共查询到20条相似文献,搜索用时 218 毫秒
1.
2.
高含H2S介质气井中,射孔段套管始终工作在腐蚀性环境中,必然会引起射孔套管发生严重腐蚀甚至突然断裂。结合材料学和电化学腐蚀知识,分析了含H2S腐蚀环境中射孔段套管的应力腐蚀开裂失效机理;并在此基础上,将射孔段套管看作带"尖角圆孔"型裂纹的无限大圆柱筒壳体,运用弹塑性断裂力学理论,得到了带环向和轴向尖角圆孔型裂纹的射孔段套管在H2S腐蚀环境中的应力腐蚀临界应力强度因子,据此推导出了射孔段套管硫化氢应力腐蚀断裂临界应力和容许的最大尖角裂纹长度。根据弹塑性力学理论,推导出了射孔段套管在H2S腐蚀环境中工作时的环向和轴向拉应力,提出了判断射孔段套管硫化氢应力腐蚀程度和敏感性两项性能指标。为高深度H2S天然气井中射孔段套管的应力腐蚀、强度安全性、腐蚀疲劳分析和寿命估算提供理论参考和技术依据。 相似文献
3.
4.
5.
目的找到不锈钢泵轴断裂原因。方法通过对断裂的泵轴进行失效分析,利用扫描电镜、金相显微镜、直读光谱仪、显微硬度计等测试方法和手段,对失效泵轴的断口形貌、组织、化学成分、显微硬度等进行分析。结果断口形貌呈明显的脆性疲劳开裂特征,且裂纹源呈现多源特征,有疲劳辉纹和二次裂纹存在。316L泵轴材质成分和组织问题不大,在近表面存在大量夹杂物,同时泵轴表面观察到点蚀和微裂纹存在。结论近表面夹杂物在酸性环境中极易引起点蚀,同时泵轴与联轴器根部结合处存在变截面,形成应力集中。当泵轴受到腐蚀、应力以及电机交变载荷作用时,形成腐蚀疲劳裂纹源,裂纹扩展造成瞬断是此次不锈钢泵轴断裂的主要原因。 相似文献
6.
7.
采用NACE TM 0177—2005标准中的A法和D法,对110钢级抗硫油套管进行抗腐蚀性能试验研究。试验结果表明:A法试验主要研究试样的屈服强度、非金属夹杂物和金相组织三方面与其腐蚀性能的关系,强度高、非金属夹杂物严重、金相组织不均匀都会导致试样断裂;D法则研究了临界应力强度因子K_(ISSC)值、平衡楔形块载荷P和裂纹长度a与屈服强度的关系,K_(ISSC)值和P值与屈服强度基本成反比,裂纹长度a与屈服强度基本成正比。 相似文献
8.
9.
10.
11.
The effect of inclusions on the initiation of stress corrosion cracking (SCC) X70 pipeline steel was investigated in an acidic soil solution using slow strain rate test, scanning electron microscopy and energy-dispersive X-ray techniques. The results demonstrated that stress corrosion cracks are not initiated in X70 steel when it is under anodic polarization. At cathodic polarization, hydrogen evolution is enhanced, and hydrogen is actively involved in SCC processes. Two types of inclusions exist in the steel and play different role in crack initiation. The inclusions enriching in Al are brittle and incoherent to the metal matrix. Microcracks and interstices are quite easily to be resulted in at the boundary between inclusions and metal. There is no crack initiating at inclusions containing mainly Si. 相似文献
12.
13.
14.
S135钻杆钢预腐蚀后的弯曲疲劳性能 总被引:1,自引:1,他引:0
目的:考察有机盐钻井液对S135钻杆材料腐蚀及疲劳性能的影响。方法首先利用高温高压釜模拟有机盐钻井液井筒的工况环境,对疲劳试样进行预腐蚀,通过点蚀仪测定试样表面的腐蚀状况;然后利用旋转弯曲疲劳试验机在不同弯曲应力条件下对预腐蚀试样和未腐蚀试样的疲劳性能进行测试,算得不同存活率下的疲劳强度,并绘制不同存活率下的S-N曲线。用体视显微镜和扫描电镜观察预腐蚀试样和未腐蚀试样的疲劳断口形貌,进而得出S135钻杆材料表面腐蚀对其疲劳寿命的影响程度和影响机制。结果经过腐蚀的试样表面有较多腐蚀坑,腐蚀坑深度在0.4~0.7 mm之间。未腐蚀试样的疲劳强度为553 MPa,其疲劳断口只观察到单个疲劳裂纹源;腐蚀试样的疲劳强度为409 MPa,其疲劳断口观察到多个疲劳裂纹源。 S135钻杆材料腐蚀疲劳开裂敏感性指数为26%。结论经过高温高压有机盐钻井液环境腐蚀后,试样表面点蚀严重,腐蚀坑底部存在应力集中并导致裂纹源的形成,多个裂纹源的同时生长加快了裂纹的扩展,最终降低S135钻杆钢的疲劳强度。 相似文献
15.
