A Nonlinear Probabilistic Pitting Corrosion Model of Ni-Ti Alloy Immersed in Shallow Seawater

Špiro Ivošević; Gyöngyi Vastag; Nataša Kovač; Peter Majerič; Rebeka Rudolf

doi:10.3390/mi13071031

A Nonlinear Probabilistic Pitting Corrosion Model of Ni-Ti Alloy Immersed in Shallow Seawater

Micromachines (Basel). 2022 Jun 29;13(7):1031. doi: 10.3390/mi13071031.

Authors

Špiro Ivošević¹, Gyöngyi Vastag², Nataša Kovač³, Peter Majerič⁴, Rebeka Rudolf⁴

Affiliations

¹ Faculty of Maritime Studies Kotor, University of Montenegro, Put I Bokeljske Brigade 44, 85330 Kotor, Montenegro.
² Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 3, 21000 Novi Sad, Serbia.
³ Faculty of Applied Sciences, University of Donja Gorica, Oktoih 1, 81000 Podgorica, Montenegro.
⁴ Faculty of Mechanical Engineering, University of Maribor, Smetanova Ulica 17, 2000 Maribor, Slovenia.

Abstract

The degradation of metal materials in a marine environment represents the consequence of the electrochemical corrosion of metals under the influence of the environment. The application of new materials in the maritime industry requires experimental, real-world research on the form of corrosive damage and the intensity of the corrosion. This paper analyses the pitting corrosion of a rod-shaped nickel-titanium (Ni-Ti) alloy that was produced by means of the continuous casting method. In total, three samples were posted in a real seawater environment and analysed after 6, 12, and 18 months. Pits were detected on the Ni-Ti alloy after 18 months of exposure to the marine environment. The database on pitting corrosion was created by measuring depth in mm, which was performed by means of a nonlinear method, and by the generation of an artificial database of a total of 120, gauged in critical pit areas. The data were obtained by the application of a nonlinear model, and under the assumption that corrosion starts after 12 months of exposure in the corrosive marine environment. The EDX analysis of the Ni-Ti alloy composition inside the pits and on the edges of the pits indicated that the corrosion process in the hole of the pit occurs due to the degradation of the Ni.

Keywords: EDX analysis; Ni–Ti alloy; nonlinear; pitting corrosion; probabilistic; seawater.

Grants and funding

This research was funded by the BILATERAL PROJECTS Slovenia—Montenegro and Serbia—Montenegro (BI-ME/18-20-024) and EUREKA PROGRAM PROCHA-SMA E!13080, funded by the Ministry of Science of the Republic of Montenegro. This research was funded by Javna Agencija za Raziskovalno Dejavnost RS (ARRS), grant number P2-0120 and I0-0029.