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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
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Numerical simulation of selective laser melting with local powder shrinkage using FEM with the refined mesh
摘要： A mathematical model of selective laser melting (SLM) of fine-grained metallic powders under the pulse laser annealing conditions has been developed. The processed powder bed is considered in the approximation of continuous medium where its effective thermophysical properties depend on local porosity. The model allows simulation of unsteady distributions of temperature, specific enthalpy, local porosity, morphology and thickness of the processed track. In the paper, all stages of problem analysis are described including its mathematical formulation and numerical implementation. To take into account shrinkage of the powder layer during sintering and remelting, the numerical model utilizes the arbitrary Lagrangian–Eulerian (ALE) method. Thus the finite element mesh provides robust control of quality and dynamic remeshing through adaptive mesh refinement. Using the proposed numerical model the unsteady thermal fields and local porosity of a Fe-based powder layer processed with a pulsed laser has been investigated.
关键词： numerical simulation,adaptive mesh refinement,finite element method,selective laser melting,powder shrinkage
更新于2025-09-23 15:19:57
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Multi-physics modelling of molten pool development and track formation in multi-track, multi-layer and multi-material selective laser melting
摘要： Selective laser melting (SLM) is a promising powder-based additive manufacturing technology due to its capability to fabricate metallic components with complex geometries. While most previous investigations focus on printing with a single material, recent industry-orientated studies indicate the need for multi-material SLM in several high-value manufacturing sectors including medical devices, aerospace and automotive industries. However, understanding the underlying physics in multi-material SLM remains challenging due to the di?culties of experimental observation. In this paper, an integrated modelling framework for multi-track, multi-layer and multi-material SLM is developed to advance the in-depth understanding of this process. The main novelty is in modelling the molten pool evolvement and track morphology of multiple materials deposited on the same and across different layers. Discrete element method (DEM) is employed to reproduce the powder deposition process of multiple materials in different deposition patterns, with particle size distribution imported from a particle size analyser. Various phenomena including balling effect, keyhole depression, and lack of fusion between layers are investigated with different laser energy inputs. As a result of the different thermal properties, several process parameters including energy density and hatch spacing are optimised for different powder materials to obtain a continuous track pro?le and improved scanning e?ciency. The interface between two layers of different materials is visualised by simulation; it was found that the phase migration at the interface is related to the convection ?ow inside the molten pool, which contributes to the mixing of the two materials and elemental diffusion. This study signi?cantly contributes to the challenging area of multi-material additive manufacturing by providing a greater in-depth understanding of the SLM process from multi-material powder deposition to laser interaction with powders across multiple scanning tracks and different building layers than can be achieved by experimentation alone.
关键词： Additive manufacturing,Discrete element method (DEM),Computational ?uid dynamics (CFD),Heat transfer,Multi-material,Selective laser melting (SLM)
更新于2025-09-23 15:19:57
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Study on process and manufacturability of metal-bonded diamond grinding wheel fabricated by selective laser melting (SLM)
摘要： Selective laser melting (SLM) technology is used to fabricate metal-bonded grinding wheel based on mixed powders consisted of metal powders and diamond abrasives. Taguchi method is adopted to obtain the optimal SLM process parameters for grinding wheel considering laser power, scanning speed and layer thickness. Specimens are fabricated with different SLM process parameters for compression and three-point bending tests. Materials characterization and manufacturing limit test are performed on the specimens fabricated by the optimal SLM process. Results indicate that laser power of 250W, scanning speed of 2.5m/s and layer thickness of 20μm are determined as the optimal SLM process in terms of comprehensive mechanical property and formed surface quality. Moreover, diamond abrasives are firmly embedded into aluminium binder with good bonding condition for SLM-fabricated composite. Furthermore, manufacturability of SLM-fabricated composite is evaluated by manufacturing limits of several common structures. In summary, work in this study fully proves the feasibility of SLM-fabricated metal-bonded grinding wheel and provides a solid basis for the further investigation on the novel grinding wheel with customized porous structures.
关键词： diamond abrasives,metal-bonded grinding wheel,manufacturability,Taguchi method,Selective laser melting (SLM)
更新于2025-09-23 15:19:57
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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
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Development of process parameters for selective laser melting of a Zr-based bulk metallic glass
摘要： Parameters for selective laser melting of Zr59.3Cu28.8Al10.4Nb1.5 (trade name AMZ4), allowing crack-free bulk metallic glass with low porosity, have been developed. The phase formation was found to be strongly influenced by the heating power of the laser. X-ray amorphous samples were obtained with laser power at and below 75 W. The as-processed bulk metallic glass was found to devitrify by a two-stage crystallization process within which the presence of oxygen was concluded to play an essential role. At laser powers above 75 W, the observed crystallites were found to be a cubic phase (Cu2Zr4O). The hardness and Young’s modulus in the as-processed samples was found to increase marginally with increased fraction of the crystalline phase.
