Research and Development Progress of Laser–Arc Hybrid Welding: A Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript reviews laser-arc hybrid welding (LAHW) technology, covering its principles, technological developments, and applications. It examines the synergistic effects between laser and arc heat sources and discusses process parameters, keyhole behaviour, weld quality assessment, and common defects. The review also highlights LAHW's industrial applications in automotive, shipbuilding, aerospace, and additive manufacturing, emphasising its advantages over conventional welding methods.

1. This review falls short of meeting the rigorous standards for a comprehensive review in Metals, MDPI. The review lacks a clear methodological framework for literature selection. How were papers chosen for inclusion? What databases were searched? What time period was covered? What inclusion/exclusion criteria were applied? Many claims are made without sufficient evidence or critical evaluation of the cited studies. The review frequently presents results without discussing limitations or contradictions in the literature. Several recent (2023-2024) developments are mentioned but insufficiently analysed, suggesting a superficial treatment of the most current research.
2. The abstract promises an analysis of "numerous studies" but fails to specify the scope or methodology of the review. Why does the introduction not clearly identify research gaps or controversies in the field? The introduction emphasises the advantages of LAHW but inadequately addresses its limitations. What is the rationale for the structure chosen for this review? The framework diagram (Fig. 2) is presented with minimal explanation.
3. The comparison of different lasers is superficial. What specific advantages make fibre lasers "poised to significantly influence future advancements," as claimed on page 4? Table 1 presents a comparison of welding methods but lacks a critical analysis of when each method is optimal. The classification of LAHW systems is inconsistent—sometimes by heat source and sometimes by application. Why is there no discussion of emerging laser technologies beyond the established CO2, Nd: YAG, and fibre lasers?
4. The mathematical models for quantifying synergistic effects (Table 2) are presented without critical evaluation of their accuracy or applicability. The discussion of DLA (distance between laser and arc) fails to reconcile contradictory findings in the literature. The review states that "the synergistic effect increases with higher laser power" (p.9) but does not adequately explain the mechanisms or limitations of this effect. How generalisable are the findings regarding heat source arrangements across different material systems?
5. The keyhole behaviour section lacks adequate discussion of computational models and their predictive capabilities. What are the critical differences in keyhole dynamics between different material systems? The droplet transfer behaviour section fails to adequately explain the relationship between transfer modes and weld quality across different alloy systems. How reliable are the existing methods for monitoring and controlling these phenomena in real-time industrial applications?
6. The residual stress analysis lacks depth. What specific methods are most reliable for measuring residual stresses in LAHW joints? The microstructure discussion is descriptive rather than analytical. What microstructural features are most critical for optimising mechanical properties? Table 3 presents phase microstructure data without adequate discussion of the mechanisms responsible for these structures. Why is there minimal discussion of non-destructive testing methods for the quality assessment of LAHW joints?
7. The porosity discussion presents causes but inadequately addresses quantitative relationships between process parameters and defect formation. What are the most effective strategies for real-time defect detection during LAHW? The crack suppression discussion is inadequate—what specific filler materials or process modifications show the most promise? The section on hump defects lacks critical analysis of competing theories explaining their formation.
8. The application section is largely descriptive and lacks critical analysis of success factors and limitations. Why is there no detailed economic analysis comparing LAHW with conventional welding techniques? The discussion of additive manufacturing applications is superficial and does not adequately address the unique challenges in this emerging area. What specific industrial standards have been developed for LAHW, and where are standardisation efforts still needed?
9. The conclusion largely repeats previous sections rather than synthesising insights. The future research directions are vague and fail to identify specific technical challenges that need addressing. What are the key barriers to wider industrial adoption of LAHW technology? The authors mention "technological innovation" and "intelligence" without specifying the most needed advances.
10. The figures and tables in this manuscript exhibit significant deficiencies that undermine their scientific value and utility to readers. Overall, the visual elements suffer from:

• Poor reproduction quality - many figures appear to be directly copied from other publications with no enhancement, resulting in pixelation and loss of detail
• Inadequate labelling - critical elements within figures often lack clear identification
• Inconsistent formatting - no standardised approach to presentation across similar figures
• Incomplete captions - many captions fail to make the figures stand-alone comprehensible

Comments on the Quality of English Language

The manuscript exhibits numerous issues with English grammar, syntax, and scientific writing conventions that significantly impair readability and comprehension. The text appears to have been written by authors for whom English is not a primary language and has not undergone adequate professional proofreading. These issues detract from the scientific content and undermine the manuscript's credibility.

Author Response

Date: March 8, 2025

Dear Reviewers:

 

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files. We appreciate you and reviewers for your positive and constructive comments and suggestions on our manuscript. We have read the comments carefully and consider all issues mentioned in the reviewers' comments carefully, and modified the comment point by point accordingly; the changes are indicated in red colored font. We greatly appreciate your further consideration of our manuscript. Thank you for your careful review.

 

As attached, please also find the detailed response to the reviewers’ comments.

 

We hope that the revision and correction will meet with approval.

 

We deeply appreciate your consideration of our manuscript. If you have any queries, please do not hesitate to contact me. Thank you.

