Extension of Gap Bridgeability and Prevention of Oxide Lines in the Welding Seam through Application of Tools with Multi-Welding Pins
Round 1
Reviewer 1 Report
Generally speaking text is a bit confusing. It seems that too many factors are involved, e.g. I see no point in presenting Ch. 3.2 and results for hardness and bending, which are really correlated with the other results.
In particular, Introduction should contain more references and appropriate explanations, especially since the cited ones are in English or too general. I would even suggest to separate results for two materials in two papers, but do not insist on it.
Microstructure and Elongation is discussed for 0.3, 0.6 and 0.9 mm, whereas tensile strength is discussed for 0.3, 2 and 3 mm.
Discussion is made for 5083 H111 microstructure (probably!) and then for 7020 T651 properties. It should be made for both alloys!
There is no Fig. 21 in the text and one reference is missing.
Parametric study in #3.2. is confusing.
Comments for author File: 
Comments.pdf
Author Response
Dear Reviewer,
Thank you very much for your comments and explanations. Pointing out the errors and change requests in the PDF document helped me a lot to improve the paper. I have incorporated almost all the comments into the text and made improvements myself.
I hope the paper is now better understandable and creates an enrichment in the FSW tool development. I personally will continue to explore multi-pen tools.
Many greetings
Marcel Hatzky
Author Response File: Author Response.pdf
Reviewer 2 Report
The paper titled “Extension of gap bridgeability and prevention of oxide lines in the welding seam through application of tools with multi-welding pins” is well written and reflects a strong knowledge of the authors about the subject. However, in my opinion, the paper should not be published without preform major improvements before re-submission.
One of these points requiring improvement is the introduction. The lack of focus on the paper’s main subject is evident. Because it is a well-known subject (in FSW), an introduction with a deeper approach of the subject, well supported by works from other authors should be presented, namely, adding more information about tool development and the consequences for welds consolidation and for oxides grinding and dispersion.
In experimental section, the authors refer that they will use two different aluminium alloys, that “differ in their composition and the associated hardening mechanisms”, which is very interesting. However, it is never mentioned what is the interest of studying two alloys with those differences. It is only because they are different? The contextualization of this choice should be supplied.
The standard used by the authors was based on the DIN EN ISO 14273, which is, Resistance welding — Destructive testing of welds — Specimen dimensions and procedure for tensile shear testing resistance spot and embossed projection welds. This standard is adequate? Why performing “tensile shear tests” if the welds were fabricated in butt-weld configuration?
The “Concept of a multi-pin tool” is presented as a result. In my opinion, for a more traditional reading, it should appear or 1st- in experimental procedure or 2nd – as separate part. Otherwise, the reader loses its focus on main message. Being the presentation of a concept, figures of the tool with 1, 3 and 4 pins should also be shown. Adding a scheme with gap, plates and tool interaction could also be an asset.
The results section is well written, and majority of statements are well supported by results. However, some imprecisions are present, ore some doubts could arise. In fact, starting in line 139 of the manuscript, it can be read “It can be said that the diameter of the welding pin should be as small as possible to keep the size of the heat affected zone small”. Since we have a heat treatable and a non-heat treatable alloy, this assumption is valid for both alloys?
In Page 7, during oxide line distribution discussion, it is possible to observe a transformation of the lazy-z into a onion-ring morphology for a certain ser of process parameters. The authors attribute this change to the tool. However, since it is one of the highly studied subjects in FSW field, it can be analysed and discussed under a deeper point of view, which will help in further analyses. Beyond lazy-Z, due to the gap existence, the authors didn’t depict any root defect such as kissing-bond?
In figures 6 and 9 the authors present very interesting cross-section pictures. Carefully observing these figures lead to feel like lack of penetration occurred for these welds. Is it correct? If yes, no gap is present. There is any justification for this phenomenon?
In Figure 15, a “transmision zone” is present, which is not common on current FSW nomenclature. Authors should explain it in the text,
Why are strength values results not presented as strain-stress curves?
-Finally, conclusions reflect the results obtained in the work.
Author Response
Dear Reviewer,
Thank you very much for your comments and clarifications. Pointing out the errors and requests for changes helped me a lot to improve the work. I have incorporated almost all the comments into the text and made improvements myself.
I hope the paper is now more understandable and an asset in FSW tool development. Personally, I will continue to work on multi-pen tools.
Best regards
Marcel Hatzky
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Paper is now ready for publishing
Author Response
Dear Sir,
Thank you very much for your comments.
Many greetings
Marcel Hatzky
Reviewer 2 Report
Dear Sirs,
The corrections performed in the document are pertinent and authors answer accordantly to reviewer’s comments. However, some typos and small text incoherencies remain present in the document and should be corrected. Finally, to improve even more the clarity of the document, authors should also clarify the difference between hot and cold welds, based in literature or descriptive definition.
Author Response
Dear Sir,
Thank you very much for your comments. I have added a text passage. I wrote something about the cold and hot welds to remove ambiguities.
Many greetings
Marcel Hatzky
