Xiangmeng Meng, Stephen Nugraha Putra, Marcel Bachmann, Michael Rethmeier
The spatial laser energy absorption inside the keyhole is decisive for the dynamic molten pool behaviors and the resultant weld properties in high-power laser beam welding (LBW). In this paper, a numerical simulation of the LBW process, considering the 3D transient heat transfer, fluid flow, and keyhole dynamics, is implemented, in which the free surface is tracked by the volume-of-fluid algorithm. The underlying laser-material interactions, i.e., the multiple reflections and Fresnel absorption, are considered by an advanced ray-tracing method based on a localized level-set strategy and a temperature-dependent absorption coefficient. The laser energy absorption is analyzed from a time-averaged point of view for a better statistical representation. It is found for the first time that a significant drop in the time-averaged laser energy absorption occurs at the focus position of the laser beam and that the rest of the keyhole region has relatively homogeneous absorbed energy. This unique absorption pattern may lead to a certain keyhole instability and have a strong correlation with the detrimental bulging and narrowing phenomena in the molten pool. The influence of different focus positions of the laser beam on the keyhole dynamics and molten pool profile is also analyzed. The obtained numerical results are compared with experimental measurements to ensure the validity of the proposed model.
{"title":"Influence of the spatial laser energy absorption on the molten pool dynamics in high-power laser beam welding","authors":"Xiangmeng Meng, Stephen Nugraha Putra, Marcel Bachmann, Michael Rethmeier","doi":"10.2351/7.0001078","DOIUrl":"https://doi.org/10.2351/7.0001078","url":null,"abstract":"The spatial laser energy absorption inside the keyhole is decisive for the dynamic molten pool behaviors and the resultant weld properties in high-power laser beam welding (LBW). In this paper, a numerical simulation of the LBW process, considering the 3D transient heat transfer, fluid flow, and keyhole dynamics, is implemented, in which the free surface is tracked by the volume-of-fluid algorithm. The underlying laser-material interactions, i.e., the multiple reflections and Fresnel absorption, are considered by an advanced ray-tracing method based on a localized level-set strategy and a temperature-dependent absorption coefficient. The laser energy absorption is analyzed from a time-averaged point of view for a better statistical representation. It is found for the first time that a significant drop in the time-averaged laser energy absorption occurs at the focus position of the laser beam and that the rest of the keyhole region has relatively homogeneous absorbed energy. This unique absorption pattern may lead to a certain keyhole instability and have a strong correlation with the detrimental bulging and narrowing phenomena in the molten pool. The influence of different focus positions of the laser beam on the keyhole dynamics and molten pool profile is also analyzed. The obtained numerical results are compared with experimental measurements to ensure the validity of the proposed model.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135718698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jeonghun Shin, Sanghoon Kang, Cheolhee Kim, Sukjoon Hong, Minjung Kang
Solidification cracking, one of the most critical weld defects in laser welding of Al 6000 alloys, occurs at the final stage of solidification owing to shrinkage of the weld metal and deteriorates the joint strength and integrity. The filler metal can control the chemical composition of the weld metal, which mitigates solidification cracking. However, the chemical composition is difficult to control in autogenous laser welding. Temporal and spatial laser beam modulations have been introduced to control solidification cracking in autogenous laser welding because weld morphology is one of the factors that influences the initiation and propagation of solidification cracking. Solidification cracks generate thermal discontinuities and visual flaws on the bead surface. In this study, a high-speed infrared camera and a coaxial charge-coupled device camera with an auxiliary illumination laser (808 nm) were employed to identify solidification cracking during laser welding. Deep learning models, developed using two sensor images of a solidified bead, provided location-wise crack formation information. The multisensor-based convolutional neural network models achieved an impressive accuracy of 99.31% in predicting the crack locations. Thus, applying deep learning models expands the capability of predicting solidification cracking, including previously undetectable internal cracks.
