scholarly journals Processability of Atypical WC-Co Composite Feedstock by Laser Powder-Bed Fusion

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 50 ◽  
Author(s):  
Mohaimen Al-Thamir ◽  
D. Graham McCartney ◽  
Marco Simonelli ◽  
Richard Hague ◽  
Adam Clare
Keyword(s):  
Laser Scanning ◽  
Single Layer ◽  
Scanning Speed ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Future Production ◽  
Laser Scanning Speed ◽  
First Time ◽  
Am Processes

Processing of tool materials for cutting applications presents challenges in additive manufacturing (AM). Processes must be carefully managed in order to promote the formation of favourable high-integrity ‘builds’. In this study, for the first time, a satelliting process is used to prepare a WCM-Co (12 wt.% Co) composite. Melting trials were undertaken to evaluate the consolidation behaviour of single tracks within a single layer. Tracks with continuous and relatively uniform surface morphology were obtained. These features are essential for high-quality AM builds in order to encourage good bonding between subsequent tracks within a layer which may reduce porosity within a 3D deposition. This study elucidates the formation of track irregularities, melting modes, crack sensitivity, and balling as a function of laser scanning speed and provides guidelines for future production of WCM-Co by laser powder-bed fusion.

scholarly journals Microstructure, Solidification Texture, and Thermal Stability of 316 L Stainless Steel Manufactured by Laser Powder Bed Fusion

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 643 ◽  
Author(s):  
Pavel Krakhmalev ◽  
Gunnel Fredriksson ◽  
Krister Svensson ◽  
Igor Yadroitsev ◽  
Ina Yadroitsava ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Stainless Steel ◽  
Laser Scanning ◽  
Scanning Speed ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
316 L Stainless Steel ◽  
Solidification Texture ◽  
Thermal Stability Of

This article overviews the scientific results of the microstructural features observed in 316 L stainless steel manufactured by the laser powder bed fusion (LPBF) method obtained by the authors, and discusses the results with respect to the recently published literature. Microscopic features of the LPBF microstructure, i.e., epitaxial nucleation, cellular structure, microsegregation, porosity, competitive colony growth, and solidification texture, were experimentally studied by scanning and transmission electron microscopy, diffraction methods, and atom probe tomography. The influence of laser power and laser scanning speed on the microstructure was discussed in the perspective of governing the microstructure by controlling the process parameters. It was shown that the three-dimensional (3D) zig-zag solidification texture observed in the LPBF 316 L was related to the laser scanning strategy. The thermal stability of the microstructure was investigated under isothermal annealing conditions. It was shown that the cells formed at solidification started to disappear at about 800 °C, and that this process leads to a substantial decrease in hardness. Colony boundaries, nevertheless, were quite stable, and no significant grain growth was observed after heat treatment at 1050 °C. The observed experimental results are discussed with respect to the fundamental knowledge of the solidification processes, and compared with the existing literature data.

scholarly journals Optimization of Laser Powder Bed Fusion Processing Using a Combination of Melt Pool Modeling and Design of Experiment Approaches: Density Control

2019 ◽  
Vol 3 (1) ◽  
pp. 21 ◽  
Author(s):  
Morgan Letenneur ◽  
Alena Kreitcberg ◽  
Vladimir Brailovski
Keyword(s):  
Scanning Speed ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Density Prediction ◽  
Melt Pool ◽  
Density Control ◽  
Pool Model ◽  
Conventional Material ◽  
Prediction Approach

A simplified analytical model of the laser powder bed fusion (LPBF) process was used to develop a novel density prediction approach that can be adapted for any given powder feedstock and LPBF system. First, calibration coupons were built using IN625, Ti64 and Fe powders and a specific LPBF system. These coupons were manufactured using the predetermined ranges of laser power, scanning speed, hatching space, and layer thickness, and their densities were measured using conventional material characterization techniques. Next, a simplified melt pool model was used to calculate the melt pool dimensions for the selected sets of printing parameters. Both sets of data were then combined to predict the density of printed parts. This approach was additionally validated using the literature data on AlSi10Mg and 316L alloys, thus demonstrating that it can reliably be used to optimize the laser powder bed metal fusion process.

