共查询到20条相似文献,搜索用时 15 毫秒
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L. Zhang X.G. Li C.W. Du Y.F. Cheng 《Journal of Materials Engineering and Performance》2009,18(3):319-323
The electrochemical corrosion and stress corrosion cracking (SCC) behaviors of X70 pipeline steel in CO2-containing solution were studied by electrochemical measurements, slow strain rate tensile tests, and surface characterization.
The results found that the electrochemical corrosion of X70 steel in aerated, alkaline solution is an activation-controlled
process, and a stable passivity cannot develop on steel. Corrosion rate of the steel increases with the CO2 partial pressure. The enhanced anodic dissolution due to the additional cathodic reaction in the presence of CO2, rather than the film-formation reaction, dominates the corrosion process. The mass-transfer step through FeCO3 deposit is the rate-controlling step in corrosion of the steel. The susceptibility of steel to SCC and the fracture brittleness
increase with the CO2 partial pressure. The enhanced fracture brittleness is attributed to the evolution and penetration of hydrogen atoms into
the steel, contributing to crack propagation. The formed deposit layer is not effective in reducing hydrogen permeation due
to the loose, porous structure. 相似文献
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Z. Y. Liu C. W. Du C. Li F. M. Wang X. G. Li 《Journal of Materials Engineering and Performance》2013,22(9):2550-2556
This paper investigates the stress corrosion cracking (SCC) behavior of welded API X70 pipeline steel in simulated underground water using the slow strain rate test, fractographic characterization by scanning electron microscopy, and potentiodynamic polarization techniques. SCC susceptibility of the heat-affected zone (HAZ) is demonstrated to be dependent on two factors: the effect of the microstructure in the HAZ on electrochemical reactions and the effect of the mechanical property on SCC occurrence. Electrochemical experiments indicate that the microstructures in the HAZ, especially the softened microstructure, can significantly facilitate the processes of hydrogen evolution when cathodic potential is positive to ?1050 mVSCE. However, when the cathodic potential is below ?1050 mVSCE, the cathode current densities of different microstructures are close to one another and greatly increase because of the decrease of the applied potentials. The SCC behavior is consistent with the electrochemical results. Under ?650 and ?850 mVSCE, SCC is most likely to occur in the softened region, and under ?1200 mVSCE, SCC occurs in both the softened and hardened regions. 相似文献
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Z. Y. Liu X. G. Li Y. F. Cheng 《Journal of Materials Engineering and Performance》2011,20(7):1242-1246
The effect of strain rate on cathodic reactions of X70 pipeline steel during stress corrosion cracking in a near-neutral pH
solution was investigated by electrochemical impedance spectroscope and potentiodynamic polarization curve measurements as
well as slow strain rate tests. A local additional potential model was used to understand mechanistically the role of strain
rate in electrochemical cathodic reaction. It was found that an application of elastic stress would not affect the electrochemical
stable state of the steel specimen at a macroscopic scale. Under a weak cathodic polarization, the interfacial charge-transfer
process occurring on steel contains both cathodic and anodic reactions. Since the anodic reaction process is still significant,
localized dissolution could occur even at such a cathodic potential, resulting in generation of corrosion pits. These pits
could be the start sites to initiate stress corrosion cracks. Strain rate affects the corrosion reaction, which is associated
with the generation of dislocation emergence points and slip steps on the specimen surface, resulting in a negative local
additional potential to enhance the cathodic reaction locally. 相似文献
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X70管线钢在硫酸盐还原菌作用下的应力腐蚀开裂行为 总被引:1,自引:1,他引:0
