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Effect of Process Parameters on Residual Stresses, Distortions, and Porosity in Selective Laser Melting of Maraging Steel 300
摘要： Selective laser melting (SLM) is one of the most well-known additive manufacturing methods available for the fabrication of functional parts from metal powders. Although SLM is now an established metal additive manufacturing technique, its widespread application in industry is still hindered by inherent phenomena, one of which is high residual stresses. Some of the e?ects of residual stresses–such as warping and thermal stress-related cracking–cannot be corrected by post processing. Therefore, establishing input process parameter combinations that result in the least residual stress magnitudes and related distortions and/or cracking is critical. This paper presents the in?uence of laser power, scanning speed, and layer thickness on residual stresses, distortions and achievable density for maraging steel 300 steel parts in order to establish the most optimum input parameter combinations. An analysis of the interdependence between process outcomes shows that high residual stress magnitudes lead to high dimensional distortions in the ?nished parts, whilst porous parts su?er relatively lower residual stresses and associated distortions.
关键词： selective laser melting,distortions,porosity,residual stresses
更新于2025-09-16 10:30:52
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Study on Fe-xGO Composites Prepared by Selective Laser Melting: Microstructure, Hardness, Biodegradation and Cytocompatibility
摘要： The problem of the degradation rate being too slow is a key technical bottleneck to clinical applications for pure iron (Fe), a promising candidate biodegradable metal. This work used powders of pure Fe and graphene oxide (GO) to prepare Fe-xGO composites (x = 0.4 wt.%, 0.8 wt.%, 1.2 wt.%, and 1.6 wt.%) via selective laser melting (SLM), aiming to obtain a higher degradation rate. The microstructure, hardness, biodegradation and cytocompatibility were investigated. The degradation rate of the SLMed Fe-xGO composites was faster than that of SLMed Fe, due to incorporating GO into Fe. The GO content had a significant effect on the microstructure, hardness and degradation rate. The SLMed Fe-0.8 GO composite presented the finest, relatively uniform grains, had the maximum degradation rate, density and hardness, and had good cytocompatibility. The mechanisms were also clarified.
关键词： biodegradation,Fe-xGO composites,hardness,cytocompatibility,selective laser melting,microstructure
更新于2025-09-16 10:30:52
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Optimization and Re-Design of a Metallic Riveting Tool for Selective Laser Melting – A Case Study
摘要： This paper discusses the topology optimization and additive manufacturing-specific re-design of a metallic C-frame as it is used in the riveting process in the automotive industry. The main objective of the optimization and re-design process is the reduction of the structural weight where special attention needs to be paid to the specific manufacturing process of selective laser melting (SLM) which is a powder based additive manufacturing process. The initial optimization and SLM specific re-design are performed under consideration of a number of free parameters that drive the performance and weight of the C-frame, and several generated solutions are compared under special consideration of the weight, the mechanical performance and the general manufacturability using SLM. The selected optimized solution then undergoes a final detailed re-design which focusses on given manufacturing restrictions. The mechanical performance of the optimized C-frame is assessed employing detailed finite element simulations by evaluating the stress and deformation state. The general manufacturability of the optimized part by SLM is demonstrated by the manufacturing of a scaled prototype. In order to enable a comparison of the new SLM solution with a classical manufacturing process, an optimized C-frame geared towards classical milling is established as well. Both solutions are compared concerning weight, mechanical performance, manufacturability and economic aspects, and it can be shown that the SLM solution offers a number of advantages that cannot be exploited when employing classical means of manufacturing. This paper may serve as an introduction to the rather complex field of additive manufacturing of load bearing structures and is an illustrated case study thereof which can be of use for engineers working in this specific field that is still the topic of global academic and industrial research.
关键词： Additive Manufacturing,C-Frame,Selective Laser Melting,Optimization,Re-Design
更新于2025-09-16 10:30:52
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A research on the surface morphology, microstructure evolution and wear property of selective laser melting Al <sub/>2</sub> O <sub/>3</sub> /P20 composites
摘要： The Al2O3/P20 composites were successfully manufactured by selective laser melting (SLM) from powder mixture of Al2O3 and P20 mold steel with different Al2O3 contents (0.5 wt%, 1 wt%, 2 wt%) in this work. The surface morphology analysis indicated that Al2O3 particles were partially or fully melted for agglomerates during the SLM process with segregating between contiguous molten tracks. The model of Al2O3 diffusing during the SLM process was built for illustrating the generated mechanism of Al2O3 agglomerates. Moreover, the densi?cation behavior of specimens became poor (the relative density declined from 99.3% to 94.2%) as the Al2O3 contents increased. The microstructure within samples had some obvious variations including coarsening martensite microstructure, tempering microstructure transformation, reverted austensite and precipitation of ?ne carbide particles. The result of Rockwll hardness test manifested that 1 wt% obtained the maximum value of 57.6 HRC, while 2 wt% had the minimum value of 45.9 HRC. Tribological test revealed that coef?cient of friction (COF) and wear rate signi?cantly declined when the Al2O3 contents were 1 wt% and 2 wt%, which emphasized the superior wear resistance property.
