AbstractThe metallurgical and electrochemical behavior of additively manufactured super duplex stainless steel (SDSS) clads on carbon steel [low-carbon steel (LCS)] substrates are investigated in a simulated concrete pore solution. The SDSS clads were manufactured using laser powder bed fusion (LPBF). Passivation and chloride-induced depassivation of the clads were studied as a function of LPBF parameters. It was shown that additively manufactured clads significantly improved the passivation characteristics and increased the chloride thresholds of the LCS substrate. The clads showed a decreasing γ-austenite phase fraction and increasing δ-ferrite phase fraction with increasing scan speeds. Increasing the δ-ferrite phase fraction resulted in faster passive film formation but lower critical chloride thresholds for the clads. The clads produced with 100-, 600-, and 1,000-mm/s laser scan speeds showed critical chloride thresholds of 4, 2.5, and 1.5 M, respectively. The as-cast SDSS alloy did not show any signs of depassivation until 5  M Cl− concentration, whereas LCS substrates depassivated at 0.75  M Cl−. The study proved the concept of additively manufactured carbon steel rebars with stainless steel clads and is a first step toward producing such rebars.

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