Review Reports - Laser Beam and Laser-Arc Hybrid Welding of Aluminium Alloys

Round 1

Reviewer 1 Report

The present paper contains a comprehensive review of laser and laser-arc hybrid welding of commercial wrought aluminium alloys. This review is based on significant number of references (314!) including newest publications.

Advantages and disadvantages of different welding methods are compared (including arc welding and friction-stir welding).

Various aspects of laser and laser-arc hybrid welding are considered: physics of laser beam welding, structure formation during welding, effect of process parameters (arc position, welding speed, torch angle, etc.) on quality of weld alloy (particularly role of porosity). The main difficulties in laser welding of aluminium alloys are marked (particularly, susceptibility of some alloys to hot cracking).

The key information on features of commercial alloys is summarized in Tables (particularly, Table 11). Conclusions reflects how various parameters affect the quality of aluminium alloys subjected by laser beam welding and laser-arc hybrid welding.

This review is sufficiently novel and interesting for professionals (particularly in the field of welding of aluminium alloys). But there are some minor remarks marked below.

Remarks

Table 1 doesn’t contain specific information and may be deleted. Moreover some values given in Table 1 should be corrected. For example, solubility of Sc in Al solid solution (maximal? Should be noted) is significantly less than 0.83% (wt.%? should be added). According to modern data this value is about 0.4%.
Classification of alloying elements given in Table 2 should be corrected. For example, Mg is alloying element (not minor!) in all 7xxx alloys. Cu is alloying element of high strength alloys (7075, 7055. 7085, etc)
The present review contains a significant number of schematic drawings (they are useful for readers) but typical microstructures of weld joints in commercial alloys are desirable also.
Typical microstructures of fracture surfaces (after tensile tests of welded specimens) are desirable also.

Author Response

Response letter to the reviewer #1

We are grateful and thank reviewers for the valuable comments and suggestions which are helpful to further improvement in quality of the manuscript. Provided article is comprehensive review, thus many questions from reviewers were expected since it is not possible to satisfy every reviewer considering its wide scope. Based on this, we would not like to contract the scope since such comprehensive review on LBW/LAHW of aluminum alloys is basically not available. Lack of some articles is mainly due to enormous amount of published work and some of them may be missed. Grammar was extensively reviewed before resubmission.

Comments from the reviewer and answers:

Comment 1: Table 1 doesn’t contain specific information and may be deleted. Moreover some values given in Table 1 should be corrected. For example, solubility of Sc in Al solid solution (maximal? Should be noted) is significantly less than 0.83% (wt.%? should be added). According to modern data this value is about 0.4%.

Answer: Table 1 was retracted and relevant information was reworked in the text when required.

Comment 2: Classification of alloying elements given in Table 2 should be corrected. For example, Mg is alloying element (not minor!) in all 7xxx alloys. Cu is alloying element of high strength alloys (7075, 7055. 7085, etc).

Answer: Table 2 has been revised and corrected.

Comment 3: The present review contains a significant number of schematic drawings (they are useful for readers) but typical microstructures of weld joints in commercial alloys are desirable also.

Answer: Since there is many different aluminium alloys, it was decided not to show microstructures in the first draft of the paper. However, most relevant examples have been added in relevant subchapters.

Comment 4: Typical microstructures of fracture surfaces (after tensile tests of welded specimens) are desirable also.

Answer: Typical fracture surfaces after tensile and fatigue testing have been added showing porosities in relevant subchapters.

Author Response File: Author Response.pdf

Reviewer 2 Report

The research status and development of laser beam and laser-arc hybrid welding of aluminum alloy were clarified in this manuscript. However, this manuscript has to major revised before it can be accepted. There are some suggestions as follows:

(1) The purpose of this manuscript is to introduce the research progress of laser and laser arc hybrid welding on aluminum alloy. However, some part of the whole manuscript is not related to the purpose, and these parts must be deleted and condensed.

(2) For content of each part of the manuscript, the author only stated the relevant literature. However, the detailed summary and evaluation for each part should be added in the whole manuscript.

(3) There were some typos and wrong sentences in all the manuscript, for example, “keyhole wells” in line 275 was incorrect. Please check these errors in the whole manuscript.

(4) In lines 358-359, the sentence “In arc welding, it is used to obtain a stable arc, desirable arc characteristics and the droplet transfer mode.” was unnecessary because it was not related with laser beam welding aluminum alloy.

