冷高压分离器在H2S环境下应力腐蚀开裂敏感性评估

针对制造过程中由于开孔失误而进行补焊的冷高压分离器在高压、高浓度的H₂S环境的使用安全问题,采用了电化学充氢、恒应变和慢拉伸的实验方法,研究了制造冷高压分离器的主体材料16Mn(HIC)钢和普通的16Mn钢及其焊缝的氢扩散系数,在不同H₂S浓度、pH值,模拟冷高压分离器操作环境溶液和实际溶液中的腐蚀规律和硫化氢应力腐蚀开裂（SSCC）敏感性,结合实际腐蚀环境的检测和分析结果,对补焊后的冷高压分离器的使用安全给出了综合评估.     

X70钢在高pH溶液中的应力腐蚀研究

许多油气管道断裂事故与高p H值应力腐蚀开裂(SCC)有关。X70钢是油气管道常用的管材。采用慢应变速率拉伸试验(SSRT)研究在不同电位下X70管线钢母材和和焊缝在高p H值溶液中的应力腐蚀开裂(SCC)行为。实验结果表明:当外加电位位于钝化区,因存在完整钝化膜,X70钢应变值、伸长率和断面收缩率最大;在自腐蚀电位下,因为阴极反应和阳极反应平衡,所以X70钢应变值、伸长率和断面收缩率位居其次;当位于活化钝化转变区时,由于钝化膜不完整,阳极活化反应仍占主导地位,应变值、伸长率和断面收缩率小于自腐蚀电位下的试样;位于活化区的试样,由于以阳极反应为主,所以应变值、伸长率和断面收缩率最小。     

35CrMo和00Cr13Ni5Mo硫化氢环境应力腐蚀开裂

用慢应变速率拉伸实验和U形试样浸泡实验、电化学极化技术并结合微观分析手段,在湿硫化氢介质中研究了35CrMo和00Cr13Ni5Mo两种钢的应力腐蚀开裂行为规律。结果表明,35CrMo和00Cr13Ni5Mo钢在实验条件下均具有一定应力腐蚀开裂（SCC）敏感性,其敏感性随着溶液pH的降低和H₂ S浓度的增大而增大;00Cr13Ni5Mo 在实验条件下抗SCC的能力均高于同条件下的35CrMo,在pH3.0的溶液中,二者性能比较接近,在pH4.5的溶液中,00Cr13Ni5Mo 耐H₂S环境SCC的性能明显提高,高于35CrMo,这主要是因为00Cr13Ni5Mo中的耐蚀合金元素增强了其钝化膜的稳定性、降低了氢脆作用所致。     

X80级管线钢的发展及腐蚀实验研究概况

分析了我国的石油天然气消费利用及油气管道建设现状,对国内外X80管线钢的研制和应用情况进行了介绍,同时介绍了国内X80管线钢的腐蚀研究情况.介绍了不同pH值对X80管线钢土壤腐蚀行为的影响以及腐蚀产物钝化膜对钢表面的腐蚀行为与过程的影响.X80级管线钢的抗硫化物应力腐蚀开裂(SSCC)和氢致开裂(HIC)行为的结果表明...     

液化气球罐Zare合金防护层涂装工艺

液化气球罐在使用过程中因球罐内壁存在SSCC(硫化物应力腐蚀开裂)腐蚀环境,造成球罐内壁焊道热影响区出现裂纹,导致球罐内壁腐蚀.本文介绍了采用涂覆稀土合金(Zare)涂层和封闭剂的方法解决液化气球罐内壁SSCC腐蚀问题,着重讨论了球罐内壁防腐涂装工艺及其注意事项.     

Cr13钢在含CO_2油田采出液中腐蚀行为的实验研究

采用静态电化学测试和动态高温高压腐蚀方法,研究了Cr13钢在含CO_2的油田采出液中的腐蚀行为,分析了Cl~-浓度和温度对Cr13钢CO_2腐蚀性能的影响规律,分析了扫描电镜腐蚀形貌。结果表明:Cr13钢在含CO_2的油田采出液中呈现出明显的钝化行为,随着温度的增加,Cr13钢钝化电流密度呈现先增加后降低的趋势,60℃时达到极值;随着Cl-浓度的增加,Cr13钢钝化电流增加,耐蚀性降低;这主要是由表面膜层疏松程度不同所导致的。     

