Chi Phase after Short-term Aging and Corrosion Behavior in 2205 Duplex Stainless Steel

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• 作者：Qi SUN^a ; ^b ; ^{imsunqi@163.com" class="auth_mail" title="E-mail the corresponding author}Author Vitae ; Jian WANG^a ; ^b ; Hua-bing LI^c ; Yue LI^a ; ^b ; Ya-di HU^a ; ^b ; Jin-gang BAI^d ; Pei-de HAN^a ; ^b ; ^{hanpeide@126.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：duplex stainless steel ; short-term aging ; χ phase ; pitting corrosion ; selective corrosion ; grain size
• 刊名：Journal of Iron and Steel Research, International
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：23
• 期：10
• 页码：1071-1079
• 全文大小：4434 K

文摘

Correlation between pitting corrosion behavior and chi (X) phase formed after a short-term aging (5, 10 and 15 min) at 850 °C of 2205 duplex stainless steel (DSS) was investigated using potentiodynamic polarization tests, optical microscopy, and scanning electron microscopy equipped with energy-dispersive spectrum system. Results showed that after aging for 5 min, the X phase initially precipitated at ferrite grain boundaries, developed and then became linked with prolonging aging time. The X phase was rich in Cr and Mo, resulting in formation of depleted zones nearby. The X phase could reduce corrosion resistance of OSS and slightly influence its stability, but the specimens still displayed the capacity for repassivation. Some lines of evidence showed that stable pitting corrosion initiated at the boundaries of precipitates. The X phase was selectively corroded during the first stage of corrosion and then the depleted zones nearby were attacked. In addition, the grain size and volume of precipitates also affected pit nucleation and progress, and suitable size and distribution of X phase could aggravate pit initiation at precipitate boundaries. The X phase with considerably low volume fraction and small size was not sensitive position for pit initiation.