- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Fracture Toughness of a Hot Work Tool Steel Fabricated by Laser‐Powder Bed Fusion Additive Manufacturing
摘要： The fracture toughness of AISI H13 tool steel, additively manufactured by laser powder bed fusion (L-PBF) technique was studied. The influence of the building direction on fracture toughness was investigated on small notched bending samples heat treated according to two different thermal cycles, namely quenching and tempering (QT) and only tempering (T). The notch was electro discharge machined parallel (P//), perpendicular (P┴) and longitudinal (L) to the building direction. Both heat treatments, even if to a different extent, delete the as-built microstructure, producing secondary carbides precipitation in the martensitic matrix. The microstructure of the directly tempered parts is finer than the quenched and tempered ones. The fracture toughness increases moving from P┴ to P//. The T samples show a higher apparent fracture toughness in the P//, despite the higher hardness. Secondary cracks formation allows toughness in P// samples. This effect is more pronounced in T samples where the stronger precipitation of carbides at the prior melt boundaries promotes secondary cracks. Moreover, in P// samples the laser tracks act as barriers to crack propagation and as stress dissipators.
关键词： Laser powder bed fusion,hot work tool steel,fracture toughness,microstructure
更新于2025-09-12 10:27:22
-
Titanium for Consumer Applications || Bone regeneration on implants of titanium alloys produced by laser powder bed fusion: A review
摘要： Bone regeneration on biomaterials is a topic of increased interest due to the possibility of creating implants that existing bone can attach to. Titanium alloys are very suitable for this purpose and have been proven to be biocompatible, while also having suitable mechanical properties [1]. Moreover, titanium alloys are one of the most widely investigated materials for metal additive manufacturing (AM), which means that custom-designed implants can be manufactured reliably by AM. The AM technology best suited to this is powder bed fusion; laser powder bed fusion (LPBF) in particular holds some advantages. In this chapter, we investigate the current state of the art for the production of pure Ti and Ti6Al4V implants by LPBF, focusing on the requirements and capabilities for osseointegration. The first section discusses bone architecture and requirements for bone implants in general, identifying different requirements for different types of implants, and describing the various bone growth processes in more detail. This is followed by a section on surface structuring; the surface morphology and chemistry strongly influence the initial stages of bone growth, making it critical to the success of such implants. The next section describes porous structures, also known as lattice structures, which allow bone in-growth and attachment. This section describes various requirements for such lattices (pore size, lattice design, etc.) in terms of bone growth and summarizes what has been achieved thus far. The following section describes the mechanical properties of titanium lattice structures of various types that have been produced by LPBF. The next two sections describe in detail successful in vitro and in vivo experiments, respectively, for bone growth on LPBF titanium alloys. Finally, a discussion section summarizes the current state of the art and highlights requirements for future research efforts.
关键词： Bone regeneration,Titanium alloys,Laser powder bed fusion,Additive manufacturing,Osseointegration
更新于2025-09-12 10:27:22
-
Multi-Laser Powder Bed Fusion Benchmarking—Initial Trials with Inconel 625
摘要： Production rate is an increasingly important factor in the deployment of metal additive manufacturing (AM) throughout industry. To address the perceived low production rate of metal AM systems based on single-laser powder bed fusion (L-PBF), several companies now offer systems in which melting has been parallelised by the introduction of multiple, independently controlled laser beams. Nevertheless, a full set of studies is yet to be conducted to benchmark the efficiency of multi-laser systems and, at the same time, to verify if the mechanical properties of components are compromised due to the increase in build rate. This study addresses the described technology gaps and presents a 4-beam L-PBF system operating in “single multi” (SM) mode (SM-L-PBF) where each of the four lasers is controlled so that it melts all of a particular components’ layers and produces specimens for comparison with standard L-PBF specimens from the same machine. That is all four lasers making all of some of the parts were compared to a single-laser manufacturing all of the parts. Build parameters were kept constant throughout the manufacturing process and the material used was Inconel 625 (IN625). Stress-relieving heat treatment was conducted on As-built (AB) specimens. Both AB and heat-treated (HT) specimen sets were tested for density, microstructure, tensile strength and hardness. Results indicate that the stress-relieving heat treatment increases specimen ductility without compromising other mechanical properties. SM-L-PBF has achieved a build rate of 14 cm3/h when four 200 W lasers were used to process IN625 at a layer thickness of 30 μm. An increase in the build rate of 2.74 times (build time reduction: 63%) has been demonstrated when compared to that of L-PBF, with little to no compromises in specimen mechanical properties. The observed tensile properties exceed the American Society for Testing Materials (ASTM) requirements for IN625 (by a margin of 22 to 26% in the 0.2% offset yield strength). Average specimen hardness and grain size are in the same order as that reported in literatures. The study has demonstrated that a multi-laser AM system opens up opportunities to tackle the impasse of low build rate in L-PBF in an industrial setting and that at least when operating in single mode there is no detectable degradation in the mechanical and crystallographic characteristics of the components produced.
