Uniform corrosion and intergranular corrosion behavior of nickel‐free and manganese alloyed high nitrogen stainless steels

The uniform and intergranular corrosion behavior of two kinds of nickel‐free and manganese alloyed high nitrogen stainless steels (HNSSs) were investigated. A type of 316L stainless steel (316L SS) was also included for comparison purpose. Both solution annealed (SA) and sensitization treated (ST) steels were examined. It was found that the SA HNSSs had much weaker resistance to uniform corrosion compared to the SA 316L SS. The addition of molybdenum, to some extent, improved the uniform corrosion resistance of the HNSSs. The sensitization treatment had little influence on the uniform corrosion resistance of all the steels. The HNSSs showed an obvious susceptibility to intergranular corrosion, in particular the ST HNSSs. The intergranular corrosion rates of the sensitized HNSSs were much higher than that of the sensitized 316L SS. The degree of interganular attack for the ST HNSSs was much more serious than that for the 316L SS. The addition of molybdenum obviously improved the resistance of the ST HNSSs to intergranular corrosion. The double loop electrochemical potentiokinetic reactivation tests also proved that the HNSSs were rather susceptible to the sensitization treatment compared to the 316L SS. The relatively weak resistance of the HNSSs to uniform and intergranular corrosion may be due to high manganese promoted anodic dissolution. The improvement of uniform and intergranular corrosion resistance caused by the addition of molybdenum could be attributed to the synergistic effects of molybdenum and nitrogen in the HNSSs on the formation and stability of passive film.     

316不锈钢在通氢稀盐酸中的腐蚀行为

采用电化学测量技术研究了316不锈钢在通高纯氢气的稀盐酸中的腐蚀行为，极化曲线和电化学阻抗谱测定结果表明，316不锈钢在腐蚀电位下处于活化区，其表面能形成多孔的腐蚀产物膜，氢渗入不锈钢试样表面将导致腐蚀阻力减小，且试样表面层的含氢量随腐蚀的进行而增加，SO4^2-对316不锈钢在测试介质中的腐蚀有抑制作用。     

Numerical simulations study of the localized corrosion resistance of AISI 316L stainless steel and pure titanium in a simulated body fluid environment

The resistance of both AISI 316L stainless steel (AISI 316L SS) and commercially pure titanium (cpTi) to localized corrosion in a simulated body fluid solution was investigated using numerical simulations. The resulting model, based on transport equations in dilute solutions, is designed to predict the susceptibility of these two biomaterials to crevice corrosion initiation. The results show that cpTi and AISI 316L SS alloy are very resistant to the initiation of crevice corrosion in 0.9% NaCl solution and AISI 316L SS alloy is more susceptible to corrosion initiation over the long term than cpTi.     

医用 316L 不锈钢表面多巴胺 / BSA 复合膜缓蚀性能研究

目的研究医用316L不锈钢表面组装多巴胺/牛血清白蛋白分子(BSA)复合膜的缓蚀性能。方法采用浸泡法在医用316L不锈钢表面制备以多巴胺自组装膜为桥接层的多巴胺/BSA复合双层自组装膜,通过动电位扫描、交流阻抗测试,SEM,EDX等手段分析BSA组装液质量浓度对复合双层自组装膜吸附行为及耐蚀性能的影响。结果在合适的自组装条件下可获得具有缓蚀效果的复合双层膜。BSA质量浓度过高和过低均对缓蚀性能有不利影响,当BSA质量浓度为40 g/L时,复合双层膜对生理盐水环境中316L不锈钢取得最佳缓蚀效率,缓蚀效率由单层多巴胺的62.4%增加至83.9%。结论多巴胺成功嫁接BSA分子,使其吸附在不锈钢表面,和单层BSA吸附相比,其吸附量大大提高,表明对于316L不锈钢人体植入材料,可以利用多巴胺桥接BSA获得兼具生物活性和耐腐蚀性的改性表面。     

天然海水中微生物膜对316L不锈钢腐蚀行为研究

采用电化学技术包括开路电位、电化学阻抗谱、动电位极化、循环极化、表面表征技术、包括扫描电镜和能谱分析研究了316L不锈钢在天然海水中微生物膜影响的初期腐蚀行为。研究表明,海洋微生物在不锈钢表面发生附着形成生物膜。在天然海水中不锈钢的开路电位正移约450mV,而在灭菌海水中不锈钢的开路电位基本保持不变。电化学阻抗和极化实验结果指出,海洋微生物膜使不锈钢阻抗增加,点蚀电位升高,生物膜抑制了不锈钢的腐蚀发生。这种抑制作用经历了一个先变大后减小的过程。天然海水中,海洋生物膜的附着和其代谢产物作用使不锈钢的耐蚀性能得到提高,这一耐蚀性能的提高与生物膜影响的阳极抑制作用有关。     

