Dynamic and localized microelectrochemical approaches to evaluate the corrosion resistance of newly developed lean duplex stainless steel alloys

• Published in: Materials and corrosion Vol. 73; no. 10; pp. 1687 - 1700
• Main Authors: Kumar, Arumugam Madhan, Toor, Ihsan‐ul‐Haq
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.10.2022
• Subjects: Alloy development; Alloy steels; Alloying elements; aorrosion; Composition; Corrosion resistance; DEIS; Duplex stainless steels; Electrochemical impedance spectroscopy; Localized corrosion; SECM; Sodium chloride; SS alloys; Stainless steel; Steel alloys; SVET
• ISSN: 0947-5117; 1521-4176
• DOI: 10.1002/maco.202213174

A combination of scanning microelectrochemical techniques along with the conventional electrochemical approaches is explored to attain insight information on the localized corrosion on the newly developed lean duplex stainless steel (LDSS) alloys. The obtained results from dynamic electrochemical impedance spectroscopic (DEIS) tests explained the beneficial role of different alloying elements on the passive and transpassive regions of the investigated LDSS alloys in a 3.5% NaCl solution. The scanning vibrating electrode technique (SVET) was effective in examining the anodic and cathodic regions on the corroding LDSS, whereas the scanning electrochemical microscopy (SECM) technique was employed to explore the localized corrosion sites on LDSS in NaCl solution. The acquired SVET results revealed a reduction in the susceptibility of the newly developed alloys to localized corrosion concerning their composition, accounting for the enhanced corrosion resistance. The obtained result from conventional and scanning microelectrochemical techniques obviously revealed the LDSS alloy with the composition of Fe–16Cr–2Ni–2Mn–1Mo exhibited higher localized corrosion resistance in NaCl solution. Lean duplex stainless steel alloys were developed with different compositions. The effect of composition on localized corrosion was assessed in chloride media. Conventional and dynamic electrochemical impedance spectroscopic was performed by applying different anodic and cathodic potentials. Scanning electrochemical microscopy and scanning vibrating electrode technique methods were utilized to attain the spatial resolution on localized corroding alloys at the micron range. Alloy 5 (Fe–16Cr–2Ni–2Mn–1Mo) exhibited lower current densities and higher impedance values at higher anodic potential.