{"title":"Identification of solidification cracking using multiple sensors and deep learning in laser overlap welded Al 6000 alloy","authors":"Jeonghun Shin, Sanghoon Kang, Cheolhee Kim, Sukjoon Hong, Minjung Kang","doi":"10.2351/7.0001112","DOIUrl":"https://doi.org/10.2351/7.0001112","url":null,"abstract":"Solidification cracking, one of the most critical weld defects in laser welding of Al 6000 alloys, occurs at the final stage of solidification owing to shrinkage of the weld metal and deteriorates the joint strength and integrity. The filler metal can control the chemical composition of the weld metal, which mitigates solidification cracking. However, the chemical composition is difficult to control in autogenous laser welding. Temporal and spatial laser beam modulations have been introduced to control solidification cracking in autogenous laser welding because weld morphology is one of the factors that influences the initiation and propagation of solidification cracking. Solidification cracks generate thermal discontinuities and visual flaws on the bead surface. In this study, a high-speed infrared camera and a coaxial charge-coupled device camera with an auxiliary illumination laser (808 nm) were employed to identify solidification cracking during laser welding. Deep learning models, developed using two sensor images of a solidified bead, provided location-wise crack formation information. The multisensor-based convolutional neural network models achieved an impressive accuracy of 99.31% in predicting the crack locations. Thus, applying deep learning models expands the capability of predicting solidification cracking, including previously undetectable internal cracks.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135858982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aluminum alloys are one of the most important materials in modern industries; however, they are susceptible to oxidation during the welding process. In an automated welding process, the online monitoring and prediction of weld bead oxidation degree are particularly important. This study proposes a novel method to real-timely predict the oxidation degree of the aluminum alloy during the laser welding process based on the laser plasma spectral signals. First, the characteristics of laser plasma spectral signals are analyzed under various oxidation degree conditions. And then, a random forest regression model is built to extract the principal characteristic wavelengths of spectral signals and predict the oxidation degree of weld bead based on these spectral signals. Finally, through experiments, the prediction validity of the proposed method is verified.
{"title":"Aluminum alloy oxidation prediction during laser welding process based on random forest regression analysis of spectral signals","authors":"Lixue Zeng, Yanfeng Gao, Genliang Xiong, Hua Zhang, Hao Pan, Zhiwu Long, Donglin Tao","doi":"10.2351/7.0001167","DOIUrl":"https://doi.org/10.2351/7.0001167","url":null,"abstract":"Aluminum alloys are one of the most important materials in modern industries; however, they are susceptible to oxidation during the welding process. In an automated welding process, the online monitoring and prediction of weld bead oxidation degree are particularly important. This study proposes a novel method to real-timely predict the oxidation degree of the aluminum alloy during the laser welding process based on the laser plasma spectral signals. First, the characteristics of laser plasma spectral signals are analyzed under various oxidation degree conditions. And then, a random forest regression model is built to extract the principal characteristic wavelengths of spectral signals and predict the oxidation degree of weld bead based on these spectral signals. Finally, through experiments, the prediction validity of the proposed method is verified.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135858980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In laser cutting, the fundamental role of the gas flow for melt removal and kerf formation is generally accepted. Beyond this vague understanding, however, the underlying physical mechanisms are not yet fully understood. In particular, detailed data concerning the momentum and heat transfer between the gas and melt have seldom been reported. This study addresses the local interactions between the cutting gas and kerf surface (melt film surface) in a fundamental way based on a combined experimental, theoretical, and numerical approach. Typical solid-state laser cut edges are analyzed considering the characteristic surface structures and the basic influences of the gas flow on the global and local melt movement. Here, apparent structures in the micrometer range indicate the effect of vortical gas structures close to the wall. Theoretical investigation of the gas boundary layer is conducted by semiempirical equations and the transfer of basic results from the boundary layer theory. It is shown that the boundary layer is in transition between the laminar and turbulent flow, and local flow separations and shock-boundary layer interactions primarily induce spatially periodic and quasistationary instability modes. An improved numerical model of the cutting gas flow confirms the theoretical results and exhibits good agreement with experimental cut edges, reproducing relevant instability modes and quantifying the local momentum and heat transfer distributions between the gas and melt. With the knowledge gained about the underlying physical mechanisms, promising approaches for improvements of the fusion cutting performance are proposed.
