Nanomechanical and microstructural characterization on the synergetic strengthening in selectively laser melted austenitic stainless steel

Abstract

The significant strengthening of selectively laser melted (SLM) 304L stainless steel that occurs due to high-pressure torsion (HPT) is examined by recourse to detailed nanomechanical and microstructural characterization. In the as-built alloy, dislocation hardening is the main strengthening mechanism. After HPT, however, the synergistic combination grain refinement and martensitic transformation dominate the strength of the alloy. In the nanocrystalline regime, the dominance of the grain boundary-mediated plasticity retards the martensite-induced hardening.