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Thermodynamics analysis and rapid solidification of laser polished Inconel 718 by selective laser melting
摘要： This paper presents thermodynamics analysis and rapid solidi?cation of laser polishing technology for selective laser melting (SLM) Inconel 718 superalloy. Signi?cant porosity reduction has been examined in the laser polished layer, where the surface porosity is reduced by 65.7% compared with that of the as-fabricated SLM surface. The results show that the temperature in the polished zone is over 1683 K, and the cooling rate is approximately up to 2.46 × 106 K/s. Besides, the polished layer consists of equiaxed grain and columnar grain with average grain size of 10 ± 2.4 μm and 5 ± 1.2 μm, respectively, and tiny cell grains with average size of 3.5 μm in the heat-a?ected zone (HAZ). Moreover, the transmission electron microscope (TEM) results show that the orientation relationship (OR) between the γ matrix and Laves phase is found to be Burgers OR [0 1 1] ‖[0 1 1ˉ 2] Laves on the as-received layer and [1ˉ 1 1] ‖[1 2ˉ 1 3ˉ] Laves on the polished layer.
关键词： Inconel 718 superalloy,Microstructural evolution,Crystallographic orientation,Selective laser melting,Laser polishing
更新于2025-09-16 10:30:52
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Microstructure development, tribological property and underlying mechanism of laser additive manufactured submicro-TiB2 reinforced Al-based composites
摘要： Al-based composites reinforced with submicro-TiB2 particles were manufactured by selective laser melting (SLM) of powder mixture under different laser powers. The microstructure evolution and tribological property of SLM-processed AlSi10Mg/TiB2 composites were investigated. Al-based composites with high manufacturing quality and uniform dispersion of TiB2 particles throughout the matrix were obtained. The EBSD results showed that incorporation of TiB2 reinforcements imposed no appreciable influence on the crystallographic orientation and average grain size, while the grain size distribution was distinctly narrowed as a result of limitation on grain growth by addition of ceramic particles. The SLM-processed composites exhibited a continuous tendency of increasing microhardness and decreasing coefficient of friction (COF) along with wear rate with a laser power increasing from 350 to 450 W. The composites showed high microhardness of 126 HV0.2, exceeding over those of the Al-Si alloys and composites processing by conventional techniques. A low COF of 0.65 and wear rate of 5.2×10?4 mm3N-1m-1 were obtained for bulk-form composites at 450 W due to the combined effects of high manufacturing quality, microstructure homogeneity, and sound interfacial bonding.
关键词： Tribological property,Microstructure development,Selective laser melting (SLM),Al-based composite
更新于2025-09-16 10:30:52
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Numerical Study on Thermodynamic Behavior during Selective Laser Melting of 24CrNiMo Alloy Steel
摘要： In this paper, a multi-layer and multi-track ?nite element model of 24CrNiMo alloy steel by selective laser melting (SLM) is established by using the ABAQUS software. The distribution and evolution of temperature ?eld and stress ?eld and the in?uence of process parameters on them are systematically studied. The results show that the peak temperature increases from 2153 C and the residual stress increases from 335 MPa to 364 MPa with increasing laser power from 200 W to 300 W; the peak temperature decreases from 2905 C and the residual stress increases from 327 MPa to 363 MPa with increasing scanning speed from 150 mm/s to 250 mm/s; the peak C and the residual stress decreases from 354 MPa to 300 temperature increases from 2621 MPa with increasing preheating temperature from 25 C. Far away from scanning area, far away from starting point, and the adjacent areas with vertical scanning direction, resulting in a uniform temperature distribution, help to reduce the residual stress. Due to the remelting e?ect, the interlayer scanning angle changing helps to release the residual stress of the former layer causing a smaller residual stress after redistribution.
