时效温度对S32750超级双相不锈钢组织和抗氢氟酸腐蚀性能的影响  

Effect of Aging Temperature on Microstructure and Corrosion Resistance of S32750 Super Duplex Stainless Steel in Hydrofluoric Acid

作　　者：逄旭光[1] 刘润青 王文涛 史艳华[1] 李飞[1] 梁平[1] 

机构地区：[1]辽宁石油化工大学机械工程学院,抚顺113001 [2]抚顺机械设备制造有限公司,抚顺113005

出　　处：《中国腐蚀与防护学报》2017年第6期519-525,共7页Journal of Chinese Society For Corrosion and Protection

基　　金：国家自然科学基金(51175240);辽宁省教育厅2012年科学研究一般项目(L2012127)~~

摘　　要：通过金相显微镜和扫描电镜观察了S32750超级双相不锈钢(SDSS)经650~1000℃时效处理后的显微组织和微观形貌;通过XRD分析了时效后各试样的物相结构;借助动电位极化、电化学阻抗和Mott-Schokkty曲线等方法,考察了时效后的S32750 SDSS在5%(体积分数)HF溶液中的腐蚀行为。结果表明:当时效温度为650和1000℃时,S32750 SDSS内并没有析出物产生。当温度上升到750~950℃时,开始产生σ析出相;且温度为850℃时,σ析出相最多,抗氢氟酸腐蚀性能最差。这主要是因为析出的σ相造成了材料内Cr和Mo分布的不均匀,促进了腐蚀微电池的形成,加快了不锈钢的溶解。同时,σ相的析出也增大了钝化膜的载流子密度,促进了F-的吸附,增大了钝化膜的溶解速率,降低了钝化膜的稳定性,加快了双相不锈钢的腐蚀。S32750 super duplex stainless steel（SDSS） was aged in the temperature range 650 ℃to 1000 ℃,and then was characterized by means of optical microscope（OM）,scanning electronic microscope（SEM） and X-ray diffractometer（XRD）.The corrosion resistance of the aged steel in 5%（volume fraction） HF solution was assessed by measurements of potentiodynamic polarization,electrochemical impedance spectra（EIS） and Mott-Schokkty plots.Results show that the σ phase precipitated in the steel in the temperature range from 750 ℃ to 950 ℃,but not at 650 ℃ and 1000 ℃ respectively.Among others,the amount of σ phase is the highest and correspondingly,the corrosion resistance is also the worst for the steel aged at 850 ℃.This is mainly because of that the precipitates of σ phase lead to the segregation of Cr and Mo within the steel,thus the non-uniform distribution of the alloying elements in the steel may induce galvanic corrosion within the steel,which accelerates the dissolution of SDSS.At the same time,the σ phase precipitation may also induce the increase of carrier densities of the formed passive film of the steel in HF solution,which enhanced the adsorption of F^-,and in turn the dissolution rate of passive film and finally reduced the stability of the passive film,thus,the corrosion rate of SDSS in HF is accelerated.

关 键 词：S32750超级双相不锈钢 氢氟酸 Σ相 时效温度 

分 类 号：TG174.2[金属学及工艺—金属表面处理]