Microstructure and mechanical properties comparison of ferritic/martensitic steel fabricated by wrought and selective laser melting

Reduction activated ferrite/martensitic (RAFM) steel has been identified as the most promising structural material for future fusion reactors due to its properties such as low activation and high thermal conductivity. However, the complex internal water cooling tubing increases the difficulty of conventional processing. Herein, RAFM steel with high strength and excellent ductility was successfully fabricated by selective laser melting (SLM) technology. Compared with wrought materials, the SLM-fabricated specimens exhibit significant superiority in mechanical properties. Furthermore, the strength is prominently enhanced in the horizontal direction, with almost no loss of ductility. However, the strength gain in the vertical direction is at the expense of ductility. This work provides a potential method for the preparation of structural materials for nuclear fusion.