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[Laser Institute of America ICALEO? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16–20, 2016)] International Congress on Applications of Lasers & Electro-Optics - Observation of keyhole and melt pool dynamics in laser welding of Al alloy by x-ray phase-contrast method
摘要： Aluminum alloy is a lightweight material frequently used for automotives parts, batteries, airplanes, etc. to reduce greenhouse gas emissions. A highly efficient and stable laser welding method has long been sought for Al alloy because of its poor weldability due to its high heat conductivity and high reflectivity of 1 μm wavelength laser light. Because welding phenomena and defect formation mechanism are still not properly understood due to their complexity, this research aims to investigate the laser welding phenomena of Al alloy. To understand the weld pool and keyhole dynamics during welding, the weld pool was observed with a high-speed camera and X-ray phase-contrast method. The keyhole behavior and solid-liquid interface during laser welding for A1050 can be observed more clearly than in X-ray absorption-contrast method. At a lower welding speed (0.5 m/min), frequent intensive keyhole expansion and high porosity could be observed. Although high porosity could be observed at a higher welding speed (1 m/min), keyhole expansion was barely observed. It is thought that at a low welding speed, intensive evaporation at keyhole bottom leads to unstable keyhole behavior due to high heat input, and as a result, high porosity is formed due to be intake of air into the keyhole. The effect of fan usage was evaluated. In the case without a fan, intensive keyhole expansion was observed frequently. It is supposed that the laser partly interacted with plume, which led to a sudden evaporation due to laser scattering. It was observed that a bubble from the keyhole bottom moved around the keyhole at a high speed, and the bubble was trapped at a solid-liquid interface. Then the bubble grew by absorbing other small bubbles in a melt pool. In all welding conditions, frequent small expansion at the keyhole bottom was observed. Therefore, the porosity formation mechanism is assumed to have a strong relationship with expansion of keyhole bottom, where major porosity was formed.
关键词： X-ray phase-contrast method,porosity formation,Aluminum alloy,laser welding,weld pool dynamics,keyhole dynamics
更新于2025-09-19 17:13:59
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A Comparative Study of Analytical Rosenthal, Finite Element, and Experimental Approaches in Laser Welding of AA5456 Alloy
摘要： The thermal regime and microstructural phenomenon are studied by using ?nite-element (FE) modelling and the analytical Rosenthal equation during laser welding of aluminum alloy 5456 (AA5456) components. A major goal is to determine the merits and demerits of this analytical equation which can be an alternative to FE analysis, and to evaluate the e?ect of imperative assumptions on predicted consequences. Using results from the analytical and numerical approaches in conjunction with experiments, di?erent physical features are compared. In this study, the results obtained from experiments in terms of melt pool shapes are compared with the predicted ones achieved from the numerical and analytical approaches in which the FE model is more accurate than the Rosenthal equation in the estimation of the melt pool dimensions. Furthermore, as to the partially melted zones, the estimations achieved from the numerical modeling are more genuine than ones from the analytical equation with regards to the experimental results. At high energy density, near keyhole welding mode, the reported results show that experimental melt widths are supposed to be narrower than the fusion widths estimated by the analytical solution. The primary explanation could be the in?uence of thermal losses that occurred during convection and radiation, which are neglected in the Rosenthal equation. Additionally, the primary dendrite arm spacing (PDAS) estimated with the numerical modeling and the analytical Rosenthal solution is comparable with the experimental results obtained.
