Achieving high strength-ductility synergy via layer-wise heterogeneous structure of additively manufactured reduced activation ferrite/martensite steel

The next generation of advanced fusion reactors requires high-performance reduced activation ferrite/martensite (RAFM) steel parts. Here, we propose a new process strategy to achieve high strength-ductility synergy of RAFM steel fabricated by laser powder bed fusion (LPBF). The key idea is to develop a layer-wise heterogeneous structure (HS) by modulating the phase composition via periodic alternation of laser process parameters between different layers. The pronounced hetero-deformation induced (HDI) strengthening effect contributed to the enhanced strength and ductility of the LPBF-fabricated HS RAFM steel. Our findings offer a new avenue for future high-performance structural material development for LPBF.