Investigation on Interfacial Bonding Characteristics of Steel/Aluminum Bi-Metal Gears by Hot Forging Processing

Round 1

Reviewer 1 Report

This paper presented the interfacial bonding characteristics of Steel/Aluminum bi-metal gears produced by hot forging process. A wide range of literature was reviewed to justify the need for this research. The experimental section is readable and reproducible. Optical microscope (OM), scanning electron microscopy (SEM) and Energy Disperse Spectroscopy (EDS) were used for the characterization. It was concluded that the interfacial bonding changes the mode from mechanical to metallurgical when the deformation degree is increased from 70% to 90%. The conclusion was drawn based on the experimental observation and the paper will attract readers who are working in this research area. However, the paper needs revision before acceptance.

1.  Please remove redundancies from the abstract. The following lines can be removed "Steel/Aluminum bimetal forging gear can combine the advantages of high strength of steel and low density of aluminum to reduce the overall weight of gears, but the quality of the interface joining zone is influenced because of the differences of thermo-physical and mechanical properties between steel and aluminum. So it is of great practical value to study the interfacial bonding characteristics of Steel/Aluminum bi-metal gears by hot forging processing."

2. Include a scale bar in figures 1-6, 11 and 15.

3. It is not clear how the tracking points were selected. Is it the first point is situated at the top surface and all the 31 points were selected at equal spacing distance?

4. There is a mixture of Figure, Fig. and Fig throughout the manuscript. Please use only one.

5. Figure 17: Please limit the x-axis to 31 points instead of 32.

6. Figure 18: Please limit the x-axis to 31 points instead of 32. Please use the same y-axis scale for a) and b).

7.  What is the coordinating system was used in figure 18? What is the difference between figure 18 and 19?

8. Please change the x and y axis limit as referred in the previous comments.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript "Investigation on interfacial bonding characteristics of Steel/Aluminum bi-metal gears by hot forging processing" has been reviewed. 

It deals with an experimental analysis and FE modeling of steel-Al bimetal gears by hot forging process.

The manuscript is clear, balanced and well organized. English almost fine.

The topic is new and interesting.

I don't have remarks. In my opinion the manuscript can be accepted as it is.

Author Response

Thank you for your useful suggestions and comments on my manuscript.

Reviewer 3 Report

1. Please revise the manuscript for grammatical and typo errors

2. If any of the figures are tables are adopted from published content, then it is recommended to take copyright.

3. Why there is a thickness variation with the increased extent of degree of deformation?

4. In Fig. 8, there is a black line at bi metallic joining?

5. What is the elemental composition of purely Al and Steel side but not the interfacial layer after forging? It is recommended to perform EDS for that as well.

6. It is recommended to reduce the similarity index especially in section 2.1 Materials.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors made significant effort to improve the manuscript by addressing the reviewers' comments. It is recommended for publication.