炼油厂冷却水系统硫酸盐还原菌对316L不锈钢点腐蚀的研究

用开路电位、动电位扫描、电化学阻抗技术和扫描电镜等方法,研究了316L不锈钢在硫酸盐还原菌(SRB)溶液中的腐蚀电化学行为,分析了炼油厂冷却水系统微生物腐蚀的特征及机制.结果表明,在含有SRB溶液中的自腐蚀电位(Ecorr)和点蚀电位(Epit)随浸泡时间的增加而负移,极化电阻(Rp)随浸泡时间的增加而减小;在含有SRB溶液中的腐蚀速率均大于在无菌溶液中;SRB的生长代谢活动影响了316L SS表面的腐蚀过程,使不锈钢表面的钝化膜层腐蚀破坏程度增加,加速了316L SS的腐蚀.     

Electrochemical and XPS studies of AISI 316L stainless steel after electropolishing in a magnetic field

The thermodynamic stability and corrosion resistance of surface oxide layer are the most important features of stainless steels. Electrochemical polishing (EP) is the most extensively used surface technology for austenitic stainless steels. We have modified this surface technology by introducing a magnetic field to the system. With this new process called the magnetoelectropolishing (MEP) we can improve metal surface properties by making the stainless steel more resistant to halides encountered in a variety of environments.In this paper, the corrosion research results are presented on the behaviour of the most commonly used material - medical grade AISI 316L stainless steel. The corrosion investigations have been concerned on the open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and polarisation curves studies in the Ringer’s body fluid under room temperature (25 °C). The X-ray photoelectron spectroscopy (XPS) was performed on 316L samples after three treatments: MP - abrasive polishing (800 grit size), EP - conventional electrolytic polishing, and MEP - magnetoelectropolishing. The comparison of the corrosion behaviour of the stainless steel’s surface after these processes was also carried out. The purpose of XPS studies was to reveal the surface film composition and the reason of this modified corrosion behaviour. It has been found that the proposed MEP process modifies considerably the composition of the surface film and improves the corrosion resistance of the same 316L SS studied.     

Corrosion resistance of different steel grades in the geothermal fluid of Molasse Basin

Long‐term corrosion resistance of carbon steels grade API L80 and API Q125 has been evaluated by means of electrochemical measurements and exposure tests in the Molasse Basin, one of the most important geothermal fluids in Europe. In addition, the localized corrosion resistance of the duplex stainless steel alloy 2205 and the austenitic stainless steel grade 316L was determined at 100 and 150 °C. In general, investigated materials showed a remarkable resistance to uniform and localized corrosion. Their corrosion behaviour at service conditions is discussed in this paper.     

Investigation on Pitting Corrosion of Nickel-Free and Manganese-Alloyed High-Nitrogen Stainless Steels

Pitting corrosion behavior of three kinds of nickel-free and manganese-alloyed high-nitrogen (N) stainless steels (HNSSs) was investigated using electrochemical and immersion testing methods. Type 316L stainless steel (316L SS) was also included for comparison purpose. Both solution-annealed and sensitization-treated steels were examined. The solution-annealed HNSSs showed much better resistance to pitting corrosion than the 316L SS in both neutral and acidic sodium chloride solutions. The addition of molybdenum (Mo) had no further improvement on the pitting corrosion resistance of the solution-annealed HNSSs. The sensitization treatment resulted in significant degradation of the pitting corrosion resistance of the HNSSs, but not for the 316L SS. Typical large size of corrosion pits was observed on the surface of solution-annealed 316L SS, while small and dispersed corrosion pits on the surfaces of solution-annealed HNSSs. The sensitization-treated HNSSs suffered very severe pitting corrosion, accompanying the intergranular attack. The addition of Mo significantly improved the resistance of the sensitization-treated HNSSs to pitting corrosion, particularly in acidic solution. The good resistance of the solution-annealed HNSSs to pitting corrosion could be attributed to the passive film contributed by N, Cr, and Mo. The sensitization treatment degraded the passive film by decreasing anti-corrosion elements and Cr-bearing oxides in the passive film.     

