Tribocorrosion Performance of Additively Manufactured 316L Stainless Steel in 3.5% NaCl Solution

Abstract

Abstract. To confirm the application of additively manufactured (AM) 316L stainless steel (SS) in seawater, the tribocorrosion performance of AM samples manufactured using direct energy deposition (DED) was investigated in comparison to commercial forged samples. Microstructural analysis revealed that the directional nature of DED produces 316L SS with columnar grain structures, differing fundamentally from the isotropic equiaxed grains in forged counterparts. Both materials maintain an FCC γ-phase constitution, but the build-direction-dependent solidification in DED promotes preferential (200) plane orientation versus the (111) dominance in forged material. These crystallographic differences account for the slightly higher microhardness measured in DED specimens. Electrochemical testing in 3.5% NaCl solution displayed superior corrosion resistance in DED specimens, evidenced by lower corrosion current density, larger Nyquist plot impedance arcs, and higher polarization resistance compared to forged counterparts. Tribocorrosion testing under three applied loads (10 N, 20 N, and 30 N) showed DED samples consistently outperformed forged material, with the most significant improvement (38.3% reduction in wear-rate) observed at 10-N loading. Worn surface morphology analysis identified the dominant wear mechanism as abrasive wear with superimposed corrosion effects. The refined columnar microstructure of DED samples not only enhanced general corrosion resistance but also demonstrated particular effectiveness under combined tribocorrosion conditions. These results demonstrate that DED-processed 316L SS exhibits superior tribocorrosion performance to forged material in simulated marine environments.