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

Abstract

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.

Improved Process Efficiency in Laser-Based Powder Bed Fusion of Nanoparticle Coated Maraging Tool Steel Powder

“…This result is in accordance with the work of Zhou et al [27], who investigated the influence of Al 2 O 3 -coated metallic powder in terms of absorption. Furthermore, Gruber et al [28] analyzed the absorption behavior of an Inconel 718 powder in four different conditions: virgin, used, overflow, and spatter. The latter was located at the inert gas outlet after the PBF-LB/M process and contained both process by-products and used powder.…”

“…Accordingly, a reduction in reflectance of up to 30% could be achieved. The degree of absorption of a powder material significantly depends on the PSD, morphology, surface roughness, and optical appearance (e.g., color) [26,28,35]. Due to the consistent results of the PSD, the cause is not attributable to a change in particle size.…”

Influence of the AlSi7Mg0.6 Aluminium Alloy Powder Reuse on the Quality and Mechanical Properties of LPBF Samples

“…Even spatters formed during the metal powder processing can be treated as contamination, even though the chemical composition remains the same. However, the oxygen content very often increases [ 10 ]. These findings push the researchers working on process LPBF development to consider the effect of powder reuse, applied strategies of operating powder between the processes, and the changes of powder characteristics on the result of the AM process.…”

“…There are many studies on powder reuse in LPBF, including nickel-based alloys [ 10 ], iron-based alloys [ 12 ], titanium-based alloys [ 13 ], and aluminium-based alloys. Recently, published works on aluminium-based alloys focus on the AlSi10Mg [ 14 ] and Al-Si-Sc-Zr [ 15 ].…”

Laser Powder Bed Fusion (LPBF) of In718 and the Impact of Pre-Heating at 500 and 1000 °C: Operando Study

“…The microstructure influences the mechanical characteristics of IN718 [74]. LPBF produces a consistent microstructure with little porosity and finer dendritic grain [74,75]. The regular dendritic structure disappears and a needle-like δ phase precipitates at grain boundaries when γ and γ" phases dissolve in the matrix when heat treatment is applied A needle-like δ phase precipitates along grain boundaries whenever the γ and γ" phases breakdown in the matrix during heat treatment, replacing the normal dendritic structure.…”