SUS304ss包埋粉末渗铝的耐蚀性能

展开了SUS304ss及其渗铝后在0.33 mol/L FeCl₃+0.05 mol/L HCl 溶液中的耐蚀性实验、1000 ℃下的抗高温氧化实验及表面沉积 碱金属氯化物和硫酸盐在500 ℃下的耐蚀性实验,用失重法和电 化学方法等综合评定了SUS304ss渗铝后的耐蚀性。研究表明：渗铝SUS304ss表面渗铝层结构致密,厚度为50μm;在 0.33 mol/L FeCl₃+0.05 mol/L HCl溶液中SUS304ss发生了严重孔蚀,渗铝后表面发生轻微孔蚀;渗铝SUS304ss在1000 ℃下加热,表面和截面形貌完好,耐高温氧化性提高了约5倍;在500 ℃下表面沉积盐碱混合物,渗铝SUS304ss耐腐蚀性约提高20倍;渗铝后SUS304ss的腐蚀电位大于未渗铝钢,耐蚀性提高。     

Novel strategies for assessing the pitting corrosion resistance of stainless steel surfaces

Pitting corrosion is one of the most common mechanisms of surface damage on stainless steels. Electrochemical methods have been preferentially applied for the evaluation of the pitting corrosion resistance of stainless steels in the laboratory. Nevertheless, some of them are not reliable enough and in general the application of electrochemical methods in the field becomes difficult because of required deep understanding of corrosive phenomena and measurement technology. Therefore, new approaches for the evaluation of the pitting corrosion susceptibility of stainless steel surfaces in the laboratory as well as in the field are necessary. In the present paper two novel strategies including electrochemical noise measurements under anodic polarization for laboratory testing, and an indicator test to assess the susceptibility of stainless steel surfaces to pitting corrosion in the field are introduced. Experimental results concerning the influence of surface treatments on the pitting corrosion resistance on stainless steels have confirmed that final surface condition has a significant effect on their future pitting corrosion susceptibility. In addition, the pitting corrosion resistance of stainless steel surfaces was observed being specifically dependent on the achieved surface topography and in some cases independent on the roughness parameters of the surface.     

常减压装置常用钢材在高温原油馏分中的腐蚀研究

利用高压釜模拟常减压装置中的腐蚀环境,采用腐蚀失重法并结合SEM,研究了4种常减压装置常用钢材在高温原油馏分中的腐蚀行为,分析了馏分、材质、温度的影响规律。结果表明,原油馏分的酸值、S含量和盐含量越高,对20钢腐蚀性越强,3种原油馏分对20钢的腐蚀性强弱为：脱盐后原油＞常二线馏分＞常一线馏分。提高钢材中Cr,Ni和Mo等合金元素的含量有助于提高其抗腐蚀能力,4种钢材在高温原油馏分中的抗腐蚀性能优劣为：316钢＞304钢＞1Cr5Mo钢＞20钢。温度对钢材在高温原油馏分中的腐蚀行为会产生多方面的影响,腐蚀速率总体上随着温度的升高而增大,某些温度范围内可能出现腐蚀速率极值。     

Oxidation of Ni-20 Cr alloy and stainless steels in the presence of chlorides

When Ni-20 Cr alloys and stainless steels are oxidized while submerged in molten salt (NaCl or NaCl-KCl), readily oxidizable alloy components, such as chromium, and in some cases iron, migrate to the surface to form non-adherent, granular, and thus nonprotective oxides. This loss of alloy constituents causes a counter current flow of vacancies which condense into an interconnecting pore network filled with salt. Since the salt penetrates into the structure, the loss of alloying metals does not require intermetallic diffusion over long distances, but instead corrosion products are largely removed by solution of alloying metals as ions in the pore-salt network. Evidence is presented which suggests that an integral part of the corrosion process is recrystallization, occurring in the porous zone, and that in the Ni-20 Cr alloy chromium diffuses down grain boundaries of the grain network to be deposited at grain boundary-pore intersections as chromium ions. The concentration gradient of chromium ions in the salt phase forces chromium diffusion out to the bulk salt where the higher effective oxygen pressure forms Cr₂O₃ and some chromate ion.     

