Degradation of AlSi10Mg powder during laser based powder bed fusion processing

Raza, Ahmad; Fiegl, Tobias; Hanif, Imran; Markström, Andreas; Franke, Martin; Körner, Carolin; Hryha, Eduard

doi:10.1016/j.matdes.2020.109358

Cited by 42 publications

(25 citation statements)

References 30 publications

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“…Several previous studies have explored the effects of powder reuse on factors of chemistry and impurity content. 19,23,47 In the present study, the amount of Fe and Mg in the alloy was measured using inductively coupled plasma mass spectrometry for all 8 build plates (Fig. 11b), with only seemingly minor and inconsistent fluctuations.…”

Section: Effect Of Powder Reusementioning

confidence: 73%

“…36 Moisture in powder can cause porosity in AlSi10Mg associated with elevated levels of hydrogen and oxygen content. 23,35,48 The oxygen and hydrogen content of four build plates, obtained from LECOÒ analysis, 49 is presented in Fig. 11c.…”

Section: Effect Of Powder Reusementioning

confidence: 99%

“…19 Porosity in AM metals, formed by keyholing, lack-of-fusion, packing gap porosity, 20 or pre-existing pores in the source powder, is often dependent on the energy density 21 determined by scan speed 22 and laser power. The size distribution of the powder and powder chemistry, also play an important role; 18,23 these factors are influenced by powder reuse. When increased porosity is induced by powder reuse, it is expected to have a deleterious effect on mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

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High-Throughput Statistical Interrogation of Mechanical Properties with Build Plate Location and Powder Reuse in AlSi10Mg

Carroll

Exil

DeJong

et al. 2021

JOM

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Additive manufacturing (AM) allows agile, rapid manufacturing of geometrically complex components that would otherwise be impossible through traditional manufacturing methods. With this maturing manufacturing technology comes the need to adopt testing methods that are commensurate with the speed of additive manufacturing and take advantage of its geometric flexibility. High-throughput tensile testing (HTT) is a technique that allows a large number of tensile bars to be tested in a short amount of time. In the present study, HTT is used to evaluate AM AlSi10Mg produced using powder bed fusion with a Renishaw AM250 machine. Three parameters were varied in this study: (1) powder reuse history, (2) location on the build plate, and (3) size of the tensile specimen. For all parameter combinations, at least 22 specimens were tested; in several cases, over 40 were tested. This large dataset, consisting of over 500 tensile tests, permits Weibull statistical analysis and provides sufficient fidelity to isolate subtle trends that would have likely been missed in smaller, traditional datasets. The observed trends are rationalized in terms of the role of porosity and surface crust on mechanical response.

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Section: Effect Of Powder Reusementioning

confidence: 73%

Section: Effect Of Powder Reusementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

High-Throughput Statistical Interrogation of Mechanical Properties with Build Plate Location and Powder Reuse in AlSi10Mg

Carroll

Exil

DeJong

et al. 2021

JOM

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“…Another unclear aspect of EBM is the spatter formation mechanism. Spatter generation is a well-documented phenomenon in laser powder bed fusion process (LPBF), due to the potential for collecting spatter powder from the gas inlet and outlet [26][27][28][29]. In EBM, it is impossible to retrieve and investigate the spatters from sintered powder cake.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Spatter and Sublimation in Alloy 718 during Electron Beam Melting

Raza¹,

Hryha²

2021

Materials

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Due to elevated temperatures and high vacuum levels in electron beam melting (EBM), spatter formation and accumulation in the feedstock powder, and sublimation of alloying elements from the base feedstock powder can affect the feedstock powder’s reusability and change the alloy composition of fabricated parts. This study focused on the experimental and thermodynamic analysis of spatter particles generated in EBM, and analyzed sublimating alloying elements from Alloy 718 during EBM. Heat shields obtained after processing Alloy 718 in an Arcam A2X plus machine were analyzed to evaluate the spatters and metal condensate. Comprehensive morphological, microstructural, and chemical analyses were performed using scanning electron microscopy (SEM), focused ion beam (FIB), and energy dispersive spectroscopy (EDS). The morphological analysis showed that the area coverage of heat shields by spatter increased from top (<1%) to bottom (>25%), indicating that the spatter particles had projectile trajectories. Similarly, the metal condensate had a higher thickness of ~50 μm toward the bottom of the heat shield, indicating more significant condensation of metal vapors at the bottom. Microstructural analysis of spatters highlighted that the surfaces of spatter particles sampled from the heat shields were also covered with condensate, and the thickness of the deposited condensate depended on the time of landing of spatter particles on the heat shield during the build. The chemical analysis showed that the spatter particles had 17-fold higher oxygen content than virgin powder used in the build. Analysis of the metalized layer indicated that it was formed by oxidized metal condensate and was significantly enriched with Cr due to its higher vapor pressure under EBM conditions.

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“…Significant work has been conducted on related topics, such as the effect of residual impurities from the atmosphere on the properties of L-PBF produced material [12][13][14], transfer of oxygen from the feedstock powder to the produced material and its effect on the microstructure [15], characterization of spatter [10,11,16] and powder recyclability [17]. Still, the understanding of the transfer of impurities from the feedstock powder to the built part and spatters is lacking.…”

Section: Introductionmentioning

confidence: 99%

Oxygen Balance During Laser Powder Bed Fusion of Alloy 718

et al. 2021

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The generation of spatters during laser powder bed fusion (L-PBF) of Alloy 718 is known to be detrimental for the re-use of the feedstock powder and the quality of the final product. In this study, dedicated powder sampling from different positions within the build chamber and powder bed was performed. The results clearly indicate the importance of the surface-to-volume ratio of the built components on powder degradation, as demonstrated by the analysis of the powder using capsules filled with dense lattice structures. Extensive formation of Al-and Cr-rich oxides on the entrained powder deposited on the gas inlet and outlet was detected. Significant oxygen pick-up by spatter particles compared to the virgin powder was measured (>300 ppm O 2 ); while the as-built material experienced a slight loss (~30 ppm O 2 ). The change in the microstructure of spatter particles in comparison to the virgin powder, namely the primary dendrite arm spacing, indicates significantly higher cooling rate during spatter solidification, estimated to be of about 10 8 K/s, compared to around 10 6 K/s for the virgin powder and 10 7 K/s for the L-PBF component. These findings allows to evaluate the extent of powder degradation during L-PBF and establish the oxygen balance of the process.

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Degradation of AlSi10Mg powder during laser based powder bed fusion processing

Cited by 42 publications

References 30 publications

High-Throughput Statistical Interrogation of Mechanical Properties with Build Plate Location and Powder Reuse in AlSi10Mg

High-Throughput Statistical Interrogation of Mechanical Properties with Build Plate Location and Powder Reuse in AlSi10Mg

Characterization of Spatter and Sublimation in Alloy 718 during Electron Beam Melting

Oxygen Balance During Laser Powder Bed Fusion of Alloy 718

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