Influence of particle size distribution and morphology on the properties of the powder feedstock as well as of AlSi10Mg parts produced by laser powder bed fusion (LPBF)

2020 ◽  
Vol 34 ◽  
pp. 101286 ◽  
Author(s):  
Kirstin Riener ◽  
Nikolaj Albrecht ◽  
Stefan Ziegelmeier ◽  
Robert Ramakrishnan ◽  
Lukas Haferkamp ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Powder Feedstock

scholarly journals Effect of Particle Size Distribution on Laser Powder Bed Fusion Manufacturability of Copper

2021 ◽  
Author(s):  
Massimiliano Bonesso ◽  
Pietro Rebesan ◽  
Claudio Gennari ◽  
Simone Mancin ◽  
Razvan Dima ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Physical And Mechanical Properties ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Cooling Channels ◽  
Scan Speed

AbstractOne of the major benefits of the Laser Powder Bed Fusion (LPBF) technology is the possibility of fabrication of complex geometries and features in only one-step of production. In the case of heat exchangers in particular, this is very convenient for the fabrication of conformal cooling channels which can improve the performance of the heat transfer capability. Yet, obtaining dense copper parts printed via LPBF presents two major problems: the high reflectivity of 1 μm (the wavelength of commonly used laser sources) and the high thermal conductivity of copper that limits the maximum local temperature that can be attained. This leads to the formation of porous parts.In this contribution, the influence of the particle size distribution of the powder on the physical and mechanical properties of parts produced via LPBF is studied. Three copper powders lots with different particle size distributions are used in this study. The effect on densification from two laser scan parameters (scan speed and hatching distance) and the influence of contours scans on the lateral surface roughness is reported. Subsequently, samples manufactured with the optimal process parameters are tested for thermal and mechanical properties evaluation.

scholarly journals Evaluation of Inconel 718 Metallic Powder to Optimize the Reuse of Powder and to Improve the Performance and Sustainability of the Laser Powder Bed Fusion (LPBF) Process

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1538
Author(s):  
Konrad Gruber ◽  
Irina Smolina ◽  
Marcin Kasprowicz ◽  
Tomasz Kurzynowski
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Inconel 718 ◽  
Chemical Properties ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Laser Absorption ◽  
Multiple Uses

In this paper, a detailed assessment of Inconel 718 powder, with varying degrees of degradation due to repeated use in the Laser Powder Bed Fusion (LPBF) process, has been undertaken. Four states of IN718 powder (virgin, used, overflow and spatter) were characterized in terms of their morphology, flowability and physico-chemical properties. Studies showed that used and overflow powders were almost identical. The fine particle-size distribution of the virgin powder, in which 50% of particles were found to be below the nominal particle-size distribution (PSD), was recognized as the main reason for its lower flowability and the main cause of the differentiation between virgin, used and overflow powders. Only spatter powder was found to be degraded enough to preclude its direct LPBF reuse. The oxygen content in the spatter powder exceeded the limit value for IN718 by 290 ppm, and aluminum oxide spots were found on the spatter particles surfaces. Laser absorption analysis showed 10 pp higher laser absorption compared to the other powders. The results of evaluation showed that IN718 powder is resistant to multiple uses in the LPBF process. Due to the low degradation rate of IN718 powder, overflow powder can be re-enabled for multiple uses with a proper recycling strategy.

scholarly journals Plasma Spheroidisation of Irregular Ti6Al4V Powder for Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1763
Author(s):  
Nthateng Nkhasi ◽  
Willie du Preez ◽  
Hertzog Bissett
Keyword(s):  
Particle Size ◽  
Additive Manufacturing ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Metal Powder ◽  
Weight Ratio ◽  
High Strength ◽  
Powder Bed Fusion ◽  
Metal Powders ◽  
Powder Bed

Metal powders suitable for use in powder bed additive manufacturing processes should ideally be spherical, dense, chemically pure and of a specified particle size distribution. Ti6Al4V is commonly used in the aerospace, medical and automotive industries due to its high strength-to-weight ratio and excellent corrosion resistance properties. Interstitial impurities in titanium alloys have an impact upon mechanical properties, particularly oxygen, nitrogen, hydrogen and carbon. The plasma spheroidisation process can be used to spheroidise metal powder consisting of irregularly shaped particles. In this study, the plasma spheroidisation of metal powder was performed on Ti6Al4V powder consisting of irregularly shaped particles. The properties of the powder relevant for powder bed fusion that were determined included the particle size distribution, morphology, particle porosity and chemical composition. Conclusions were drawn regarding the viability of using this process to produce powder suitable for additive manufacturing.

scholarly journals Reuse of Grade 23 Ti6Al4V Powder during the Laser-Based Powder Bed Fusion Process

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1700
Author(s):  
Ryan Harkin ◽  
Hao Wu ◽  
Sagar Nikam ◽  
Justin Quinn ◽  
Shaun McFadden
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Compositional Analysis ◽  
Powder Bed Fusion ◽  
Property Variation ◽  
Powder Bed ◽  
Melt Pool ◽  
Powder Particles ◽  
Powder Recycling

