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制备了含N量分别为0.11%,0.26%和0.42%的29Cr铸造超级双相不锈钢,利用XRD,SEM,EDS,电化学工作站和XPS研究了含N量对双相不锈钢显微组织、力学性能和耐蚀性的影响.结果表明:N能增加双相不锈钢中奥氏体含量,并且有φ(γ)=60×ω(N)+21.97的线性关系;由于N具有固溶强化和降低(Mn,Cr)S夹杂粒子的作用,能有效提高材料的抗拉强度和延伸率,两者与含N量的关系分别为σ_b=318.33×ω(N)+626.3和δ=60×ω(N)+10.83.在海水腐蚀过程中,铁素体优先腐蚀.N使Cr的分布均匀化,并参与腐蚀反应生成NH_4~+和NO_3~-,促进钝化膜的再钝化;Mo可以生成MoO_4~(2-).提高钝化膜的稳定性,增强耐蚀性.钢中含N量越高,腐蚀电流密度越低,耐蚀性越好.
29Cr cast super duplex stainless steels containing 0.11%, 0.26% and 0.42% of N were prepared. The effects of N content on the microstructure and mechanical properties of duplex stainless steel were studied by XRD, SEM, EDS, electrochemical workstation and XPS. The results show that: N can increase the austenite content in duplex stainless steel and has a linear relationship of φ (γ) = 60 × ω (N) +21.97; as N has solid solution strengthening and decreasing Mn, Cr) S mixed particles can effectively improve the tensile strength and elongation of the material, the relationship between them and the content of N are respectively σ_b = 318.33 × ω (N) +626.3 and δ = 60 × ω (N ) +10.83. During seawater corrosion, ferrite is preferentially corroded. N homogenizes the distribution of Cr and participates in the corrosion reaction to produce NH_4 ~ + and NO_3 ~ -, which promotes the passivation of passivation film. Mo can generate MoO_4 ~ (2-) to improve the stability of the passivation film and enhance corrosion resistance steel with higher N content, the lower the corrosion current density, the better the corrosion resistance.