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Single-step process of microstructural functionally graded Ti6Al4V by laser powder bed fusion additive manufacturing
摘要： The objectives of this study are: (1) to verify whether using linear heat input alone is sufficient to predict the resulting microstructure of Ti6Al4V and (2) to demonstrate the potential of single-step process of functionally graded material using powder bed fusion. In laser powder bed fusion, linear heat input is defined as the ratio of laser power to scan speed. It is a key process variable that describes the unit energy input. Therefore, linear heat input has been extensively linked with the resulting microstructure. However, review of existing studies shows that when similar linear heat input was used, a marked difference in mechanical properties exists. Using proportionally changed laser power and scan speed in five zones, functionally graded specimens were fabricated in this study. All other parameters remain the same for these zones. Variation of microstructure and hardness across the five zones were obtained. This implies that linear heat input is not sufficient to determine the resulting microstructure and mechanical properties. The amplitude of laser power and scan speed has an effect on the resulting microstructure, so they need to be separately considered in future studies.
关键词： Linear heat input,Functionally graded material,Ti6Al4V,Microstructure,Powder bed fusion
更新于2025-09-23 15:21:01
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A review of technological improvements in laser-based powder bed fusion of metal printers
摘要： Additive manufacturing (AM) is an emerging process that has been extremely improved in terms of technology and application in recent years. In this technology review, new industrial improvements in laser powder bed fusion (LPBF) of metals are discussed. LPBF has the lowest build rate among all AM processes that produce metals such as electron beam powder bed fusion, direct energy deposition, binder jetting and sheet lamination. The findings of the current research show that the most innovations and future directions of LPBF printers are toward increasing the speed of the process by using interchangeable feedstock chamber, closed-loop control powder handling, automated powder sieving, multi-layer concurrent printing, 2-axis coating and multi powder hoppers. To increase the speed of the process, the new improvements for transferring time and using fast lasers are presented. Another innovation in the building of LPBF printers is enhancing part quality by improving lasers with the shorter beam diameter, multi-lasers, uniform inert gas flow, accurate positioning systems, using high vacuum systems and using sensors and automation.
关键词： Industrial improvement,Additive manufacturing,Laser,Powder bed fusion
更新于2025-09-23 15:21:01
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Connecting Diffraction-Based Strain with Macroscopic Stresses in Laser Powder Bed Fused Ti-6Al-4V
摘要： The laser powder bed fusion (LPBF) production process often results in large residual stress (RS) in the parts. Nondestructive techniques to determine RS are badly needed. However, a reliable quantification of macro-RS (i.e., stress at the component level) by means of diffraction-based techniques is still a great challenge, because the link between diffraction-based strain and macro-RS is not trivial. In this study, we experimentally determine (by means of in-situ synchrotron radiation diffraction) this link for LPBF Ti-6Al-4V. We compare our results with commonly used models to determine the so-called diffraction elastic constants (DECs). We show that LPBF materials possess different DECs than wrought alloys, simply because their microstructural and mechanical properties are different. We also show that the existing models can be used to calculate DECs only if high accuracy of the RS values is not required. If the peculiarities of the microstructure have to be taken into account (as is the case of additively manufactured materials), a radically new approach is desirable.
关键词： synchrotron radiation diffraction,Laser powder bed fusion,residual stress,Ti-6Al-4V,diffraction elastic constants
更新于2025-09-23 15:21:01
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Preliminary Characterization of Glass/Alumina Composite Using Laser Powder Bed Fusion (L-PBF) Additive Manufacturing
摘要： Powder bed fusion (PBF) additive manufacturing (AM) is currently used to produce high-efficiency, high-density, and high-performance products for a variety of applications. However, existing AM methods are applicable only to metal materials and not to high-melting-point ceramics. Here, we develop a composite material for PBF AM by adding Al2O3 to a glass material using laser melting. Al2O3 and a black pigment are added to a synthesized glass frit for improving the composite strength and increased laser-light absorption, respectively. Our sample analysis shows that the glass melts to form a composite when the mixture is laser-irradiated. To improve the sintering density, we heat-treat the sample at 750°C to synthesize a high-density glass frit composite. As per our X-ray diffraction (XRD) analysis to confirm the reactivity of the glass frit and Al2O3, we find that no reactions occur between glass and crystalline Al2O3. Moreover, we obtain a high sample density of ≥95% of the theoretical density. We also evaluate the composite’s mechanical properties as a function of the Al2O3 content. Our approach facilitates the manufacturing of ceramic 3D structures using glass materials through PBF AM and affords the benefits of reduced process cost, improved performance, newer functionalities, and increased value addition.
