硫酸盐还原菌和极化电位对海洋结构用钢在海泥中应力腐蚀开裂敏感性的影响

IOCAS-IR > 海洋环流与波动重点实验室

	硫酸盐还原菌和极化电位对海洋结构用钢在海泥中应力腐蚀开裂敏感性的影响
其他题名	The Effects of Sulfate Reducing Bacteria and Polarization Potential on the Stress Corrosion Cracking Sensitivity of 16Mn and API X56 Steel in Sea-mud
	朱永艳
学位类型	博士
	2007-06-01
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	应力腐蚀开裂硫酸盐还原菌极化电位氢渗透
摘要	海洋设施长期处于恶劣的腐蚀环境中，如不加以防护，一旦发生应力腐蚀开裂（SCC），损失就会极为惨重。海底泥土区环境十分重要，因为管线和平台桩腿等都埋在海底泥中。海底泥中硫酸盐还原菌（SRB）十分活跃，而且为了防止腐蚀，海泥中的设施无一例外地采取了阴极保护，相当于设施处在长期稳定的充氢状态。因此非常有必要研究海泥中的活性SRB和极化电位对海洋结构用钢在海泥中的氢渗透行为和SCC敏感性造成的影响，弄清SCC发生和发展的过程以便采取相应的措施减缓或防止SCC。本文通过慢应变速率拉伸实验（SSRT）、电化学阻抗谱（EIS）技术、动电位扫描极化曲线测定实验和氢渗透实验等研究了海泥中SRB和极化电位对16Mn钢和管线钢X56（API X56）的SCC敏感性造成的影响。从渤海海泥中富集得到SRB菌种，并做出了SRB在海泥中的生长曲线；在荧光显微镜下观察SRB为弧状，可以归为脱硫弧菌属，为革兰氏阴性菌；海泥中活性SRB数量与硫电位等主要腐蚀环境因子具有一定的对应关系。 SSRT结果表明，施加阴极极化电位可以使试样断裂脆性特征明显，SCC敏感性增大；海泥中活性SRB浓度越高，断裂脆性特征越明显，SCC敏感性越大。在含SRB海泥中或阴极极化电位条件下，两种钢都容易发生SCC，氢脆（HIC）起主要作用。随着浸泡天数的增加，试样在灭菌海泥中的Rp一直增大；在含SRB海泥中Rp先增大，又变小，并呈现出显著的Warburg阻抗特征；在灭菌海泥中，两种试样在阳极电位范围内无SCC敏感区，而在阴极电位范围内有明显的SCC敏感区；在含SRB海泥中，在阳极电位范围和阴极电位范围内均有SCC敏感区；SRB代谢产物既有阳极去极化作用，又有阴极去极化作用，能使腐蚀电流密度增加。活性SRB的存在能够促进试样在海泥中的氢渗透；在实海工程应用中，两种钢在含SRB海泥中的氢渗透电流密度大约是在不含SRB海泥中的3~4倍。阴极极化电位能够促进试样在灭菌海泥中的氢渗透。在含SRB海泥中对试样施加阴极极化电位，氢渗透电流密度大于不加阴极极化电位时的氢渗透电流密度，也大于在不含SRB的海泥中的氢渗透电流密度。
其他摘要	The facilities under sea environment for a long time had corrosion danger. If they were not protected well, once stress corrosion cracking (SCC) occurred, serious losses would be caused. The sea-mud zone environment is very important, because the pipelines, the stakes of oil plat, etc. were all in the zone. In the sea-mud zone, sulfate reducing bacteria (SRB) are very active, and in order to prevent corrosion, almost all of the marine facilities are in the state of cathodic protection. At the cathodic potential, hydrogen would permeate steadily into the marine steels all the time. So in order to take measures to prevent SCC, it is very necessary to study the effect of active SRB in the sea-mud and the polarization potential on the hydrogen permeation of the marine steels, and make clear of the relationship between the hydrogen permeation and the SCC sensitivity. In this text, slow stress rate test (SSRT), electrochemistry impedance spectrum (EIS) technique, dynamic potential polarization curve and hydrogen permeation experiments were used to investigate the effect of active SRB in the sea-mud and the polarization potential on the SCC sensitivity of the marine steels. SRB were concentrated successfully from the sea-mud of Bo Hai, and the growth curve of SRB in the sea-mud was obtained. Experimental results showed that the quantity of active SRB were relevant to the main corrosion environmental factors of the sea-mud, such as E (S), E (Ag), pH, the open circuit potential and the conductivity and so on. The results of SSRT indicated that the cathodic potential added to the specimens and the existence of active SRB in the sea-mud could cause the brittle characteristics of the cracking more obvious and increase the sensitivity of SCC. The existence of active SRB in the sea-mud could affect the EIS of the marine steels. SRB could accelerate the cathode depolarization and increase the dissolution of the anode, which could accelerate the corrosion of the metals. The hydrogen permeation of the marine steels in the sea-mud could be accelerated respectively by active SRB and the cathodic potential added to the specimens. With the existence of active SRB in the sea-mud, the hydrogen permeation of the marine steels could also be accelerated by the cathodic potential. Finally this paper summarized: the existence of active SRB in the sea-mud and the cathodic potential added to the specimens could increase the hydrogen permeation and the SCC sensitivity of the marine steels.
页数	128
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/761
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	朱永艳. 硫酸盐还原菌和极化电位对海洋结构用钢在海泥中应力腐蚀开裂敏感性的影响[D]. 海洋研究所. 中国科学院海洋研究所,2007.

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