 

Best Regards.

 

Sincerely,

Zhidong Yang

 

College of Materials Science and Engineering,

Jiangsu University of Science and Technology

No.2, Mengxi Road, Zhenjiang, Jiangsu, China

E-mail: yangzhidong@just.edu.cn

Tel: +86-13852911342

Fax: +86-511-84416867

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Overall, it is a well-structured and nicely written paper.

Line 30. The meaning of abbreviation should be given at the first time in the text.

Line 37. Exceeding the optimal welding speed does not cause itself grain coarsening

Figure 2. Figure quality could be improved, font size could be enlarged.

Line 206 In CO2 “2” should be put to lower index.

In Table 2. in I0 “0” should be put to lower index.

Line 428. Space is missing between A and Schematic

Line 440. Space is missing between quality and [32

The high speed camera images are hardly visible in Figure 7.

Figure 10. is not visible at all.

The resolution of Figure 11. could be improcved.

Line 572. There is a double space before “In tensile”

The resolution of Figure 13. could be improved.

Line 658. However => however

Line 806. weld joint crack => welded joint crack

The resolution of Figure 15. is not so good.

Author Response

Date: March 8, 2025

Dear Reviewers:

 

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files. We appreciate you and reviewers for your positive and constructive comments and suggestions on our manuscript. We have read the comments carefully and consider all issues mentioned in the reviewers' comments carefully, and modified the comment point by point accordingly; the changes are indicated in red colored font. We greatly appreciate your further consideration of our manuscript. Thank you for your careful review.

 

As attached, please also find the detailed response to the reviewers’ comments.

 

We hope that the revision and correction will meet with approval.

 

We deeply appreciate your consideration of our manuscript. If you have any queries, please do not hesitate to contact me. Thank you.

 

Best Regards.

 

Sincerely,

Dr. Zhidong Yang

 

College of Materials Science and Engineering,

Jiangsu University of Science and Technology

No.2, Mengxi Road, Zhenjiang, Jiangsu, China

E-mail: yangzhidong@just.edu.cn

Tel: +86-13852911342

Fax: +86-511-84416867

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Review of the article «Research and development progress of laser-arc hybrid welding: A review»

The main question adressed by the research is resent progress and future perspectives of the laser-arc hybrid welding.

This article is a review study devoted to the modern applications of laser-arc hybrid welding (LAHW). The authors aim to provide a comprehensive overview of the current state of LAHW, evaluate its advantages and disadvantages, and propose recommendations for future research. Particular attention is paid to the significance of LAHW in the development of industrial applications.

This Topic is relevant tothe Metals and actual for metallurgy and mechanical engineering industry.

Paper structure

The article is structured into four main sections:

1. Overview of modern LAHW systems: This section reviews the existing lasers and arc sources used in hybrid welding and describes the latest developments in LAHW systems.
2. Properties of LAHW: This section explains the principle of integrating different heat sources and their effect on the welding process.
3. Basic phenomena and weld quality: This section is based on a significant amount of recent research and analyzes the basic phenomena occurring during the process, as well as the weld quality.
4. Current Status of Implementation in Various Industries: This section discusses the current application of LAHW in various industrial sectors.
5. Industrial applications

Key Points (new information for subject area)

- Process Complexity: LAHW, by combining two different heat sources, significantly complicates the welding process. This requires synchronization of more parameters, making the optimal parameters for individual processes not always applicable to hybrid welding.

- Cost Savings: Having a secondary heat source can reduce the laser power requirement, leading to lower manufacturing costs.

- Accuracy and Quality: Accurate modeling of the parameters is critical to ensure a weld with high mechanical properties and accurate dimensions. Hybrid welding requires high quality welding materials and skilled workers.

- Technologies: The article provides a detailed description of the various lasers (CO2, Nd:YAG, fiber lasers) and arc systems (GMAW, GTAW) used in LAHW. Special attention is paid to CO2 lasers, which can operate in continuous and pulsed modes, providing high output power and processing efficiency.

Weaknesses:

1. Many paragraphs end with figures and there is no analysis after them. Please add analysis after all the figures.
2. Theoretical and fundamental principles that influence the technologies you write about are not sufficiently covered. For example, doi.org/10.3390/app14219774.

Methodology of the review is qood orginised, but don’t has paragraph about Theoretical and fundamental principles that influence to the quality of the laser-arc hybrid welding.

Conclusion answer to the maion qiestion of this paper.

References are appropriate.

The article provides a comprehensive overview of modern LAHW technologies and applications, emphasizing its importance in industry. The authors emphasize the need for further research to improve the process and expand its application. The work is a valuable resource for welding specialists and engineers interested in hybrid technologies. After supplementing with theoretical work and analysis after the figures, it is recommended for publication in the Metals journal.

 

Best regards, reviewer

Author Response

Date: March 8, 2025

Dear Reviewers:

 

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files. We appreciate you and reviewers for your positive and constructive comments and suggestions on our manuscript. We have read the comments carefully and consider all issues mentioned in the reviewers' comments carefully, and modified the comment point by point accordingly; the changes are indicated in red colored font. We greatly appreciate your further consideration of our manuscript. Thank you for your careful review.