关键词： wear resistance,selective laser melting,Al2O3,P20 mold steel,microstructure,composite
更新于2025-09-16 10:30:52
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Influences of Horizontal and Vertical Build Orientations and Post-Fabrication Processes on the Fatigue Behavior of Stainless Steel 316L Produced by Selective Laser Melting
摘要： In this paper, the influences of build orientation and post-fabrication processes, including stress-relief, machining, and shot-peening, on the fatigue behavior of stainless steel (SS) 316L manufactured using selective laser melting (SLM) are studied. It was found that horizontally-built (XY) and machined (M) test pieces, which had not been previously studied in the literature, in both stress-relieved (SR) or non-stress-relieved (NSR) conditions show superior fatigue behavior compared to vertically-built (ZX) and conventionally-manufactured SS 316L. The XY, M, and SR (XY-M-SR) test pieces displayed fatigue behavior similar to the XY-M-NSR test pieces, implying that SR does not have a considerable effect on the fatigue behavior of XY and M test pieces. ZX-M-SR test pieces, due to their considerably lower ductility, exhibited significantly larger scatter and a lower fatigue strength compared to ZX-M-NSR samples. Shot-peening (SP) displayed a positive effect on improving the fatigue behavior of the ZX-NSR test pieces due to a compressive stress of 58 MPa induced on the surface of the test pieces. Fractography of the tensile and fatigue test pieces revealed a deeper understanding of the relationships between the process parameters, microstructure, and mechanical properties for SS 316L produced by laser systems. For example, fish-eye fracture pattern or spherical stair features were not previously observed or explained for cyclically-loaded SLM-printed parts in the literature. This study provides comprehensive insight into the anisotropy of the static and fatigue properties of SLM-printed parts, as well as the pre- and post-fabrication parameters that can be employed to improve the fatigue behavior of steel alloys manufactured using laser systems.
关键词： fracture,fatigue,selective laser melting,defect,stainless steel 316L
更新于2025-09-16 10:30:52
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Process-Structure-Properties-Performance Modeling for Selective Laser Melting
摘要： Selective laser melting (SLM) is a promising manufacturing technique where the part design, from performance and properties process control and alloying, can be accelerated with integrated computational materials engineering (ICME). This paper demonstrates a process-structure-properties-performance modeling framework for SLM. For powder-bed scale melt pool modeling, we present a diffuse-interface multiphase computational fluid dynamics model which couples Navier–Stokes, Cahn–Hilliard, and heat-transfer equations. A computationally efficient large-scale heat-transfer model is used to describe the temperature evolution in larger volumes. Phase field modeling is used to demonstrate how epitaxial growth of Ti-6-4 can be interrupted with inoculants to obtain an equiaxed polycrystalline structure. These structures are enriched with a synthetic lath martensite substructure, and their micromechanical response are investigated with a crystal plasticity model. The fatigue performance of these structures are analyzed, with spherical porelike defects and high-aspect-ratio cracklike defects incorporated, and a cycle-amplitude fatigue graph is produced to quantify the fatigue behavior of the structures. The simulated fatigue life presents trends consistent with the literature in terms of high cycle and low cycle fatigue, and the role of defects in dominating the respective performance of the produced SLM structures. The proposed ICME workflow emphasizes the possibilities arising from the vast design space exploitable with respect to manufacturing systems, powders, respective alloy chemistries, and microstructures. By digitalizing the whole workflow and enabling a thorough and detailed virtual evaluation of the causal relationships, the promise of product-targeted materials and solutions for metal additive manufacturing becomes closer to practical engineering application.
