低磁不锈钢表面处理工艺及防护涂层体系设计研究

研究了不同表面处理工艺对低磁不锈钢基材自身耐蚀性能及涂层附着性能的影响,通过电化学阻抗及耐阴极剥离性测试确定了适用于低磁不锈钢表面的防护涂层体系.研究结果表明,以棕刚玉为喷砂磨料对基材进行喷砂处理,不仅可以提高基材表面粗糙度,满足涂层高附着需求,同时可降低基材表面残留粒料对基材引起的电化学腐蚀.以环氧锌黄为底层的防护涂...     

Interaction between austein-ferrite phases on passive performance of 2205 duplex stainless steel

The passive behavior of 2205 duplex stainless steel (DSS) and its individual phases (α-phase, γ-phase) in neutral 3.5% NaCl solution was investigated by various electrochemical methods. The results indicated that galvanic effect between α and γ phases cannot deteriorate local corrosion, but favors the enhancement of the passive film. Under the galvanic effect, the diffusion of the dissolved passive cations would be promoted in a short distance between α and γ zones, leading to modifications of the chemical composition and semiconductive property of the passive film and therefore the enhancement of the corrosion resistance of DSS 2205.     

AM355不锈钢在酸性溶液中的腐蚀电化学行为

结合腐蚀形貌,通过极化曲线、交流阻抗谱(EIS)和莫特肖特基(MS)曲线的测定,分析了溶液pH值对AM355不锈钢腐蚀电化学行为的影响。结果表明:随溶液pH值的减小,腐蚀电位正移,腐蚀电流密度增大,致钝电位发生了正移,致钝电流密度、维钝电流密度增大。钝化膜由铬氧化物和铁氧化物组成,酸性增加使得铁氧化物施主浓度增大,钝化膜表面吸附氢离子电荷密度增加。钝化膜的厚度及其电阻随pH值的减小而减小,钝化膜更容易被破坏,酸性达到一定程度,钝化膜局部区域优先腐蚀。溶液pH值减小,AM355在溶液中保持自钝化性能降低,材料的腐蚀速率增加。     

Effects of deformation on hydrogen degradation in a duplex stainless steel

Hydrogen embrittlement of annealed, 20 and 40% cold worked 2205 duplex stainless steels has been evaluated using electrochemical permeation measurement, hydrogen microprint technique and tensile test in this study. Due to hydrogen transport in 2205 duplex stainless steel is mainly lattice diffusion in ferritic phase, more hydrogen distribution, higher permeation rate and effective diffusion in ferritic phase were detected. Hydrogen trapping and mechanical property effects were studied for cold worked specimens. Fractographic investigation revealed that hydrogen absorption promoted transgranular fracture in cold worked specimens. These results exhibits that the cold worked duplex stainless steels are more susceptible to hydrogen embrittlement.     

Pitting corrosion of 2Cr13 stainless steel in deep-sea environment

Pitting corrosion of 2Cr13 stainless steel was investigated by deep-sea exposure test at various depths of 500 m,800 m and 1200 m in the South China Sea for 4 months.With the aid of electrochemical measurements in simulated deep-sea environments and grey relational analysis,the influence of deepsea environments on passive film and the mechanism of pitting corrosion were discussed.The results indicated that with the increase of sea depth,pitting depth of 2Cr13 stainless steel increased,which can be attributed to the change of chemical composition and the degradation of pitting resistance of passive film.Film growth was greatly retarded in the condition of low seawater temperature and low dissolved oxygen content of deep sea,resulting in an unstable and vulnerable film.Pitting depth was most influenced by hydrostatic pressure,which can increase the adsorption and penetration of Cl-ion,and promote the proliferation of point defects in passive film,leading to rapid deconstruction of protective oxides of the film.Pitting sensitivity of 2Cr13 stainless steel increased eventually with the combination of accelerated dissolution and suppressed self-healing of passive film in deep sea.     

海滨盐碱土壤中硫酸盐还原菌对X100管线钢腐蚀行为的影响

为了进一步明确X100管线钢在含硫酸盐还原菌(SRB)海滨盐碱土壤中的耐蚀性,采用表面分析技术、电化学技术和失重法,研究了SRB对X100管线钢腐蚀过程与行为的影响。结果表明:X100管线钢在有无SRB海滨盐碱土壤中的腐蚀均属于中度腐蚀,无SRB时腐蚀产物主要为Fe_2O_3,Fe_3O_4和γ-Fe O(OH),有SRB时腐蚀产物主要为Fe_2O_3,Fe_3O_4,α-Fe O(OH)和Fe7S8;SRB代谢形成的活性生物膜影响了X100管线钢的腐蚀行为,随着腐蚀时间的增加,SRB可在X100管线钢表面形成由微生物膜与腐蚀产物结合的膜,其更加致密,对腐蚀传质具有物理阻碍作用,可以减缓X100管线钢的腐蚀;无SRB菌时X100管线钢表面的腐蚀产物疏松多孔并分布有裂纹,且对基体的保护作用差,其腐蚀速率大于有SRB时的值;SRB的代谢活动抑制了X100管线钢的腐蚀。     

