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Observation of the keyhole behavior, spatter, and keyhole-induced bubble formation in laser welding of a steel/glass sandwich
摘要： Laser welding of a steel/glass sandwich is carried out to clearly observe the keyhole behavior, spatter, and keyhole-induced bubble formation. The formation mechanisms of the spatter and keyhole-induced bubble are analyzed, and the relationship between the spatter and keyhole-induced bubble formation is also discussed. There are five necessary steps for the spatter formation around the keyhole: the formation of the bulges at the keyhole wall, the decrease of the keyhole entrance size caused by the upward flow of the bulges, the formation of the melt column around the keyhole, the increasing of the melt column size, and the spatter formation around the keyhole. The decrease of the keyhole entrance size contributes to the increase of the vapor shear stress, and thus accelerates the spatter formation. The large deformation of the top rear keyhole wall decreases the vertical component of the vapor shear stress, so few spatters are formed at the rear keyhole wall. Two types of the keyhole-induced bubble are formed by the whole keyhole collapse between the front keyhole wall and rear keyhole wall, and the rear keyhole wall collapse. The influence of the keyhole-induced bubble formation on the spatter formation is not obvious.
关键词： Spatter,Keyhole behavior,Keyhole-induced bubble,Laser welding
更新于2025-11-28 14:24:20
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Analysis of back-weld spatters in laser welding of CP-Ti
摘要： The laser welding of commercial grades of pure titanium plate TA2 with 0.5 mm was taken, and the back area of the molten pool was photographed by high-speed camera. Also, the reasons of back spatters were studied. Spatters on the back side of the plate have three main types: continuous spatters, periodic spatters and no spatters. All continuous back spatters are accompanied by the appearance of keyhole, and the keyhole can be observed at the moment when periodic spatters appear. The downward shear stress applied by the downward jet of metal vapor from the keyhole is an important reason for backside spatter. Increased laser power or welding speed will increase shear force, eventually contributing to more spatters. When the defocused distance is increased to 30 mm, the keyhole is completely obscured on the back side, so there is no spatter at this time.
关键词： Backside spatter,Laser welding,Keyhole behavior,Commercial pure titanium
更新于2025-09-23 15:19:57
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Spatter feature analysis in laser welding based on motion tracking method
摘要： In this work, the spatter motion features in laser welding process have been investigated using image motion tracking method. According to the acquired results, both the distribution and motion features of extracted spatters exhibit two characteristic ejection directions, forward and backward along the welding direction. Along with the welding speed increase, the spatter motion trend of being ejected backward along the welding direction enhances. The spatter motion features are discussed according to the pressure induced by the vapor plume. The joint force synthesised from the impact force (induced by hydrodynamic pressure) and the shear force (induced by the viscosity between vapor plume and molten metal) have been found driving the molten metal to move upward. The maximum joint force is performed when the vapor plume is ejected in two certain inclinations, respectively -40 ° forward and 50 ° backward to the vertical axis. In addition, the molten metal behind the keyhole is easiest to be pushed away from the weldpool and form the spatters compared to rest of the directions.
关键词： laser welding,spatter formation,motion track method
更新于2025-09-23 15:19:57
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Influence of Magnesium on Spatter Behavior in Laser Deep Penetration Welding of Aluminum Alloys
摘要： The quality of welds, as well as the necessity of post-processing, is challenged by spatter generation during the laser keyhole welding process. In this study, the influence of the magnesium content on spatter behavior is studied for three aluminum alloys (Al99.5, AlMg3, and AlMg5). A synchronized dual high-speed camera system is used to observe the spatter behavior and to reconstruct 3D spatter trajectories as well as determine the characteristics of spatter velocity, flight path angle, and approximate spatter size. The mean spatter velocities and flight path angles of the welding experiments with the three alloys were in welding direction between 4.1 m/s and 4.6 m/s and 44.8°, respectively. Furthermore, the AlMg alloys show excessive spatter behavior with spray events of more than 50 spatters at a time, and less frequently spatter explosions. Spatter spray events show a character similar to spatter explosions. Volumetric evaporation is proposed as effecting these events. In contrast, and resulting from a different mechanism, pure aluminum (Al99.5) shows group ejection events with at least 10 spatters at a time. In this study, there are no correlations between spatter velocities and flight path angles, nor between velocities and approximate spatter sizes.
关键词： high-speed imaging,keyhole welding,aluminum alloy,welding,laser welding,spatter
更新于2025-09-19 17:13:59
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Material Reuse in Laser Powder Bed Fusion: Side Effects of the Lasera??Metal Powder Interaction
摘要： Metal additive manufacturing is changing the way in which engineers and designers model the production of three-dimensional (3D) objects, with rapid growth seen in recent years. Laser powder bed fusion (LPBF) is the most used metal additive manufacturing technique, and it is based on the efficient interaction between a high-energy laser and a metal powder feedstock. To make LPBF more cost-efficient and environmentally friendly, it is of paramount importance to recycle (reuse) the unfused powder from a build job. However, since the laser–powder interaction involves complex physics phenomena and generates by-products which might affect the integrity of the feedstock and the final build part, a better understanding of the overall process should be attained. The present review paper is focused on the clarification of the interaction between laser and metal powder, with a strong focus on its side effects.