Crevice Corrosion of Several Supper Stainless Steels in the Simulated LT-MED Environment

Susceptibility and morphological characteristics of crevice corrosion for SS316, SS904 L, SS254 sMo and SS2507 in the simulated low-temperature multi-effect distillation environment were investigated by cyclic polarization test, scanning electron microscope and laser microscope. The results show that the crevice corrosion resistance of four kinds of stainless steel is ranked as SS254 sMo ≈ SS2507SS316 SS904 L. There are ‘‘cover' structures over the edge of active crevice corrosion regions of SS904 L, SS254 sMo and SS2507, but SS316 is an exception. Galvanic corrosion characteristics appeared in the crevice of duplex supper stainless steel SS2507.     

316L不锈钢在模拟体液中的腐蚀行为

目的研究316L不锈钢生物医用材料植入体内初期的表面行为。方法在模拟体液中,采用浸泡实验,表征了316L不锈钢浸泡不同时间的表面形貌、润湿性及耐腐蚀性。结果白光干涉测试结果表明,样品表面粗糙度随浸泡时间的延长而变大。浸泡1 d后,在样品表面出现大量无规则的腐蚀坑,腐蚀坑内出现金属的溶蚀。润湿性测试结果显示,随浸泡时间的延长,316L不锈钢的接触角减小,亲水性增强,表面能增加。电化学测试表明,浸泡1周后,316L不锈钢的自腐蚀电流为浸泡前的3倍多,腐蚀速度增大,耐腐蚀性变差。结论在模拟体液中,316L不锈钢表面存在局部腐蚀,材料的表面形貌、成分、润湿性及耐腐蚀性均发生改变。     

Electrochemical corrosion behavior of LDX 2101® duplex stainless steel in a fluoride-containing environment

The effect of fluoride on the electrochemical corrosion behavior of an LDX 2101® duplex stainless steel (DSS) was studied. Open-circuit potential (E_OC) and electrochemical impedance spectroscopy (EIS) measurements were carried out in artificial saliva and with the addition of fluoride (1 wt% NaF). The electrochemical corrosion behavior of the AISI 316L austenitic stainless steel (SS) was also evaluated for comparison. Both open-circuit potential and EIS results indicate that DSS and austenitic SS undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the simulated aggressive environments. However, LDX 2101® exhibits superior corrosion resistance as compared with AISI 316L, and this improvement is ascribed to the formation of a passive film which shows a higher protective effect than the one formed on AISI 316L.     

Enhancing the localised corrosion resistance of 316L stainless steel via FBR-CVD chromising treatment

The resistance of stainless steels to localised corrosion can be adversely affected by environmental and metallurgical heterogeneities existed in complex industrial infrastructures such as seawater desalination plants exposed to aggressive evnironments. It is therefore critical to enhance the localised corrosion resistance and understand the corrosion behaviour of stainless steels in complex and aggressive industrial environmental conditions. In this work, the localised corrosion resistance of chromised stainless steel 316L (SS316L) in simulated seawater desalination systems has been investigated by electrochemical and surface analytical techniques. It has been found that chromising processes have improved the localised corrosion resistance of SS316L by reducing its susceptibility to pitting, crevice, and welding zone corrosion in simulated seawater desalination environments. This increased corrosion resistance has been explained by electrochemical polarisation studies and surface analysis showing that the chromising treatment at 1050°C resulted in a continuous and stable chromium-enriched layer on the SS316L surface.     

2205和316L不锈钢在氢氟酸中的电化学腐蚀行为

通过动电位极化和电化学阻抗方法考察了2205双相不锈钢和316L不锈钢在5%(体积分数)HF溶液中的电化学行为,借助Mott-Schokkty曲线分析了两种不锈钢表面钝化膜的半导体特性。结果表明：两种不锈钢在氢氟酸溶液中都能发生钝化,且2205双相不锈钢的钝化区间范围更宽,维钝电流密度更低。2205双相不锈钢表面钝化膜表现出更高的钝化膜电阻和电荷转移电阻,其抗氢氟酸腐蚀性能优于316L不锈钢,这主要与2205双相不锈钢中的Mo和Cr含量高、表面钝化膜缺陷少、钝化膜易修复等因素有关。     

尿素级316L不锈钢的非敏化态晶间腐蚀与电位的关系

用恒电位浸蚀方法在高压釜中研究了供货态316 L钢在尿素介质中发生非敏化态晶间腐蚀与电位区段的关系,并在常温硫酸溶液中研究了316 L钢非敏化态晶间腐蚀的发展过程及其与电位值的关系。结果表明,固溶态316 L钢在活化或活化—钝化过渡电位区仅产生全面腐蚀。而在过钝化电位区,既产生全面腐蚀,也产生晶间腐蚀。在过钝化电位区进行恒电位浸蚀时,在等电量条件下,随着浸蚀电位值升高,晶间腐蚀所占比例逐渐减小;在非等电量条件下,随浸蚀时间推移(即随浸蚀电量增加),晶间腐蚀深度和宽度都增加,腐蚀断面形态呈“V”字形。使用高纯不锈钢可以减轻非敏化态晶间腐蚀。     