Effect of dissolved oxygen on electrochemical corrosion behavior of 2205 duplex stainless steel in hot concentrated seawater

The corrosion behavior of 2205 duplex stainless steel was investigated in hot concentrated seawater with different dissolved oxygen(DO) concentration by electrochemical measurement techniques and surface analysis methods. DO obviously enhances the cathodic reaction process, the formation of passive film and polarization resistance. With increasing the DO concentration from 0.34 to 3.06 mg L^-1, the relative contents of Fe₂O₃ and Cr₂O₃ and the Cr-enrichment gradually enlarge in the passive film. The higher DO concentrations result in lower defect densities and thicker of space charge layers in the passive films,whichmayeffectively inhibit the intrusion of aggressive chloride ions. The increment inDOconcentration clearly increases the pitting potential, but decreases the repassivation potential. It may weaken both the occurrence and repassviation tendencies of stable pitting corrosion.     

Effect of nitrogen on biocorrosion behavior of high nitrogen nickel-free stainless steel in different simulated body fluids

The aim of this research is to study the biocorrosion behavior of high nitrogen nickel-free stainless steel (HNS) with different nitrogen content, also with comparison to AISI 317L, in three different simulated body fluids. The comparison was focused on the influence of nitrogen in HNS and different protein solutions on the passive behavior using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and capacitance measurements (Mott-Schottky approach). The study revealed that HNS possessed thicker and more protective passive films with increase of nitrogen, which could improve the biocorrosion resistance and biocompatibility after implanted. The passive films behaved as n-type semiconductors and showed a decrease in donor density by nitrogen addition, thus indicating more beneficial for haemocompatibility. The electrochemical behavior recorded in the albumin and fibrinogen solutions revealed protein played an important role in the biocorrosion of HNS, which could result in the breakout of passive films and enhance the corrosion rate by means of chelation.     

Cl~-和应力对X80管线钢电化学腐蚀行为的影响

目前,对于Cl~-和应力同时作用时钢铁腐蚀行为及机理的研究不多。采用动电位极化和交流阻抗谱,研究了Cl~-和应力对X80管线钢在高pH值溶液中腐蚀行为的影响。结果表明:Cl~-对X80管线钢的钝化行为有显著影响,当Cl~-浓度小于0.10 mol/L时,X80管线钢表面会形成稳定的钝化膜,当Cl~-浓度大于0.10 mol/L时,则不会形成稳定的钝化膜。在自腐蚀电位下,少量的Cl~-可增加X80管线钢的腐蚀倾向,但大量Cl~-可降低其腐蚀倾向。外加应力使交流阻抗谱低频区出现第二段容抗弧,并且提高自腐蚀电位下X80管线钢的溶解速率。     

304不锈钢表面化学钝化膜对Sn粘附行为的影响

为了研究化学酸洗钝化在低熔点金属Sn与304不锈钢粘附过程中的作用,通过浸泡腐蚀实验分析了液态Sn与U型弯曲后的酸洗钝化不锈钢的交互作用行为,探讨了Sn粘附对不锈钢基体浸泡腐蚀性能的影响.实验结果表明:Sn与304不锈钢相互作用在界面处形成了片状(Fe,Cr)Sn2化合物冶金层,酸洗钝化处理改变了冶金结合,使液态Sn与304不锈钢界面成为直接物理接触;U型弯曲破坏了钝化膜的完整性,未能阻止Sn与不锈钢的界面冶金结合,但降低了界面化合物层的厚度.浸泡腐蚀实验结果表明,Sn粘附层促进了不锈钢基体腐蚀.     

油气输送管道钝化行为的交流阻抗谱研究

油气输送管道表面的钝化膜易遭受HCO-3破坏,从而引起管道报废造成重大损失.采用动电位扫描技术研究了管道用材(X70钢)在4种不同NaHCO3/Na2CO3浓度溶液中的极化曲线,并根据极化曲线确定其电位范围,测试了X70钢在NaHCO3/Na2CO3溶液中钝化膜的电化学交流阻抗谱(EIS),提出了X70钢在NaHCO3/Na2CO3溶液中的等效电路模型.结果表明:X70钢在NaHCO3/Na2CO3溶液中具有二次钝化行为,表面先后形成两种性能不同的钝化膜,随着HCO-3浓度的增加,一次钝化膜逐渐溶解,二次钝化膜逐渐增厚,耐蚀性增强,起到了很好的保护作用.     

