Innovations in Monitoring, Control and Design of Laser and Laser-Arc Hybrid Welding Processes

Round 1

Reviewer 1 Report

Authors discuss laseer welding as a modern technnique in metallurgy. The field is rapidly growing and gives many new discoveries. Online monitoring is important part of further development of the field. Review is written in perfeect manner with much information and representative illustrations.

Author Response

Thanks for your approval.

Reviewer 2 Report

In my opinion, the paper is not yet ready for publication. The authors should perform major revisions to the article to address the comments below.

1. Reviews should provide concise and precise updates on the latest progress made in the presented area of research. Systematic reviews should follow the PRISMA guidelines: https://www.mdpi.com/editorial_process#standards

2. Authors should have read the Aims & Scope to gain an overview and assess if this manuscript is suitable for the journal “Metals”. In any case, the extensive listing of works on the welding of thermoplastic materials glass and ceramics (Refs. 8–18) does not seem sufficiently substantiated in a review article for this journal.

3. As is known, the Introduction section should briefly present the research in its broad context and highlight why it is important. The current state of the research field should be reviewed carefully, and key publications should be cited. In the Introduction section, it should be mentioned that in the field of laser (and laser-arc hybrid) welding, for example, there is a problem of joining dissimilar metallic materials. Only a comprehensive application of innovations in the monitoring, control and design of welding processes can achieve the required welding quality. In this case, it is necessary to make references to well-known publications. doi: 10.1016/j.matdes.2021.109533, 10.3390/met11040622, 10.18287/2412-6179-2017-41-6-848-855, 10.1007/s40516-017-0049-8, 10.1016/j.jmatprotec.2020.116994. There are also other problems in this field, which are addressed by such comprehensive application of innovations. It is also possible to note this in the paper.

4. In the Introduction section, it is always recommended to provide a brief description of the main aim of the work and highlight the main conclusions. The introduction should be kept comprehensible for the scientists that are working outside the subject of the paper. It would be rational in addition to highlighting the main conclusions, to briefly mention the main purpose of the paper, to exclude the phrase “is reviewed” from the narration, replacing it with “the purpose of this work is”.

5. Despite the interesting content of the article, the conclusions seem too short and do not reveal many details. There are obvious misprints in the References section (eg Refs. 12, 24, 31).

Author Response

Reviewer2：In my opinion, the paper is not yet ready for publication. The authors should perform major revisions to the article to address the comments below.

1. Comments:

Reviews should provide concise and precise updates on the latest progress made in the presented area of research. Systematic reviews should follow the PRISMA guidelines:    https://www.mdpi.com/editorial_process#standards

Response:

Thanks for your suggestions. This paper reviews the research progress of monitoring and quality control of laser welding and laser arc-hybrid welding process, as well as the intelligent design of welding process based on numerical simulation. The development of laser welding quality control is summarized from two aspects of laser welding quality control and numerical simulation of laser welding process. Monitoring and quality control of laser welding process has always been an important content of research and development in the field of laser welding. Various sensors such as inductance, capacitance, acoustic wave, photoelectric and vision are used to realize weld tracking, defect detection and weld forming quality monitoring according to different laser welding processes and requirements through artificial intelligence and computer processing methods, the welding process parameters are adjusted through feedback control, so as to realize high-quality automatic laser welding process. Digital twin technology allows reasoning from the information content, combines the current situation with the expected process, and aims to predict the possibility of the future according to the information content. Therefore, it is very important to carry out the research on laser welding quality monitoring and control technology and digital twin technology, which is of great significance to ensure the quality of laser welding, give full play to its advantages of high speed and efficiency, and speed up the process of its application. It can also deepen the understanding of the relevant mechanisms of laser welding, such as energy transfer process, "keyhole" behavior, plasma behavior and so on.

 

2. Comments:

Authors should have read the Aims & Scope to gain an overview and assess if this manuscript is suitable for the journal “Metals”. In any case, the extensive listing of works on the welding of thermoplastic materials glass and ceramics (Refs. 8–18) does not seem sufficiently substantiated in a review article for this journal.

