Corrosion behavior of the steel used as a huge storage tank in seawater

Open-circuit potential (OCP), polarization curve, and electrochemical impedance spectroscopy (EIS) measurement were used to investigate the corrosion behaviors of high-strength low-alloy (HSLA) steel and mild steel in seawater. Both steels were used in the construction of a huge oil storage tank. The OCP results show that the HSLA steel quickly reached more negative E _OCP values than the mild steel. Polarization curve results reveal that the HSLA steel exhibits higher corrosion currents and more negative corrosion potentials than the mild steel. EIS measurements reveal that both steels exhibit similar corrosion behaviors up to 144 h, one increased capacitance loop can be shown in EIS diagrams. The mild steel presents higher corrosion resistances than the HSLA steel at former stage, which is associated with the effect of the grain size. After 240 h of immersion, both steels present different corrosion behaviors. The EIS diagrams exhibit two capacitance arcs for the HSLA steel and one capacitance arc for the mild steel, which is due to the formation of intact corrosion scales on the electrode surface of the HSLA steel as to introduce a new reaction interface. The HSLA steel exhibits higher corrosion resistances than the mild steel at latter stage of experiment, which is ascribed to the synthetic actions of residual Fe₃C and the protective property of corrosion products.     

碳钢在碳酸铵溶液中的腐蚀研究实验改进

采用线性扫描伏安法和交流阻抗法研究了碳钢在不同实验条件下的腐蚀规律,碳钢在碳酸铵溶液中的阳极过程为溶解、钝化、过钝化溶解,溶解初期在电极界面的传质为线性扩散控制;随着溶液温度的升高,阻抗谱表示为单一时间常数的容抗弧,容抗弧直径逐渐减小,电阻变小,碳钢的腐蚀速度增大;Cl~-浓度越大,钝化区域变小,碳钢更容易腐蚀;加入硫脲缓蚀剂,碳钢容抗弧直径增大,电阻变大,有利于保护碳钢。     

Contact corrosion of metals in concentrated aqueous-glycolic solutions

Corrosion behavior of aluminum, steel, and cast iron was studied both in their individual state and in systems constituted of aluminum and steel, aluminum and cast iron, steel and cast iron, and aluminum, steel, and cast iron in ethylene glycol solutions containing 5 and 30 vol % of fresh water.     

钢铁中稀土合金化的内耗研究及其理论

扼要地回顾了稀土钢及其合金化研究的发展历程；阐明合金化、合金化耗及用内耗研究合金化的基本思想和铁内耗谱及其机制等理论理论基础；介绍了用内耗方法研究钢中稀土合金化取得的进展；最后，从钢中稀土的作用结构材料的发展，展望了用稀土处理钢的前景。     

混凝土中钢筋的腐蚀行为研究

本文探讨了在不同 pH和Cl- 含量的模拟混凝土孔隙液介质中 ,混凝土中钢筋的腐蚀电化学行为 .电化学技术测试结果表明 ,正常情况下 ,钢筋在混凝土中受到高碱性环境的保护 ,耐蚀性好 .但随着介质 pH的降低、Cl- 含量的上升 ,钢筋腐蚀电流升高 ;动电位阳极极化曲线的测试表明 ,钢筋的维钝电流增大 ,击穿电位负移 ,混凝土中钢筋的耐蚀性下降 .这是钢筋表面钝性受破坏的缘故 .     

Determination of trace amounts of some elements in armco steel by the neutron activation method

The previously elaborated methods of the determination of As, Sc, La, Au, W, Mo, Ga and In have been adapted to the analysis of steel. Samples of Armco steel taken from three various points of a steel bar section were analysed. On the basis of the results obtained the distribution of the elements determined along the steel bar section is discussed.     

The Multi-variable Analysis Method Used for Studying the Influence of Trace Elements in Steel on the Mechanical Properties of Steel

The main mechanical properties indexes of steel are submit intention (σs), anti-pull intention (σb)5 extend rate (δ5). The primary influences on the mechanical properties of steel are trace elements included in steel and some technical conditions during heat treatment. For example, the higher the content of C in steel is, the harder the steel is.     