Titanium alloy powder used for laser-based powder bed fusion (L-PBF) process is costly. One of the solutions is the inclusion of a powder recycling strategy, allowing unused or exposed powder particles to be recuperated post manufacture, replenished and used for future builds. However, during a L-PBF process, powder particles are exposed to high levels of concentrated energy from the laser. Particularly those in close proximity to the melt pool, leading to the formation of spatter and agglomerated particles. These particles can settle onto the powder bed, which can then influence the particle size distribution and layer uniformity. This study analysed extra-low interstitial (ELI) Ti6Al4V (Grade 23) powder when subjected to nine recycle iterations, tracking powder property variation across the successive recycling stages. Characterisation included chemical composition focusing upon O, N, and H content, particle size distribution, morphology and tapped and bulk densities. On review of the compositional analysis, the oxygen content exceeded the 0.13% limit for the ELI grade after 8 recycles, resulting in the degradation from Grade 23 level.

scholarly journals Tailoring hydroxyapatite microspheres by spray-drying for powder bed fusion feedstock

2021 ◽  
Author(s):  
Pedro Navarrete-Segado ◽  
Christine Frances ◽  
David Grossin ◽  
Mallorie Tourbin
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Spray Drying ◽  
Laser Processing ◽  
Operating Conditions ◽  
Air Pressure ◽  
Final Particle ◽  
Powder Bed ◽  
Powder Feedstock

The present work deals with a study on the physical characteristics of hydroxyapatite microspheres produced by spray-drying process through different operating conditions. Obtained hydroxyapatite microspheres will be used as powder feedstock in powder bed selective laser processing additive manufacturing technologies where the flowability and the particle size distribution of the powder feedstock is of special importance. Spray air pressure and solid content of the slurries were the most influent parameters to control the final particle size distribution, while higher air pressure and temperatures gave the higher process recovery rate. The use of polyvinyl alcohol as organic binder increased the granules strength. The produced hydroxyapatite microspheres were found to fulfil the powder bed selective laser processing feedstock requirements, keeping the physico-chemical properties of the material. These promising results confirm the use of a spray dryer as an efficient method for the production of hydroxyapatite microspheres for powder bed selective laser processing.

A SIMULATION STUDY ON THE EFFECT OF PARTICLE SIZE DISTRIBUTION ON THE PRINTED GEOMETRY IN SELECTIVE LASER MELTING

2021 ◽  
pp. 1-14
Author(s):  
Vaishak Ramesh Sagar ◽  
Samuel Lorin ◽  
Johan Göhl ◽  
Johannes Quist ◽  
Christoffer Cromvik ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Layer Thickness ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
Powder Bed ◽  
Mean Particle Size ◽  
Final Layer ◽  
Effect Of Particle Size

Abstract Selective laser melting (SLM) process is a powder bed fusion additive manufacturing process that finds applications in aerospace and medical industries for its ability to produce complex geometry parts. As the raw material used is in powder form, particle size distribution (PSD) is a significant characteristic that influences the build quality in turn affecting the functionality and aesthetics aspects of the product. This paper investigates the effect of PSD on the printed geometry for 316L stainless steel powder, where three coupled in-house simulation tools based on Discrete Element Method (DEM), Computational Fluid Dynamics (CFD), and Structural Mechanics are employed. DEM is used for simulating the powder bed distribution based on the different powder PSD. The CFD is used as a virtual testbed to determine thermal parameters such as heat capacity and thermal conductivity of the powder bed viewed as a continuum. The values found as a stochastic function of the powder distribution is used to analyse the effect on the melted zone and deformation using Structural Mechanics. Results showed that mean particle size and PSD had a significant effect on the packing density, melt pool layer thickness, and the final layer thickness after deformation. Specifically, a narrow particle size distribution with smaller mean particle size and standard deviation produced solidified final layer thickness closest to nominal layer thickness. The proposed simulation approach and the results will catalyze in development of geometry assurance strategies to minimize the effect of particle size distribution on the geometric quality of the printed part.

scholarly journals Effect of the Process Atmosphere Composition on Alloy 718 Produced by Laser Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1254
Author(s):  
Camille Pauzon ◽  
Andreas Markström ◽  
Sophie Dubiez-Le Goff ◽  
Eduard Hryha
Keyword(s):  
Powder Bed Fusion ◽  
Alloy 718 ◽  
Oxygen Level ◽  
Laser Powder Bed Fusion ◽  
Oxygen Loss ◽  
Powder Bed ◽  
Powder Feedstock ◽  
Traditional Manufacturing ◽  
Kinetic Calculations ◽  
Process Atmosphere

The detrimental effect of nitrogen and oxygen when it comes to the precipitation of the strengthening γ’’ and γ’ phases in Alloy 718 is well-known from traditional manufacturing. Hence, the influence of the two processing atmospheres, namely argon and nitrogen, during the laser powder bed fusion (L-PBF) of Alloy 718 parts was studied. Regardless of the gas type, considerable losses of both oxygen of about 150 ppm O2 (≈30%) and nitrogen on the level of around 400 ppm N2 (≈25%) were measured in comparison to the feedstock powder. The utilization of nitrogen as processing atmosphere led to a slightly higher nitrogen content in the as-built material—about 50 ppm—compared to the argon atmosphere. The presence of the stable nitrides and Al-rich oxides observed in the as-built material was related to the transfer of these inclusions from the nitrogen atomized powder feedstock to the components. This was confirmed by dedicated analysis of the powder feedstock and supported by thermodynamic and kinetic calculations. Rapid cooling rates were held responsible for the limited nitrogen pick-up. Oxide dissociation during laser–powder interaction, metal vaporization followed by oxidation and spatter generation, and their removal by processing atmosphere are the factors describing an important oxygen loss during L-PBF. In addition, the reduction of the oxygen level in the process atmosphere from 500 to 50 ppm resulted in the reduction in the oxygen level in as-built component by about 5%.

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