关键词： density,powder bed fusion,additive manufacturing,mechanical property,3D printing,glass/alumina composite
更新于2025-09-23 15:21:01
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Computational Assessment of Thermokinetics and Associated Microstructural Evolution in Laser Powder Bed Fusion Manufacturing of Ti6Al4V Alloy
摘要： Although most of the near non-equilibrium microstructures of alloys produced by laser powder bed fusion (LPBF) additive manufacturing (AM) are being reported at a rapid rate, the accountable thermokinetics of the entire process have rarely been studied. In order to exploit the versatility of this AM process for the desired properties of built material, it is crucial to understand the thermokinetics associated with the process. In light of this, a three-dimensional thermokinetic model based on the finite element method was developed to correlate with the microstructure evolved in additively manufactured Ti6Al4V alloy. The computational model yielded the thermal patterns experienced at given location while building a single layer through multiple laser scans and a whole part through multiple layers above it. X-ray analysis of the resultant microstructure confirmed the presence of acicular martensitic (α′) phase of (002) texture within the build-plane. Computationally predicted magnitude of the thermal gradients within the additively manufactured Ti6Al4V alloy in different directions (X, Y, and Z) facilitated the understanding about the evolution of grain morphology and orientation of acicular martensite in prior β grains. The scanning electron microscopy observations of the alloy revealed the distinct morphology of phase precipitated within the martensitic phase, whose existence was, in turn, understood through predicted thermal history.
关键词： Thermokinetics,Additive manufacturing,Microstructural evolution,Laser powder bed fusion,Ti6Al4V alloy
更新于2025-09-23 15:21:01
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Direct observation of pore formation mechanisms during LPBF additive manufacturing process and high energy density laser welding
摘要： Laser powder bed fusion (LPBF) is a 3D printing technology that can print parts with complex geometries that are unachievable by conventional manufacturing technologies. However, pores formed during the printing process impair the mechanical performance of the printed parts, severely hindering their widespread application. Here, we report six pore formation mechanisms that were observed during the LPBF process. Our results reconfirm three pore formation mechanisms - keyhole induced pores, pore formation from feedstock powder and pore formation along the melting boundary during laser melting from vaporization of a volatile substance or an expansion of a tiny trapped gas. We also observe three new pore formation mechanisms: (1) pore trapped by surface fluctuation, (2) pore formation due to depression zone fluctuation when the depression zone is shallow and (3) pore formation from a crack. The results presented here provide direct evidence and insight into pore formation mechanisms during the LPBF process, which may guide the development of pore elimination/mitigation approaches. Since certain laser processing conditions studied here are similar to the situations in high energy density laser welding, the results presented here also have implications for laser welding.
关键词： Pore formation,Laser powder bed fusion,X-ray imaging,Laser welding,Additive manufacturing
更新于2025-09-23 15:21:01
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Microstructure of a Tia??50??wt% Ta alloy produced via laser powder bed fusion
摘要： Ti–Ta alloys have been widely studied for biomedical applications due to their high biocompatibility and corrosion resistance. In this work, nearly fully dense and in situ alloyed Ti–50 wt% Ta samples were fabricated by the laser powder bed fusion (LPBF) of mechanically mixed powders. With increased exposure time, and thereby increased laser energy density, insoluble Ta particles were almost dissolved, and a Ti–50 wt% Ta alloy was formed. Cellular and dendritic structures were formed due to constitutional undercooling, which was caused by the high cooling rate of LPBF process. Both retained β phases and α″ phases were observed in the LPBFed Ti–50 wt% Ta alloy. The α″ phase was found at the boundary of the cellular structures, where the tantalum content was not high enough to suppress the bcc lattice transition completely but could suppress the β phase → α′ phase transition.
