Investigation of corrosion behaviors at different solutions of boronized AISI 316L stainless steel

Abstract

In this study, corrosion behaviors of boronized and non-boronized AISI 316L stainless steel (AISI 316L SS) were investigated with Tafel extrapolation and linear polarization methods in different solutions (1 mol dm−3 HCl, 1 mol dm−3 NaOH and 0.9% NaCl) and in different immersion times. AISI 316L SS were boronized by using pack boronizing method for 2 and 6 hours at 800 and 900°C within commercial Ekabor®-2 powder. Surface morphologies and phase analyses of boride layers on the surface of AISI 316L SS were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis. SEM-EDS analyses show that boride layer on AISI 316L SS surface had a flat and smooth morphology. It was detected by XRD analyses that boride layer contained FeB, Fe2B, CrB, Cr2B, NiB and Ni2B phases. Boride layer thickness increases with increased boronizing temperature and time. The corrosion experiments show that boride layer significantly increased the corrosion resistance of the AISI 316L SS in 1 mol dm−3 HCl solution. While no positive effect of the boride layer was observed in the other solutions the corrosion resistance of the borid layer on AISI 316L SS was increased in all solution with the increase of the waiting periods.