High-temperature oxidation and aqueous corrosion performance of ferritic, vacuum-sintered stainless steels prealloyed with Si

The corrosion behavior at high-temperature and the aqueous corrosion behavior of sintered stainless steels manufactured from non-commercial prealloyed powder (434L with 2% Si) are studied and their results are compared with those of sintered stainless steels manufactured from commercial 434L powder, that has lower Si content. Both types of powders have been sintered in vacuum at three different temperatures, so materials with different porosity levels have been obtained. Several oxidation tests have been carried out from 700 to 1000 °C. Long-term experiments have proven the better oxidation resistance of 434L + 2% Si steels. Electrochemical measurements of the corrosion rate show a decrease on this parameter caused by the increase of Si-content on powders.     

节约型高强韧不锈钢及其薄带连铸制备技术

双辊薄带连铸技术自上世纪80年代至今已有近40年,但在常规不锈钢的工业化生产方面一直未取得成功。究其原因,主要归因于生产消耗、产品利润与产能之间的不匹配。近年来,国际国内开始将薄带连铸应用于制备节约型高强韧不锈钢,从而简化了热轧生产工艺,解决了因热塑性差而造成的钢板边裂和中裂等缺陷,大大提高了成材率。韩国浦项制铁采用薄带连铸技术生产出节约型双相不锈钢,耐腐蚀性能与SUS304奥氏体不锈钢相当,而抗拉强度可提高1倍,产品主要用于取代材料成本过高的奥氏体不锈钢。我国东北大学开发出高强韧节约型不锈钢的成分体系及其薄带连铸技术,制备出0.30~15 mm厚薄带,其强塑积高达62 000 MPa·%且其耐腐蚀性能较SUS304高出10%~15%,可以应用于核电、石化、铁路交通及汽车结构等领域。本文就薄带连铸高强韧不锈钢的现状、应用及未来发展趋势进行了综述和分析。     

Effect of boron concentration on the corrosion resistance of cast B‐bearing steel in molten zinc

The microstructures, mechanical properties and corrosion resistance in molten zinc of five kinds of cast B‐bearing steels containing X wt% B ‐ 0.8 wt% Si ‐ 1.0 wt% Mn ‐ (1.0～2.0) wt% Cr ‐ (0.3～0.5) wt% C (X = 0.50, 1.00, 1.50, 2.00, 2.50) were studied. The effects of boron concentration on microstructure and mechanical properties of cast B‐bearing steels have been investigated by optical microscopy (OM), X‐ray diffraction (XRD) analysis, hardness and impact tester. The evaluation of corrosion resistance in molten zinc of cast B‐bearing steel is calculated from the slopes of mass loss versus dipping time and surface area of sample at 480 °C. The results showed that boride volume fraction and hardness increased and the impact toughness of cast B‐bearing steel decreased with the increase in boron concentration. The corrosion rate of cast B‐bearing steels decreased and corrosion resistance in molten zinc increased with the increase in boron concentration. Moreover, the corrosion rate of cast B‐bearing steels decreased with the increase in temperature of molten zinc.     

奥氏体不锈钢SUS316及SUS316L在含Cl-的饱和H2S水溶液中的应力腐蚀行为研究

采用U型弯曲试样研究了固溶及敏化奥氏体不锈钢SUS31 6和SUS31 6L在四种不同的含Cl- 的饱和H2 S水溶液中的应力腐蚀开裂 (SCC)行为。研究结果表明Cl- 的加入和pH值的降低会增大实验钢种的应力腐蚀敏感性 ,而微量的Na2 CO3则可降低其SCC敏感性。     

The influence of alloying elements on the corrosion behaviour of ferritic steels in simulated combustion atmospheres

The low‐chromium steels (Cr content 0.7–1.4 wt.%) are usually being used in low temperature boiler applications where the environments are not so aggressive as in waste‐fire boilers. To improve their mechanical properties and corrosion resistance several alloying elements have been used. In the present study the new low‐chromium steels modified with Si, Ni and Ce have been investigated. These steels were compared with the common boiler steel – 2.25Cr1M. The multi‐sample exposure tests were made in moist air (8% O₂ + 15% H₂O) with and without 200 ppm SO₂ or 2000 ppm HCl addition at the isothermal temperature of 500°C. Corrosion products were analysed by Scanning Electron Microscope with Energy Dispersive Spectrometer (SEM/EDS) and XRD techniques. The results of the study show that addition of Ni and Si to the steels studied could improve their corrosion resistance, but only in moist air atmospheres. In SO₂‐containing atmospheres the corrosion resistance seems to remain the same, when in HCl‐containing atmospheres Ni and Si additions seem to have a negative effect on the corrosion behaviour. As could by seen from SEM analysis, the scales formed, on the steels with above elements, are more adherent to the metallic core. The cerium was added to the studied materials mainly to improve their mechanical properties. This alloying element seems to increase the corrosion rate of materials, especially in atmospheres containing Cl.     