关键词： Multi-laser powder bed fusion,Inconel 625,Selective laser melting,Additive manufacturing,Mechanical properties
更新于2025-09-12 10:27:22
-
Temperature Profile, Bead Geometry, and Elemental Evaporation in Laser Powder Bed Fusion Additive Manufacturing Process
摘要： Powder bed fusion processes have been a focus of research in recent years. Computational models of this process have been extensively investigated. In most cases, the distribution of heat intensity over the powder bed during the laser–powder interaction is assumed to follow a Gaussian beam pattern. However, the heat distribution over the surface is a complicated process that depends on several factors such as beam quality factor, laser wavelength, etc. and must be considered to present the laser–material interaction in a way that represents the actual beam. This work presents a process in which a non-Gaussian laser beam model is used to model the temperature pro?le, bead geometry, and elemental evaporation in the powder bed process. The results are compared against those of a Gaussian beam model and also an experiment using Inconel 718 alloy. The model offers good predictions of the temperature, bead shape, and concentration of alloying elements.
关键词： Additive manufacturing,Temperature profile,Powder bed fusion,Laser powder bed fusion,Bead geometry,Non-Gaussian beam,Elemental evaporation
更新于2025-09-11 14:15:04
-
Effect of powder characteristics on production of oxide dispersion strengthened Fe 14Cr steel by laser powder bed fusion
摘要： In order to assess the potentialities of additive manufacturing in nuclear industry, Oxide Dispersion Strengthened (ODS) Fe\14Cr steels are produced by laser powder bed fusion (L-PBF). Such materials are currently manufactured by milling a Fe\14Cr atomized powder with Y2O3 and TiH2 powders. The resulting powder has a non-spherical shape being coarser than powders typically used in L-PBF equipment. The influence of powder characteristics on the processability of ODS Fe\14Cr by L-PBF are studied in details. Four different powders are used. These powders differ from size, morphology and chemical composition. Finer is the powder; wider is the process range to obtain dense samples. This phenomenon could be mitigated by transferring an amount of energy superior to 110 J.mm?3. The presence of yttrium and titanium gives columnar microstructure for ODS samples, whereas Fe\14Cr samples have stirred microstructure. Titanium and yttrium form oxides, which enlarge the melt pool and induce columnar growth.
关键词： Additive manufacturing,Powder flowability,Metal Matrix Composites (MMCs),Chemical composition,Laser Powder Bed Fusion (L-PBF),Particle size distribution
更新于2025-09-11 14:15:04
-
A cybermanufacturing and AI framework for laser powder bed fusion (LPBF) additive manufacturing process
摘要： In Laser Powder Bed Fusion (LPBF) along, more than 50 process parameters are known to affect print quality. The current state-of-the-art practice in process control only considers a small fraction of them – mainly on laser power and scanning speed affecting temperature gradient and geometry of a melting pool. This letter proposes a system-wide platform involving various machine learning principles and leveraging production data stored in the cloud. The proposed framework aims to identify process parameters that may affect print quality so that a viable process control strategy can be formulated.