Stress corrosion cracking of 2205 duplex stainless steel in H<Subscript>2</Subscript>S–CO<Subscript>2</Subscript> environment

Stress corrosion cracking (SCC) behavior of 2205 duplex stainless steel (DSS) in H₂S–CO₂ environment was investigated by electrochemical measurements, slow strain rate test (SSRT), and scanning electron microscopy (SEM) characterization. Results demonstrated that the passive current density of steel increases with the decrease of solution pH and the presence of CO₂. When solutions pH was 2.7, the steel SCC in the absence and presence of CO₂ is expected to be a hydrogen-based process, i.e., hydrogen-induced cracking (HIC) dominates the SCC of the steel. The presence of CO₂ in solution does not affect the fracture mechanism. However, the SCC susceptibility is enhanced when the solution is saturated simultaneously with H₂S and CO₂. With elevation of solution pH to 4.5, the hydrogen evolution is inhibited, and dissolution is involved in cracking process. Even in the presence of CO₂, the additional cathodic reduction of H₂CO₃ would enhance the anodic reaction rate. Therefore, in addition to the hydrogen effect, anodic dissolution plays an important role in SCC of duplex stainless steel at solution pH of 4.5.     

混凝土养护期间HRB400钢筋钝化行为研究

为了研究HRB400钢筋在模拟养护阶段混凝土孔隙液中表面钝化膜的生长过程,采用3种电化学测试技术(开路电位、电化学阻抗谱、动电位极化曲线)研究钢筋表面钝化膜的性能随着浸泡时间的变化特征,此外通过XPS对稳定钝化膜的成分与结构进行分析。结果表明,同传统钢筋材料一样,HRB400钢筋在模拟混凝土养护条件的溶液中展现出良好的耐蚀性能,浸泡5 d后便能够生成稳定钝化膜。XPS分析发现钢筋钝化膜为双层结构,内层以二价铁离子化合物为主,外层主要由三价铁离子化合物组成。     

An impedance study of two types of stainless steel in Ringer physiological solution containing complexing agents

The effect of complexing agents EDTA and citric acid on the electrochemical behaviour of AISI 304 and orthopaedic stainless steels in Ringer physiological solution was investigated by potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS). The content of Mo has a pronounced effect on the corrosion resistance, as evident by the broader passive range of the orthopaedic stainless steel containing Mo. The addition of complexing agents induces significant changes in polarization and impedance characteristics, i.e., the shift of corrosion and breakdown potentials in a more negative direction, an increase in current density, and a significant decrease in charge transfer resistance. The results were interpreted by the formation of soluble complexes of metal ions with chelating agents, especially EDTA, which suppressed the formation of the outer Fe(III) layer of the passive film. The impact of complexing agent on the electrochemical parameters was found to be related to its concentration in electrolyte and the stability constant of the complex formed with the related metal ion.     

双相不锈钢2205激光焊接接头组织和性能研究

目的 针对双相不锈钢激光焊接接头两相比例失衡的问题,研究双相不锈钢2205激光焊接接头组织和性能。方法 采用Disk 6002碟片激光器对2205双相不锈钢进行激光焊接,通过在纯氩气保护气中添加体积分数为60%的氮气,向熔池中过渡氮元素,以提高焊缝中的奥氏体含量;采用金相显微镜、电子背散射衍射技术、电子探针X射线显微分析仪、显微硬度仪和上海辰华CHI760E电化学工作站等手段,对激光焊接接头表面组织、元素含量、显微硬度和耐腐蚀性能进行表征和测试。结果 与纯氩气保护焊接接头相比,当在保护气中添加60%（体积分数,下同）的氮气后,奥氏体相体积分数达到39.89%,提升了25.94%,奥氏体中氮元素的质量分数达到0.679%时,氮元素的质量分数提升了0.196%,焊缝中奥氏体显微硬度为307.4HV,铁素体显微硬度为298.9HV,极化曲线腐蚀电流密度升高,阻抗弧半径减小。结论 在保护气中添加60%的氮气后,激光焊接接头中奥氏体的体积分数提升,增加的奥氏体组织以晶内奥氏体为主,并且更多的氮元素进入到奥氏体相中,焊缝中的奥氏体和铁素体硬度略有升高,耐蚀性和钝化膜稳定性有所下降。     

Improvement in the corrosion-erosion resistance of 304 stainless steel with alloyed yttrium

It has been previously demonstrated that yttrium can improve the resistance of stainless steel to sliding wear in corrosive environment. However, the mechanism responsible for the beneficial effect of yttrium on corrosive wear is not well understood. In this work, the erosion behavior of Y-free and Y-containing 304 stainless steel in a dilute H₂SO₄ slurry containing silica sand was investigated, with the aim of exploring the role that yttrium plays. The failure and self-healing of passive films on Y-free and Y-containing 304 stainless steel samples under combined attack by corrosion and mechanical scratch were studied, using an electrochemical scratch technique. The failure of the passive films during dry scratch and identation was also investigated using a micro-mechanical probe with in situ monitoring changes in the electrical contact resistance. In addition, effect of yttrium on electron work function was investigated. All the results demonstrated that yttrium effectively improved properties of the passive film, including corrosion resistance, mechanical behavior and the film stability, resulting in enhanced resistance to corrosion-erosion.     

城市污水作冷却水时影响316L不锈钢耐蚀性的因素

用电化学方法研究了水质中的Cl-、NH4 -N、化学需氧量(COD)和pH值对316L不锈钢耐蚀性的影响.试验表明:在测试水质条件下,Cl-浓度达到300 mg/L时316L不锈钢点蚀电位有明显的下降;NH4 -N浓度的增加使点蚀电位显著降低;COD的增大使钝化电流有所增大;pH值增大到9时使316L不锈钢钝化电流有明显的增加.     

固溶处理对2205双相不锈钢耐蚀性能的影响

利用箱式电阻炉、金相显微镜、电化学工作站等设备研究固溶处理温度对2205不锈钢在不同介质中显微组织和耐蚀性的影响。结果表明,随着固溶温度升高,奥氏体含量不断减少,铁素体含量不断增多;在p H值不同的溶液中,双相不锈钢的耐蚀性能有一定差异:酸性溶液中,在1 050℃左右进行固溶处理,此时的双相不锈钢奥氏体与铁素体含量比接近1∶1,耐酸性能较好,而在碱性溶液中,1 100℃固溶处理时的腐蚀速度较小,耐蚀性能较好;1 100℃固溶处理的双相不锈钢在含氯离子的环境中虽无明显钝化区,但腐蚀速率较小,具有一定耐点蚀性能。     

Electrochemical properties of 316L stainless steel with culturing L929 fibroblasts.

Potentiodynamic polarization and impedance tests were carried out on 316L stainless steel with culturing murine fibroblast L929 cells to elucidate the corrosion behaviour of 316L steel with L929 cells and to understand the electrochemical interface between 316L steel and cells, respectively. Potential step test was carried out on 316L steel with type I collagen coating and culturing L929 cells to compare the effects of collagen and L929 cells. The open-circuit potential of 316L steel slightly shifted in a negative manner and passive current density increased with cells, indicating a decrease in the protective ability of passive oxide film. The pitting potential decreased with cells, indicating a decrease in the pitting corrosion resistance. In addition, a decrease in diffusivity at the interface was indicated from the decrease in the cathodic current density and the increase in the diffusion resistance parameter in the impedance test. The anodic peak current in the potential step test decreased with cells and collagen. Consequently, the corrosion resistance of 316L steel decreases with L929 cells. In addition, collagen coating would provide an environment for anodic reaction similar to that with culturing cells.     

Microstructure and Corrosion Resistance of Dissimilar Weld-Joints between Duplex Stainless Steel 2205 and Austenitic Stainless Steel 316L

The microstructure and corrosion resistance of dissimilar weld-joints between stainless steel SAF 2205 and stainless steel AISI 316 L were investigated. Welding was accomplished by different types of welding wires AWS ER 347, AWS ER 316 L and AWS ER 309 L. To verify soundness of welded samples, nondestructive tests were performed. Metallographic samples were prepared from cross-section areas of weldjoints to investigate microstructure of different regions of weld-joints by optical microscopy and scanning electron microscopy. Corrosion resistance of weld-joints was evaluated in NaCl solution by potentiodynamic polarization and electrochemical impedance techniques. In the weld metal AWS ER 347, the brittle sigma phase was created, resulting in the decrease of weld-joint corrosion resistance. According to the results of metallurgical investigations and corrosion tests, welding wire AWS ER 309 L was suitable for welding duplex stainless steel(SAF 2205) to austenitic stainless steel(AISI 316L) by gas tungsten arc welding(GTAW)process.