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Impacts of Defocusing Amount and Molten Pool Boundaries on Mechanical Properties and Microstructure of Selective Laser Melted AlSi10Mg
摘要： The influences of processing parameters such as volumetric energy density (ε) and, particularly, defocusing amount (DA) on densification, microstructure, tensile property, and hardness of the as-printed dense AlSi10Mg alloy by selective laser melting (SLM) were studied systematically. The molten pool boundaries (MPBs) were found overwhelmingly at regular and complex spatial topological structures affected by DA value to exist in two forms, while the “layer–layer” MPB overlay mutually and the “track–track” MPBs intersect to form acute angles with each other. The microstructure of MPBs exhibits a coarse grain zone near the MPBs and the characteristics of segregation of nonmetallic elements (O, Si) where the crack easily happened. The DA value (?2 to 2 mm) affected both the density and the tensile mechanical properties. High tensile strength (456 ± 14 MPa) and good tensile ductility (9.5 ± 1.4%) were achieved in the as-printed condition corresponding to DA = 0.5 mm. The tensile fracture surface features were analyzed and correlated to the influence of the DA values.
关键词： selective laser melting (SLM),mechanical properties,aluminum alloys
更新于2025-09-23 15:22:29
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Characterisation of elemental analysis, carbon sulphur analysis and impact test of stent manufacturing using medical grade ASTM F75 cobalt chromium (CoCrMo) by selective laser melting (SLM) technology
摘要： This paper explains and demonstrates the capabilities of metal additive manufacturing (MAM) technology in producing intricate stent structure with a customise design by using ASTM F75 cobalt chromium powder. The elemental analysis (EDX-SEM), carbon sulphur analysis and Impact Test are being develop and tested and thus exploring the potential area of MAM process for future proof stent manufacturing. By alternatively switching to MAM, the step of production can be minimised and thus customisation of stent can be carried out according to the patient’s need. The suggested model of the stent was taken from the third-party vendor and fabrication was carried out using EOSINT M280 metal printer with the aid of Materialise Magics 19.0 software for support generation.
关键词： stent,scanning electron microscope (SEM),selective laser melting (SLM),cobalt chromium (CoCrMo),energy-dispersive X-ray spectroscopy (EDX),Metal additive manufacturing (MAM)
更新于2025-09-23 15:21:01
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Selective laser melting 316L/CuSn10 multi-materials: Processing optimization, interfacial characterization and mechanical property
摘要： Adopting selective laser melting (SLM), a typical technology of additive manufacturing (AM), to form multi-material metallic composites is a challenging and promising field. In this study, SLM 316L/CuSn10 multi-material composites was an innovative attempt to develop functional and structural materials with excellent properties of steel and copper alloys. Dense 316L/CuSn10 specimens with no interfacial macrocracks were successfully fabricated. Results showed that the Vickers microhardness gradually decreased from 329.5±12.5 HV in 316L region to 172.8HV±7.4 in CuSn10 region. The ultimate tensile strength and flexural strength of 316L/CuSn10 sample was 210 MPa, which was higher than the steel/copper alloys fabricated by other methods. It indicated an ideal interfacial bonding condition of 316L/CuSn10 multi-material, which was benefited from sufficient agitation of the molten pools and elements diffusion in the term of continuous distribution of elements and the enrichment of the heterogeneous alloy phases. Also, the grain refinement by re-melting and recrystallization upgraded the bonding performance at the interface. Finally, the 316L/CuSn10 lattice structure was formed by SLM, hinting at the prospects for industrial applications of steel/copper multi-material by SLM in future.
