Rahul Shrivastava, Rita Maurya, Prvan Kumar Katiyar
This study evaluates the crevice corrosion behaviour of 316Ti and 310 austenitic stainless steels (ASSs) and 32750 and 32760 super duplex stainless steels (SDSSs) in 6% FeCl3 solution following ASTM G48. A multi-technique approach, including gravimetric analysis, macroscopic examination, field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDX), optical profilometry, and Raman spectroscopy, was employed to assess degradation mechanisms. Results indicate significantly higher susceptibility of ASSs, with corrosion rates of 3.52 ± 0.89 mm/y (316Ti) and 3.44 ± 1.06 mm/y (310). In contrast, SDSSs show markedly lower rates of 0.0045 ± 0.0016 mm/y (32750) and 0.0064 ± 0.0042 mm/y (32760). Profilometry reveals deeper crevice attack and higher roughness in ASSs, whereas SDSSs exhibit minimal surface damage. Raman analysis identifies metastable phases (β-FeOOH, γ-Fe2O3) in ASSs and stable phases (α-Fe2O3, α-FeOOH) in SDSSs. The superior performance of SDSSs, particularly 32750, is attributed to enhanced passive film stability due to Cr–Mo-N-W synergy. These findings confirm the suitability of SDSSs for chloride-rich environments such as marine and chemical processing applications.