关键词： metal powder,condensate,spatter,LPBF,laser radiation
更新于2025-09-19 17:13:59
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Spatter formation during laser beam melting of AlSi10Mg and effects on powder quality
摘要： Cost and resource efficiency of Laser Beam Melting (LBM) highly depend on powder recycling procedures. Non-solidified powder can be sieved and reused in subsequent build cycles. However, due to quality concerns, powder recycling is not commonly practiced. One effect, which can impair the powder quality, lies in the formation and insertion of spatter particles during the melting process. In this paper, spatter particles emerging during LBM of AlSi10Mg are characterized regarding geometric (size, morphology), chemical (alloy composition, oxygen content, oxide layer thickness) properties as well as mass. Spatter particles are collected during the process using two isolation methods. Three types of spatter particles can be differentiated by their formation mechanism. It is found that spatter particles can differ significantly in oxide layer thickness and particle size. A significant share of spatter particles can be segregated by sieving. However, a certain fraction of the spatter particles will be included in the recycled powder.
关键词： Laser beam melting,AlSi10Mg,Powder recycling,Powder quality,Powder bed fusion,Powder reuse,Additive manufacturing,Reusability,Oxidation,Spatter
更新于2025-09-12 10:27:22
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Process monitoring of meltpool and spatter for temporal-spatial modeling of laser powder bed fusion process
摘要： L-PBF is an additive manufacturing process which can produce nearly fully dense parts with complex geometry by using laser which follows layer-to-layer scanning on powder material. In-process statistical monitoring techniques are required to detect localize material spatter and control the meltpool. High speed video imaging provides process insights for identifying meltpool and spatter and can be integrated into process monitoring for L-PBF process. We demonstrate the use of high speed camera videos for in-situ monitoring of L-PBF of nickel alloy 625 to detect spatter and over melting regions to improve the process control capability. The quantities that can be measured via in-situ sensing can be referred to as process signatures and can represent the source of information to detect possible defects. The video images are processed for temporal-spatial analysis by using principal component analysis and T2 statistical descriptor for identifying the history of pixel intensity levels through the process monitoring. These results are correlated as over melting and spatter regions.
关键词： Meltpool,Monitoring,Powder bed fusion,Spatter,Laser
更新于2025-09-12 10:27:22
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Real-time spatter detection in laser welding with beam oscillation
摘要： Spatter formation is a longstanding issue in laser welding. This research addresses this topic and proposes a machine vision algorithm executed on a graphics processing unit to detect spatters in real time. Using this approach, a control system detecting spatter at a rate of 1 kHz and with a resolution of 900 x 900 pixels was implemented. Based on an experimental series, it is shown that the variation of the process parameters has a significant influence on the formation of spatter. It was also possible to quantify the variance of the spatter formation for a given set of process parameters.
关键词： machine vision,beam oscillation,laser welding,spatter formation,graphics processing unit
更新于2025-09-12 10:27:22
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Characterization of Laser Spatter and Condensate Generated during the Selective Laser Melting of 304L Stainless Steel Powder
摘要： The selective laser melting process, commonly referred to as laser powder-bed fusion (L-PBF), is an Additive Manufacturing (AM) technique that uses a laser to fuse successive layers of powder into near fully dense components. Due to the large energy input from the laser during processing, vaporization causes instabilities in the melt pool leading to the formation of laser spatter and condensate, collectively known as heat-affected powder. Since heat-affected powder settles into the powder bed, the properties of the unconsolidated powder may be altered compromising its reusability. In this study, characterization of 304L heat-affected powder was performed through particle size and shape distribution measurements, energy-dispersive spectroscopy, Raman spectroscopy, inert gas fusion, metallography, and x-ray diffraction. The results show morphological, chemical, and microstructural differences between the virgin powder and heat-affected powder formed during processing which aid in the understanding of laser spatter and condensate that form in the L-PBF process.
关键词： condensate,powder characterization,laser spatter,selective laser melting
更新于2025-09-12 10:27:22
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Influences of synergy effect between laser and arc on laser-arc hybrid welding of aluminum alloys
摘要： Researchers generally believe that synergy effect between laser and arc enables laser-arc hybrid welding to acquire obvious advantages of efficiency and quality in welding aluminum alloys. However, influences of physical essence of the synergy effect on welding process were not clear. In this study, basic principle of the synergy effect and its influences on welding process were obtained by spectral analysis of hybrid plasma plume and high-speed photographic analysis of welding process. First, the principle of the synergy effect is that laser interacts with arc to render electron energy level to transition. This process emits more photons, which enhance the heat input to the weld materials. The synergy effect is quantified by spectral intensity. It increases with the laser power, and decreases with the arc current and laser-arc distance. It is proportional to the cross section of weld, especially the upper, and beneficial to improve the welding energy utilization. Secondly, the amount of spatter in laser-arc hybrid welding is significantly less than that of arc welding. The bigger weld pool, the downward melt flow, and the reduced droplet transfer force generated by the synergy effect make the transferring droplets more easily absorbed by the weld pool, which stabilizes the transfer process and reduces the generation of spatter. The research results are beneficial for understanding hybrid welding mechanism and optimizing the welding process.
关键词： Synergy effect,Laser-arc hybrid welding,Welding penetration,Welding energy utilization,Spatter
更新于2025-09-12 10:27:22