关键词： Selective laser melting (SLM),Mechanical properties,Interface,316L/CuSn10,Multi-material,Microstructure
更新于2025-09-23 15:21:01
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Grain refinement in laser manufactured Al-based composites with TiB2 ceramic
摘要： Al-based composites reinforced with TiB2 ceramics (1 wt.%, 2 wt.% and 5 wt.%) have been manufactured through selective laser melting (SLM). The results show that the densification, microstructure and mechanical properties of the SLM-processed composites are sensitive to the ceramic particle fraction. The average grain size of the composites decreased from ～6.32 μm with increasing TiB2 fraction from 1 to 5 wt.% respectively. Fine equiaxed grains with narrow size distribution were obtained for composites with relatively high amount of TiB2 particles. The effects of TiB2 ceramic fraction on grain refinement and strengthening mechanisms of SLM-processed composites were discussed. Al-based composite with 2 wt.% TiB2 ceramic was determined to be optimum, especially in the view of manufacturing quality, grain refinement and mechanical properties. The composites at an optimum fraction of 2 wt.% TiB2 exhibited high microhardness of ～127 HV0.2, tensile strength of ～444 MPa, yield strength of ～283 MPa and elongation of ～4.2% owing to collective effects of dispersion and grain refinement strengthening as well as high degree of densification. This study can readily offer reference values for laser additive manufacturing of other metal matrix composites to obtain a good compromise of strength and ductility by tuning reinforcement fraction.
关键词： Selective laser melting (SLM),Mechanical property,Al-based composites,Grain refinement,TiB2 ceramic
更新于2025-09-23 15:21:01
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Abrasive flow machining (AFM) finishing of conformal cooling channels created by selective laser melting (SLM)
摘要： Conformal cooling channels are widely adopted in the mold industry because of rapid and uniform cooling during injection molding. These complicated cooling channel geometries become feasible via selective laser melting (SLM) technology. However, the SLM fabricated internal channel surface shows high surface roughness of about 10 μm Ra. This rough surface can cause stress concentration, reducing the fatigue life of the mold. Therefore, the objective of this study is to investigate the surface finish of the SLM fabricated conformal channels by abrasive flow machining (AFM), which is widely used in the surface finishing of internal channels. To fulfill this objective, a combination of single/multiple and straight/helical channels for conformal cooling channel geometries are employed. Seven different types of conformal cooling channels (?3mm) inside the bar are fabricated using SLM. The bar is put in the AFM fixture, and the internal channels are polished by flowing AFM media (ULV50%-54) through the channel at the same extrusion pressure of 80 bars for ten cycles. Fourteen bars (seven before AFM and seven after AFM) are machined to have the internal channel surfaces exposed for surface roughness measurement. Surface topographies of the exposed surfaces of seven types of internal channels are obtained using focus variation microscopy. The areal roughness parameters, such as arithmetical mean height (Sa) on the internal channel surfaces before and after AFM. By comparing SLM as-built conformal channel surfaces with AFM finished ones, AFM is shown to be effective in improving all SLM conformal cooling channels’ arithmetical mean height, Sa. Areal roughness parameters, such as developed interfacial area ratio (Sdr), root mean square gradient (Sdq), reduced peak height (Spk), reduced valley height (Svk), and skewness (Ssk), on those internal surfaces, were found to be sensitive to surface finishing by AFM.
关键词： Conformal cooling channel,Selective laser melting (SLM),Abrasive flow machining (AFM),Straight/helical and single/multiple channels,Areal roughness parameters
更新于2025-09-23 15:21:01
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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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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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CoCr alloy processed by Selective Laser Melting (SLM): effect of Laser Energy Density on microstructure, surface morphology, and hardness
摘要： Selective Laser Melting (SLM) was used to realize Co-28Cr-6Mo samples. Several process parameters were considered, resulting in a wide range of Laser Energy Density (LED). The study was focused on the investigation of both process and material-related aspects, such as surface morphology, laser tracks dimension and defects formation mechanisms. In addition, macro (HRC) and microhardness (HV0.5) was assessed. A correlation between LED value and density, surface quality, microstructural features and hardness of SLM parts was defined. The final goal was to identify, for the biomedical Co-28Cr-6Mo alloy, the optimal LED window to be considered in order to maximize the overall quality of SLM parts.
关键词： Additive Manufacturing (AM),Biomaterial,Selective Laser Melting (SLM),Laser Beam Melting (LBM),Co28Cr6Mo,Co-based alloys
更新于2025-09-19 17:13:59