{"title":"Laser fusion cutting: The missing link between gas dynamics and cut edge topography","authors":"Madlen Borkmann, Achim Mahrle, Andreas Wetzig","doi":"10.2351/7.0001103","DOIUrl":"https://doi.org/10.2351/7.0001103","url":null,"abstract":"In laser cutting, the fundamental role of the gas flow for melt removal and kerf formation is generally accepted. Beyond this vague understanding, however, the underlying physical mechanisms are not yet fully understood. In particular, detailed data concerning the momentum and heat transfer between the gas and melt have seldom been reported. This study addresses the local interactions between the cutting gas and kerf surface (melt film surface) in a fundamental way based on a combined experimental, theoretical, and numerical approach. Typical solid-state laser cut edges are analyzed considering the characteristic surface structures and the basic influences of the gas flow on the global and local melt movement. Here, apparent structures in the micrometer range indicate the effect of vortical gas structures close to the wall. Theoretical investigation of the gas boundary layer is conducted by semiempirical equations and the transfer of basic results from the boundary layer theory. It is shown that the boundary layer is in transition between the laminar and turbulent flow, and local flow separations and shock-boundary layer interactions primarily induce spatially periodic and quasistationary instability modes. An improved numerical model of the cutting gas flow confirms the theoretical results and exhibits good agreement with experimental cut edges, reproducing relevant instability modes and quantifying the local momentum and heat transfer distributions between the gas and melt. With the knowledge gained about the underlying physical mechanisms, promising approaches for improvements of the fusion cutting performance are proposed.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136059947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper proposes a scheme for simultaneous classical communication and continuous variable quantum key distribution with a true local oscillator. In this scheme, the emitter’s laser, after binary phase-shift keying (BPSK) modulation, is multiplexed in polarization with the quantum signal and sent to the receiver. After BPSK demodulation and correction, this signal is used for local oscillator regeneration by an optical injection phase-locked loop method. Comparing the effective noise sources in this scheme with typical local local oscillator schemes revealed that continuous variable quantum key distribution (CV-QKD) with a true local oscillator based on the optical injection phase-locked loop encounters lower levels of noise in comparison to the pre-existing genuine local oscillator CV-QKDs.
{"title":"Simultaneous BPSK classical communication and continuous variable quantum key distribution with a locally local oscillator regenerated by optical injection phase locked loop","authors":"Zeinab Sadat Khaksar, Alireza Bahrampour","doi":"10.2351/7.0001068","DOIUrl":"https://doi.org/10.2351/7.0001068","url":null,"abstract":"This paper proposes a scheme for simultaneous classical communication and continuous variable quantum key distribution with a true local oscillator. In this scheme, the emitter’s laser, after binary phase-shift keying (BPSK) modulation, is multiplexed in polarization with the quantum signal and sent to the receiver. After BPSK demodulation and correction, this signal is used for local oscillator regeneration by an optical injection phase-locked loop method. Comparing the effective noise sources in this scheme with typical local local oscillator schemes revealed that continuous variable quantum key distribution (CV-QKD) with a true local oscillator based on the optical injection phase-locked loop encounters lower levels of noise in comparison to the pre-existing genuine local oscillator CV-QKDs.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136059789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thomas Kaster, Jan-Hendrik Rissom, Leon Gorissen, Philipp Walderich, Jan-Niklas Schneider, Christian Hinke
Laser-based production systems have become more and more popular in recent years due to their potential to achieve high precision and accuracy in a wide range of different applications. However, the kinematic systems used for laser materials processing (LMP) are often inherited from other production technologies such as milling. The use of mobile robots (MRs) equipped with laser processing optics could disprove the current paradigm of adapted kinematic systems: scaling the size of the material processing system with the size of the components being processed and, thus, the resources used. The trend of autonomous MRs replacing classical kinematic systems in the field of material handling in industrial applications has been evident for years due to their higher flexibility, efficiency, and lower operating costs. In this paper, the prototype of a corresponding MR system is presented. In addition, the general design of the MR is presented. One challenge is the accuracy of an MR; for a common LMP such as laser cutting, the MR must be able to follow a predefined trajectory as accurately as possible. For this purpose, two different measurement systems are presented and compared. To demonstrate the potential of the mobile robot, an exemplary LMP process is also performed and evaluated. Finally, possibilities for improvement or further development, such as integration of scanner optics or the use of several autonomous MRs to increase productivity, are shown.
