Corrosion and Nanomechanical Behaviors of 16.3Cr-0.22N-0.43C-1.73Mo Martensitic Stainless Steel

Abstract

The effect of nitrogen on the electrochemical corrosion and nanomechanical behaviors of martensitic stainlesssteel was examined using potentiodynamic polarization and nanoindentation test methods. The results indicatethat partial replacement of carbon with nitrogen effectively improved the passivation and pitting corrosionresistance of conventional high-carbon and high- chromium martensitic steels. Post-test observation of thesamples after a potentiodynamic test revealed a severe pitting attacks in conventional martensitic steel comparedwith nitrogen- containing martensitic stainless steel. This was shown to be due to (i) microstructural refinementresults in retaining a high-chromium content in the matrix, and (ii) the presence of reversed austenite formedduring the tempering process. Since nitrogen addition also resulted in the formation of a Cr2N phase asa process of secondary hardening, the hardness of the nitrogen- containing steel is slightly higher thanthe conventional martensitic stainless steel under tempered conditions, even though the carbon content islowered. The added nitrogen also improved the wear resistance of the steel as the critical load (Lc2) isless, along with a lower scratch friction coefficient (SFC) when compared to conventional martensitic stainlesssteel such as AISI 440C.