(5) More literature on laser welding of aluminum alloys should be cited and discussed. Such as “ Influence of waveforms on Laser-MIG hybrid welding characteristics of 5052 aluminum alloy assisted by magnetic field[J]. Optics & Laser Technology, 2020, 132:106508.”

Author Response

Response letter to the reviewer #2

Comments from the reviewer and answers:

Comment 1: The purpose of this manuscript is to introduce the research progress of laser and laser arc hybrid welding on aluminum alloy. However, some part of the whole manuscript is not related to the purpose, and these parts must be deleted and condensed.

Answer: The request cannot be fully fulfilled, otherwise reviewer should specify which exact parts seems excessive and too detailed. The article contains both technological and metallurgical aspects, thus both should be explicitly discussed. Article has explicit explanation of keyhole physics because it is not possible to understand/comply how porosity and other imperfections are formed and how to eliminate them. Another example, LAHW is detailed reviewed and showed since most of researchers do not even understand what means hybrid welding and which kind of configurations it has; thus, it must be showed. This also belongs to all presented chapters. Moreover, some reviewers requested expansion of some parts. However, the summary of results table was condensed because it was overwhelmingly to detailed, table 1 was deleted, and figure 2 condensed.

Comment 2: For content of each part of the manuscript, the author only stated the relevant literature. However, the detailed summary and evaluation for each part should be added in the whole manuscript.

Answer: Most of chapters have the summary in the last paragraphs. A whole special subchapter (8.5) is dedicated for this and explicitly shown.

Comment 3: There were some typos and wrong sentences in all the manuscript, for example, “keyhole wells” in line 275 was incorrect. Please check these errors in the whole manuscript.

Answer: the grammar was revised before resubmission.

Comment 4: In lines 358-359, the sentence “In arc welding, it is used to obtain a stable arc, desirable arc characteristics and the droplet transfer mode.” was unnecessary because it was not related with laser beam welding aluminum alloy.

Answer: The statement was retracted.

Comment 5: More literature on laser welding of aluminum alloys should be cited and discussed. Such as “ Influence of waveforms on Laser-MIG hybrid welding characteristics of 5052 aluminum alloy assisted by magnetic field[J]. Optics & Laser Technology, 2020, 132:106508.”

Answer: Taking advantage of revision, the mentioned paper was added along other recent publications. Specifically, laser beam oscillations and assisting electromagnetic fields.

Author Response File: Author Response.pdf

Reviewer 3 Report

This is a well written review article for laser beam and laser-arc hybrid welding of aluminum alloys. Following issues should be addressed for its improvement.

(1) A review article should give some useful suggestions for next step research. Thus, "future work" is an indespensable part.

(2) Nowdays, the oscillating mode of laser beam and laser-arc hybrid welding has been developed. But there is no such information introduced in this article.

(3) Page 2, lines 81-82: the description of disadvantages of FSW seems inappropriate, since it has become one of the prevailing joining processs for aluminum alloys.

(4) Table 2: the strength of 2xxx is lower than that of 6xxx?

Author Response

Response letter to the reviewer #3

Comments from the reviewer and answers:

Comment 1: A review article should give some useful suggestions for next step research. Thus, "future work" is an indispensable part.

Answer: a new paragraph was added before summary.

Comment 2: Nowadays, the oscillating mode of laser beam and laser-arc hybrid welding has been developed. But there is no such information introduced in this article.

Answer: Oscillation mode of laser beam (moving beam by optics) was mentioned few times in the article. However, we agree that it deserves much more attention, thus more elaboration was added with recent published works.

Comment 3: Page 2, lines 81-82: the description of disadvantages of FSW seems inappropriate, since it has become one of the prevailing joining process for aluminum alloys.

Answer: We are aware that FSW may provide excellent quality welds and is indispensable in some applications. To reflect lower negativity towards FSW, the statement was retracted.

Comment 4: Table 2: the strength of 2xxx is lower than that of 6xxx?

Answer: Table 2 was revised. Please, note that provided range was based on specified references which also contains many discrepancies in data, thus lower/higher strength limit may vary nowadays. It might be a situation, that some AA2xxx may have lower strength than specific AA6xxx because it depends on manufacturing route and many other factors.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript has been revised in accordance with the reviewer’s comments. The research is of great significance for expanding your understanding of aluminum alloy laser welding or laser-arc hybrid welding. Therefore, the manuscript could be accepted in my view.

Reviewer 3 Report

All issues have been addressed.