{"title":"Approach toward the application of mobile robots in laser materials processing","authors":"Thomas Kaster, Jan-Hendrik Rissom, Leon Gorissen, Philipp Walderich, Jan-Niklas Schneider, Christian Hinke","doi":"10.2351/7.0001127","DOIUrl":"https://doi.org/10.2351/7.0001127","url":null,"abstract":"Laser-based production systems have become more and more popular in recent years due to their potential to achieve high precision and accuracy in a wide range of different applications. However, the kinematic systems used for laser materials processing (LMP) are often inherited from other production technologies such as milling. The use of mobile robots (MRs) equipped with laser processing optics could disprove the current paradigm of adapted kinematic systems: scaling the size of the material processing system with the size of the components being processed and, thus, the resources used. The trend of autonomous MRs replacing classical kinematic systems in the field of material handling in industrial applications has been evident for years due to their higher flexibility, efficiency, and lower operating costs. In this paper, the prototype of a corresponding MR system is presented. In addition, the general design of the MR is presented. One challenge is the accuracy of an MR; for a common LMP such as laser cutting, the MR must be able to follow a predefined trajectory as accurately as possible. For this purpose, two different measurement systems are presented and compared. To demonstrate the potential of the mobile robot, an exemplary LMP process is also performed and evaluated. Finally, possibilities for improvement or further development, such as integration of scanner optics or the use of several autonomous MRs to increase productivity, are shown.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"172 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136308677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The weld morphology of aluminum alloy oscillating laser welding has an important influence on the quality of welded joints. To understand the formation process of the weld morphology, the three-dimensional numerical simulation model and energy distribution model for circular shaped oscillating laser welding of 6061 aluminum alloy are developed in this paper to analyze the characteristics of weld morphology and the effect of the energy distribution on the weld width. The cross section of the weld and the energy distribution on the processing surface are obtained under the conditions of different oscillation frequencies. It is found that the left width of the weld is larger than the right width of the weld and the energy density on the left side of the weld is more concentrated than that on the right side of the weld. With the oscillation frequency increases, the weld width and peak of energy density decrease. Furthermore, the formation mechanism of the difference in weld width is revealed based on the energy distribution law of the oscillating laser welding process, which is of great significance for improving the quality of aluminum alloy oscillating laser welding.
{"title":"Numerical analysis of the effect of energy distribution on weld width during oscillating laser welding of aluminum alloy","authors":"Yuewei Ai, Yachao Yan, Shibo Han","doi":"10.2351/7.0001131","DOIUrl":"https://doi.org/10.2351/7.0001131","url":null,"abstract":"The weld morphology of aluminum alloy oscillating laser welding has an important influence on the quality of welded joints. To understand the formation process of the weld morphology, the three-dimensional numerical simulation model and energy distribution model for circular shaped oscillating laser welding of 6061 aluminum alloy are developed in this paper to analyze the characteristics of weld morphology and the effect of the energy distribution on the weld width. The cross section of the weld and the energy distribution on the processing surface are obtained under the conditions of different oscillation frequencies. It is found that the left width of the weld is larger than the right width of the weld and the energy density on the left side of the weld is more concentrated than that on the right side of the weld. With the oscillation frequency increases, the weld width and peak of energy density decrease. Furthermore, the formation mechanism of the difference in weld width is revealed based on the energy distribution law of the oscillating laser welding process, which is of great significance for improving the quality of aluminum alloy oscillating laser welding.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135014434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aniruddha Kumar, Suman Neogy, N. Keskar, Y. Pushpalatha Devi, D. B. Sathe, R. B. Bhatt
In this work, we report full penetration welding of 1.6 mm thick AISI 304L stainless steel sheets in a butt joint configuration using a pulsed nanosecond fiber laser of an average power of 200 W. The welding was carried out by a focused laser beam oscillating in a circular path. The effects of beam oscillation parameters, e.g., amplitude, frequency, and weld speed, on weld morphology and microstructure were studied. Electron back scattered diffraction was used to characterize the weld microstructure and to map the distribution of austenite and ferrite phases in the weld. The solidification mode of the weld was found to change from the equilibrium FA (Ferrite-Austenite) to AF (Austenite-Ferrite) to A (Austenite) on an increase in the cooling rate with a concomitant drop in the fraction of δ-ferrite. The welds were found to be without any cracks with the sporadic presence of porosities. The welds were found to be mechanically strong.