Formability of the Layer Additive Ceramic Part

2008 ◽  
Vol 594 ◽  
pp. 241-248 ◽  
Author(s):  
Fwu Hsing Liu ◽  
Yunn Shiuan Liao ◽  
Hsiu Ping Wang
Keyword(s):  
Surface Roughness ◽  
Laser Scanning ◽  
Selective Laser Sintering ◽  
Single Layer ◽  
Dimensional Accuracy ◽  
Scanning Speed ◽  
Laser Sintering ◽  
Single Line ◽  
Laser Scanning Speed ◽  
Silica Slurry

The material in powder state has long been used by selective laser sintering (SLS) for making rapid prototyping (RP) parts. A new approach to fabricate smoother surface roughness RP parts of ceramic material from slurry-sate has been developed in this study. The silica slurry was successfully laser-gelling in a self-developed laser sintering equipment. In order to overcome the insufficient bonding strength between layers, a strategy is proposed to generate ceramic parts from a single line, a single layer, to multi-layers of gelled cramic in this paper. It is found that when the overlap of each single line is 25% and the over-gel between layers is 30%, stronger and more accurate dimensional parts can be obtained under a laser power of 15W, a laser scanning speed of 250 mm/s, and a layer thickness of 0.1 mm. The 55:45 wt. % of the proportion between the silica powder and silica solution results in suitable viscosity of the ceramic slurries without precipitation. Furthermore, the effects of process parameters for the dimensional accuracy and surface roughness of the gelled parts are investigated and appropriate parameters are obtained.

scholarly journals In situ microstructure analysis of Inconel 625 during laser powder bed fusion

2021 ◽  
Author(s):  
Felix Schmeiser ◽  
Erwin Krohmer ◽  
Christian Wagner ◽  
Norbert Schell ◽  
Eckart Uhlmann ◽  
...  
Keyword(s):  
Laser Power ◽  
Scanning Speed ◽  
High Energy ◽  
Mechanical Anisotropy ◽  
Ex Situ ◽  
Inconel 625 ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed

AbstractLaser powder bed fusion is an additive manufacturing process that employs highly focused laser radiation for selective melting of a metal powder bed. This process entails a complex heat flow and thermal management that results in characteristic, often highly textured microstructures, which lead to mechanical anisotropy. In this study, high-energy X-ray diffraction experiments were carried out to illuminate the formation and evolution of microstructural features during LPBF. The nickel-base alloy Inconel 625 was used for in situ experiments using a custom LPBF system designed for these investigations. The diffraction patterns yielded results regarding texture, lattice defects, recrystallization, and chemical segregation. A combination of high laser power and scanning speed results in a strong preferred crystallographic orientation, while low laser power and scanning speed showed no clear texture. The observation of a constant gauge volume revealed solid-state texture changes without remelting. They were related to in situ recrystallization processes caused by the repeated laser scanning. After recrystallization, the formation and growth of segregations were deduced from an increasing diffraction peak asymmetry and confirmed by ex situ scanning transmission electron microscopy. Graphical Abstract

scholarly journals Qualification of a Ni–Cu Alloy for the Laser Powder Bed Fusion Process (LPBF): Its Microstructure and Mechanical Properties

2020 ◽  
Vol 10 (10) ◽  
pp. 3401 ◽  
Author(s):  
Iris Raffeis ◽  
Frank Adjei-Kyeremeh ◽  
Uwe Vroomen ◽  
Elmar Westhoff ◽  
Sebastian Bremen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Scanning Speed ◽  
Tensile Tests ◽  
Industrial Applications ◽  
Fusion Process ◽  
Material Base ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Significant Difference

As researchers continue to seek the expansion of the material base for additive manufacturing, there is a need to focus attention on the Ni–Cu group of alloys which conventionally has wide industrial applications. In this work, the G-NiCu30Nb casting alloy, a variant of the Monel family of alloys with Nb and high Si content is, for the first time, processed via the laser powder bed fusion process (LPBF). Being novel to the LPBF processes, optimum LPBF parameters were determined, and hardness and tensile tests were performed in as-built conditions and after heat treatment at 1000 °C. Microstructures of the as-cast and the as-built condition were compared. Highly dense samples (99.8% density) were achieved after varying hatch distance (80 µm and 140 µm) with scanning speed (550 mm/s–1500 mm/s). There was no significant difference in microhardness between varied hatch distance print sets. Microhardness of the as-built condition (247 HV0.2) exceeded the as-cast microhardness (179 HV0.2.). Tensile specimens built in vertical (V) and horizontal (H) orientations revealed degrees of anisotropy and were superior to conventionally reported figures. Post heat treatment increased ductility from 20% to 31% (V), as well as from 16% to 25% (H), while ultimate tensile strength (UTS) and yield strength (YS) were considerably reduced.

scholarly journals Dual-Laser PBF-LB Processing of a High-Performance Maraging Tool Steel FeNiCoMoVTiAl

