Selective laser melting of ferritic/martensitic oxide dispersion-strengthened steel: Processing, microstructure, and mechanical properties

Oxide dispersion-strengthened (ODS) ferritic/martensitic steels have emerged as a promising structural material for nuclear power applications due to their high heat resistance. However, the fabrication of complex ODS steel components remains a significant challenge. This study presents the influence of the main selective laser melting process parameters and heat treatment on the densification, microstructure, and tensile properties at room and elevated temperatures of high chromium ferritic/martensitic ODS steel strengthened with 0.25 wt.% yttrium oxide (Y2O3). The optimization of process parameters and platform pre-heating enabled the production of parts with a density above 98%. The application of pre-heating allowed for higher scanning speeds to be used to achieve similar relative density and avoid cracking. Partial recrystallization after heat treatment was noted, affecting grain morphology by increasing equiaxedness and decreasing size. X-ray analysis was employed to determine the phase composition. However, the results were ambivalent and required confirmation by other methods. The addition of 0.25 wt.% Y2O3 resulted in an ultimate tensile strength value of 978 MPa for the as-built material at room temperature. At elevated temperatures, the properties are comparable to those of the base steel, indicating the necessity for further research.