Response:

Thank you for your patience and carefulness very much. We have carefully read Aims & scope and deleted the relevant contents about thermoplastic composite materials, glass and ceramic in the manuscript.

 

3. Comments:

As is known, the Introduction section should briefly present the research in its broad context and highlight why it is important. The current state of the research field should be reviewed carefully, and key publications should be cited. In the Introduction section, it should be mentioned that in the field of laser (and laser-arc hybrid) welding, for example, there is a problem of joining dissimilar metallic materials. Only a comprehensive application of innovations in the monitoring, control and design of welding processes can achieve the required welding quality. In this case, it is necessary to make references to well-known publications. doi: 10.1016/j.matdes.2021.109533, 10.3390/met11040622, 10.18287/2412-6179-2017-41-6-848-855, 10.1007/s40516-017-0049-8, 10.1016/j.jmatprotec.2020.116994. There are also other problems in this field, which are addressed by such comprehensive application of innovations. It is also possible to note this in the paper.

Response:

Thank you very much for your professional advice. According to your suggestion, we have modified the introduction section. For the convenience of review, it is attached below:

In recent years, laser welding technology has been steadily improved, increasingly mature, which has obtained more and more attention [8-13]. Oliveira et al [14] reported for the first time that the aged NiTi-20Zr high temperature shape memory alloy was laser welded. The results showed that the aged and welded NiTi-20Zr was mechanically loaded up to 500 MPa at room temperature and 200 °C, there was no fracture, and showed the same behavior as the reference base metal. The aged NiTi-20Zr alloy shows good Laser Weldability, which opens a new door for the use of these materials in drive based applications, and this preliminary study shows a new possibility of using advanced laser bonding methods in these alloys. Li et al. [15] Studied the effects of linear, sinusoidal and cycloid scanning paths on flow dynamics and weld formation during laser welding of 5A06 aluminum alloy. The results show that when the scanning path is cycloid, it is helpful to reduce the formation of porosity due to its large heating area. Long et al. [16] Studied the effect of the increase of ambient pressure on the penetration depth of laser welded molybdenum alloy. The results show that with the increase of ambient pressure, the energy required to form the penetration depth per unit length in the process of laser deep penetration welding increases. When the total energy of laser output is constant, the penetration depth of molybdenum alloy will decrease with the increase of ambient pressure. Because of its many advantages such as low heat input, small deformation, rapid cooling rate and high energy beam concentration, laser welding has good material adaptability. It can not only weld homogeneous materials but also suitable for welding dissimilar materials[17-21]. In production practice, dissimilar welding of different metals can reduce the weight of the structure and reduce the production cost. Moreover, the connection technology of heterogeneous materials plays an important role in the manufacture of complex structures, which has attracted the attention of many researchers[22-26]. Murzin et al. [27] studied the pulsed laser welding of aluminum alloy AK4 and titanium alloy VT5-1, and obtained a uniform structure without voids, which indicates that the welded joint has high enough performance. Wallerstein et al. [28] reviewed the latest progress of laser welding between aluminum alloy and steel, and pointed out that connecting aluminum and steel is a challenging task, mainly because of the formation of brittle intermetallic compounds at the joint interface. Liedl et al. [29] studied the laser welding of 1mm aluminum alloy and steel dissimilar metals. The experimental research shows that by adjusting the laser power and welding speed, the ultra-thin diffusion zone with the minimum intermetallic layer thickness can be obtained, and then the weld without defects such as cracks and pores can be obtained. Wallerstein et al. [30] studied the optical fiber laser welding brazing of 6061-T6 aluminum alloy with a thickness of 1.6 mm and S235-JR structural steel with a thickness of 1.5 mm. The results show that the best AA6061 to S235 dissimilar joints can be obtained by combining AlSi5 welding wire with ALSi12 powder mixed in brazing flux.

Please see:

Page 1: line 36-43.

Page 2: line 44-69.

