Tribocorrosion behavior of nickel-free duplex and 316L stainless steels fabricated by laser powder bed fusion in artificial seawater
Abhinav Anand, Chinmayee Nayak, Ermei Mäkilä, Zaiqing Que, Heidi Piili, Sneha Goel, Antti Salminen, Ashish Ganvir
Abstract
In this work, nickel-free duplex stainless steel (NiFDSS) and 316L stainless steel were produced by laser powder bed fusion (PBF-LB/M) under optimized parameters, reaching 98.83 % and 99.80 % relative densities, respectively. Microstructural analysis showed transformation from fully ferritic in the as-built condition to duplex after heat treatment (950 °C/1 h, followed by water quenching) for NiFDSS. Corrosion resistance was evaluated by potentiodynamic polarization in artificial seawater (0.6 M NaCl with pH 8.2), while tribocorrosion performance was measured in a ball-on-disc setup under the same electrolyte. As-built NiFDSS exhibited a lower corrosion current density (1.30 μA/cm 2 ) than 316L (1.78 μA/cm 2 ), and heat treatment further reduced it to 0.65 μA/cm 2 , reflecting enhanced corrosion resistance. Under tribocorrosion, NiFDSS and heat-treated NiFDSS maintained lower corrosion rates but incurred higher wear rates than 316L, driven by residual porosity along with cleavage-prone fragmentation in the as-built alloy and sigma-phase-assisted cracking after heat treatment. Overall, PBF-LB/M of NiFDSS provided superior corrosion resistance while exhibiting lower wear performance than 316L. Porosity control through further PBF-LB/M parameters refinement and heat-treatment optimization is required to minimize residual pores and suppress sigma-phase precipitation, thereby improving wear resistance of NiFDSS.