高钢级油井管硫化物应力腐蚀试验的研究

对高钢级高强高韧油套管钢110S和140V进行应力环硫化氢应力腐蚀试验,研究了这两种高钢级油井管钢在硫化氢环境下的应力腐蚀规律。实验结果表明,在H2S环境下1 4 0 V比11 0 S更容易发生应力腐蚀开裂断裂得更快,断口的脆性断裂特征更明显。分析表明,高强钢的硫化物应力腐蚀开裂是通过氢脆(HE)理论实现的,材料的微观组织成分通过影响氢在材料内部的分布和扩散来影响到材料的应力腐蚀开裂敏感性。     

在役07MnCrMoVR球罐板材组焊再热裂纹敏感性研究

通过热模拟HAZ粗晶区应力释放试验,评价了07MnCrMoVR高强钢400m3球罐焊接时的再热裂纹敏感性,并对该球罐重新组装时的最佳焊后热处理温度进行研究,确定该材料的后热处理再热裂纹敏感区域,保证了现场施工的顺利进行。     

不锈钢管在聚酯生产行业中的选用

采用慢应变速率拉伸试验、扫描电镜断口分析以及金相显微组织分析检测等方法对0Cr13Al铁素体不锈钢及2205双相不锈钢在酸性介质中应力腐蚀开裂行为进行了研究。并评定不锈钢管在腐蚀性介质中应力腐蚀开裂的敏感性。为在聚酯生产行业中选择容器用钢提供依据。结果表明,拉伸试样全部断裂在焊缝或热影响区。试样断口形貌呈准解理断裂和韧性断裂。2205双相不锈钢的应力腐蚀敏感性比0Cr13Al铁素体不锈钢低。     

长管拖车用气瓶硫化氢应力腐蚀试验研究

本文对长管拖车用气瓶的硫化氢应力腐蚀试验进行了研究,进行了气瓶材料空气室温环境下断裂韧度KIC性能试验、硫化氢环境中(中等浓度溶液)临界应力强度因子K1SCC试验、硫化氢环境中(高浓度及中等浓度两种溶液)恒负荷拉伸σ th试验,并对试验结果进行了分析,最后提出了防止应力腐蚀的建议.     

Slow strain rate and constant load tests of A 285 and A 516 steels in Bayer solutions

Stress corrosion cracking (SCC) experiments were carried out on A 285 and A 516 steels by slow strain rate and constant load techniques. The influence of the impurities contained in Bayer solution on the susceptibility to SCC was studied. The results obtained by both techniques indicated that aluminate ions promote passivation but the oxide layer includes numerous defects and the SCC susceptibility increases. The slow strain rate experiments provided a rapid method for investigating caustic stress corrosion cracking and intensified the susceptibility to SCC compared to the results obtained by the constant load technique. In the passive potential region, some shallow cracks were detected only when the experiments were conducted at slow strain rate in solutions containing aluminate ions. The presence of such cracks indicated that anodic protection could not entirely prevent SCC in the Bayer solution.     

304不锈钢应力腐蚀的临界氯离子浓度

通过慢拉伸实验得出了304不锈钢应力腐蚀敏感性与溶液中Cl-浓度的关系,用扫描电镜对拉伸试样的断口形貌进行了分析,得出了304不锈钢发生应力腐蚀的临界氯离子浓度。采用自行设计的装置对304不锈钢试样施加拉应力,通过恒应变条件下的电化学原位测试研究了304不锈钢钝化膜破裂电位与氯离子浓度的关系。得出导致钝化膜破裂电位突变的Cl-浓度与发生应力腐蚀破裂的临界Cl-浓度是基本一致的结论。     

Investigations of the passive layer cracking by means of Dynamic Electrochemical Impedance Spectroscopy

The Dynamic Electrochemical Impedance Spectroscopy has been applied for stress corrosion cracking (SCC) investigations. The effect of applied potential and tensile stresses on the stress corrosion cracking behaviour of type 304L stainless steel (SS) immersed in 0.5 M NaCl solution of room temperature has been examined. This paper presents impedance spectra obtained for 304L stainless steel samples at the different potential values. The results obtained proved the possibility of providing new details about the dynamics of the initiation and propagation of the crack path compared to classical electrochemical techniques.     

