- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Influence of the Wire Feeding on the Wetting Process during Laser Brazing of Aluminum Alloys with Aluminum-Based Braze Material
摘要： The wetting behavior in laser brazing can be designated as inconstant, caused largely by external process discontinuities such as the wire feeding. To reveal periodic melt pool propagation effects that occur during laser brazing of aluminum and for a better understanding of those effects in laser brazing in general, this paper analyzes high-speed recordings of the brazing process with aluminum alloy. It is demonstrated that two main effects of periodic melt pool behavior in different frequency scales occur during the process, related directly to the wire feeding.
关键词： laser brazing,aluminum,process frequencies,melt pool behavior,process dynamics
更新于2025-09-23 15:21:01
-
Probing a novel heat source model and adaptive remeshing technique to simulate laser powder bed fusion with experimental validation
摘要： A finite element method based three-dimensional heat transfer model with adaptive remeshing is presented to simulate the building of multiple tracks and layers in laser powder bed fusion of metallic powders with enhanced computational competence. A dimensional analysis is undertaken to define the heat source dimensions as function of laser parameters and properties of alloy powder. The computational model is used to calculate the melt pool cross sections for multiple combinations of laser power and scanning velocities considering multi-track-multi-layer builds of SS316L powder. The computed results are verified extensively with the corresponding experimentally measured ones. The model is utilized further to examine its ability to predict defects such as melt track discontinuity and incomplete fusion between neighboring tracks and layers. Overall, the adaptive remeshing and the proposed heat source expression could significantly enhance the model competence by reducing the computational time and memory while maintaining the accuracy of results in simulating laser powder bed fusion of multiple tracks and layers.
关键词： Selective laser melting (SLM),Pool dimensions,Adaptive remeshing,Laser powder bed fusion (L-PBF),Melt pool defects,SS316L alloy
更新于2025-09-23 15:19:57
-
Crystallographic Orientation Control of 316L Austenitic Stainless Steel via Selective Laser Melting
摘要： In recent years, additive manufacturing has attracted attention as a technology that enables control of the crystallographic texture of metallic materials. We achieved successful control of the crystallographic texture of 316L austenitic stainless steel using selective laser melting (SLM). Three distinguished textures were achieved by changing the laser scan speed, namely: the single crystalline-like texture with {001} orientation in the build direction, the crystallographic lamellar texture in which two kinds of grains with {011} and {001} orientations in the build direction are alternately stacked, and polycrystalline with relatively random orientation. The melt pool shape and the solidification behavior (thermal gradient and migration velocity of solid/liquid interface) in a melt pool could be important controlling factors for the evolution of the crystallographic texture under the SLM process.
关键词： anisotropy,crystallographic texture,metal additive manufacturing (AM),selective laser melting (SLM),melt pool
更新于2025-09-23 15:19:57
-
In-process measurement of melt pool cross-sectional geometry and grain orientation in a laser directed energy deposition additive manufacturing process
摘要： Understanding the behaviour of melt pool during laser directed energy deposition (L-DED) is essential for the prediction and control of process quality. Previous effort was focused on the observation of melt pool surface characteristics. In this paper, a coaxial imaging system was employed to determine the melt pool cross sectional geometry and to predict solidified grain orientation during a high deposition rate L-DED process. The image processing procedure, deposition track cross-sectional profile prediction and the relationship between melt pool shape and melt pool dynamics, and grain growth orientation were investigated. Results show that sharp melt pool edges can be obtained so that melt pool width can be predicted with an accuracy of more than 95%. The estimation method of melt pool length has an accuracy of 90%. With the experimental melt pool width and depth data, the cross-sectional profiles of deposited track are predicted at an accuracy of 92% and a good match with experimental data is obtained. The melt pool formation is found to be able to allow the prediction of crystal growth directions during solidification.
关键词： Melt pool dimension,Laser additive manufacturing,Track geometry,Laser directed energy deposition,Grain growth
更新于2025-09-23 15:19:57
-
Interaction between powder particle and gas-liquid interface of the melt pool during laser solid forming process
摘要： The three-dimensional (3-D) simulation of powder particle entering melt pool during laser solid forming (LSF) was carried out in our quest to establish a general representative model of this phenomenon. The effect of the gas-liquid interface on the motion state of the powder was analyzed, and the accuracy and universality of the model were verified using a high-speed photographic experimental approach. Further, the simulation process of the Ti-6Al-4V powder particle entering the high-temperature Ti-6Al-4V melt pool was carried out. The effects of the gas-liquid interface of the melt pool on the motion state of the powder particle and the disturbing of the powder particle on the melt pool were studied. It was found that the running speed of the particle experienced a rapid decrease and then a slower decrease in the process of entering the pool. Also, the particle serves as a transport medium of gases and carries the gases into the pool, which could form pores in the deposited layer. When the particles enter the melt pool at varied speeds, the ratio of the instantaneous speed of the particle entering the pool to the initial incident speed differs, which increases with increasing initial speed.