不锈钢盐酸露点腐蚀行为的原位研究

利用一种新型的露点腐蚀模拟装置结合原位的电化学阻抗谱,电化学噪声等测试手段评价了304和316L两种不锈钢的盐酸露点腐蚀行为.结果表明,316L不锈钢表现出更优异的耐盐酸露点腐蚀性能,主要原因可归结为两点:一是316L不锈钢钝化膜中含有较高的Cr/(Cr+Fe) 比以及较低含量的Fe;二是316L不锈钢钝化膜中含有能改善抗点蚀性能的Mo.     

Characterization, Corrosion Resistance, and Cell Response of High-Velocity Flame-Sprayed HA and HA/TiO2 Coatings on 316L SS

The main aim of this study is to evaluate corrosion and biocompatibility behavior of thermal spray hydroxyapatite (HA) and hydroxyapatite/titania bond (HA/TiO₂)-coated 316L stainless steel (316L SS). In HA/TiO₂ coatings, TiO₂ was used as a bond coat between HA top coat and 316L SS substrate. The coatings were characterized by x-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy, and corrosion resistance determined for the uncoated substrate and the two coatings. The biological behavior was investigated by the cell culture studies using osteosarcoma cell line KHOS-NP (R-970-5). The corrosion resistance of the steel was found to increase after the deposition of the HA and HA/TiO₂ bond coatings. Both HA, as well as, HA/TiO₂ coatings exhibit excellent bond strength of 49 and 47?MPa, respectively. The cell culture studies showed that HA-coated 316L SS specimens appeared more biocompatible than the uncoated and HA/TiO₂-coated 316L SS specimens.     

核级316NG控氮奥氏体不锈钢的局部腐蚀行为

采用电化学测试法、点腐蚀试验法、盐雾腐蚀试验法和慢应变速率测试法,分别对比研究了核级316NG控氮奥氏体不锈钢和321奥氏体不锈钢的局部腐蚀行为,并利用扫描电子显微镜、光学显微镜等分别观察腐蚀后不锈钢的表面形貌。结果表明:316NG和321不锈钢晶间腐蚀再活化率分别为3.83%和4.47%,点腐蚀速率分别为10.74g/(m2·h)和45.97g/(m2·h),盐雾腐蚀速率分别为2.14×10-2 g/(m2·h)和12.32×10-2 g/(m2·h),应力腐蚀开裂敏感指数分别为0.078和0.10;316NG不锈钢中N和Mo元素提高了其耐局部腐蚀性能,因此其耐局部腐蚀性能均优于核电站结构材料321不锈钢的。     

Micro‐electrochemical characterization of galvanic corrosion of TA2/316L composite plate

Galvanic corrosion behavior of TA2/316L composite plate was investigated in the solution of 3.5 wt% NaCl by galvanic potential monitoring, scanning localized electrochemical impedance spectroscopy (LEIS) and scanning vibrating micro‐electrode (SVME) techniques. The results demonstrated that the pitting corrosion resistance of 316L for the galvanic combination sample is lower, and the coupled current density is higher than for the single 316L sample. It indicates that the galvanic action works on the corrosion behavior of the TA2 titanium alloy/316L stainless steel galvanic combination in sodium chloride solution. The galvanic effect width was determined as 1500 µm.     

316Ti在含氯离子300℃高温水中的应力腐蚀开裂

采用慢应变速率拉伸(SSRT)试验方法研究了316Ti在300℃高温水中的应力腐蚀开裂(SCC)行为。结果表明,在空气饱和条件下,试样的断裂时间、延伸率以及断裂能的值随着Cl^-浓度的增大显著降低,应力腐蚀敏感指数随着Cl^-浓度的增大则显著递增,二者具有一定相关性。316Ti不锈钢在300℃空气饱和水中发生SCC的临界Cl^-质量浓度为5 mg/L,只有在Cl^-质量浓度高于或等于5 mg/L,试样才发生穿晶型和部分沿晶混合型SCC。SCC裂纹多萌生于滑移台阶或蚀坑,也可能萌生于接近表面的铁素体相处;裂纹在向基体扩展过程中,铁素体相的存在阻碍了其扩展过程,从而提高了316Ti的抗SCC能力。氧在SCC裂纹萌生和扩展过程中都起着非常重要的作用。