Review on development of reduced activated ferritic/martensitic steel for fusion reactor

Materials are still one of the main technical bottlenecks restricting the development of fusion reactors. Reduced activated ferritic/martensitic steel (RAFM) is considered one of the main candidate structural materials for fusion reactor cladding due to its good radiation resistance and mechanical properties. In the past 40 years, RAFM steel has made considerable progress, but numerous problems remain to be solved. The improvements in RAFM steel in recent years, such as chemical composition optimization, clean preparation technology, radiation performance, and applicable welding technology, were systematically summarized. A systematic review of new RAFM steels was conducted, the development direction of the traditional smelting process was analyzed, and the application of laser additive manufacturing technology to RAFM steel was introduced. The effect of irradiation on the microstructure and mechanical properties of RAFM steel was described, and welding methods of RAFM steel and their research progress were reviewed. Finally, the potential applications of Si, Ti, and Zr in improving the performance of RAFM steel, electroslag remelting technology in clean smelting, heat treatment process in optimizing radiation performance, and laser-beam welding in RAFM welding were prospected and summarized.