 

4. Comments:

In the Introduction section, it is always recommended to provide a brief description of the main aim of the work and highlight the main conclusions. The introduction should be kept comprehensible for the scientists that are working outside the subject of the paper. It would be rational in addition to highlighting the main conclusions, to briefly mention the main purpose of the paper, to exclude the phrase “is reviewed” from the narration, replacing it with “the purpose of this work is”.

Response:

Thank you very much for your professional advice. According to your suggestion, we have modified the introduction section and replaced "is reviewed" with "the purpose of this work is". For the convenience of review, it is attached below:

Laser welding (especially deep penetration laser welding) process involves many complex physical phenomena of material melting, strong evaporation, plasma, fresnel absorption, multiple reflection etc. As well as the dynamic equilibrium conditions for the stable existence of keyhole and the influence mechanism of various factors on the shape of molten pool. In addition to the complex physical phenomena of single laser welding, the interaction between the two heat sources of laser and arc intensifies the complexity of the laser-arc hybrid welding process. Therefore, in order to ensure the quality of laser welding, give full play to its advantages of high speed and efficiency, and speed up its application process, revealing the mechanism, predicting and controlling the welding process is very difficult and important.

The purpose of this work is the research progress of the monitoring and quality control of laser welding and laser-arc hybrid welding process as well as the intelligent design of welding process based on numerical simulation. The development of laser welding quality control is summarized from two aspects of laser welding quality control and numerical simulation of laser welding process. The laser welding quality control is mainly discussed from two aspects of welding signal monitoring and quality control technology. There are also other problems in this field, which are addressed by such comprehensive application of innovations. At the last, the research hotspots and development trends of laser welding and laser-arc hybrid welding are forecasted.

Please see:

Page 2: line 78-81.

Page 2: line 84-86.

Page 3: line 105-107.

Page 3: line 110-111.

 

5. Comments:

Despite the interesting content of the article, the conclusions seem too short and do not reveal many details. There are obvious misprints in the References section (e.g. Refs. 12, 24, 31).

Response:

Thanks for your suggestions. We have supplemented the conclusion and corrected the errors in the references. For the convenience of review, it is attached below:

In summary, compared with the traditional material connection methods, laser welding has the characteristics of high quality, high precision and high efficiency. It can weld various special materials and has strong adaptability. Moreover, laser welding has the advantages of easy automatic control of parameters, good repeatability and reproducibility, and can improve the stability of product quality. Therefore, it has been widely used in many fields. Based on the industry's demand for automatic and intelligent welding, the research on the monitoring, quality control and monitoring-feedback-parameters adjust integrated control of laser welding process has attracted extensive attention. Monitoring and quality control of laser welding process has always been an important content of research and development in the field of laser welding. Various sensors such as inductance, capacitance, acoustic wave, photoelectric and vision are used to realize weld tracking, defect detection and weld forming quality monitoring according to different laser welding processes and requirements through artificial intelligence and computer processing methods, the welding process parameters are adjusted through feedback control, so as to realize high-quality automatic laser welding process. Signal monitoring of welding process is an important means to evaluate welding quality. The selection of detection signal should not only ensure that the detection signal can reflect the welding state, but also meet the requirements of convenient signal acquisition, fast response speed, high reliability of production environment and high signal-to-noise ratio. Signals can reflect the laser welding process and weld quality from different sides. In practical use, people often choose one or several signals to monitor the welding process and quality. At present, scholars are committed to establishing a high-precision and reliable correlation between the optical, electrical and acoustic signals monitored in the laser welding process and the joint quality and weld appearance, and expect to use this correlation to adjust the laser welding process in real time through deep machine learning methods, so as to realize the weld tracking, defect detection and weld forming quality monitoring, and finally realize the automation and intelligence of laser welding process. In recent years, with the rapid development of modern optical technology, information technology and computer technology, the diagnosis of laser welding quality has made great progress in signal pickup, information extraction, defect identification and universality.

Please see:

Page 10: line 370-374.

Page 10: line 377-388.

Page 10: line 392-396.