目的油气管输中X70钢的应力腐蚀开裂问题日趋严重,而且土壤环境中微生物腐蚀现象备受关注,因此拟通过实验室模拟土壤环境下X70管线钢的腐蚀,获得高强度管线钢在硫酸盐还原菌作用下的应力腐蚀开裂规律。方法采用自制的应力电化学测试装置,通过慢应变速率拉伸试验(SSRT)对材料的应力腐蚀敏感性进行分析,利用交流阻抗以及扫描电镜(SEM)对断口形貌以及生物膜的成分进行研究。结果当应变速率为5×10~(-7)s~(-1)时,无菌模拟溶液中试样的应力腐蚀敏感性远大于含SRB模拟溶液中试样的应力腐蚀敏感性,SRB的存在对X70管线钢应力腐蚀起到很大程度的促进作用。当应变速率为1×10~(-6)s~(-1)时,SRB对于X70管线钢应力腐蚀敏感性的影响较小,断裂主要由力学因素主导,SRB起辅助作用。结论 X70管线钢在沈阳土壤模拟溶液中具有一定的应力腐蚀敏感性。SRB对于X70管线钢在沈阳土壤模拟溶液中的应力腐蚀起到一定程度的促进作用。 相似文献
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采用电化学技术、慢应变速率拉伸实验和扫描电镜(SEM)对电化学充氢后的X80管线钢在鹰潭土壤模拟溶液中的应力腐蚀行为进行了研究。结果表明:X80管线钢静态充氢后在鹰潭土壤模拟溶液中具有较高的应力腐蚀(SCC)敏感性,其断口模式为穿晶断裂;随着电化学充氢时间的延长,氢致塑性损失不断增加,拉伸断口由韧窝状韧性断口向脆性解理断口发展,SCC敏感性增大;电化学充氢促进了点蚀坑的萌生,点蚀坑和第二相夹杂是SCC裂纹萌生的重要原因。 相似文献
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Min Zhu Cuiwei Du Xiaogang Li Zhiyong Liu Shengrong Wang Tianliang Zhao Jinghuan Jia 《Journal of Materials Engineering and Performance》2014,23(4):1358-1365
The stress corrosion cracking (SCC) behaviors and mechanisms of X80 pipeline steels with different strength and microstructure in high pH carbonate/bicarbonate solution were investigated by slow strain rate testing and electrochemical test. The results showed that the cracking mode of low strength X80 steel composed of bulky polygonal ferrite and granular bainite in high pH solution was intergranular (IGSCC), and the SCC mechanism was anodic dissolution (AD). While the mixed cracking mode of high strength X80 steel consisted of fine acicular ferrite and granular bainite was intergranular (IGSCC) in the early stage, and transgranular (TGSCC) in the later stage. The decrease of pH value of crack tip was probably the key reason for the occurrence of TGSCC. The SCC mechanism may be a mixed mode of AD and hydrogen embrittlement (HE), and the HE mechanism may play a significant role in the deep crack propagation at the later stage. The cracking modes and SCC mechanisms of the two X80 steels were associated with its microstructure and strength. 相似文献
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X70管线钢点蚀行为研究 总被引:1,自引:0,他引:1
对X70管线钢的凹坑进行了SEM观察,并对控轧控冷工艺以及层流冷却水进行了分析研究。实验结果表明,X70管线钢凹坑是由于点蚀腐蚀所引起,而点蚀产生的原因是由于层流冷却水中的氯离子浓度偏高。另外,对X70管线钢的点蚀形成机理进行了讨论。 相似文献
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郭浩 《中国腐蚀与防护学报》2004,24(4):208
采用慢应变速率试验(SSRT)研究了不同电位下X70管线钢在近中性pH溶液中的应力腐蚀破裂(SCC)行为,同时研究了溶液中通往不同含量CO2对SCC的影响。结果表明,X70管线钢在近中性pH溶液中的开裂方式是穿晶型的,具有准解理特征,并且随着外加阴极电位的降低,SCC敏感性增加,随CO2含量的增加,pH值降低,SCC敏感性增加,均表现为氢致开裂占主导。 相似文献
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Nenasheva T. A. Marshakov A. I. Ignatenko V. E. 《Protection of Metals and Physical Chemistry of Surfaces》2020,56(7):1223-1231
Protection of Metals and Physical Chemistry of Surfaces - Alternating current accelerates stress corrosion cracking of grade X70 pipe steel in electrolytes of various compositions: 3.5% NaCl... 相似文献
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碳酸盐硫化氢复杂环境中16MnR钢应力腐蚀敏感性研究 总被引:1,自引:0,他引:1
采用慢应变速率拉伸试验研究了16MnR钢在碳酸盐和硫化氢复杂环境中的应力腐蚀开裂敏感性.结果表明,在含碳酸盐和硫化氢的复杂介质环境中,16MnR钢的应力腐蚀敏感性指数低于25%;温度由常温升高至57.5℃时,16MnR钢母材与热影响区的应力腐蚀敏感性略有升高,碳酸盐和硫化氢浓度对16MnR钢在此复杂环境中的应力腐蚀敏感... 相似文献
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目的研究酸性土壤环境中剥离涂层下X80管线钢应力腐蚀行为及机理。方法采用电化学极化曲线测试、慢应变速率拉伸试验和腐蚀形貌扫描电子显微镜观察,对服役于鹰潭土壤环境的X80管线钢在剥离涂层下滞留液中的应力腐蚀行为及机理进行了分析研究。结果 X80管线钢在剥离涂层下的滞留液中具有一定的SCC敏感性,应力腐蚀开裂类型属于TGSCC,敏感性较大位置为近漏点处、剥离区中下部及剥离区底部,且近漏点处滞留液体系中X80钢的SCC机理受阳极溶解(AD)机制控制,剥离区底部滞留液中SCC机理受阳极溶解+氢脆(AD+HE)的混合机制控制。结论服役于酸性土壤中的X80管线钢在外防腐涂层破损后,除开放破损处将发生腐蚀外,剥离涂层下的管线钢还会存在一定的应力腐蚀敏感性。 相似文献
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采用动电位极化、电化学阻抗谱技术、Mott-Schottky等测试方法,研究了温度对X70钢在高pH值溶液 (0.5 mol/L Na2CO3+0.5 mol/L NaHCO3) 中钝化膜性能和电化学腐蚀行为的影响。结果表明:随着温度升高,X70管线钢的点蚀电位降低,维钝电流密度和钝化膜的极化电阻减小。在实验温度范围内,钝化膜为Fe2O3和Fe3O4的混合物,半导体类型为n型半导体,且不随温度升高而改变。但是随着温度的升高,钝化膜缺陷密度增加,膜厚度减小,腐蚀倾向增大。因此,温度升高会降低钝化膜的稳定性,导致其保护作用下降。 相似文献
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采用慢拉伸(SSRT)、动电位极化和SEM观察等方法,研究了在不同的阴极保护电位条件下X100钢在酸性土壤模拟溶液中的应力腐蚀行为.结果表明,X100钢发生穿晶裂纹的应力腐蚀,裂纹的萌生和发展与阴极保护电位有关.完全阳极过程控制时,X100钢无裂纹出现,但出现晶间腐蚀;在混合过程控制时,应力腐蚀敏感性较低,裂纹发展缓慢;在完全阴极过程控制时,氢脆机制起主要作用,裂纹扩展迅速. 相似文献