Pit growth kinetics of additively manufactured MoNi over-alloyed type 316L stainless steel

The microstructure and corrosion performance of wrought, laser powder bed fusion (LPBF), and MoNi over-alloyed LPBF type 316L stainless steel is compared. Adding Mo and Ni to LPBF 316L stainless steel resulted in ẟ-ferrite. Potentio-dynamic polarisation was used to rank all microstructures, with LPBF + MoNi has more resistant than LPBF and wrought material. Bipolar electrochemistry was applied, with LPBF samples having the lowest critical pitting potential and highest pit growth kinetics. The best corrosion performance was for LPBF + MoNi stainless steel. Different pitting corrosion resistance as function of process directions were found. The tiny pores negatively impacted the pitting performance.