Oxidation in Reused Powder-Bed Fusion Additive Manufacturing Ti-6Al-4V Feedstock: A Brief Review
Nicholas Derimow, Nik Hrabe
Unmelted titanium alloy (Ti-6Al-4V) feedstock powder oxidizes during powder-bed fusion (PBF) additive manufacturing (AM), which limits the useful lifetime of a batch of powder and affects the overall AM process cost. Critical understanding of key factors influencing oxidation and oxidation rate are necessary optimize PBF-AM processes. This review focuses on the potential effect powder reuse method variations may have on oxidation and oxidation rate over multiple builds for titanium powder in both electron beam powder bed fusion (EB-PBF) as well as laser powder bed fusion (L-PBF) processes. Oxidation rates are higher for EB-PBF compared to L-PBF, which makes sense considering the higher background temperature (400 C -- 800 C) due to layer preheating in EB-PBF techniques. No correlation of oxidation rate based on powder reuse method has been observed, but significant variation in oxidation rate has been observed among reuse methods. The authors feel these results highlight a need for better reporting of powder reuse method details (e.g. mixing) to appropriately assess the potential for reuse method to affect oxidation rate. Recommendations for powder reuse and details for a higher level of reporting are provided. Multiple instances of variable oxidation rate within a given experiment have been observed, which suggests the potential for heterogeneous oxygen content in a given build area as well as persisting and compounding over multiple builds in a batch of powder. The implications of this heterogeneity on mechanical property variability might be significant.
and Hrabe, N.
Oxidation in Reused Powder-Bed Fusion Additive Manufacturing Ti-6Al-4V Feedstock: A Brief Review, Jom, [online], https://doi.org/10.1007/s11837-021-04872-y, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932159
(Accessed December 7, 2021)