Study of Microstructure and Properties of Aluminum/Steel Inertia Radial Friction Welding

Round 1

Reviewer 1 Report

In the Introduction, you write that various authors have dealt with the problem of welding friction of aluminum with steel. You do not indicate what problems these researchers had, and then it is not clear why your work is needed. It is necessary to describe in a little more detail what the authors have achieved before you, what problems they have encountered, and how your work will help solve these problems.

 

Table 1 shows the composition of the studied material, but it is not written how you received this data. Is this the result of chemical analysis or reference data? If chemical analysis, what equipment was it performed on? All this should be indicated in the paper.

 

Also describe in more detail in the methodology how mechanical tests, modes and equipment were carried out.

How and on what equipment were metallographic studies performed? What controlled the force applied to the ring? All this should be indicated in the article.

 

It would also be good to describe in the Methodology why you chose such a scheme for study. Does this scheme have a practical application? 

 

Has the temperature arising in the surfaces to be welded been evaluated? These data would be extremely useful, since temperature largely determines the amount of diffusion of elements and the weldability of surfaces.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The Authors' choice of research topics is topical, with the welding of different materials presenting many new challenges for designers and technologists alike. Particularly interesting and difficult to answer questions arise when joining (welding) materials with significantly different mechanical and physical properties. Formulating answers requires the application of state-of-the-art testing and analysis techniques, which are also used by Authors.

Please separate references [1-7] as listed in the sentence. Please provide the steel and aluminium material grades tested in references [14] and [15], as Authors have done for references [16] and [17].

In my opinion, Figure 1 does not show the welded joints, but the elements to be welded before welding. Please correct this, and check the drawing rules in the diagram, too. Please add the geometric dimensions to Figure 5.

Please use the identifications used in the "Number" column of Table 2 consistently in Figures 7, 11 and 13 and in section (1) of the "Conclusions" chapter.

Please describe the method for selecting the "Fine grained region" shown in Figure 8D.

Authors analyse sample 2 in Figure 8, samples 3, 2, 5 and 1 in Figure 9, sample 5 in Figure 10 and finally sample 5 again in Figure 12. Please describe why these samples were presented or analysed in more detail.

Please present the relationship calculating the "strength fluctuation coefficient" in the form of a mathematical formula.

Please address the following questions in the chapter "Conclusions". Have you succeeded in finding optimal welding parameters? What are the directions for further research? What practical applications could the research results have?

Please check the use of subscripts throughout the manuscript.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

 

Zhengtao Liu et al., elaborated the manuscript “Study on microstructure and properties of Aluminum/Steel Inertia fraction welding” and focusing their study towards the inertia friction welding (IFW) and following the formation mechanism of aluminum / steel friction joints. Also, consistent outputs regarding welding parameters related with mechanical properties at the macro/microstructure scale were conducted. The structure of the manuscript is well elaborated and the outputs are important enough to be considered by the R&D sector. English language is well written, but some minor aspects should be considered by the authors, pointed out in the following:

 

-          In the introduction section, there is mentioned “In recent years, many researchers have conducted researches on aluminum/steel welding processes, including electron beam welding, laser welding, arc brazing, pressure welding, friction stir welding, and rotary friction welding [1-7].” However, several citations used are more than 20 years old, thus not so “recent”. Please modify accordingly;

-          Abbreviations mentioned in the abstract should be included once also in the content of the manuscript (example: IMC);

-          Please better define the use of colors in figure 2;

-          Please add XYZ coordinates to figure 3; Also add scale;

-          Authors should include manufacturer information for all used instruments and materials;

-          Key information is missing to the applied methods (example FE-SEM: WD and keV). Same for the microhardness tester, EDS etc;

-          “Figure 8 shows the cross-sectional microstructure of the aluminum/steel joint of sample 2#.” Please correct the symbol;

-          Increase the contrast and scale bar in figure 8; Please include the “a blue box”;

-          “The micromorphology of the aluminum/steel welding interface is observed under an SEM (Figure 9).” Please rephrase;