The nonmetallic inclusions in low‐alloy pressure vessel steel A533B were carefully examined and the low cycle fatigue (LCF) behavior of the steel was investigated in 288°C air and water. Much attention was paid to the roles of inclusions on fatigue crack initiation and propagation in high temperature water. Three types of inclusions were observed in the steel, consisting of isolated or clustered sulfide inclusions, duplex oxide‐sulfide inclusions and isolated oxide inclusions. In high temperature air, fatigue cracks initiated predominantly from subsurface inclusions. In high temperature water, however, fatigue cracks initiated primarily at corrosion pits on the specimen surfaces resulted mainly from the dissolution of large or clustered sulfide inclusions. The subsurface and bulk inclusions also contributed to the fatigue cracking in high temperature water. Possible influence of the above three types of inclusions on environmentally assisted cracking (EAC) was evaluated. The fatigue fractographic features suggested a synergism between sulfide inclusions and hydrogen‐induced cracking dominate the present EAC in high temperature water. 相似文献
16.
Q235B 钢含硫污水罐的腐蚀开裂失效分析 总被引:2,自引:1,他引:1
目的对某炼油厂原料水罐Q235B钢腐蚀开裂失效原因进行分析。方法采用宏观形貌、金相组织和断口观察以及成分分析和力学性能测定等手段,分析Q235B钢腐蚀开裂失效的宏观和微观行为。结果 Q235B钢在污水罐罐顶形成的湿硫化氢环境中发生沿晶型应力腐蚀开裂。腐蚀过程中,电化学反应产生的氢渗入基体,导致微裂纹的萌生。腐蚀产物在基体表面积聚,其自身体积膨胀以及涂层的闭塞作用对基体形成非常大的拉应力。结论结合应力分析和环境分析,Q235B钢含硫污水罐的腐蚀开裂失效机制为硫化氢应力腐蚀开裂,应力来源于氢渗透和腐蚀产物膨胀。 相似文献
17.
在役液化石油气储罐硫化物应力腐蚀开裂、氢鼓泡和氢致开裂等缺陷可能会扩展,需要监控其扩展状况。介绍了针对这些不同类型缺陷的超声波监控方法,总结了超声波监测过程中所必须注意的要点。 相似文献
18.
M. Ziomek-Moroz 《Journal of Materials Engineering and Performance》2012,21(6):1061-1069
Corrosion fatigue (CF), hydrogen induced cracking (HIC) and sulfide stress cracking (SSC), or environmentally assisted cracking (EAC) have been identified as the most challenging causes of catastrophic brittle fracture of drill pipes during drilling operations of deep oil and natural gas wells. Although corrosion rates can be low and tensile stresses during service can be below the material yield stress, a simultaneous action between the stress and corrosive environment can cause a sudden brittle failure of a drill component. Overall, EAC failure consists of two stages: incubation and propagation. Defects, such as pits, second-phase inclusions, etc., serve as preferential sites for the EAC failure during the incubation stage. Deep oil and gas well environments are rich in chlorides and dissolved hydrogen sulfide, which are extremely detrimental to steels used in drilling operations. This article discusses catastrophic brittle fracture mechanisms due to EAC of drill pipe materials, and the corrosion challenges that need to be overcome for drilling ultra-deep oil and natural gas wells. 相似文献
19.
none 《腐蚀工程科学与技术》2013,48(4):206-207
AbstractNucleation and growth of transgranular stress corrosion cracks has been studied in Type 316 austenitic steel stressed in MgCl2 solutions of various degrees of acidity and under a narrow range (?0·24 to ?0·40 V SCE) of controlled potential. Slip line attack occurs in relatively acid solutions and is accompanied by the formation of {110} slots which are covered with a chromium rich oxide. In well boiled solutions, which are of low acidity, nucleation occurs at inclusions. MnS particles are efficient crack nuclei, but for other inclusions the size and geometry is of greater importance than chemical composition. High potentials favour pitting and crevice corrosion and such sites are particularly important crack nuclei at low stresses.Edge notched sheet specimens have shown very low threshold stress intensities for crack growth and a sensitivity to prior deformation. Crack tips are extremely narrow and the crack sides show evidence of corrosion. Data pertinent to aslip dissolution model are discussed. 相似文献