A new strategy for additive manufacturing ODS steel using Y-containing gas atomized powder

Abstract

The 3D printing technology is gradually applied on oxide dispersion strengthened (ODS) steels to address its processing issue and prepare complex components for generation IV nuclear reactor. However, the nanoparticles always aggregate and coarsen during the printing process because of the severe repining behavior in the high-temperature melt. This leads to a large degradation of the strengthening effect of nanoparticles. This study proposes a strategy of in situ synthesis of nanoparticles in ODS steel during the printing process by using pre-alloyed powder with controlling the partial pressure of oxygen to overcome the abnormal growth behavior of nanoparticles. After printing, a large number of nanoparticles were in situ formed and distributed uniformly in the ODS steel. The average size and number density of nanoparticles were ~ 21.09 nm and ~ 4.1 ± 0.5 × 10 21 /m 3 , respectively. As compared with the majority of 3D printed ODS steels from mechanical alloyed powder, the in situ formed nanoparticles in this study exhibit the combination of smaller size, higher number density, and better distribution homogeneity and size uniformity. This provides an outstanding secondary strengthening effect and produces ODS steel with the UTS and YS of printed ODS steel are 725 and 673 MPa, respectively. In addition, the microstructural characterization and formation mechanism of nanoparticles in this newly printed ODS steel are also given and discussed in detail. • An ODS alloys was prepared by SLM technology using the original Y and Ti atomized powders without being mechanical alloyed. • The prepared ODS alloy shows high number density and better uniformity of in situ growth dispersed particles. • The fabricated ODS steel has good tensile property at room temperature, high strength with good plasticity.