Initiation mechanism of pitting corrosion in weld heat affected zone of duplex stainless steel. (June 2022)

• Record Type: Journal Article
• Authors: Hou, Yuyang; Nakamori, Yudai; Kadoi, Kota; Inoue, Hiroshige; Baba, Hayato
• Is Part Of: Corrosion science. Volume 201(2022)
• Publication Date: 2022-06
• Subjects: Stainless steel -- Welding -- Pitting initiation -- Inclusion -- Passive films -- TEM; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2022.110278
• Languages: English
• ISSNs: 0010-938X

Abstract

Abstract: The pitting corrosion resistance of duplex stainless steel welds was investigated. Pitting corrosion mainly occurs in high-temperature heat-affected zone (HT-HAZ), where the peak temperature reaches ferrite single-phase region. Most pitting corrosion in the HT-HAZ initiates from (Ti, Cr)N in the ferrite. Even the titanium content is less than 50 ppm, titanium-containing nitrides precipitate in the HT-HAZ. While no clear Cr-depleted zone develops around (Ti, Cr)N, almost no passive film forms on (Ti, Cr)N surface. Therefore, pitting corrosion is initiated not only by Cr-depleted zone around Cr nitride but also by the lack or vulnerability of the passive film on the (Ti, Cr)N surface. Highlights: Pitting corrosion resistance of duplex stainless steel welds was investigated. Pitting mainly initiated in the ferrite of high-temperature heat-affected zone. Passive film was absence on (Ti, Cr)N surface with no Cr-depleted zone around. Clear Cr-depleted zone was detected around CrN and Cr2 N. Pitting corrosion is initiated by both passive film loss and Cr-depleted zone.