Corrosion behavior of various steels in black liquor recovery boiler environment

It is important to examine characteristics of ash in order to understand the high temperature corrosion behavior of steels in the black liquor recovery boiler (BLRB) environment. The ash collected from the corroded superheater tubes was mainly composed of alkali-sulfates, alkali-chlorides and alkali-carbonates. The mole ratio of Na/K in the ash from BLRB ranged from 3 to 17. The concentration of sulfates varied over a range from 50 to 90 wt%, and chlorides from 0.1 to 10 wt%. On the base of these results, the corrosion behavior of various steels and the effect of alloying elements on the corrosion behavior of stainless steels in the BLRB environment were studied. From the results, Cr, Mn and Mo were significantly beneficial elements. N and Ni were also beneficial above 600 °C while C was an extremely harmful element. Subsequently, a new corrosion resistant stainless steel was selected as the material for the superheater in the BLRB.     

Seawater resistance of a second generation superaustenitic stainless steel

The first generation of superaustenitic 6Mo steels like 254 SMO® has been further developed into a new steel–654 SMO®–containing very high amounts of those alloying elements most beneficial for the resistance to localized corrosion. 654 SMO is compared with other stainless steels and nickel-base alloys in tests performed in various kinds of seawater. The new steel is much superior to the 6Mo steel under all conditions investigated and compares favourably with Alloy C–276 in most tests. The most corrosive condition among those investigated represents a seawater system where aerobic and anaerobic areas exist simultaneously.     

氮合金化堆焊硬面合金组织与耐高温磨损性能

对马氏体不锈钢堆焊硬而合金进行了氮合金化,研究了其组织和耐高温磨损性能.结果表明,氮合金化马氏体不锈钢堆焊层显微组织主要为马氏体和铌、钛的复合碳氮化物;堆焊马氏体不锈钢硬面合金与碳钢的高温金属间磨损,为碳钢表面高温下形成的氧化皮,粘着于堆焊马氏体不锈钢硬面合金表面,导致堆焊马氏体不锈钢硬面合金产生磨粒磨损.氮合金化堆焊...     

Effect of tungsten on the corrosion behavior of sulfuric acid-resistant steels for flue gas desulfurization system

Flue gas desulfurization systems (FGDs) are operated in severely corrosive environments that cause sulfuric acid dew-point corrosion. The corrosion behavior of low-alloy steels was tested using electrochemical techniques (electrochemical impedance spectroscopy, potentiodynamic tests, potentiostatic tests), and the corrosion products were analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical results showed that alloying W with small amounts of Sb, Cu, and Co improves the corrosion resistance of steels. The results of surface analyses showed that the surface of the steels alloyed with W consisted of W oxides and higher amounts of Sb and Cu oxides. This suggests that the addition of W promotes the formation of a protective WO₃ film, in addition to Sb₂O₅ and CuO films on the surface.     

SUS304不锈钢在浓缩自来水中的点蚀敏感性

采用极化曲线研究了SUS304不锈钢在不同温度浓缩不同倍率的自来水中的点蚀敏感性,比较了含不同浓度氯化钠的去离子水和自来水对不锈钢耐点蚀性能的影响。结果显示,随自来水温度和浓缩倍率的提高,不锈钢的点蚀敏感性增大;与自来水相比,在去离子水中氯离子对不锈钢点蚀敏感性的影响更显著。     

改善0Cr17Mn14Mo2N钢抗稀硫酸腐蚀性能的电化学研究

常用的铬镍奥氏体不锈钢含有贵缺的元素镍,这类钢代镍的问题,早就引起人们的注意。从1958年起,中国科学院金属研究所开展了以锰和氮代镍的铬锰氮奥氏体—铁素体复相不锈钢的研究。经过生产和使用部门的共同努力,已将一种0Cr17Mn14Mo2N钢作成设备和部件,应用到腐蚀性的尿素、醋酸、合成纤维和印染等工业介质。实践证明其耐蚀性和使用性良好。实验室的研究得出,这种钢在稀硝酸、磷酸、草酸和柠檬酸中具有与铬镍不锈钢相近或更高的耐蚀性。但在稀硫酸中,耐蚀性很差,不能使用。因此,有必要改善它的耐蚀性能。本文研究了合金元素在提高铬氮锰不锈钢腐蚀中的作用。     