关键词： substrate preheating,?nite element analysis,thermodynamic behavior,selective laser melting,scanning strategy,24CrNiMo alloy steel
更新于2025-09-16 10:30:52
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Experimental observation of stress formation during selective laser melting using in situ X-ray diffraction
摘要： Despite the ongoing success of metal additive manufacturing and especially the selective laser melting (SLM) technology, process-related defects, distortions and residual stresses impede its usability for fracture-critical applications. In this paper, results of in situ X-ray diffraction experiments are presented that offer insights into the strain and stress formation during the manufacturing of multi-layer thin walls made from Inconel 625. Using different measuring modes and laser scanning parameters, several experimental observations are discussed to validate and extend theoretical models and simulations from the literature. As a sample is built-up layer by layer, the stress state changes continuously up until the last exposure. The localized energy input leads to a complex stress field around the heat source that involves alternating tensile and compressive stresses. The correlation of temperature and yield strength results in a stress maximum at a certain distance to the top layer. The present study demonstrates the potential of high-energy synchrotron radiation diffraction for in situ SLM research.
关键词： Inconel 625,Selective laser melting,Stress formation,In situ,High energy synchrotron radiation diffraction
更新于2025-09-16 10:30:52
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Influence of Abrasive Materials in Fluidised Bed Machining of AlSi10Mg Parts Made through Selective Laser Melting Technology
摘要： Metal Additive Manufacturing technologies development is increasing in a remarkable way due to their great potential concerning the production of complex parts with tailored characteristics in terms of design, material properties, usage and applications. Among all, the most widespread technologies are the Powder Bed Fusion based technologies such as Selective Laser Melting and Electron Beam Melting. However, the high surface roughness of the as-built parts still represents one of the major limitations, making necessary the adoption of post-process finishing to match the technological requirements for most of the fields of application. In this scenario, Fluidised Bed Machining represents an emerging finishing technology that could overcome some of the limitations of the most common methods, especially in terms of feasibility for the treatment of complex parts thanks to the fluid-like mobility of the abrasive material. This work deals with the preliminary tests of the Fluidised Bed Machining of additive manufactured samples using alumina as the abrasive material, investigating the effects of a high abrasive/substrate hardness ratio condition. The experiments were carried out on small plates of AlSi10Mg alloy made through Selective Laser Melting technology, built in the vertical direction with respect to the building plate. The influence of the impact angle and treatment time were investigated under bubbling fluidization conditions. Surface morphology evaluations were carried out pre and post process by means of Confocal Microscopy and Scanning Electron Microscopy (SEM). Weight loss measurements were conducted to evaluate the material removal rates as well. Results show a small influence of the specific impact angle, a slight reduction of the surface roughness and an asymmetrical effect of treatment, acting mostly on the sintered powders forming the peaks of the as-built surface.
关键词： Additive Manufacturing,Fluidised Bed,Selective Laser Melting,Surface finishing
更新于2025-09-16 10:30:52
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Electrochemical Studies on CaP Electrodeposition on Three Dimensional Surfaces of Selective Laser Melted Titanium Scaffold
摘要： In this work, calcium phosphate (CaP) coating was electrodeposited on the three dimensional surface of SLM-Ti sca?olds. The in situ measurement showed that the potential variation within 5 mm thickness porous selective laser melting (SLM)-Ti samples was about 80 mV as a result of the low conductivity of CaP coatings. SEM observation results revealed that the coating morphology depended on the distance between the surface position of porous SLM-Ti electrode and the auxiliary electrode. Based on the compared electrochemical experiments, it was found that the top and the bottom surfaces of SLM-Ti sca?olds exhibited continuous nucleation and instantaneous nucleation behavior respectively. The Electrochemical impedance spectroscopy (EIS) results also revealed that the electrodeposition processes at di?erent depth of SLM-Ti sca?olds were not synchronized. These di?erences were ultimately caused by the non-uniform distribution of the potential and the current inside porous SLM-Ti electrodes. The present work provides a basic research method for studying the mechanism of the electrochemical process on three dimensional surfaces of SLM-Ti sca?olds.
关键词： porous titanium,selective laser melting,electrochemical deposition,CaP coating
更新于2025-09-16 10:30:52
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Control of Deviations in Lattice Structures Manufactured by Selective Laser Melting
摘要： The paper presents the study of lattice structures and deviations in them caused by the phenomena of the selective laser melting. Experimental samples were compared with their computer models and deviations were assessed. The most accurate control method for this material was determined and relative density was calculated from the results of the method.
