Quantitative analysis of initiation site of pitting corrosion on type 304 austenitic stainless steel

• Published in: Corrosion science Vol. 221; p. 111312
• Main Author: Eguchi, Kenichiro
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.08.2023
• Subjects: Austenitic stainless steel; Non-metallic inclusion; Pitting corrosion; Type 304; Austenitic stainless steel; Pitting corrosion; Type 304; Non-metallic inclusion
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2023.111312

The initiation site of pitting corrosion on type 304 stainless steel was quantitatively analysed using an automatic inclusion analyser and electron backscatter diffraction. In a sample anodically polarised at 0.43 VSSE, the fraction of stable pits initiated from inclusions was only 23 %. Pits initiated from sites other than inclusions probably initiated from grain boundaries, strain-induced martensite and scratches. In mixed inclusions of MnS and oxides, the probability of pit initiation increased with the S concentration. The Ti concentration had no effect on the probability of pit initiation, suggesting that whether Ti exists as TiO2 or TiN is important. [Display omitted] •The initiation sites of pitting corrosion on type 304 stainless steel were quantitatively analysed.•Most pits initiated from grain boundaries, strain-induced martensite and scratches.•Among inclusions, MnS was the most likely to initiate pits.•In mixed inclusions of MnS and oxides, the probability of pit initiation increased at higher S concentrations.•The elements released from Ti-based inclusions may affect the tendency of pit initiation.