Influence of friction stir processing (FSP) on arc directed energy deposited 316 L stainless steel: A corrosion science study

Friction stir processing (FSP) was employed as a post-printing surface modification technique to enhance surface properties of arc-directed energy deposited 316 L austenitic stainless-steel parts. Corrosion properties and passivity of stir zone and base metal were investigated in 3.5 wt.% NaCl solution. Results reveal a gradual improvement in corrosion protection ability of formed passive film on the alloy's surface over time. Specifically, FSPed region exhibited superior passive behavior and uniform corrosion resistance compared to base metal. This improvement was attributed to a more homogeneous microstructure of stir zone, which hindered micro-galvanic coupling effect. However, it was observed that FSP-treatment did not effectively impede the propagation of pitting corrosion.