Influence of surface roughness anda build position on the corrosion resistance of AISI316L stainless steel obtained via v SML

The use of selective laser melting (SLM) technology to produce stainless steel near-net-shape components for industrial applications is definitely increasing. Despite the presence in literature of different studies that evaluate the corrosion resistance of AISI316L samples/components obtained via SLM, all them apply a controlled polishing (usually obtaining high finishing) in order to relate the corrosion resistance to the microstructure of the alloy. In this work different AISI 316L samples realized through SLM were characterized in as built condition (without polishing) and after polishing to a controlled surface roughness, in order to assess: i) the influence that surface polishing have on corrosion resistance of AISI 316L SLM components and ii) the influence that the building position (i.e. the position of the sample inside the SLM building chamber) have on microstructure, porosity and corrosion resistance. The results obtained not only show that the surface polishing is mandatory to obtain interesting corrosion resistance (i.e. to obtain a correct passivation of the surface) but that in polished condition the samples obtained via SLM have higher pitting resistance than those obtained by cold rolling; furthermore, the pitting potential of the SLM samples is strongly affected by the building position inside the SLM chamber.