Corrosion Behavior of Supermartensitic Stainless Steel 13Cr and Stainless Steel 316L Under Chloride Solution and H₂S/CO₂ Environments

Corrosion-resistant alloys (CRAs) include various stainless steels and nickel alloys used in corrosion-aggressive environments encountered in oil and gas operations. Supermartensitic stainless steel (SMSS 13Cr) has been used in the manufacture of steel tubes for oil drilling due to a more financially viable option to replace the austenitic stainless steel (SS 316L) in the oil and gas market. This present work estimates the effect of the hydrogen sulfide (H₂S) on SMSS 13Cr and SS 316L in a saline solution, simulating the operating conditions in the oil and gas industry. Corrosion behavior was monitored using a potentiodynamic-potentiostatic-potentiodynamic technique to obtain pitting potential (E_p) or crevice potential (E_crev) and repassivation potential (E_rp) while the long-term open-circuit potential technique was applied to estimate the stable corrosion potential (E_corr*). A scanning electron microscope equipped with energy dispersive x-ray spectroscopy and optical microscopy was used for surface characterization. With all analyses performed, it was possible to propose a trend regarding the pitting probability. The pitting increases with increasing H₂S concentration on SSSM 13Cr; consequently, larger and deeper pits were observed, making it possible to develop into cracks if there are mechanical stresses. On the contrary, the pitting probability for the SS 316L is low (compared with SMSS 13Cr) for all environments reproduced here in this research.