洁净钢痕量分析最新进展

评述了当前钢铁痕量分析的一些成果和应用前景：炉前及连铸现场临线快速分析新技术;超痕量氧、氮、碳、硫的高精度检测;各种夹杂分析方法的组合改进和适用场合;精炼过程中夹杂物在线和临线分析技术的开发;钢中极微细析出相的鉴定和分离定量。     

Fabrication of IrO2 H+ Sensor and Its Application in the Measurement of pH at Steel/Concrete Interface

Corrosion of steel reinforcement is the most serious threat to the service life of modem reinforced concrete structure and the corrosion behavior of the steel reinforcement has a close dependence on the chemical environment at the steel/concrete interface. Among all the species which can affect the corrosion rate, H⁺ is of the greatest influence on the stability of the steel bars. However, the in-situ measurement of pH value at steel/concrete interface is still underway. In this paper fabrication of Ir oxide electrode which serves as the pH probe working at the steel/concrete interface was explored.     

LD-2复合缓蚀剂对海水介质混凝土中钢筋阻锈作用研究

利用电化学检测技术和海水浸泡试验等方法 ,观测和研究了经筛选研制的LD_2复合缓蚀剂对海水介质中钢筋腐蚀电化学行为的影响 ,考察和评价了复合缓蚀剂对钢筋的阻锈作用 .结果表明 ,LD_2复合缓蚀剂主要起阳极型缓蚀剂作用 .在海水中加入 2 5 g·L- 1复合缓蚀剂后 ,钢筋的腐蚀电位提高约 0 .2 2 0V ,腐蚀电流降低至未加缓蚀剂的 1% ,缓蚀效率达 99% .钢筋混凝土试样在海水中浸泡 2年 ,表明混凝土中加入占水泥重量 1.0 %～ 2 .5 %LD_2复合缓蚀剂时 ,能有效阻止混凝土中钢筋的腐蚀     

Identification and quantification of sources of variation in the analysis of steel

In steel industries a need exists for the reduction of variation in the element concentrations. This need is triggered by an increasing demand for high quality steel products by clients. The results of a large-scale experiment concerning the identification and quantification of sources of variation in the production, sampling and analysis of steel are presented. The results are obtained by means of a strategic approach that consists of six steps. By means of this strategic approach, insight is obtained in the build-up of the total variation. This knowledge can be used to reduce the influence of those factors that have a major impact on the total variation. Attention is focused on estimating the magnitude of sources of variation apparent in sampling of certain stages of the steel making process and in analysis of steel samples by means of spark emission spectrometry.     

渗铝钢在海水中的电化学行为研究

应用化学浸泡实验,电化学测试技术研究渗铝钢在海水中的电化学行为.试验表明,在海水中渗铝钢的腐蚀电位比20#钢的负,其阳极活性大于后者,在低电位下发生阳极溶解.20#钢和渗铝钢的腐蚀速率分别为5.80mg/dm2·d和3.36mg/dm2·d.渗铝钢在海水中具有优良的耐蚀性能是由于环境遮断和电偶保护的综合效果.其腐蚀产物含有氯离子,说明氯离子参与海水中的腐蚀过程,是导致腐蚀的主要原因.渗铝钢除了表层形成的Al、Fe化合物和致密、连续、具有高效防护作用Al的氧化物保护膜外,Al Fe合金层起到牺牲阳极的电化学保护作用.     

硫酸盐还原菌的含硫代谢产物在加速碳钢腐蚀中的作用

应用电化学阻抗谱(EIS)研究了硫酸盐还原菌(SRB)对碳钢腐蚀过程的促进作用,应用稳态极化法研究了SRB代谢硫化物对碳钢阳极活性溶解的增强作用。研究结果表明,代谢硫化物通过对铁的吸附增强了碳钢阳极活性溶解,因为依据吸附态E-pH图可知,在很宽的电位范围和pH值范围内,硫在铁上都能以稳定的吸附态存在。吸附态硫提升了碳钢表面铁原子能量,使铁阳极溶解所需活化能降低,从而增强其阳极溶出过程。     

