N含量对29Cr铸造超级双相不锈钢组织及性能的影响

来源期刊：金属学报2010年第3期

论文作者：向红亮 黄伟林 刘东 何福善

文章页码：304 - 310

关键词：29Cr超级双相不锈钢； N含量； 抗拉强度； 延伸率； 极化曲线； 钝化膜

Key words：29Cr super duplex stainless steel； N content； tensile strength； elongation； polarization curve； passive film

摘    要：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NH₄⁺和NO₃^-,促进钝化膜的再钝化;Mo可以生成MoO₄^2-.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.

Abstract: Microstructures,mechanical properties and corrosion resistances of 29Cr super duplex stainless steel (SDSS) with N contents of 0.11%,0.26% and 0.42% have been investigated by XRD, SEM,EDS,electrochemical workstation and XPS.The results show that with increasing N content the distribution of Cr becomes homogeneous,the amount of γ phase increases according to a linear relationship of φ(γ) = 60×w(N)+21.97,and the tensile strength and elongation of the steel are improved according to the relationships of σ_b= 318.33×(w(N))^1/2+626.3 and δ= 60×w(N)+10.83, respectively.due to the roles of solution strengthening and reducing (Mn,Cr)S precipitation.In the process of seawater corrosion,α phase in the steel would be corroded first,N can form NH₄⁺ and NO₃^- to promote the re-passivation effect of passive film;and Mo can form MoO₄^2- to improve the stability of passivated layer and strengthen the corrosion resistance of the steel.The higher the N content,the lower the corrosion current density and the better the corrosion resistance for the steel.