关键词： heat-transfer modeling,additive manufacturing,phase field modeling,integrated computational materials engineering,crystal plasticity,selective laser melting,micromechanical modeling
更新于2025-09-16 10:30:52
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Numerical simulation of selective laser melting temperature conduction behavior of H13 steel in different models
摘要： With considering the latent heat of melting and the temperature-dependent thermo-physical properties, a Gauss body heat source is employed to analyze the temperature field and the morphology of molten pool with a single-track and multi-track scan strategy in Substrate-Powder (SP) model, Full-Powder (FP) model and Partial-Solid model (PS), respectively. It is shown that the maximum temperature (Tmax) and maximum cooling rate (vcmax) of single-track increase with preheating temperature, while the maximum heating rate (vhmax) presenting an opposite trend. The preheating temperature has the greatest influence on the length and depth of the molten pool of SP model and the width of FP model. For the reason of heat accumulation, the Tmax of each track increases with the decrease of solid volume in the model and increases with the number of scan tracks in a multi-track scan strategy. Due to prominent thermal conductivity of SP model, heat accumulation of multi-track scanning has the smallest effect on the size of pool, but it drives the molten pool length of PS model and FP model increasing seriously. The verification experiment of SP model was in good agreement with the simulation results, proved that numerical simulation is capable of predicting the temperature field and molten pool morphology during the SLM process.
关键词： numerical simulation,H13 steel,temperature field,molten pool morphology,selective laser melting
更新于2025-09-16 10:30:52
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A brief introduction to the selective laser melting of Ti6Al4V powders by supreme-speed plasma rotating electrode process
摘要： In the present study, Ti6Al4V spherical powders were prepared by supreme-speed plasma rotating electrode process and the particle size fit log-normal distribution. The average diameter of the powders was successfully determined by a model developed in this work, suggesting that the particle size distribution is mainly affected by the rotating speed. The log-normal distribution factor of the particle size distribution maintains stable as the rotating speed ω varies. The particle size distribution indicates that the main atomization mode of Ti6Al4V under supreme-speed plasma rotating electrode process is of the characteristics of direct drop formation. The mechanical properties of the samples prepared by selective laser melting of Ti6Al4V powders were characterized, indicating that such Ti6Al4V samples with isotropy structure exhibit high yield strength and good ductility.
关键词： Atomization,Ti6Al4V,Selective laser melting,Rapid solidification,Particle size distribution,Plasma rotating electrode process
更新于2025-09-16 10:30:52
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Surface morphology evolution during pulsed selective laser melting: Numerical and experimental investigations
摘要： A novel physical model for the selective laser melting (SLM) was proposed, providing insights into the surface morphology evolution in the pulsed SLM process. Both Marangoni effect and recoil pressure, which were the prevailing driving forces for the melt flow, were incorporated in the model. It was found that the melt track was characterized by regular fish scale patterns in pulsed remelting process, due to the periodic variation of the molten pool, while the melt track exhibited with a smooth surface under a continuous laser mode. The effect of the exposure time on the surface morphology was also investigated during pulsed SLM process. It was shown that the longer exposure time could produce greater recoil pressure and sufficient molten liquid, leading to a more congested fish scale patterns. The surface defects such as distortions and breakups were strongly associated with the distribution characteristics of the powders. The partially melted particles which attached to the melt flow were the main reasons to the formation of distortions. And the formation the breakups could be attributed to the local lacking of the powders. The simulated results were in good agreement with the experimental results.
关键词： Surface morphology,Surface defects,Pulsed selective laser melting,Exposure time,Molten pool evolution
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019 - Tomsk, Russia (1a??5 October 2019)] PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019 - Surface modification of selective laser melted Ti-6Al-4V by ultrasonic impact treatment and electron beam irradiation
摘要： Changes of the surface roughness, microstructure, phase composition and microhardness of selective laser melted Ti-6Al-4V samples during electron beam irradiation and ultrasonic impact treatment were investigated by contact profilometry, optical microscopy, X-ray analysis, and hardness measurement. It was shown that electron beam irradiation and ultrasonic impact treatment of the selective laser melted Ti-6Al-4V samples smooth their surface. Significant refinement of the microstructure and TiO nanoparticles formation under ultrasonic impact treatment occur causing the increase in surface microhardness. Electron beam irradiation leads to a more significant increase in both the microhardness and thickness of the melted surface layer due to martensitic transformation.
关键词： Ti-6Al-4V,surface modification,ultrasonic impact treatment,Selective laser melting,electron beam irradiation
更新于2025-09-16 10:30:52