Strong and ductile reduced activation ferritic/martensitic steel additively manufactured by selective laser melting

Selective laser melting (SLM) was successfully applied to fabricate strong and ductile reduced activation ferritic/martensitic (RAFM) steel by introducing heterogeneous multi-/bimodal microstructure. The SLM-built RAFM steel exhibited an excellent combination of strength and ductility (i.e. yield strength of 1053 ± 4.7 MPa and elongation of 16.9 ± 0.4%), well surpassing the previously reported counterparts. The superior strength was expected from the refined grains and lath martensites, and the high ductility was associated with the improved dislocation-controlled strain hardening capability. This work provides a basis for developing high-performance RAFM steel by microstructural design via SLM. A new strategy, refers to heterogeneous multi-/bimodal microstructure, is proposed to develop strong and ductile RAFM steel via SLM and the achieved superior mechanical properties overcome the classic strength-ductility trade-off.