关键词： Selective Laser Melting,AMZ4,Bulk Metallic Glass
更新于2025-09-23 15:19:57
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Enhancement of the surface properties of selective laser melted maraging steel by large pulsed electron-beam irradiation
摘要： The present work aimed to decrease the surface roughness of maraging steel (MS) by selective laser melting (SLM) using large pulsed electron-beam (LPEB) irradiation as a post-treatment. The MS samples were fabricated using different combinations of laser power, scanning speed, hatch distance, and build angle. The morphological features, surface roughness, phase content, and corrosion resistance of the MS samples in their as-fabricated (ASF) state were compared after LPEB irradiation. The ASF SLM-MS samples exhibit the presence of partially melted particles that spread over the entire surface and many cracks in both the longitudinal and transverse directions. A higher arithmetical mean height (Sa: 2-17 μm), large variations in Sa measured at various locations, and a strong dependence of Sa on build angle were also observed. Post-treatment by LPEB irradiation removed the partially melted particles, while reflow of the molten mass filled the cracks and voids and facilitated the formation of a uniform surface with a bright metallic finish. This has resulted in a significant decrease in Sa (0.50-4.50 μm) and a smaller variation in Sa measured at different locations. Body-centered cubic α-martensite was the predominant phase for the ASF SLM-MS samples, along with a small fraction face-centered cubic γ-austenite phase. After LPEB irradiation, the martensite was reverted to the austenite phase. The corrosion resistance of the LPEB-irradiated samples was moderately better than that of the ASF SLM-MS samples. The uniform surface morphology, removal of partially melted particles, absence of pores and cracks, decrease in Sa, and moderate improvement in corrosion resistance suggests that LPEB irradiation can be used as a post-treatment for SLM-MS samples.
关键词： corrosion resistance,large pulse electron beam irradiation,maraging steel,Selective laser melting,surface roughness
更新于2025-09-23 15:19:57
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Preparation method and underlying mechanism of MWCNTs/Ti6Al4V nanocomposite powder for selective laser melting additive manufacturing
摘要： The fabrication of high-performance metal matrix nanocomposites is a new development direction in laser additive manufacturing (AM); however, the unique localized line-by-line and layer-by-layer forming process of AM has special requirements on the applicable powder materials for AM. The feedstock powder preparation is an important factor in laser AM, especially the CNTs/metal nanocomposite powder for selective laser melting (SLM) due to the agglomeration of the CNTs. This work focused on the preparation of multi-walled carbon nanotubes/Ti6Al4V (MWCNTs/TC4) nanocomposite powder for laser AM by a planetary ball-milling (PBM). The effect of ball-milling time on the characteristics of nanocomposite powder was studied and the underlying physical mechanism for powder preparation was disclosed. Three nanocomposite powders with milling time of 2 h, 4 h and 16 h were used for SLM processing to determine the optimal nanocomposite powders. The results showed that although the MWCNTs were dispersed uniformly in the matrix powder at increased milling time, severely plastic deformation of nanocomposite powder occurred with loss of its spherical shape. It was concluded that a ball-milling time of 4 h at a speed of 300 rpm was determined to achieve optimal nanocomposite powder for SLM. SLM processing of the nanocomposite powder demonstrated a smooth laser-powder interaction, yielding good metallurgical bonding of scanning tracks with previous tracks and relatively flat surface of samples. This work provided the significant reference to prepare high quality CNTs/metal nanocomposite powder for SLM, which has great potentials to fabricate high-performance metal matrix nanocomposite.
关键词： Planetary ball milling,Selective laser melting,Ti6Al4V (TC4) powder,Multi-walled carbon nanotubes (MWCNTs),Powder characteristics
更新于2025-09-23 15:19:57
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Grain growth in IN718 superalloy fabricated by laser additive manufacturing
摘要： The grain growth mechanism of IN718 superalloy fabricated by selective laser melting (SLM) was studied. Epitaxial growth with the same crystallographic orientation or rotating by 90° across the melting pool boundary and competitive growth in the same melting pool were observed. Either of the two patterns of epitaxial growth can maintain the same grain across the melting pool boundary. Competitive growth is determined by both the heat flow direction and preferred crystallographic orientation. In SLM, the grains grow along the preferred crystallographic orientation owing to a high solidification rate. The smaller the deviation angles between the heat flow direction and the preferred crystallographic orientation, the faster the grain growth rate.
关键词： competitive growth,crystallographic orientation,selective laser melting,IN718,Epitaxial growth
更新于2025-09-23 15:19:57
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Selective laser melting of Inconel 718 under high laser power
摘要： Selective laser melting (SLM) process has been lately extensively applied in manufacturing of Nickel-based super alloys, which compared to conventional manufacturing routes offers increased design flexibility and simplification of the manufacturing process. However, in order to make SLM process even more beneficial, its process time has to be reduced. One of the ways to tackle this problem is by tailoring process parameters through application of high laser power and base plate pre-heating. In this paper, a comparative study of optimum SLM fabrication conditions of Inconel 718 superalloy under high laser power and with and without plate pre-heating was conducted. Furthermore, the effect of layer thickness on melt pool characteristics, porosity and hardness were investigated to determine how laser power and pre-heating affect microstructure development.
关键词： Additive manufacturing,Texture,Grain structure,Selective laser melting,Nickel alloy
更新于2025-09-23 15:19:57