【作者】 毕凤琴；

【导师】 戴光；

【作者基本信息】 大庆石油学院 ， 油气储运工程， 2008， 博士

【摘要】 石油天然气储运、石油炼制加工及其它相关工业的机械和设备,广泛选用低合金钢制作,一般都处于湿H2S腐蚀环境中。近年来随着我国石油深度开采和中东进口石油量的增加,由湿H2S引起的低合金钢应力腐蚀开裂问题愈加突出,成为相关生产部门、科研机构研究和解决的重要课题,由于应力腐蚀开裂影响因素的复杂性,需要开展进一步的深入研究和探讨。本文选取三种典型石油、石化用低合金钢材料(换热器管束用钢08Cr2AlMo、输油输气管线用钢X70、压力容器用钢16MnR)作为实验研究对象。采用慢应变速率拉伸腐蚀实验研究08Cr2AlMo钢、X70钢母材及其焊接接头湿H2S应力腐蚀开裂;采用电化学腐蚀测试方法研究16MnR钢湿H2S应力腐蚀开裂;对16MnR钢焊接接头表面纳米复合化学镀层和表面纳米复合电镀层在湿H2S环境中抗应力腐蚀破坏进行实验研究。在研究过程中借助于金相显微镜、扫描电子显微镜、能谱仪、电化学工作站等先进测试技术,进行微观组织、成分、形貌的观察与测试;同时应用数理统计、回归分析等数学方法及计算机技术进行量化和模拟处理,建立了相应的数学模型。本文主要研究结果如下:1.运用均匀设计法,对08Cr2AlMo钢、X70钢母材及其焊接接头在具有不同H2S浓度、Cl-浓度、pH值和温度等介质参数的湿H2S腐蚀环境中进行慢应变速率拉伸腐蚀实验,通过扫描电镜分析试样断口的微观形貌,定性确定其应力腐蚀敏感性,并根据实验结果计算在各实验环境下的应力腐蚀敏感指数。运用回归分析软件,建立08Cr2AlMo钢、X70钢母材及其焊接接头各自应力腐蚀敏感指数与实验介质参数(H2S浓度、Cl-浓度、pH值和温度)之间关系的交互型数学模型。2.X70钢母材和焊接接头的慢应变速率拉伸腐蚀实验结果显示,X70钢焊接接头的应力腐蚀敏感性高于母材,且断裂部位均发生在热影响区或焊缝区,表明X70钢焊接接头对应力腐蚀比母材更敏感,为研究管线钢H2S应力腐蚀开裂提供一个重要的观测点。3.通过动电位快慢扫描技术,测试16MnR钢在不同H2S浓度、Cl-浓度、pH值、温度时的极化曲线,研究H2S浓度、Cl-浓度、pH值、温度不同时,16MnR钢的电化学腐蚀行为;针对16MnR钢在不同湿H2S环境下的应力腐蚀敏感电位区间,建立了16MnR钢在各种影响因素下的安全运行图。4.测试16MnR钢在不同应力、应变作用下的电化学极化曲线,研究不同慢应变速率拉伸条件下的应力、应变对16MnR钢在湿H2S环境中极化曲线的影响;研究外加电位对16MnR钢的应力-应变曲线及敏感性影响,进而判断16MnR钢发生湿H2S应力腐蚀开裂的可能性及相关机理。5.通过实验优选纳米复合化学镀和纳米复合电镀的最佳工艺配方,研究各因素对镀层中纳米TiO2含量、沉积速度和镀层密度的影响,利用金相显微镜、扫描电镜和能谱仪对表面纳米化处理前后的样品组织结构形貌进行表征;通过恒载荷拉伸实验,研究16MnR钢焊接接头经表面纳米复合化学镀和表面纳米复合电镀后的试样抗湿H2S应力腐蚀性能。研究结果表明:纳米复合化学镀层的抗湿H2S应力腐蚀性能是普通化学镀层的1.7倍,纳米复合电镀层抗湿H2S应力腐蚀性能是普通电镀层的1.5倍,纳米复合化学镀抗湿H2S应力腐蚀性能优于纳米复合电镀。本文为纳米复合化学镀和纳米复合电镀在湿H2S环境下运行设备上的应用提供了科学依据。作者认为,针对低合金钢进行的上述研究工作,以及获得的规律性认识,对于解决湿H2S环境下运行设备的应力腐蚀开裂问题,提供了很好的科学依据,具有重要的参考价值。更多还原