关键词： thermal regime,microstructure,analytical Rosenthal equation,AA5456,numerical ?nite-element modeling,laser welding
更新于2025-09-19 17:13:59
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Microstructure and Performance of Laser-Welded GH3128/Mo Dissimilar Joints
摘要： Laser beam offset welding of GH3128 and molybdenum (Mo) dissimilar joints was studied with an emphasis on the role of laser beam offset (LBO). It was found that the change of LBO significantly affected the properties of GH3128/Mo dissimilar joints. When the LBO increased from 2 0.1 mm (i.e., laser spot was centered on Mo surface) to + 0.3 mm (i.e., laser spot was centered on GH3128 surface) at the step size of 0.1 mm, the amount of melted Mo gradually declined; the welding mode gradually changed from fusion welding to welding–brazing; macro-segregation of Mo-rich phases in fusion zone (FZ) gradually disappeared; the average microhardness of FZ significantly decreased, and therefore, microhardness distribution in FZ became more uniformly; the quantity of grain boundary liquation observed in heat-affected zone (HAZ) of GH3128 side gradually decreased; and recrystallization of grains in the HAZ of Mo was gradually suppressed. Joints with the optimal LBO of + 0.2 mm reached the maximum tensile strength of about 560 MPa. When using a small LBO, i.e., LBOs were + 0.1, 0, 2 0.1 mm, the HAZ of Mo was greatly softened and embrittled. When adopting a large LBO, i.e., LBO was + 0.3 mm, the melt near Mo-FZ interface might fail to moisten Mo surface and spread on Mo surface, thus resulting in the reduction in tensile strength.
关键词： laser welding,GH3128 and Mo dissimilar joint,grain boundary segregation,macro-segregation,grain boundary liquation
更新于2025-09-19 17:13:59
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Laser Welding of Transmitting High-Performance Engineering Thermoplastics
摘要： Laser processing is a rapidly growing key technology driven by several advantages such as cost and performance. Laser welding presents numerous advantages in comparison with other welding technologies, providing high reliability and cost-effective solutions. Significant interest in this technology, combined with the increasing demand for high-strength lightweight structures has led to an increasing interest in joining high-performance engineering thermoplastics by employing laser technologies. Laser transmission welding is the base method usually employed to successfully join two polymers, a transmitting one through which the laser penetrates, and another one responsible for absorbing the laser radiation, resulting in heat and melting of the two components. In this work, the weldability of solely transmitting high-performance engineering thermoplastic is analyzed. ERTALON 6 SA, in its white version, is welded by a pulsed Nd:YAG laser. Tensile tests were performed in order to evaluate the quality of each joint by assessing its strength. A numerical model of the joint is also developed to support the theoretical approaches employed to justify the experimental observations.
关键词： pulsed Nd:YAG laser welding,numerical model,polyamide 6,ERTALON 6 SA,high-performance engineering thermoplastic,mechanical testing
更新于2025-09-19 17:13:59
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A spectroscopic method based on support vector machine and artificial neural network for fiber laser welding defects detection and classification
摘要： Diverse welding processes have been utilized in manufacturing industry for years. But up to date, welding quality still cannot be guaranteed, due to the lack of an efficient and on-line welding defects monitoring method, and this leads to increased manufacturing costs. In this paper, a method based on feature extraction and machine learning algorithm for on-line quality monitoring and defects classification was presented. Plasma radiation was captured by an optical fiber probe, and delivered by an optical fiber to the spectrometer. The captured spectral signal was processed by selecting sensitive emission lines and extracting features of spectral data’s evolution, which realized spectral data compression with low computational cost. After selecting the proper training data set, the designed ANN and SVM allows automatic detection and classification of welding defects. The validity of proposed method was successfully approved by test data set in welding experiments. Welding experiments on galvanized steel sheets showed the corresponding relationship between the output of classifiers and welding defects. Finally, the two classifiers were compared. Experiments indicated the performance of ANN is slightly better than that of SVM, while both of them have its own advantages.
关键词： Laser welding,Support vector machine,Plasma spectral analysis,Artificial neural network
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Novel Foil Interconnects for Back-Contact Silicon Solar Cells
摘要： Large area back-contact solar cells enable module costs almost as low as those of PERCs but with higher efficiency. Traditional tabbing and stringing interconnects are problematic for back-contact cells, however, as placing all the tabs on one side of the wafer causes bowing due to CTE mismatch. Back-contact cells can be effectively encapsulated using Cu conductive back-sheets (CBS) with electrically conductive adhesive (ECA) interconnects but the cost is higher than for ribbon tabbing. In this paper we present a method for replacing the Cu CBS with a cheaper Al version and the ECA with several cheaper and potentially more robust methods for connecting the foil to the cell.
