Unique bottom-up microstructure hierarchy and improved mechanical properties in stainless steel formed by selective laser melting

Selective laser melting was used for production of 316L stainless steel. The SLM 316L steel shows unique structural hierarchies from the macro-scale melt pools down to the submicron/nano scale intragranular cellular sub-grains. The Structural hierarchies and heterogeneities and associated dislocations increased the mechanical strength and hardness of the laser melted stainless steel samples to 700 MPa and 325HV. The small sized confined intragranular subgrains and multi scale interlocking of the subgrains ensured high yield strength of 456 MPa and good ductility. The mechanical properties are considerably higher than a fully densified HIP316L and conventional 316L steel and comparable to dual phase stainless steel.