{"title":"Studies on welding of thin stainless steel sheets with pulsed nanosecond fiber laser in butt joint configuration","authors":"Aniruddha Kumar, Suman Neogy, N. Keskar, Y. Pushpalatha Devi, D. B. Sathe, R. B. Bhatt","doi":"10.2351/7.0001082","DOIUrl":"https://doi.org/10.2351/7.0001082","url":null,"abstract":"In this work, we report full penetration welding of 1.6 mm thick AISI 304L stainless steel sheets in a butt joint configuration using a pulsed nanosecond fiber laser of an average power of 200 W. The welding was carried out by a focused laser beam oscillating in a circular path. The effects of beam oscillation parameters, e.g., amplitude, frequency, and weld speed, on weld morphology and microstructure were studied. Electron back scattered diffraction was used to characterize the weld microstructure and to map the distribution of austenite and ferrite phases in the weld. The solidification mode of the weld was found to change from the equilibrium FA (Ferrite-Austenite) to AF (Austenite-Ferrite) to A (Austenite) on an increase in the cooling rate with a concomitant drop in the fraction of δ-ferrite. The welds were found to be without any cracks with the sporadic presence of porosities. The welds were found to be mechanically strong.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135063451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pure copper parts are commonly used in many industrial products because of their low thermal resistance and high electrical conductivity. However, connecting high-quality and high-efficiency copper materials remains a challenge. This is because pure copper has low absorption of near-infrared light, making it difficult to weld stably with a near-infrared laser. Visible light lasers should realize high-efficiency laser welding of pure copper. However, there are few reports comparing the laser wavelength dependence of welding efficiency for pure copper. In this study, bead-on-plate welding was performed on pure copper plates of 2 mm thickness using a 1.5 kW blue diode laser (445 nm), a 16 kW IR disk laser (1030 nm), and a 3 kW green disk laser (515 nm). Bead-on-plate welding of pure copper was performed in the thermal conduction mode or the keyhole mode by varying the laser spot diameter and power, and the amount of melting was measured from cross-sectional observations. As a result, compared to the IR disk laser, blue and green lasers showed higher melting efficiency in both the thermal conduction and keyhole modes, and the melting behavior was more stable. In thermal conduction mode welding, the melting efficiency was 0.2% with the IR disk laser and 0.7% with the blue diode laser. In keyhole mode welding, the melting efficiency with the blue diode laser or green disk laser was about 7%, which is equivalent to that with the IR disk laser with 2.5 times the output power.