关键词： Laser powder bed fusion,Metal 3D printing,Machine learning,Process monitoring
更新于2025-09-11 14:15:04
-
Pore Closure Effect of Laser Shock Peening of Additively Manufactured AlSi10Mg
摘要： This article reports on an exceptional insight provided by nondestructive X-ray tomography of the same samples before and after laser shock peening (LSP). The porosity in two additively manufactured aluminum alloy (AlSi10Mg) tensile samples before and after LSP was imaged using identical X-ray tomography settings and overlap of the data was performed for direct comparison. The results indicate clearly that near-surface pores are closed by the process, while internal pores remain unaffected. LSP has become well known as a method to improve the fatigue properties of materials, including those of additively manufactured aluminum alloys. This improvement is usually attributed to the compressive residual stress induced by the process. The additional effect of closure of near-surface pores that is illustrated in this work is of interest for additive manufacturing because additive manufacturing is not yet able to produce completely pore-free components. Since the critical pore initiating fatigue cracks are always attributed to surface or subsurface pores, the closure of these pores may play an additional role in improving the fatigue properties. While more work remains to unravel the relative importance of near-surface porosity compared to the compressive residual stress effect, this work clearly shows the effect of LSP—closing of pores near the surface. For the processing conditions demonstrated here, all pores up to 0.7 mm from the surface are closed without damaging the surface, while higher peening power results in surface damage.
关键词： additive manufacturing,laser shock peening,X-ray tomography,aluminum alloys,laser powder bed fusion
更新于2025-09-11 14:15:04
-
Scalable laser powder bed fusion processing of nitinol shape memory alloy
摘要： The authors report on pulsed laser powder bed fusion fabrication of nitinol (NiTi) shape memory materials. The authors ?rst performed single-track laser parameter sweeps to assess melt pool stability and determine energy parameters and hatch spacing for larger builds. The authors then assessed the melt pool chemistry as a function of laser energy density and build plate composition. Brittle intermetallics were found to form at the part/build plate interface for both N200 and Ti-6-4 substrates. The intermetallic formation was reduced by building on a 50Ni–50Ti substrate, but delamination still occurred due to thermal stresses upon cooling. The authors were able to overcome delamination on all substrates and fabricate macroscopic parts by building a lattice support structure, which is both compliant and controls heat transfer into the build plate. This approach will enable scalable fabrication of complex NiTi parts.
关键词： additive manufacturing,shape memory alloy,nitinol,scalable fabrication,laser powder bed fusion
更新于2025-09-11 14:15:04
-
Variation of Surface Topography in Laser Powder Bed Fusion Additive Manufacturing of Nickel Super Alloy 625
摘要： This document provides details on the files available for download in the dataset “Variation of Surface Topography in Laser Powder Bed Fusion of Nickel Super Alloy 625.” The following sections provide details on the experiments, methods, and data files. The experiment detailed in this document methodically varies part position and surface orientation relative to the build plate and relative to the recoater blade. This dataset provides surface height data for analysis and development of correlations by the greater research community.
关键词： additive manufacturing,focus variation,IN625,surface texture,surface topography,nickel super alloy 625,laser powder bed fusion
更新于2025-09-11 14:15:04
-
Influence of heat treatment under hot isostatic pressing (HIP) on microstructure of intermetallic-reinforced tool steel manufactured by laser powder bed fusion
摘要： Microstructure and properties of as-built laser powder bed fusion (LPBF) steels differ from the conventional ones, and they may contain some porosity and lack of fusion. Therefore, post-treatments, including hot isostatic pressing (HIP), are used to densify the material, and tailor the properties of the final product. Usually, HIP is performed as an operation separate from heat treatment. In the present investigation a new approach was used, in which the whole cycle of the heat treatment was carried out in HIP under pressure, and the influence of HIP on microstructure of an advanced stainless maraging tool steel manufactured by LPBF was investigated. For a comparison, a conventional steel grade of the same chemical composition, after a heat treatment at the same temperature-time conditions, was also characterized. The microstructure of the steel was investigated by means of advanced microscopy and atom probe tomography. The influence of the manufacturing route, heat treatment and HIP on microstructure, austenitic phase fraction and size distribution of precipitates was investigated, and the role of high pressure in stabilization of austenite in the microstructure was discussed. It was concluded that since HIP influences phase transformations, a fundamental understanding of the influence of HIP on microstructure is necessary, and development of new post processing regimes guaranteeing the best performance of the material is required.
关键词： Hot isostatic pressing (HIP),Atom probe tomography,Transmission electron microscopy,Maraging steel,Precipitation hardening,Laser powder bed fusion
更新于2025-09-11 14:15:04