Abstract:The S31609 austenitic stainless steel containing residual delta-ferrite was sensitized at 650 ℃ for 2 h. The corrosion characteristics of residual delta-ferrite and austenite grain boundary were analyzed and compared by metallographic etching, electron probe microanalyzer and scanning Kelvin probe. The results show that the residual delta-ferrite is rapidly decomposed into sigma phase, secondary austenite phase (γ2) and Cr23C6 during the sensitization process. Although there is no obvious Cr and Mo solute depleted zone at austenite grain boundary and δ/γ grain boundary, the potential difference between the precipitated phase and the adjacent substrate always exists. The Fermi energy of the secondary phase, such as the sigma phase, γ2 and Cr23C6is lower than that of the matrix, which makes it easier for electrons to jump from the Fermi surface of the surrounding matrix. As a result, the matrix acts as an anode in the electrochemical corrosion system, and the corrosion occurs preferentially.
庞宗旭, 王勇, 胡昕明, 孙殿东, 王储. S31609奥氏体不锈钢中残留δ铁素体的腐蚀行为[J]. 中国冶金, 2021, 31(3): 59-65.
PANG Zong-xu, WANG Yong, HU Xin-ming, SUN Dian-dong, WANG Chu. Influence of delta-ferrite on corrosion behavior of S31609 austenitic stainless steel[J]. China Metallurgy, 2021, 31(3): 59-65.
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