关键词： Melt pool,Laser solid forming,Powder particle,Gas-liquid interface,Interaction
更新于2025-09-23 15:19:57
-
A scan-wise adaptive remeshing framework for thermal simulation of the selective laser melting process
摘要： Physics-based thermal simulation of laser powder bed fusion can greatly help understanding the process and reducing time and cost associated with experimental approaches. Numerical methods including the finite element method have been widely used to predict parts thermal-structural history during the build process. However, the simulation has scalability issues because both layer thickness and laser spot diameter are too tiny compared to the part-scale. Therefore, it is only feasible to run these simulations with massive computational resources or if the boundary conditions are simplified, which inevitably reduces the prediction accuracy. This paper proposes a tetrahedral element-based scan-wise adaptive remeshing framework for thermal simulation of the selective laser melting (SLM) process. Results show that a significant reduction of the computational time and resources can be achieved due to the reduction of the number of nodes. The proposed framework enables part-scale thermal modeling of the SLM process with detailed thermal history without sacrificing the accuracy. The effectiveness of the proposed framework is demonstrated through a large size cantilever problem.
关键词： Selective laser melting,Melt pool,Adaptive remeshing,Thermal simulation
更新于2025-09-23 15:19:57
-
Surface morphology evolution with laser surface re-melting in selective laser melting
摘要： Laser surface re-melting (LSR) is a promising method for improving the surface quality of parts fabricated via selective laser melting (SLM). In this research, LSR under different linear energy densities (LEDs) was conducted numerically and experimentally. Additionally, double LSR using an LED of 225 J/m was conducted, and the surface morphology, melt pool flow behavior, melt pool size, and thermal behavior was investigated. The results show that for LSR with a low LED, the maximum flow velocity and maximum temperature was rather low, such that the surface was not reconfigured sufficiently. Furthermore, the surface between adjacent scan paths may not be entirely re-melted with a low LED, because the melt pool width was insufficient. However, when the LED was high, the maximum temperature gradient was rather large, giving rise to cracks. For double LSR with a moderate LED, the surface morphology was quite smooth and did not contain obvious defects. The results indicate that LSR is a feasible method for improving the surface quality, and repeated LSR with a moderate LED and small hatch space is recommended in SLM.
关键词： Selective laser melting,Laser surface re-melting,Melt pool flow,Surface morphology evolution
更新于2025-09-19 17:13:59
-
A convolutional neural network for prediction of laser power using melt-pool images in laser powder bed fusion
摘要： In laser powder bed fusion, a convolutional neural network could build a good regression model to predict a laser power value from a melt-pool image. To empirically validate it, we used the acquired image data from a monitoring system inside metal additive manufacturing equipment and optimally configured a convolutional network by the grid search of hyper-parameters. The proposed network showed only 0.12 % of test images were out of the criterion for judging the predicted laser power value to be reliable and showed more accurate results than deep feed-forward neural network in the prediction of laser power states unseen in training steps. We expect that the proposed model could be utilized to discover the problematic position in additive-manufactured layers causing defects during a process.
关键词： convolutional neural network,melt-pool image,process monitoring,metal additive manufacturing,laser powder bed fusion
更新于2025-09-19 17:13:59
-
Beyond the Toolpath: Site-Specific Melt Pool Size Control Enables Printing of Extra-Toolpath Geometry in Laser Wire-Based Directed Energy Deposition
摘要： A variety of techniques have been utilized in metal additive manufacturing (AM) for melt pool size management, including modeling and feed-forward approaches. In a few cases, closed-loop control has been demonstrated. In this research, closed-loop melt pool size control for large-scale, laser wire-based directed energy deposition is demonstrated with a novel modification, i.e., site-specific changes to the controller setpoint were commanded at trigger points, the locations of which were generated by the projection of a secondary geometry onto the primary three-dimensional (3D) printed component geometry. The present work shows that, through this technique, it is possible to print a specific geometry that occurs beyond the actual toolpath of the print head. This is denoted as extra-toolpath geometry and is fundamentally different from other methods of generating component features in metal AM. A proof-of-principle experiment is presented in which a complex oak leaf geometry was embossed on an otherwise ordinary double-bead wall made from Ti-6Al-4V. The process is introduced and characterized primarily from a controls perspective with reports on the performance of the control system, the melt pool size response, and the resulting geometry. The implications of this capability, which extend beyond localized control of bead geometry to the potential mitigations of defects and functional grading of component properties, are discussed.
关键词： closed-loop control,lasers,metal,directed energy deposition,additive manufacturing,3D printing,titanium,site-specific,melt pool size
更新于2025-09-19 17:13:59
-
Influence of Process Parameters and Deposition Strategy on Laser Metal Deposition of 316L Powder
摘要： In blown powder additive manufacturing technologies the geometrical stability of the built parts is more complex with respect to more conventional powder bed processes. Because of this reason, in order to select the most suitable building parameters, it is important to investigate the shape and the properties of the single metal bead formation and the effect that a scan track has on the nearby ones. In the present study, a methodology to identify an appropriate laser metal deposition process window was introduced, and the effect of the building parameters on the geometry of circular steel samples was investigated. The effect of the scanning strategy on the deposited part was also investigated. This work draws the attention to the importance of the obtainment of the most suitable melt pool shape, demonstrating that the laser power and the scanning strategy have a strong influence not only on the shape but also on the mechanical properties of the final component.
关键词： steel,additive manufacturing,melt pool,overlap,scanning strategy,directed energy deposition,AISI 316L
更新于2025-09-16 10:30:52