Reference

36. Ogundimu, E. O.; Akinlabi, E. T.; Erinosho, M.F. Study on microstructure and mechanical properties of 304 stainless steel joints by TIG-MIG hybrid welding. Surface Review & Letters 2018, 25, 1850042.
37. Matsui, H.; Chiba, T.; Yamazaki, K. Detection and amplification of the molten pool natural oscillation in consumable electrode arc welding. Welding International 2014, 28, 5-12.

Reviewer 3 Report

The authors presented a review on Innovations in Monitoring, Control and Design of Laser and Laser-Arc Hybrid Welding Processes. The manuscript in the present form does not serve the purpose of a review paper.

What has been done in this manuscript is that one or two lines from the abstract are picked and bunched. No efforts have been made in presenting the state-of-the-art by analysing the published literature on a given sub-topic. By reading the manuscript, the reader reaches nowhere.

There are several typo errors in the manuscript. The manuscript is not acceptable in the present form.

Author Response

Manuscript Number: ISSN 2075-4701

Article Title: Innovations in Monitoring, Control and Design of Laser and Laser-Arc Hybrid Welding Processes

 

Reviewer3：The authors presented a review on Innovations in Monitoring, Control and Design of Laser and Laser-Arc Hybrid Welding Processes. The manuscript in the present form does not serve the purpose of a review paper.

1. Comments:

What has been done in this manuscript is that one or two lines from the abstract are picked and bunched. No efforts have been made in presenting the state-of-the-art by analyzing the published literature on a given sub-topic. By reading the manuscript, the reader reaches nowhere

Response:

Thanks for your suggestions. This paper reviews the research progress of monitoring and quality control of laser welding and laser arc-hybrid welding process, as well as the intelligent design of welding process based on numerical simulation. The development of laser welding quality control is summarized from two aspects of laser welding quality control and numerical simulation of laser welding process. On line monitoring of welding process is an important means to evaluate welding quality .Detecting the emission signal from the working area is an important means to monitor the welding process. Monitoring and quality control of laser welding process has always been an important content of research and development in the field of laser welding. Various sensors such as inductance, capacitance, acoustic wave, photoelectric and vision are used to realize weld tracking, defect detection and weld forming quality monitoring according to different laser welding processes and requirements through artificial intelligence and computer processing methods, the welding process parameters are adjusted through feedback control, so as to realize high-quality automatic laser welding process. In recent years, with the rapid development of modern optical technology, information technology and computer technology, the diagnosis of laser welding quality has made great progress in signal pickup, information extraction, defect identification and universality. Digital twin technology allows reasoning from the information content, combines the current situation with the expected process, and aims to predict the possibility of the future according to the information content. The application of digital twin technology is expected to solve the dilemma of slow application of laser welding research results in industrial field. Therefore, it is very important to carry out the research on laser welding quality monitoring and control technology and digital twin technology, which is of great significance to ensure the quality of laser welding, give full play to its advantages of high speed and efficiency, and speed up the process of its application. It can also deepen the understanding of the relevant mechanisms of laser welding, such as energy transfer process, "keyhole" behavior, plasma behavior and so on.

According to your suggestion, we have further carefully modified the manuscript. For the convenience of review, it is attached below:

