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Laser-based powder bed fusion (PBF-LB/M) is a well-established additive manufacturing (AM) process capable of producing high quality parts with excellent mechanical properties. Industrial applications of additively manufactured parts require the usage of fresh powder which makes the process expensive, especially in case of AM machines with enlarged build envelopes. Processing long-term reused powder fits to economic yields with the drawback of increased porosity and incorporated oxides. In this study, a detailed analysis of components made of virgin and long-term reused AlSi10Mg0.4 powder is provided. The experiments reveal that process parameters qualified for the virgin powder are not working offhand for the reused powder, as an increase of porosity from less than 1 % up to 3 % and a decline of tensile strength as well as yield strength of about 15 % are observed. The results indicate that powder degradation, which is based on the formation of hydroxides and oxides, has a significant impact on as-built microstructure as well as mechanical properties of additively manufactured parts. The amount of hydrogen and oxygen is measured for different powder conditions and the powder ageing process of AlSi10Mg0.4 is discussed in detail.
Fiegl et al. (Mon,) studied this question.