26-28 September 2022
TU Graz
Europe/Vienna timezone

Powder for Metal Additive Manufacturing: Properties and degradation

26 Sep 2022, 10:30
30m
Room i7

Room i7

Plenary Talk Plenary Talk Plenary Talk

Speaker

Eduard Hryha (Chalmers University of Technology/Centre for Additive Manufacturing - Metal (CAM2))

Description

Metal powder is the most common feedstock for metal additive manufacturing (AM), including powder bed fusion (laser beam PBF-LB, and electron beam - PBF-EB), binder jetting (BJT) and powder blown directed energy deposition (DED). However, even if the same alloys systems are used for these technologies, they have different requirements to the powder feedstock when it comes to its physical properties and chemistry and utilize different size fractions of the metal powder. On the other hand, metal powder properties are determined by the powder manufacturing methods, where variety of properties can be obtained for the same alloy system, determining their behavior and suitability for AM processing by different AM technologies. During AM process, metal powder is further exposed to the processing conditions that also differ significantly between different AM technologies. This will result in changes in powder properties during manufacturing cycle, its further handling and hence its impact on the final component properties differ significantly.
Powder behavior is strongly affected by its surface chemistry due to the high large surface area of the powder, that is about 10 000 times larger than the surface area of the bulk material of the same mass. This leads to high surface reactivity, that in combination with the alloy composition will determine powder sensitivity to the powder manufacturing method, handling and AM processing. Initial chemical composition of the powder is determined by the powder manufacturing method. This state, however, is not stable, and progressively changes with time in dependance on powder handling and processing by metal additive manufacturing. Such changes in powder surface chemistry during powder reuse have a strong impact on powder quality and processability by specific AM technologies and hence final component properties. This talk summarizes recent experimental observations and thermodynamic simulations of the changes in powder surface chemistry during the whole life-cycle of metal powder: from its manufacturing, following powder handling and AM processing by variety of powder-based metal AM technologies. Generic model of the powder degradation in dependance on initial powder properties and type of AM process is elaborated. Effect of the reused powder on the defect formation during AM processing and its impact on material properties is discussed.

Speaker Country Sverige

Primary author

Eduard Hryha (Chalmers University of Technology/Centre for Additive Manufacturing - Metal (CAM2))

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