In recent years, laser welding technology has been steadily improved, increasingly mature, which has obtained more and more attention [8-13]. Oliveira et al [14] reported for the first time that the aged NiTi-20Zr high temperature shape memory alloy was laser welded. The results showed that the aged and welded NiTi-20Zr was mechanically loaded up to 500 MPa at room temperature and 200 °C, there was no fracture, and showed the same behavior as the reference base metal. The aged NiTi-20Zr alloy shows good Laser Weldability, which opens a new door for the use of these materials in drive based applications, and this preliminary study shows a new possibility of using advanced laser bonding methods in these alloys. Li et al. [15] Studied the effects of linear, sinusoidal and cycloid scanning paths on flow dynamics and weld formation during laser welding of 5A06 aluminum alloy. The results show that when the scanning path is cycloid, it is helpful to reduce the formation of porosity due to its large heating area. Long et al. [16] Studied the effect of the increase of ambient pressure on the penetration depth of laser welded molybdenum alloy. The results show that with the increase of ambient pressure, the energy required to form the penetration depth per unit length in the process of laser deep penetration welding increases. When the total energy of laser output is constant, the penetration depth of molybdenum alloy will decrease with the increase of ambient pressure. Because of its many advantages such as low heat input, small deformation, rapid cooling rate and high energy beam concentration, laser welding has good material adaptability. It can not only weld homogeneous materials but also suitable for welding dissimilar materials[17-21]. In production practice, dissimilar welding of different metals can reduce the weight of the structure and reduce the production cost. Moreover, the connection technology of heterogeneous materials plays an important role in the manufacture of complex structures, which has attracted the attention of many researchers[22-26]. Murzin et al. [27] studied the pulsed laser welding of aluminum alloy AK4 and titanium alloy VT5-1, and obtained a uniform structure without voids, which indicates that the welded joint has high enough performance. Wallerstein et al. [28] reviewed the latest progress of laser welding between aluminum alloy and steel, and pointed out that connecting aluminum and steel is a challenging task, mainly because of the formation of brittle intermetallic compounds at the joint interface. Liedl et al. [29] studied the laser welding of 1mm aluminum alloy and steel dissimilar metals. The experimental research shows that by adjusting the laser power and welding speed, the ultra-thin diffusion zone with the minimum intermetallic layer thickness can be obtained, and then the weld without defects such as cracks and pores can be obtained. Wallerstein et al. [30] studied the optical fiber laser welding brazing of 6061-T6 aluminum alloy with a thickness of 1.6 mm and S235-JR structural steel with a thickness of 1.5 mm. The results show that the best AA6061 to S235 dissimilar joints can be obtained by combining AlSi5 welding wire with ALSi12 powder mixed in brazing flux.

Laser welding (especially deep penetration laser welding) process involves many complex physical phenomena of material melting, strong evaporation, plasma, fresnel absorption, multiple reflection etc. As well as the dynamic equilibrium conditions for the stable existence of keyhole and the influence mechanism of various factors on the shape of molten pool. In addition to the complex physical phenomena of single laser welding, the interaction between the two heat sources of laser and arc intensifies the complexity of the laser-arc hybrid welding process. Therefore, in order to ensure the quality of laser welding, give full play to its advantages of high speed and efficiency, and speed up its application process, revealing the mechanism, predicting and controlling the welding process is very difficult and important.

The purpose of this work is the research progress of the monitoring and quality control of laser welding and laser-arc hybrid welding process as well as the intelligent design of welding process based on numerical simulation. The development of laser welding quality control is summarized from two aspects of laser welding quality control and numerical simulation of laser welding process. The laser welding quality control is mainly discussed from two aspects of welding signal monitoring and quality control technology. There are also other problems in this field, which are addressed by such comprehensive application of innovations. At the last, the research hotspots and development trends of laser welding and laser-arc hybrid welding are forecasted.

In summary, compared with the traditional material connection methods, laser welding has the characteristics of high quality, high precision and high efficiency. It can weld various special materials and has strong adaptability. Moreover, laser welding has the advantages of easy automatic control of parameters, good repeatability and reproducibility, and can improve the stability of product quality. Therefore, it has been widely used in many fields. Based on the industry's demand for automatic and intelligent welding, the research on the monitoring, quality control and monitoring-feedback-parameters adjust integrated control of laser welding process has attracted extensive attention. Monitoring and quality control of laser welding process has always been an important content of research and development in the field of laser welding. Various sensors such as inductance, capacitance, acoustic wave, photoelectric and vision are used to realize weld tracking, defect detection and weld forming quality monitoring according to different laser welding processes and requirements through artificial intelligence and computer processing methods, the welding process parameters are adjusted through feedback control, so as to realize high-quality automatic laser welding process. Signal monitoring of welding process is an important means to evaluate welding quality. The selection of detection signal should not only ensure that the detection signal can reflect the welding state, but also meet the requirements of convenient signal acquisition, fast response speed, high reliability of production environment and high signal-to-noise ratio. Signals can reflect the laser welding process and weld quality from different sides. In practical use, people often choose one or several signals to monitor the welding process and quality. At present, scholars are committed to establishing a high-precision and reliable correlation between the optical, electrical and acoustic signals monitored in the laser welding process and the joint quality and weld appearance, and expect to use this correlation to adjust the laser welding process in real time through deep machine learning methods, so as to realize the weld tracking, defect detection and weld forming quality monitoring, and finally realize the automation and intelligence of laser welding process. In recent years, with the rapid development of modern optical technology, information technology and computer technology, the diagnosis of laser welding quality has made great progress in signal pickup, information extraction, defect identification and universality.

