A new methodology to efficiently test pitting corrosion: design of a 3D-printed sample holder to avoid the occurrence of crevice corrosion in chemically aggressive media.

Pitting susceptibility of metals in corrosive environment is usually measured using a three-electrode set-up to conduct accelerated corrosion tests. A widely accepted methodology consists in mounting a sample in epoxy resin and connect it with a copper wire. However, in chloride-rich environments, this often results in the occurrence of crevice corrosion instead of pitting. In this study, a new 3D-printed sample holder was designed and its efficiency to study pitting corrosion of metals validated. The new method enables to study of pitting corrosion by improving edge enclosure, thus avoiding crevice corrosion. The validation is based on two case studies where stainless steel samples are polarized in (i) 500-ppm Cl− at ambient temperature and (ii) saturated Ca(OH)2 with 1-M Cl− at 60 °C. The specifically chosen grade (AISI 316 L) shows failure of the electrode clearly initiated at the epoxy sample edge in traditional tests and poor reproducibility. Results showed that the use of the 3D-printed sample holder significantly improved the reliability and efficiency of the testing method, clearly avoiding unrealistic crevice corrosion in the tested conditions. The designed sample holder therefore enables more realistic and representative pitting results in corrosion research opening the possibility of conducting far less-expensive repetitive tests. [ABSTRACT FROM AUTHOR]