Effect of powder characteristics on production of oxide dispersion strengthened Fe-14Cr steel by laser powder bed fusion

In order to assess the potentialities of additive manufacturing in nuclear industry, Oxide Dispersion Strengthened (ODS) Fe-14Cr steels are produced by laser powder bed fusion (L-PBF). Such materials are currently manufactured by milling a Fe-14Cr atomized powder with Y2O3 and TiH2 powders. The resulting powder has a non-spherical shape being coarser than powders typically used in L-PBF equipment. The influence of powder characteristics on the processability of ODS Fe-14Cr by L-PBF are studied in details. Four different powders are used. These powders differ from size, morphology and chemical composition. Finer is the powder: wider is the process range to obtain dense samples. This phenomenon could be mitigated by transferring an amount of energy superior to 110 J.mm(-3). The presence of yttrium and titanium gives columnar microstructure for ODS samples, whereas Fe-14Cr samples have stirred microstructure. Titanium and yttrium form oxides, which enlarge the melt pool and induce columnar growth. (C) 2019 Elsevier B.V. All rights reserved.