Reaction scheme of ammonia synthesis in the ECR plasmas

The reaction scheme of ammonia synthesis in the ECR plasma apparatus teas investigated from both identifications of the species in the plasmas and the adsorbed species on the surface of a steel substrate placed in the plasmas. The adsorbed species were considerably different when different kinds of plasmas are used. NH, species were adsorbed on the steel substrate surface in the nitrogen-hydrogen plasma, and N₂ molecules were adsorbed in the nitrogen plasma. By the application of a negative bias potential on the substrate, the adsorption of N atom or Fe-N bond formation was identified on the steel substrate surface. When the stainless steel wall of the chamber was covered with aluminum foil, the yield of NH,, radicals, which were on both the substrate and in the plasma, decreased. By exposure of the substrate, on which N₂ molecules or N atoms adsorbed, to the hydrogen plasma, N₂ and N disappeared from the steel substrate surface, forming ammonia. Moreover, the adsorption of NH,, radicals disappeared when the stainless steel wall surface was covered with aluminum foil. Thus, the surface of the stainless steel wall acts as a catalyst in ammonia formation. The formation of ammonia in the nitrogen-hydrogen ECR plasma, in which the steel substrate served as the catalyst, is not only through the dissociative adsorption of excited nitrogen molecules but also through the dissociative adsorption of nitrogen molecular ions.     

Identification and quantification of sources of variation in the analysis of steel

In steel industries a need exists for the reduction of variation in the element concentrations. This need is triggered by an increasing demand for high quality steel products by clients. The results of a large-scale experiment concerning the identification and quantification of sources of variation in the production, sampling and analysis of steel are presented. The results are obtained by means of a strategic approach that consists of six steps. By means of this strategic approach, insight is obtained in the build-up of the total variation. This knowledge can be used to reduce the influence of those factors that have a major impact on the total variation. Attention is focused on estimating the magnitude of sources of variation apparent in sampling of certain stages of the steel making process and in analysis of steel samples by means of spark emission spectrometry. Received: 6 November 1999 / Revised: 10 February 2000 / Accepted: 19 March 2000     

碳锰洁净钢中镧和铈在晶界的行为

应用高分辨TEM，SEM和XRD研究碳锰洁净钢中镧和铈的存在形式、分布以及在晶界的行为。研究结果表明，镧和铈在洁净钢中存在固溶态、稀土夹杂物和稀土第二相。固溶稀土偏析在晶界，洁净钢中稀土仍有净化钢液和变质夹杂的作用。适量稀土能减少S和P在晶界的偏析，净化晶界提高钢的冲击韧性。过量稀土在晶界产生有害的稀土第二相，导致性能显著降低。     

稀土对铬锰氮不锈钢在稀硫酸介质中腐蚀磨损性能的影响

研究了稀土对铬锰氮不锈钢的腐蚀性能及腐蚀磨损性能的影响，稀土使各锰氮不锈钢的腐蚀电位正移、维钝电流降低、热力学稳定性提高，故其耐蚀性提高，抗磨性改善，铬锰氮不钢的最佳稀土含量为０．０２－０．０６％，为生产提供了必要的工艺参数。     

18／8型不锈钢在受力形变条件下腐蚀电化学行为的研究

应用电化学稳态技术、电化交流阻、抗微区电化学技术及扫描电等方法，研究１８／８型不锈钢在Ｎａ２Ｓ２Ｏ３稀溶液中，受外力形变条件下，的腐蚀电化学行为，结果表明，力学因素可使表面腐蚀电化学活性增加，表面微裂纹的发生、消失和再钝化的动态过程，同时受电位和拉应力的影响；点腐蚀可优先发生在应力集中位置，点蚀的发展可能诱导不锈钢的应力腐蚀开裂。     

Temperature dependence of the formation of the passivation layer on carbon steel in high alkaline environment of concrete pore solution

In this study, the formation and the strength of the passive layer on carbon steel in concrete pore solution were investigated for temperatures ranging from room temperature to 850 °C. Two sets of carbon steel specimens were first exposed to different temperatures for an hour. One group cooled to room temperature in the air and the other one in the water. The steel specimens were then immersed in concrete pore solution and the passive layer formed on the steel was investigated. Results showed that in the extreme conditions, i.e. very high temperature, and water-cooled condition, the passive layer rarely formed on the steel. Increasing the exposure temperature led to a decrease in the thickness of the passive layer. This decrease was more apparent when steel was cooled in water compared to air cooled specimens. Results from this study contribute to the knowledge base that may be used to advance the state of the art in predictive models for steel reinforcement in concrete exposed to high temperatures (e.g., fire, power plants).     

Heat transfer analysis of energy and exergy improvement in water-tube boiler in steam generation process

Journal of Thermal Analysis and Calorimetry - Steam generation is an essential process in steel production. Saturated steam is used in the cold-rolling mills of sample steel company to raise the...