 

As attached, please also find the detailed response to the reviewers’ comments.

 

We hope that the revision and correction will meet with approval.

 

We deeply appreciate your consideration of our manuscript. If you have any queries, please do not hesitate to contact me. Thank you.

 

Best Regards.

 

Sincerely,

Dr. Zhidong Yang

 

College of Materials Science and Engineering,

Jiangsu University of Science and Technology

No.2, Mengxi Road, Zhenjiang, Jiangsu, China

E-mail: yangzhidong@just.edu.cn

Tel: +86-13852911342

Fax: +86-511-84416867

 

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The paper summarizes several aspects of laser-arc hybrid welding. The review explores hybrid welding classifications, welding principles, keyhole dynamics, droplet transfer, and defect prevention to improve weld quality. Additionally, it analyzes residual stress effects on weld shape, microstructure, phase composition, and the impact of welding parameters on post-weld deformation and mechanical properties. The review lacks several key aspects and has other shortcomings as well.

1. In Lines 97-112, the structure of the manuscript is described. However, the numbering of sections in the description does not align with the manuscript, e.g., it is stated that ‘The fourth section discusses the current implementation status across various industries’. Nevertheless, it is the fifth section in the paper. On the other hand, effect of LAHW on residual stresses, distortion, microstructure, mechanical properties, etc. is missing from this paragraph. In addition, it is recommended to add residual stresses, etc. in Figure 2 as another aspect (probably a fifth segment in the figure) as well (see comment 8).
2. Quality of subfigures in Figure 2 need to be improved or could be deleted. A figure containing only the most important aspects and expressions (with text) is recommended.
3. Please clarify what the ‘1+1>2 effect’ means in Line 121.
4. Please do not mix American and European nomenclature for welding processes (e.g., use Tungsten Inert Gas (TIG) welding instead of GTAW, and use MIG/MAG instead of GMAW in the text or vice versa, please check e.g., EN ISO 4063 for adequate technical expressions for welding processes).
5. In Section 2, the description is a bit rough-and-ready. In the literature, there are a lot of combinations. Different laser welding processes may cover the following:
   1. 521 solid state laser welding,
   2. 522 gas laser welding,
   3. and 523 diose laser wedding in accordance with EN ISO 4063.

Description of the combined arc welding processes in LAHW is kind of vague. Again, in accordance with EN ISO 4063, there is submerged are welding (121-126 welding processes), MIG/MAG welding processes (131-138), TIG welding processes (141-147), and plasma welding processes (151-155). Thus, there are several options within e.g., MIG/MAG welding, MIG/MAG is just a group of welding processes. Subgroups, denoted with the denoted three-digit reference numbers could be combined with the aforementioned laser welding processes theoretically. Please add a table systematically summarizing all the previous combinations of laser and arc welding processes in the literature with also highlighting the main findings of the referred publications.

6. In Table 2, make sure to use the same font types, subscripts, etc. in the ‘Parameter explanation’ column as in the ‘Models’ column.
7. Quality of Figure 5 needs to be improved. Since font size is very small, it is nearly impossible to interpret the plots.
8. It is recommended to restructure the manuscript and move Subsections 4.3 and 4.4 in a new Section (possibly create Section 5 for this purpose and renumber the subsequent sections).
9. Modelling aspects of LAHW is not addressed in the paper in details, while the Reviewer believes it is a key in understanding the behaviour. The following should be addressed somehow in the paper such as heat source models in finite element analysis or possibilities in computational fluid dynamics, modelling of cracking, porosity, etc. during LAHW. It is described as a possible future research goal (in Lines 970-977). However, numerical simulation is already a widely used tool for investigating these aspects. Thus, results of research in this field should be addressed somehow in the manuscript.
10. In the review, it is recommended to highlight research gaps.

Author Response

Date: March 8, 2025

Dear Reviewers:

 

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files. We appreciate you and reviewers for your positive and constructive comments and suggestions on our manuscript. We have read the comments carefully and consider all issues mentioned in the reviewers' comments carefully, and modified the comment point by point accordingly; the changes are indicated in red colored font. We greatly appreciate your further consideration of our manuscript. Thank you for your careful review.

 

As attached, please also find the detailed response to the reviewers’ comments.

 

We hope that the revision and correction will meet with approval.

 

We deeply appreciate your consideration of our manuscript. If you have any queries, please do not hesitate to contact me. Thank you.

 

Best Regards.

 

Sincerely,

Dr. Zhidong Yang

 

College of Materials Science and Engineering,

Jiangsu University of Science and Technology

No.2, Mengxi Road, Zhenjiang, Jiangsu, China

E-mail: yangzhidong@just.edu.cn

Tel: +86-13852911342

Fax: +86-511-84416867

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

All revisions directly address the concerns raised by the Reviewer and help ensure the manuscript meets Metals, MDPI's publication standards.

Reviewer 4 Report

Comments and Suggestions for Authors

Manuscript has been modified according to the author's comments, and the quality has been improved a lot.