-          In figure 9, the EDS graphs are not visible (too small); Please modify accordingly;

-          Increase the XY coordinates in figure 11;

-          At conclusion section, authors should finalize this section by adding / restating the importance of the conducted work and the applicability of the findings, interestingly enough, to the industry etc.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

This manuscript provides a detailed characterization of Inertia Friction welding of an Aluminum steel joint. The microstructure and properties of the joint were reported. The abstract is written well including the purpose, procedure, and principle findings in the context. However, they have a few redundancies which can be removed. A wide range of literature was reviewed to justify the need for this research. The experimental section is clear and reproducible. It was concluded that the joint provides a shear strength of 176 MPa. It was also concluded that no IMCs were detected in the joint interface. The conclusions were drawn from the experimental observations and it definitely expanded the current knowledge on this topic.  The followings need to be addressed before accepting the manuscript:

1. Abstract: Lines 9-11: These lines are redundant. Please start with, 'In this paper....'

2. Introduction: Please avoid grouped citations [1-7]. Proper credit should be given to authors you cited by writing 1-2 sentences for each citation. Seven references for one single statement is not acceptable.

3. Line 64: The description of the aluminum ring (Φ45mm×9mm×5mm) does not match figure 1. Please make the necessary corrections.

4. What is the machine "CJ- 30-J proprietary inertia friction welding machine" in line 64? Can you add a reference for this machine?

5. Please mention the reason behind choosing the friction welding parameters in Table 2. Additionally, it appears that  3 different friction speeds, 4 different friction pressures, and 4 different upsetting pressures were considered which makes a total of 4*4*3 =48 possible joining combinations. Out of these 48 combinations why only 9 were chosen? A solid and meaningful explanation of this aspect is necessary.

6. Figure 6a: Which joint it is?

7. Figure 7a: What are the friction pressures and upsetting pressures?

8.. Figure 7b: What are the friction speed and upsetting pressures? 

9. Figure 7c: What are the friction speed and friction pressures? 

10. Section 3.2: lines 140-149. Are they necessary? Figure 8: Why you need to show B and C. A and D should be able to tell the full story.

11. Figure 11: Please make the Y axis the same for all to see a visual comparison.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors answered my questions.

I would recommend a slight revision - to indicate the manufacturer of the equipment in brackets.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Thanks to the Authors for completing the manuscript, making changes and clarifications. The changes were well tracked in the "coverletter" file and in the revised manuscript. Overall, the manuscript has undergone significant changes and its overall quality has improved.

Authors of references [1-7] (previous numbering) were not considered relevant to the manuscript after the review. It is a pity, because an important element has been lost in the manuscript.

For references [14] and [15] (previous numbering), Authors have provided the aluminium and steel material grades tested.

The title of Figure 1 was clarified by Authors, but the figure still does not comply with the rules of mechanical drawing. Please amend. In Figure 5, the scale has been added by Authors, but this was not my original proposal. I still request the addition of real geometric dimensions to Figure 5.

The notations used in the "Number" column of Table 2 have been consistently used by Authors in the manuscript. This was an important and clarity-enhancing change, thank you.

The change to "fine grained region" vs "large plastic deformation zone" was a necessary change, "fine grained region" was not reliably supported.

I accept Authors' response regarding the selection and presentation of each sample

The relationship calculating the "strength fluctuation coefficient" was presented in the form of a mathematical formula by the Authors.

I accept the authors' answers to the questions raised in the chapter "Conclusions".

Please check the use of the words "inertia" and "inertial" throughout the manuscript.

I am not a native English speaker, but I think that the manuscript should be linguistically checked and the necessary changes made.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Please mention the reason behind choosing the friction welding parameters in Table 2. Additionally, it appears that 3 different friction speeds, 4 different friction pressures, and 4 different upsetting pressures were considered which makes a total of 4*4*3 =48 possible joining combinations. Out of these 48 combinations why only 9 were chosen? A solid and meaningful explanation of this aspect is necessary.

Response of this needs more detailed. It still needs a proper explanation. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf