22Cr双相不锈钢点蚀研究

简单介绍了22Cr双相不锈钢点蚀的试验测试方法,并采用模拟溶液高压釜浸泡实验对22Cr双相不锈钢点腐蚀性能进行了研究,结果表明：点蚀指标小于lOOmdd的22Cr双相不锈钢管材具有优良的耐点蚀性能。     

醋酸装置不锈钢设备点蚀原因浅析

在高温含杂质醋酸中,不锈钢设备点腐蚀是最普遍的腐蚀形式,危及安全生产。点腐蚀源自Cl-、Br-等有害离子的作用。本文探讨了氧与氧化剂同卤素离子竞争与吸附对点蚀的影响,探讨了钢组织与组分、介质、温度、应力、流速等差异对点蚀的影响,介绍了点蚀与其他腐蚀类型的关系,并提出了防护建议。     

敏化不锈钢在含溴醋酸溶液中的点蚀研究

用电化学法对敏化热处理的奥氏体不锈钢316L和双相不锈钢SAF2205在含溴醋酸溶液中的点蚀行为进行了研究，并用光学显微镜观察了敏化试样浸泡前后的金相组织。结果发现：随着Br^-浓度的增加，两种不锈钢原始材料和敏化材料的点蚀电位都降低，敏化热处理使两种不锈钢的耐点蚀性能下降；无论是两种不锈钢的原始材料还是敏化材料，SAF2205的耐点蚀性能均优于AISI316L。对于敏化的AISI316L不锈钢，Br^-诱发点蚀优先发生在奥氏体晶界附近；对于敏化的SAF2205不锈钢，Br^-诱发点蚀优先发生在γ晶界、某些α／γ相界及α晶界附近。     

SAF2205双相不锈钢的焊接工艺确定

通过对大量焊接工艺评定结果的分析,最终确定SAF2205双相不锈钢的焊接方法采用氩弧焊加焊条电弧焊。     

不锈钢点蚀缓蚀剂的研究进展

详述了不锈钢点蚀缓蚀剂的研究进展,主要介绍了无机缓蚀剂、有机缓蚀剂和复合缓蚀剂等类型的缓蚀剂,并从不锈钢点蚀缓蚀剂的性能、测试方法及其缓蚀作用机理等方面进行了初步阐述,展望了未来不锈钢点蚀缓蚀剂的开发研究方向和前景。     

不锈钢点蚀缓蚀剂的研究进展

详述了不锈钢点蚀缓蚀剂的研究进展,主要介绍了无机缓蚀剂、有机缓蚀剂和复合缓蚀剂等类型的缓蚀剂,并从不锈钢点蚀缓蚀剂的性能、测试方法及其缓蚀作用机理等方面进行了初步阐述,展望了未来不锈钢点蚀缓蚀剂的开发研究方向和前景。     

2205双相不锈钢的焊接工艺研究

在2205双相不镑钢焊接过程中,通过对焊缝金属和焊接热影响区内金属相变的分析研究,总结出了合理的焊接工艺。     

304L不锈钢在溴离子作用下的点蚀行为

通有含溴离子氮气的３０４ Ｌ不锈钢管,经一段时期的使用后产生了严重点蚀。通过解剖被蚀钢管,采用金相分析,ＳＥＭ 形貌分析及ＥＤＳ成分分析的方法,对本案例点蚀特征进行研究, 发现：蚀孔形核于晶界,并以蚀孔自身扩张和孔内形成次生蚀孔两种方式生长,且蚀孔内壁产生富Ｃｒ 层。最后,就相关的电化学理论进行了探讨,并推测活化态蚀孔内壁的溶解导致了富Ｃｒ 层的产生,而富Ｃｒ 层的存在则是孔内建立局部活化态,次生蚀孔形核的物质基础。     

双相不锈钢2205的埋弧焊焊接

本文通过对双相不锈钢采用埋弧焊焊接,通过外观、力学性能及其它性能的检验,结果表明:埋弧焊焊接在双相不锈钢压力容器设备中,完全能焊制出符合制造标准要求的焊接接头,提高生产效率。     

双相不锈钢在硫酸介质中的应用探讨

介绍了硫酸的腐蚀特性和双相不锈钢的合金化原理、机械性能、耐腐蚀性能。通过分析比较,双相不锈钢凭借优良的耐腐蚀性能、较高的机械强度及低廉的价格,在烟气脱硫、湿法冶炼、硫酸生产等硫酸介质中具有良好的应用前景,可以替代奥氏体不锈钢甚至镍基合金制作罐、槽和管道等。     

应变和氯离子浓度对304不锈钢点蚀敏感性的影响

The effects of strain and chloride concentration on pitting susceptibility for type 304 stainless steel were studied in situ using the electrochemical technology under constant strain. The impact factor fc was brought forward to value the effect of strain on pitting. The pitting behaviors of type 304 stainless steel in various chloride concentrations under the strain levels 0%, 10%, and 30% were investigated. Potentiostatic polarization technology was used to study how the chloride concentration affected corrosion current density. The results indicated that fc increased substantially and pitting potential varied remarkably when chloride concentration was over 90 mg.L . Under the three levels of strain mentioned above, when chloride concentration was below 463 mg.L^-1,121 mg.L^-1, and 98 mg.L^-1 respectively, the pitting potential shifted towards positivity and, the passive film became more stable. When the strain was below 10%, the pitting susceptibility of type 304 stainless steel varied greatly as strain increased, whereas the susceptibility only changed a little when the strain was over 10%.     

Electrochemical pitting behaviour of type 321 stainless steel in sulfide-containing chloride solutions

The pitting behaviour of type 321 stainless steel in sulfide-containing chloride aqueous environments was studied using cyclic potentiodynamic polarization. A well-established correlation between H₂S and Na₂S₂O₃ in the study of corrosion was applied, that is, H₂S was simulated by Na₂S₂O₃. The major factors affecting the pitting corrosion of type 321 stainless steel are the Cl^- concentration, solution pH and temperature. The results clearly indicate that both E_pit and E _pp decrease with increasing Cl^- concentration and temperature, while I _pass is more sensitive to temperature variation. E _pit decreased with decreasing pH in the range 2 < pH < 7.5. The surface morphology and chemistry of the corroded type 321 stainless steel resulting from anodic polarization in 0.01 M S₂O ₃ ^2- -containing Cl^- solution were analysed by XRD, SEM and EPMA. A higher concentration of sulfur was found in the pits, and the dark surface film was mainly composed of FeS and -Fe₂O₃. The results describe the pitting behaviour of type 321 stainless steel in sulfide-containing Cl^- aqueous environments.     

PTA装置双相不锈钢管线失效分析

PTA生产装置的PX氧化工段2205双相不锈钢设备和管线多次发生腐蚀泄漏。通过宏观分析,成分分析,金相分析,SEM扫描,EDS(色散谱)分析,对该工段泄漏原因进行分析,结果表明,管线中的乙酸蒸气和水蒸气冷凝,形成乙酸溶液并携带残渣对管壁造成冲刷腐蚀,最终造成管线的穿孔失效。     

Electrochemical investigations of pitting corrosion behaviour of type UNS S31603 stainless steel in thiosulfate-chloride environment

The pitting corrosion behaviour of type UNS S31603 stainless steel (316L SS) in 0.01, 0.05 and 0.1 M thiosulfate ion (S₂O₃ ^2–) in the absence and presence of various concentrations of chloride ion (Cl^–) was studied using the cyclic potentiodynamic polarization method. The influence of major factors which affect pitting corrosion such as pH and temperature, were also investigated. It was found that both the pitting potential (E _pit) and the repassivation potential (E _rp) decreased with increase in Cl^– concentration and solution temperature and a more pronounced difference in E _pit values for various concentrations of S₂O₃ ^2– in 1.0 M Cl^– was obtained at lower temperatures. The effect of pH on E _pit, E _corr and E _rp values for different concentrations of S₂O₃ ^2– in the presence of 1.0 M Cl^– was also determined.     

Critical pitting and repassivation temperatures for duplex stainless steel in chloride solutions

Both the critical pitting temperature (CPT) and critical repassivation temperature (T_r) for two kinds of duplex stainless steels (DSS, namely UNS S31803 and UNS S32750) were investigated in 1 mol/L NaCl solution using the cyclic thermammetry method. Potentiodynamic anodic polarization technique was employed to validate the cyclic thermammetry technique. In addition, the site of pitting nucleated preferentially on the DSS had been confirmed by scanning electron microscopy (SEM). The results demonstrated that there exhibits a hysteresis loop in cyclic thermammetry curve, revealing that the propagating pits could repassivate during the cooling half-cycle. The CPT and T_r for UNS S31803 were 59.6 °C and 36.5 °C, whilst the CPT and T_r for UNS S32750 were 87.5 °C and 70.5 °C, respectively. Pitting was always observed preferentially in the austenite phase. The results can be partially explained based on the changes in chemical composition of ferrite and austenite phases. Moreover, a semi-quantitative model is proposed to explain the existence of T_r.     

Determination of pitting initiation of duplex stainless steel using potentiostatic pulse technique

Duplex stainless steel simultaneously comprises various phases, inclusions, precipitates and grain boundaries. It is full of academic and valuable significance for materials designing and processing optimization to ascertain the corrosion resistance of corresponding phases and various microstructures. However, up to date, efficient evaluation technique is still scare mainly due to difficulty in controlling of micropits. In this work, for the first time, optimized potentiostatic pulse technique (PPT) was established and applied to study the rule of initiation of pits of solution annealed and aged DSS in 1.0 mol/L NaCl solution. The results showed that the size of pits can be well-controlled by adjusting the condition of potential pulse. Combined with SEM/EDS system observation, it was found that for solution-annealed specimens, sulphide and oxide mixed inclusions were the preferential pit initiation sites, while for aged specimens, majority pits occurred at inclusions in area impoverished in Cr/Mo, which is vicinal to σ phase. The phenomena that growing pits is retarded by precipitation rich in Cr/Mo, i.e. σ phase, was testified and explained.     

Evaluation of localized corrosion in duplex stainless steel aged at 850 °C with critical pitting temperature measurement

Effect of aging at 850 °C on pitting corrosion of UNS S31803 duplex stainless steel was examined in chloride solution by potentiostatic critical pitting temperature (CPT) measurements. The quantitative metallography coupled with X-ray diffraction technique was employed to follow the microstructure evolution. Moreover, the initiation and propagation of pitting corrosion had been imaged in relation to microstructure variations using scanning electron microscopy (SEM). The results demonstrated that the corrosion behavior is strongly dependent on the microstructure, namely the presence of sigma phase. A deterioration of pitting corrosion resistance is found after aging 4 min, resulting in a drop in CPT. In particular, the metastable current transients during CPT test can clearly reflect the initiation of pitting process. Pitting nucleates preferentially in the austenite phase for the solution-annealed specimen, while the initiation of pitting corrosion takes place around sigma phase, in the newly formed secondary austenite for the aged specimen.     

用于制备冷冻盐水的不锈钢列管式蒸发器的制作和维护

从理论上阐述321奥氏体不锈钢在冷冻氯化钠盐水中没有发生由Cl-诱发点腐蚀的原因,并提出用于制备冷冻盐水的不锈钢材质蒸发器在制作、使用及维护保养中的注意事项。     

氯离子与冷却水系统中不锈钢的腐蚀

综述了有关氯离子对冷却水系统中不锈钢腐蚀研究的最新进展,涉及冷却水中氯离子引发不锈钢孔蚀、缝隙腐蚀和应力腐蚀开裂的机理,氯离子的限度,以及影响水中不锈钢腐蚀的其他因素.对如何应对冷却水中氯离子的负面效应提出了见解.