Achieving a chromium rich surface upon steels via FBR-CVD chromising treatments

Surface alloying via fluidised bed reactor (FBR) chemical vapour deposition (CVD) can be used to produce adherent and highly corrosion resistant surface layers. In this work, 304, 316, and 409 stainless steels and 1020 steel were chromised, producing distinct surface layers tens of micrometres thick. The composition and surface of these layers was characterised using microscopy, GDOES, and XPS. Surfaces were highly enriched in Cr and displayed improved corrosion resistance as determined by electrochemical evaluations. This work demonstrates that it is possible to form continuous, functional and corrosion resistant Cr-rich surface layers via FBR-CVD on a variety of steels.     

Electrochemical behaviour of duplex stainless steels in caustic environment

Recent studies have shown that duplex stainless steels can be susceptible to general corrosion and stress corrosion cracking in high pH caustic environments. This difference in the corrosion resistance can be attributed to changes in the electrochemical behaviour of steels. The present study has shown that the corrosion rates of duplex stainless steels increase with an increase in temperature and sulphide addition to caustic environments. Moreover, alloying Fe with Cr and Ni helps to raise the corrosion potential and lower critical current density of DSS in an alkaline environment whereas Mo can be detrimental to the corrosion resistance of the steel.     

Die Oberflächenbehandlung von Schweißverbindungen hochkorrosionsbeständiger 6% Mo-Stähle und Nickel-Basis-Legierungen

Surface treatments of high alloy 6 Mo stainless steel and nickel alloy weldments High alloy stainless steels (6% Mo) and a high nickel alloy (alloy 625) weldment have been tested in order to answer the question whether post-treatment of the weldment has an effect on the corrosion resistance, especially on pitting corrosion. Therefore, the critical pitting temperature of weldments was tested in acidic chloride solution (standard tests). As a result grinding with rough emery paper as well as sand blasting lowers the localized corrosion resistance in the weldment area, while pickling has a positive effect, especially after blasting. Pickling can be done either by a solution of nitric + hydrofluoric acid or by a commercial pickling paste. In any event pickling is recommended as a final surface treatment for high alloy stainless steels and nickel alloys, especially in case of prevailing highly corrosive conditions such as pitting and crevice corrosion.     

The potentiodynamic screening of materials for high efficiency gas-fired appliances

As part of an overall programme to select materials for secondary heat exchangers in gas-fired condensing appliances, the corrosion characteristics of a number of commercially available austenitic stainless steels, and wrought and cast aluminium alloys were determined with a potentiostat. Results indicated that austenitic stainless steels performed generally better than the wrought or cast aluminium alloys evaluated. Wrought aluminium alloys showed better corrosion resistance than the various aluminium ‘LM’ casting alloys investigated. Of the stainless steels tested, type 316 showed the best overall characteristics. Amongst the wrought aluminium alloys assessed, AlMgSi showed the most corrosion resistance, closely followed by Al1SiMgMn and Al1Mn. Alloys Al7Si1Mg and Al12Si showed superior corrosion resistance to that of Al5Si3Cu.     

碳钢和铁-铬-镍基合金在相变储能材料用熔融共晶氯化钠和氯化镁中的腐蚀行为

研究了3种铁-铬-镍基合金(Fe-Cr-Ni)和一种碳钢试样在520℃熔融共晶NaCl-MgCl2盐中的腐蚀行为。结果表明,碳钢试样晶界处Fe原子优先变为亚铁离子(Fe2+)和铁离子(Fe3+),发生了严重的沿晶腐蚀,但表面形成了厚而致密的MgO壳,对试样起到了一定的保护作用。3种Fe-Cr-Ni基试样表面也形成了MgO壳,但因铬元素优先被腐蚀,试样表面形成了疏松的富Ni骨架状微观组织结构,MgO壳或颗粒极易剥落,未能起到有效的保护作用;Cr含量越高,腐蚀越严重。对于太阳能储能技术,在廉价的铁基合金中添加镍元素作为熔融氯化盐相变储热介质的容器或者管道材料,具有良好发展前景。