Effects of Applied Torque on the Crevice Corrosion of AISI 316L Stainless Steel in a Chloride-Containing Solution

In the present study, potentiodynamic polarization was employed to investigate the effect of the applied torque on the crevice corrosion behavior of AISI 316L stainless steel in 0.9% NaCl solution. A multiple crevice assembly was used to induce crevice corrosion, and the influence of the torque magnitude was evaluated by measuring the corroded area and the penetration depth within the occluded regions. Natural exposure tests of creviced and uncreviced systems were conducted over approximately 50 days to evaluate the development of crevice corrosion under freely corroding conditions. Potentiodynamic polarization revealed corrosion potentials around − 100 mV Ag/AgCl and pitting potentials around 250 mV Ag/AgCl for all applied torques and the crevice-free condition, indicating that these parameters were not significantly affected by the presence of crevices or the applied torque. In contrast, the repassivation potential decreased from approximately − 14 mV Ag/AgCl at 7 N.m to − 120 mV Ag/AgCl at 1 N.m, shifting progressively toward more noble values with increasing torque and approaching the crevice-free condition. Under natural exposure, crevice-free specimens showed a shift in open circuit potential toward nobler values, indicating gradual stabilization of the passive film, whereas creviced systems shifted toward more active potentials, reflecting the development of aggressive conditions within the crevice. Accelerated tests produced corrosion predominantly near the crevice mouth, whereas natural exposure resulted in corrosion concentrated near the central region of the crevice. Furthermore, natural exposure resulted in penetration depths below 26 µm, whereas polarization experiments produced depths of approximately 40 µm, demonstrating that accelerated electrochemical testing substantially increases the severity of localized attack while altering its characteristic morphology.