关键词： laser welding,conductive adhesives,reliability,Back-contact modules,aluminum interconnects,conductive back-sheets
更新于2025-09-19 17:13:59
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Analysis of the Application of Laser Welding Technology on Maintenance of the Underwater Components of Nuclear Power Station
摘要： This paper put its eyes on the PWR’s underwater components which have the risk of early failure after long-term inservice because the material tends to deteriorate and embrittle due to irradiation and other factors, and should be maintenanced. In this paper, we contrastively analyse two main technologies used as underwater welding, named underwater wet laser welding and underwater local dry laser welding. It is difficult to obtain high quality weld seam by underwater wet laser welding for the reason of some disadvantages on laser beam underwater, such as water attenuation, bubble reflection and so on. On constract, underwater local dry laser-welding can obtain high quality weld-joints, and becomes the current hotshot. But, there are still some problems to be settled, such as the way to obtain stable underwater chamber and the protection of back of full penetration weld. Analysis of the retrieva of underwater laser welding on Web Science, we can find that underwater laser welding technology has step out laboratory to engineering application and the in-depth theoretical research is also actively carried out on the fields of picosecond, femtosecond laser.
关键词： local dry laser welding,PWR,underwater laser welding,maintenance,wet laser welding
更新于2025-09-16 10:30:52
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A Vision-Based Robotic Laser Welding System for Insulated Mugs with Fuzzy Seam Tracking Control
摘要： The symmetrical insulated mug is composed of two layers. The two ends of the two layers form the mouth and bottom seams of the insulated mug. The weld quality of the two seams is very important to keep the vacuum degree of the air between the two layers, which is vital for the heat-insulating property of the mug. Due to the narrow seam, laser welding is used. Since laser welding has high demand on the relative position of the seam and the laser torch, a vision-based seam tracking system is designed. Before welding is started, the vision sensor scans the seam and feature sample points are collected. A reconstruction algorithm is proposed to form the image containing the seam. Then, a least square fitting (LSF) method combined with random sample consensus (RANSAC) method is proposed to detect the smooth seam from the sample points. In the welding process, a seam tracking system with fuzzy logic control method is presented to keep the torch precisely on the seam. Finally, full experiments are conducted in the welding factory of the insulated mugs to verify the effectiveness of the proposed system and method.
关键词： fuzzy control,insulated mug,vision sensor,seam tracking,welding robot,RANSAC,laser welding
更新于2025-09-16 10:30:52
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Optimization of Process Parameters Using Surface Response Methodology for Laser Welding of Titanium Alloy
摘要： Laser beam welding input conditions are greatly influence the quality of the welded joints and they have significant role on the controlling of their strength and metallurgical properties. The metallurgical properties and weld bead geometry and mechanical properties of the joints determine the quality of the joints. In this study, the fusion zone width, penetration, width of the heat affected zone and strength of the titanium alloy welds were investigated using laser welding process. The surface response methodology design is carried out for the experimental design by the development of regression equations. Analysis of variance (ANOVA) was used to check the validity of the model. In order to identify the significant parameters, student’s test is conducted. The obtained results from response surface methodology were compared with the experimental results and validated.
关键词： Optimization,Fusion zone,Mechanical properties,Laser welding,Welding parameters,Titanium alloy,Bead geometry
更新于2025-09-16 10:30:52
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Parameter Optimization for Laser Welding of High Strength Dissimilar Materials
摘要： Dissimilar joining of high strength tensile steels are joined using laser beam welding. The selection of the welding conditions for joining of dissimilar materials is highly required to satisfy the quality of the joints. In the present investigation, optimization technique were used to determine the optimal welding conditions. Initially welding conditions were optimized for weld geometry and formation of different zones in the weldment. The metallurgical and mechanical properties of the welds are greatly influenced by the geometry of the welds. The surface response methodology design is carried out for the experimental design by the development of regression equations. Analysis of variance (ANOVA) was used to check the validity of the model. The output of the welding conditions were compared with the predicted values to identify the accuracy of the model. The obtained results from response surface methodology were compared with the experimental results and validated.
关键词： Optimization,Fusion zone,Mechanical properties,Laser welding,Welding parameters,High strength steel,Bead geometry
更新于2025-09-16 10:30:52