Effect of scanning strategy on microstructure and mechanical properties of selective laser melted reduced activation ferritic/martensitic steel

摘要

Two types of scanning strategies were adopted to study the effect of scanning strategy, i.e., bidirectional scanning without (SS-X) and with 45 degrees deviation from X/Y-axis and 90 degrees rotation (SS-XY45) between adjacent layers, on microstructure and mechanical properties of reduced activation ferritic/martensitic (RAFM) steel fabricated by selective laser melting (SLM). The SLM-built RAFM steel exhibited a better combination of strength and ductility than the previously reported counterparts. The SS-X had higher yield strength of 911 MPa and higher elongation of 18.7% than the SS-XY with yield strength of 893 MPa and elongation of 15.0%. The results reveal that the variation in the yield strength was mainly ascribed to the different grain size and the improved ductility was associated with the modified grain structure that altered the tensile fracture mode with concurrent occurrence of intergranular brittle and transgranular ductile fracture. This finding provides an alternative to fabricate high-performance RAFM steel by tailoring the microstructure with different scanning strategies.