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4251
Author(s):  
Gregor Graf ◽  
Niki Nouri ◽  
Stefan Dietrich ◽  
Frederik Zanger ◽  
Volker Schulze
Keyword(s):  
Tool Steel ◽  
High Performance ◽  
Laser Scanning ◽  
Calibration Procedure ◽  
Functionally Graded ◽  
Material Structure ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Dual Laser

As part of an international research project (HiPTSLAM), the development and holistic processing of high-performance tool steels for AM is a promising topic regarding the acceptance of the laser powder bed fusion (PBF-LB) technology for functionally optimized die, forming and cutting tools. In a previous work, the newly developed maraging tool steel FeNiCoMoVTiAl was qualified to be processed by laser powder bed fusion (PBF-LB) with a material density of more than 99.9% using a suitable parameter set. To exploit further optimization potential, the influence of dual-laser processing strategies on the material structure and the resulting mechanical properties was investigated. After an initial calibration procedure, the build data were modified so that both lasers could be aligned to the same scanning track with a defined offset. A variation of the laser-based post-heating parameters enabled specific in-situ modifications of the thermal gradients compared to standard single-laser scanning strategies, leading to corresponding property changes in the produced material structure. An increase in microhardness of up to 15% was thus obtained from 411 HV up to 471 HV. The results of the investigation can be used to derive cross-material optimization potential to produce functionally graded high-performance components on PBF-LB systems with synchronized multi-laser technology.

scholarly journals Fused Filament Fabrication of NiTi Components and Hybridization with Laser Powder Bed Fusion for Filigree Structures

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4399
Author(s):  
Johannes Abel ◽  
Anne Mannschatz ◽  
Robert Teuber ◽  
Bernhard Müller ◽  
Omar Al Noaimy ◽  
...  
Keyword(s):  
Fine Fraction ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Fused Filament Fabrication ◽  
New Production ◽  
Decomposition Products ◽  
Powder Bed ◽  
Design Options ◽  
Am Processes ◽  
Powder Fraction

The present study introduces an approach to the powder metallurgical shaping of a pseudo-elastic nickel–titanium (NiTi 44 alloy) combining two different additive manufacturing (AM) processes, namely fused filament fabrication (FFF) and laser powder bed fusion (LPBF), by manufacturing filigree structures on top of sintered FFF parts. Both processes start with commercial gas atomized NiTi powder, which is fractionated into two classes. Using the fine fraction with particle sizes <15 µm, robust thermoplastic filaments based on a non-commercial binder system were produced and processed to different auxetic and non-auxetic geometries employing a commercial standard printer. FTIR analysis for thermal decomposition products was used to develop a debinding regime. After sintering, the phase transformation austenite/martensite was characterized by DSC in as sintered and annealed state. Precipitates resulting from residual impurities were detected by micrographs and XRD. They led to an increased transformation temperature. Adjusting the oxygen and carbon content in the alloy remains a challenging issue for powder metallurgical processed NiTi alloys. Filigree lattice structures were built onto the surfaces of the sintered FFF parts by LPBF using the coarser powder fraction (15–45 µm). A good material bond was formed, resulting in the first known NiTi hybrid, which introduces new production and design options for future applications.

scholarly journals Mesoscopic simulation of overlapping behavior in laser powder bed additive manufacturing

2021 ◽  
Author(s):  
Pan Lu ◽  
Liu Tong ◽  
Wang Wen-hao ◽  
Gao Yu ◽  
Zhang Cheng-lin ◽  
...  
Keyword(s):  
Energy Density ◽  
Molten Pool ◽  
Laser Power ◽  
Laser Scanning ◽  
Flow Behavior ◽  
Pure Copper ◽  
Scanning Speed ◽  
Powder Bed ◽  
Volume Energy ◽  
Laser Scanning Speed

Abstract The prediction of the flow behavior of Metal micro-molten pool is prerequisite for high-quality Laser Powder Bed Fusion (L-PBF). In this study, mesoscopic scale numerical simulation modelling for L-PBF process was used to help understand the melting process of pure copper micro-melt pool.In this study, the orthogonal test was designed to study the influence of laser power, laser scanning velocity, hatching space on the flow behavior of molten pool and the overlapping rate of adjacent molten tracks. The results shows that laser scanning speed has the greatest influence on both the size and overlapping rate of the molten pool, and the overall trend was that the size of molten pool continues to increase as the volume energy density increases, and the maximum molten pool size was 243.6um × 110um with volume energy density 370.037 J/mm3, overlapping rate of adjacent molten tracks was 48.84% with volume energy density 285.71 J/mm3. The optimized pure copper laser process parameters were obtained: laser power 300 KW, laser scanning speed 500 mm/s, hatching space 0.07mm, overlapping rate 48.84%.

Sign in / Sign up

Export Citation Format

Share Document