to be unified for readability.

Reply: The fonts in figures were unified.

 

Reference

1. Roberts, G.A.; Kraus, G.; Kennedy, R.L. Tool Steels, Materials Park; ASM International: Novelty, OH, USA, 1998.
2. Højerslev, C. Tool steels; Roskilde: Risø National Laboratory. Denmark.Forskningscenter Risoe. Risoe-R, No. 1244 (EN), 2001. http://orbit.dtu.dk/files/7728903/ris_r_1244.pdf
3. von Goldbeck, O.K. Iron—Boron Fe—B. In IRON—Binary Phase Diagrams. Springer: Berlin, Heidelberg, 1982. https://doi.org/10.1007/978-3-662-08024-5_8
4. Li, X.; Scherf, A.; Heilmaier, M. et al. The Al-Rich Part of the Fe-Al Phase Diagram. J. Phase Equilib. Diffus. 2016, 37, 162–173. https://doi.org/10.1007/s11669-015-0446-7
5. Lyakishev, N.P. Phasovie Diagrammi Binarnikh Metallicheskikh System [Phase Diagrams of Binary Metallic Systems]; Mashinostroenie: Moscow, Russia, 1996, p. 992.

Round 2

Reviewer 3 Report

The authors have revised the paper carefully point by point. It can meet the requirement now. Accept!