Role of water chemistry and microstructure in stress corrosion cracking in the fusion boundary region of an Alloy 182-A533B low alloy steel dissimilar weld joint in high temperature water

• Published in: Corrosion science Vol. 53; no. 12; pp. 4309 - 4317
• Main Authors: Peng, Qunjia, Xue, He, Hou, Juan, Sakaguchi, Kazuhiko, Takeda, Yoichi, Kuniya, Jiro, Shoji, Tetsuo
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2011; Elsevier
• Subjects: A. Alloy; A. Low alloy steel; Alloy steels; Alloying elements; Applied sciences; B. SEM; B. TEM; Boundaries; C. Stress corrosion; C. Welding; Corrosion; Corrosion environments; Crack propagation; Exact sciences and technology; Joining, thermal cutting: metallurgical aspects; Mathematical analysis; Metals. Metallurgy; Microstructure; Stress corrosion cracking; Water chemistry; Welding; B. SEM; C. Stress corrosion; A. Low alloy steel; A. Alloy; C. Welding; B. TEM; Water corrosion; Nickel base alloys; Scanning electron microscopy; Temperature; Welding; Stress corrosion cracking; High temperature; Low alloy steel; Transmission electron microscopy; Welded joint; Microstructure; Dissimilar metals
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2011.08.046

► Hardness gradient in the high hardness zone adjacent to fusion boundary in dilution zone. ► Combined effect of dissolved oxygen and sulfate concentration on crack growth in fusion boundary region. ► 400-ppb Sulfate in water for reactivating crack growth at fusion boundary at K = 30 MPa√m under normal water chemistry. ► Decreased crack growth rate in the high hardness zone is expected due to the hardness gradient. ► Reactivation of crack growth from the pitting at fusion boundary by preferential oxidation along the grain boundary. Stress corrosion cracking (SCC) in the fusion boundary (FB) region of an Alloy 182-low alloy steel (LAS) dissimilar weld joint in 288 °C water was investigated by experiments and finite element simulation. Creviced bent beam and crack growth rate (CGR) experiments showed that, while the FB was a barrier to SCC growth, further crack growth into LAS was activated by a combined effect of sulfate and dissolved oxygen in water. Finite element simulation suggested that a positive gradient of hardness as the crack approached to the FB in dilution zone caused decreased CGR. Role of microstructure and water chemistry in SCC was discussed.