关键词： Additive manufacturing,3D Scanning,Deviation Control,Selective Laser Melting,Lattice structures
更新于2025-09-16 10:30:52
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Effect of Ultrasonic Nanocrystal Surface Modification on the Microstructure and Martensitic Transformation of Selective Laser Melted Nitinol
摘要： Nitinol has significant potential for biomedical and actuating-sensing devices, thanks to its functional properties. The use of selective laser melting (SLM) with Nitinol powder can promote novel applications aimed to produce 3D complex parts with integrated functional performances. As the final step of the production route, finishing processing needs to be investigated both for the optimization of the surface morphology and the limit alteration of the Nitinol functional properties. In this work, the effect of an advanced method of surface modification, ultrasonic nanocrystal surface modification (UNSM), on the martensitic transformation and microstructure of SLM built Ni50.8Ti49.2 (at.%) was investigated. Scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry indicated that the UNSM process can generate stress-induced martensite, at least partially suppressing the martensitic transformation. The microhardness profile indicates that the UNSM process can affect the mechanical properties of the SLMed Nitinol sample in a range of up to approximately 750 μm in depth from the upper surface, while electron backscatter diffraction analysis highlighted that the initial austenitic phase was modified within a depth below 200 μm from the UNSMed surface.
关键词： NiTi,ultrasonic nano-crystal surface modification,EBSD,XRD,selective laser melting,microstructure
更新于2025-09-16 10:30:52
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Silver Electroless Finishing of Selective Laser Melting 3D-Printed AlSi10Mg Artifacts
摘要： Additive manufactured selective laser melting (AM-SLM) parts often need post-printing coatings. The current research presents a method for surface finishing of AM-SLM AlSi10Mg parts coated by electroless silver plating. Such coating can be applied as a decorative film on printed replicas of antique artifacts. For this purpose, silver was deposited for the first time on AlSi10Mg printed disk-shaped specimens and coins, making their appearance close to the original artifact. The silver was plated with and without adhesion-promoting silane self-assembled monolayers. Dimensions and mass measurements, pilling test, light microscopy, optical profilometer, SEM–EDS examination, XRD analysis, and FIB-SEM technique were applied to characterize the coated samples. The results displayed good silver quality with a satisfactory appearance. The roughness of the plated samples was slightly reduced as the thickness of the silver layer was increased. The developed coating can be adapted for different applications, including printed replicas of coins in museum exhibitions.
关键词： Surface coating,Selective laser melting,Additive manufacturing,AlSi10Mg alloy,Macro and microstructure,Electroless silver plating
更新于2025-09-16 10:30:52
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Analysis of Melt-Pool Behaviors during Selective Laser Melting of AISI 304 Stainless-Steel Composites
摘要： The melt-pool behaviors during selective laser melting (SLM) of Al2O3-reinforced and a eutectic mixture of Al2O3-ZrO2-reinforced AISI 304 stainless-steel composites were numerically analyzed and experimentally validated. The thermal analysis results show that the geometry of the melt pool is significantly dependent on reinforcing particles, owing to the variations in the melting point and the thermal conductivity of the powder mixture. With the use of a eutectic mixture of Al2O3-ZrO2 instead of an Al2O3 reinforcing particle, the maximum temperature of the melt pool was increased. Meanwhile, a negligible corresponding relationship was observed between the cooling rate of both reinforcements. Therefore, it was identified that the liquid lifetime of the melt pool has the effect on the melting behavior, rather than the cooling rate, and the liquid lifetime increases with the eutectic ratio of Al2O3-ZrO2 reinforcement. The temperature gradient at the top surface reduces with the use of an Al2O3-ZrO2 reinforcement particle due to the wider melt pool. Inversely, the temperature gradient in the thickness direction increases with the use of an Al2O3-ZrO2 reinforcement particle. The results of melt-pool behaviors will provide a deep understanding of the effect of reinforcing particles on the dimensional accuracies and properties of fabricated AISI 304 stainless-steel composites.
关键词： FEM,Al2O3,Al2O3-ZrO2,304,composite,SLM,additive manufacturing,selective laser melting,stainless
更新于2025-09-16 10:30:52