关键词： Cellular and dendritic structures,Phase transformation,Ti–Ta alloys,Laser powder bed fusion,Microsegregation
更新于2025-09-23 15:21:01
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A Quantitative Approach To Assess High Temperature Flow Properties Of A Pa 12 Powder For Laser Sintering
摘要： In order to consider thermal conditions involved in laser sintering (LS), the effect of temperature on the flow properties of a polyamide 12 powder was assessed. Shear tests were carried out at temperatures from ambient up to values close to the melting temperature of the polymer. The measurement method provides quantitative descriptors of powder flowability. Experiments indicate that flowability significantly deteriorates when temperature rises and approaches a value of about 20°C lower than the melting temperature. The spreading process may be hindered by natural agglomeration of the material. A simple analysis based on the extrapolation of the bulk flow properties at zero consolidation shows that agglomeration is excluded in the temperature range between 100 and 140°C. This turns out to be the range in which it is known that the material can be used safely for LS applications.
关键词： powder bed fusion,powder flow,flow function,high temperature,agglomeration
更新于2025-09-23 15:19:57
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Production Tools Made by Additive Manufacturing Through Laser-based Powder Bed Fusion; Herstellung von Produktionswerkzeugen mittels additiver Fertigung durch laserbasiertes Pulverbettschmelzen;
摘要： This paper deals with the design and production of stamping tools and dies for sheet metal components and injection molds for plastic components. Laser-based Powder Bed Fusion (LPBF) is the additive manufacturing method used in this investigation. Solid and topology optimized stamping tools and dies 3D-printed in DIN 1.2709 (maraging steel) by LPBF are approved/certified for stamping of up to 2-mm thick hot-dip galvanized DP600 (dual-phase steel sheet). The punch in a working station in a progressive die used for stamping of 1-mm thick hot-dip galvanized DP600 is 3D-printed in DIN 1.2709, both with a honeycomb inner structure and after topology optimization, with successful results. 3D printing results in a significant lead time reduction and improved tool material efficiency. The cost of 3D-printed stamping tools and dies is higher than the cost of those made conventionally. The core (inserts) of an injection mold is 3D-printed in DIN 1.2709, conformal cooling optimized and 3D-printed in Uddeholm AM Corrax, and compared with the same core made conventionally. The cooling and cycle time can be improved, if the injection molding core (inserts) is optimized and 3D-printed in Uddeholm AM Corrax. This paper accounts for the results obtained in the above-mentioned investigations.
关键词： Design,Injection molding,Tools,Stamping,Powder bed fusion,Optimization,Topology,Metal,Additive manufacturing,Cooling
更新于2025-09-23 15:19:57
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Design of a laser control system with continuously variable power and its application in additive manufacturing
摘要： system adjusts the laser position. This paper will also discuss the development and advanced laser control techniques enable a higher level of control over the processing process relies heavily on understanding and controlling the thermodynamics of the polymer melt temperatures and lead to more uniform components. Currently, there are no commercial options for a laser power controller that allows continuously variable power to be used as a galvanometer process. One of the biggest challenges SLS faces is lack of adequate process control, which leads to comparatively high component variations. It has been shown that implementing more manufacturing processes with applications in aerospace, biomedical, tooling, prototyping, and beyond. SLS is capable of creating unique, functional parts with little waste and no tooling by using a high-powered laser to selectively melt powdered polymer into desired shapes. This Selective laser sintering (SLS) is one of the most popular industrial polymer additive implementation of a galvanometer controller solution that works in conjunction with an off-the-shelf unit to enable this crucial functionality and will present results showing that, when applied laser sintering (SLS) additive manufacturing. The work contained in this paper is a continuation of previous work that developed a method of controlling laser power is SLS in order to improve the consistency of components built [1]. This previous effort was capable of improving temperature uniformity of SLS components by up to 57% and strength uniformity by up to 45%. Powder Bed Fusion
关键词： Laser Control,Additive Manufacturing,Surrogate Modeling,Powder Bed Fusion,Process Control
更新于2025-09-23 15:19:57