【Abstract】 Many machinery and equipments of petroleum natural gas storage and transportation, petroleum refine process and other correlation industries selected the low alloy steels widely, which used in wet hydrogen sulfide environment. Recently, along with the deepness exploitation of nation crude oil and increase of Middle East crude oil importation, the wet hydrogen sulfide (H2S) stress corrosion cracking of low alloy steels were extruded increasingly and became the key problem for production branch and scientific research institution to be studied and resolved. As the complexity of stress corrosion influence factors, some problems deserved to be lucubrated and discussed.This paper selected three representative low alloy steels that widely used in petroleum and petrifaction industry, they were heat exchangers tube steel 08Cr2AlMo, oil and natural gas pipeline steel X70 and pressure vessel steel 16MnR. Through the slow strain rate testing(SSRT) and corrosion testing, the H2S stress corrosion behavior of 08Cr2AlMo steel, X70 pipeline steel and its welded joints were presented. Based on the electrochemistry corrosion testing, the H2S stress corrosion behavior of 16MnR was discussed, and the corrosion cracking behavior of 16MnR steel welded joints surface made of nanometer composite chemistry plating and nanometer composite electrochemistry plating in wet H2S environment were tested and studied. Besides, Some advanced testing techniques such as the metallurgical microscope(MM), scanning electron microscope(SEM), energy dispersive spectrum(EDS) and electrochemistry station were also used for observing and testing the microcosmic structure, component and surface morphology. Simultaneity, the methods of numerical value calculating, regression analysis and computer embedded the studies too. Some mathematical models were established.The conclusions of this research can be generalized as:1. Based on the uniformity design method, the SSRT of 08Cr2AlMo steel, X70 base metal and its welded joints steel in different concentration of H2S, concentration of Cl- , pH and temperature were tested. After analysed the microcosmic morphology by SEM, determined the nature of stress corrosion sensitivity and calculated the stress corrosion sensitivity index in different examination environment. Based on the regression analysis software, the intercross mathematics model of stress corrosion sensitivity index of 08Cr2AlMo steel , X70 base metal and X70 welded joints steel and medium parameters (concentration of H2S, concentration of Cl-, pH and temperature)were established.2. The differenences of X70 base metal and its welded joints in SSRT corrosion testing were: the stress corrosion sensitivity index of X70 welded joints priority to the base metal, and the rupture position existed in heat affected zone(HAZ) and welding line, which can be indicated that the stress corrosion sensitivity of X70 welded joints priority to the base metal even more, which provided an observation point for investigating the pipeline steels H2S stress corroion cracking further.3. The polarization curves of 16MnR steel in different concentration of H2S, Cl-, pH and temperature were tested by vitue of zeta potential speed scaning technics. The electrochemistry corrosion behavior of 16MnR steel in different concentration of H2S, Cl-, pH and temperature were studied. Based on the different wet H2S stress corrosion sensitivity potential section of 16MnR steel, the static state safegy function figure of 16MnR steels in different influence factors was constructed.4. The polarization curves of 16MnR steel in different stress and strain states were tested, the influences of stress and strain on 16MnR steel in H2S environment were studied, and the influences of potential on the 16MnR steel stress-strain curve and sensitivity were also described. The possibility of 16MnR steels wet H2S stress corrosion cracking and correlation mechanisms were also investigated.5. In this paper, the excellent constitutes and technics of nanometer composite electroless plating and nanometer composite electroplating were selected by examnination. An investigation was made on the effects of various factors on the plating nano-TiO2 content, aggradation velocity and plating density, and the organize and structure morphology of samples disposed or not were performed by means of metallurgical microscope(MM), scanning electron microscope(SEM). The H2S stress corrosion performance of 16MnR welded joints treated with surface nanocrystallization were investigated by constant load tensile examination. The results of this study showed that the stress anticorosion of nanometer composite electroless plating is the 1.5 times of general plating, nanometer composite electroplating is the 1.7 times of general plating, and the wet H2S stress anticorosion of nanometer composite electroless plating was higher than the nanometer composite electroplating, which the value exceeded the national standards. This paper provided a science basis on nanometer composite electroless plating and nanometer composite electroplating applied for run equipments in wet H2S environment.The author considered that what we studied on the low alloy steels and the rules from the examination provided a science basis to solve the stress corrosin cracking of equipments in wet H2S environment, and also had the significant reference value.更多还原