PTA加氢反应器在碱洗条件下的安全分析

通过用SUS304L不锈钢制作的楔形张开加载预裂纹试样,在280℃、质量分数为3．0%的NaOH溶液的条件下进行应力腐蚀试验,以模拟对苯二甲酸(PTA)装置的加氢反应器PD-201不停车碱洗工作过程中SUS304L不锈钢在该介质环境下的抗应力腐蚀性能。结果表明：SUS304L不锈钢在此条件下经720h的浸泡,未发生应力腐蚀开裂现象,设备泵用SUS304L不锈钢作为内衬复合层是安全的。     

基于混沌理论的电化学噪声谱数据解析及其在局部腐蚀检测中的应用

将混沌理论引入电化学噪声（EN）谱的数据解析,对有机涂层失效过程和应力腐蚀过程的EN数据进行分析,采用关联维数表征局部腐蚀过程,取得了一些有意义的结果。分析了环氧酚醛/镀锡薄钢板失效过程的EN特征,通过计算涂覆镀锡薄钢板腐蚀过程的电化学电位噪声（EPN）谱特征,发现EPN对应的关联维数值随着局部腐蚀程度的加剧有增加的趋势。采用混沌相空间重构理论分析了304不锈钢应力腐蚀过程的电流噪声谱,利用关联维数表征应力腐蚀过程。数据计算结果表明应力腐蚀初期其相空间轨迹呈圆球形,应力腐蚀后期则变为椭圆形。研究结果表明,当裂纹萌生和扩展时,关联维数值增大,表明电化学噪声信号的不确定性与复杂性增加。     

Fundamentals of hydrogen evolution reaction and its implications on near-neutral pH stress corrosion cracking of pipelines

In this work, electrochemical techniques were utilized to investigate the hydrogen evolution reaction on X-70 pipe steel and the hydrogen permeation through the steel in near-neutral pH environmental condition. The results demonstrate that the steel has always been in an active-dissolution state in near-neutral pH solution and there is no film formed on the steel surface. Hydrogen evolution is inhibited by anodic polarization of the steel, which is attributed to the alternation of hydrogen evolution mechanism and kinetics on the anodially polarized steel. Combined with slow strain rate tensile tests, it is found that the high susceptibility of steel to stress corrosion cracking (SCC) is always associated with a high hydrogen permeation current. A thermodynamic model was developed, by analyzing the change in free-energy of the steel in the presence and absence of hydrogen and stress, to determine the interactions of hydrogen, stress and anodic dissolution at the crack-tip. The role of hydrogen involvement in pipeline near-neutral pH SCC could be determined quantitatively by characterizing the effect of hydrogen concentration on the dissolution rate of steel and the synergism of hydrogen and stress to promote crack growth.     

Phase angle analysis for stress corrosion cracking of carbon steel in fuel-grade ethanol: Experiments and simulation

The stress corrosion cracking (SCC) of carbon steel in simulated fuel-grade ethanol (SFGE) was investigated using electrochemical impedance spectroscopy (EIS) and slow strain rate test (SSRT). Phase angle at low frequency range (<1 Hz) is sensitive to SCC process of carbon steel in SFGE. Phase angle decreases during an active crack growth. Frequency at maximum phase angle also increases towards an active cracking region at around 1 Hz. A transmission line model (TLM) is used to simulate the EIS response for SCC based on real geometrical parameters. By systematically changing the values of the circuit elements, the activities of the sample surface, crack tip and crack wall were studied in detail. By comparing the Bode plots from both experiment and simulation during SCC, a detailed mechanistic picture is derived to describe the behavior of the stress corrosion crack on carbon steel in the fuel-grade ethanolic environment.     

Effect of stress on the passivation of Si-DLC coating as stent materials in simulated body environment

DLC coating can be used for vascular stents to prevent the stainless steel substrate from eluting Ni and Cr by plastic deformation and corrosion environment. The stress corrosion cracking (SCC) of Si-diamond-like carbon (Si-DLC) coated on 316L stainless steel was studied in a simulated body environment of a deaerated 0.89 wt.% NaCl electrolyte at 37 °C. This paper investigated the effect of Si-DLC coating on the SCC of 316L SS by slow-strain-rate test (SSRT), constant load test (CLT), and electrochemical impedance spectroscopy (EIS). The EIS data were monitored for the elastic and plastic regions under CLT to determine the electrochemical behavior of the passive film during SCC phenomena. The Si-DLC coated steel exhibited more ductility than uncoated steel and less susceptibility to SCC in this environment. According to X-ray photoelectron spectroscopy (XPS) analysis, the film repassivation occurs due to the presence of the silicon oxide layer on the Si-DLC film surface.