{"title":"Comparison of melting efficiency between blue, green, and IR lasers in pure copper welding","authors":"Keisuke Takenaka, Yuji Sato, Shumpei Fujio, Masahiro Tsukamoto","doi":"10.2351/7.0001177","DOIUrl":"https://doi.org/10.2351/7.0001177","url":null,"abstract":"Pure copper parts are commonly used in many industrial products because of their low thermal resistance and high electrical conductivity. However, connecting high-quality and high-efficiency copper materials remains a challenge. This is because pure copper has low absorption of near-infrared light, making it difficult to weld stably with a near-infrared laser. Visible light lasers should realize high-efficiency laser welding of pure copper. However, there are few reports comparing the laser wavelength dependence of welding efficiency for pure copper. In this study, bead-on-plate welding was performed on pure copper plates of 2 mm thickness using a 1.5 kW blue diode laser (445 nm), a 16 kW IR disk laser (1030 nm), and a 3 kW green disk laser (515 nm). Bead-on-plate welding of pure copper was performed in the thermal conduction mode or the keyhole mode by varying the laser spot diameter and power, and the amount of melting was measured from cross-sectional observations. As a result, compared to the IR disk laser, blue and green lasers showed higher melting efficiency in both the thermal conduction and keyhole modes, and the melting behavior was more stable. In thermal conduction mode welding, the melting efficiency was 0.2% with the IR disk laser and 0.7% with the blue diode laser. In keyhole mode welding, the melting efficiency with the blue diode laser or green disk laser was about 7%, which is equivalent to that with the IR disk laser with 2.5 times the output power.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135153195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rabi Lahdo, Sarah Nothdurft, Oliver Seffer, Jörg Hermsdorf, Stefan Kaierle
Thick dissimilar joints of steel and aluminum are still of high interest for shipbuilding in order to reduce the weight and the center of gravity of the ship. Thereby, a reduction of the CO2 emissions as a result of lower fuel consumption and a higher ship stability are achievable. The steel and aluminum ship parts are joined with the aid of an explosive-welded adapter, whose manufacturing is complex, time-consuming, and expensive. Furthermore, the adapter must be oversized to meet strength requirements. Therefore, the shipbuilding industry demands a better alternative. In this study, laser beam welding processes are developed for joining steel S355 J2 (t = 5 mm) with aluminum alloy AA6082-T651 (t = 10 mm) in a lap configuration using a laser beam source with a maximum output power of PL = 6 kW. Laser beam welding of this dissimilar material combination brings certain challenges, such as the formation of brittle microstructures in the weld metal depending on the aluminum content. To improve the microstructure and the associated mechanical properties of the weld seam, a filler material in the form of iron welding powder is used. The welding powder is provided in a groove in the aluminum bottom sheet. In this way, an iron-rich microstructure results, which leads to an increase in the weld seam quality, as shown in metallographic analysis and tensile tests. For example, the cross tension force can be increased by 100%.
{"title":"Investigations on improving the properties of laser beam welded thick dissimilar joints of steel and aluminum by using filler material","authors":"Rabi Lahdo, Sarah Nothdurft, Oliver Seffer, Jörg Hermsdorf, Stefan Kaierle","doi":"10.2351/7.0001172","DOIUrl":"https://doi.org/10.2351/7.0001172","url":null,"abstract":"Thick dissimilar joints of steel and aluminum are still of high interest for shipbuilding in order to reduce the weight and the center of gravity of the ship. Thereby, a reduction of the CO2 emissions as a result of lower fuel consumption and a higher ship stability are achievable. The steel and aluminum ship parts are joined with the aid of an explosive-welded adapter, whose manufacturing is complex, time-consuming, and expensive. Furthermore, the adapter must be oversized to meet strength requirements. Therefore, the shipbuilding industry demands a better alternative. In this study, laser beam welding processes are developed for joining steel S355 J2 (t = 5 mm) with aluminum alloy AA6082-T651 (t = 10 mm) in a lap configuration using a laser beam source with a maximum output power of PL = 6 kW. Laser beam welding of this dissimilar material combination brings certain challenges, such as the formation of brittle microstructures in the weld metal depending on the aluminum content. To improve the microstructure and the associated mechanical properties of the weld seam, a filler material in the form of iron welding powder is used. The welding powder is provided in a groove in the aluminum bottom sheet. In this way, an iron-rich microstructure results, which leads to an increase in the weld seam quality, as shown in metallographic analysis and tensile tests. For example, the cross tension force can be increased by 100%.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"205 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135396357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：