Effects of Sigma and Chi Phases on the Localized Corrosion Resistance of SR50A Super Austenitic Stainless Steel

• Published in: Corrosion (Houston, Tex.) Vol. 69; no. 4; pp. 364 - 371
• Main Authors: SHIN, J. K, JANG, H. J, CHO, K. W, PARK, C. J
• Format: Journal Article
• Language: English
• Published: Houston, TX NACE International 01.04.2013
• Subjects: Ageing; Aging; Aging (metallurgy); Alloys; Applied sciences; Austenitic stainless steels; Corrosion; Corrosion effects; Corrosion environments; Corrosion resistance; Corrosion resistant steels; Electrodes; Exact sciences and technology; Grain boundaries; Localized corrosion; Metals. Metallurgy; Nuclear power plants; Phases; Pitting (corrosion); Precipitates; Precipitation; Scanning electron microscopy; Sigma phase; Sigma phase precipitation; Stainless steel; Temperature; Corrosion resistance; Austenitic stainless steel; super austenitic stainless steel; Austenitic steel; Stainless steel; sigma phase; Localized corrosion; Sensitization; chi phase
• ISSN: 0010-9312; 1938-159X
• DOI: 10.5006/0723

The precipitation behavior of secondary phases and its effects on the localized corrosion of SR50A super austenitic stainless steel were investigated. Chi phase began to precipitate after aging for 1 h at 700°C and 20 min at 800°C ~ 900°C, and sigma phase appeared after 10 h at 700°C, 1 h at 800°C, and 20 min at 900°C. The degradation of pitting resistance was closely associated with the precipitation of sigma phase, and pits initiated in the vicinity of sigma phase. The degree of sensitization was most severe for specimens aged at 800°C, because of a large amount of small precipitates involving a large interphase area.