Please see:

Page 1: line 36-43.

Page 2: line 44-69.

Page 2: line 78-81.

Page 2: line 84-86.

Page 3: line 105-107.

Page 3: line 110-111.

Page 10: line 370-374.

Page 10: line 377-388.

Page 10: line 392-396.

 

2. Comments:

There are several typo errors in the manuscript. The manuscript is not acceptable in the present form.

Response:

Thanks for your suggestions. We have carefully corrected the language errors and corrected the spelling mistakes in the manuscript. For the convenience of review, it is attached below:

With the rapid development of high power laser, laser welding has been widely used in many fields including manufacturing, metallurgy, automobile, biomedicine, electronics, aerospace etc. Because of its outstanding advantages, such as high energy density, small weld size, easy automation. Combining the two heat sources of laser and arc for welding can achieve excellent results due to the synergistic effect.

Compared with traditional fusion welding, such as arc welding, laser welding has higher welding speed and can produce high penetration, which significantly improve manufacturing productivity and reduce cost [7].

With the increasing requirements of automation and intelligence in modern industry and the increasing dependence of modern manufacturing environment on high-performance monitoring system, the monitoring and quality control of laser welding process has become an important content in the research and development of laser welding field[43-47].

In the process of laser welding, it is difficult to accurately and quantitatively characterize important information, such as laser shielding rate caused by plasma and nano metal particle jet flow, metal evaporation behavior and flow and heat transfer behavior of molten pool, while these information is very important and necessary for controlling of weld formation and quality prediction.

1. Zhou et al. [66] studied the laser welding quality evaluation method based on two-dimensional array ultrasonic probe, which is used to inspect the weld joint, analyzing the effect of fusion state on A-scan echo amplitude, and C-scan image of internal contact surface is established. Testing results show that this method is simple and feasible, while the accuracy error is less than 0.05 mm and hence it could completely meet the requirements of engineering application.
2. Sun et al. [27] used the sensor fusion of infrared, ultraviolet (UV), audible sound (as) and acoustic emission (AE) sensors to evaluate the feasibility of real-time non-destructive weld penetration detection. The use of multiple sensors increased the reliability because the sensors tended to give complementary information.
3. Y. you et al. [93] introduced an innovative method to perform laser welding process monitoring and welding defect diagnosis.

Please see:

Page 1: line 8-12.

Page 1: line 32-34.

Page 1: line 29: replace " has being " with " has ".

Page 2: line 82: replace " phenomenon " with " phenomena ".

Page 2: line 90-94.

Page 3: line 98-102.

Page 4: line 144-148.

Page 4: line 187: replace " nondestructive " with " non-destructive ".

Page 4: line 177-179.

Page 6: line 233: replace " porosity " with " porosities ".

Page 7: line 282-283.

Page 10: line 397: replace " research " with " researches ".

 

We replaced Figure 5 in the manuscript. Modified Fig. 5:

 

Figure 5. Distributions of temperature (a), pressure (b), Mach number (c), density (d), and velocity (e) and (f) of the metallic vapor inside keyhole at 15.006 ms (P=1.5 kW, V=3 m/min). [95]

Please see:

Page 8: line 314.

Round 2

Reviewer 2 Report

Authors have addressed all the comments made by the reviewers. The paper is well read now. In my opinion, the paper is suitable for publication.

Author Response

Thank you very much for your approval.

Reviewer 3 Report

The authors have improved the manuscript to some extent. May be accepted.

Author Response

Thanks for your approval.