共查询到20条相似文献,搜索用时 31 毫秒
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采用冷轧工艺生产的1Cr18Ni9Ti不锈钢管内表面出现了大量白色斑点状缺陷,导致产品不能正常出厂交付。为确定白色斑点形成原因,使用扫描电子显微镜+能谱仪、金相显微镜、激光诱导击穿光谱仪,对该批钢管表面形貌、金相组织、晶粒度和微区成分进行了分析检验。结果表明:钢管内外表面都出现了表面增碳现象,内表面上的白斑缺陷区增碳最为严重,酸洗钝化时出现了严重的晶间腐蚀,表层晶粒大量剥落,使局部表面粗糙度变差,形成白斑缺陷。钢管表面除油脱脂不彻底使热处理过程中出现表面增碳是导致出现白斑缺陷的主要原因。 相似文献
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目的分析煤气化黑水处理系统管道的失效行为,明确失效特征,分析失效机理及影响因素,指导弯管的失效预防,延长其服役寿命。方法采用扫描电子显微镜(SEM)对管道进行微观形貌检测,并采用能量色散谱(EDS)和X射线衍射(XRD)对腐蚀产物进行检测分析,最后通过计算流体动力学(CFD)仿真分析其流场情况。结果失效管道内壁面有着明显的流水冲蚀形貌,且布满小凹坑及疏松多孔的褐色腐蚀产物。EDS结果显示,腐蚀产物主要由Fe、S和O元素构成,XRD进一步测得腐蚀产物多为FeS、Fe3O4及FeO等。CFD仿真结果与实际失效工况吻合,二次流、粒径、速度以及斯托克斯数的变化对固体颗粒运动轨迹影响较大,并进一步影响管道冲蚀的高危区位置。结论管道失效的主要原因是黑水中的H2S腐蚀和煤粉颗粒冲蚀的耦合作用,其弯管区域外拱出口位置和下游水平管底部位置为主要高危区,同时管道高危区位置受多种因素影响,相应部位要提前做好预防准备,实际工况中适当减小流速可以实现一定减磨防护作用。 相似文献
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Roozbeh Siavash Moakhar Mehrad Mehdipour Mohammad Ghorbani Milad Mohebali Behrad Koohbor 《Journal of Materials Engineering and Performance》2013,22(9):2691-2697
In this study, failure of a high pressure economizer tube of a boiler used in gas-Mazut combined cycle power plants was studied. Failure analysis of the tube was accomplished by taking into account visual inspection, thickness measurement, and hardness testing as well as microstructural observations using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD). Optical microscopy images indicate that there is no phase transformation during service, and ferrite-pearlite remained. The results of XRD also revealed Iron sulfate (FeSO4) and Iron hydroxide sulfate (FeOH(SO4)) phases formed on the steel surface. A considerable amount of Sulfur was also detected on the outer surface of the tube by EDS analysis. Dew-point corrosion was found to be the principal reason for the failure of the examined tube while it has been left out-of-service. 相似文献
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采用化学分析、体视显微镜和SEM/EDS对核电机组泄漏的高温取样冷却器蛇形管材料的化学成分、腐蚀宏观和微观形貌进行了分析观察,结合冷却器的环境工况,提出了蛇形管腐蚀失效的机理。腐蚀产物的EDS能谱分析显示,蛇形管腐蚀失效部位有大量Fe、P和微量Na元素存在,说明蚀坑和穿孔是因为磷酸盐诱发的碱性腐蚀所致。蛇形管外壁局部过热,促进局部液体沸腾汽化,使得近壁处水中的磷酸盐和杂质含量达到饱和,从而以固相析出附着在管壁上。一方面,析出的磷酸盐与蛇形管表面氧化物发生磷酸盐反应;另一方面,介质的浓缩与沉积使传热恶化,导致磷酸盐隐藏和碱性腐蚀的发生,从而造成蛇形管形成蚀坑和穿孔。 相似文献
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超高速碰撞后在纯铁靶板材料弹坑底部形成了超细晶结构。通过光学显微镜(OM)、扫描电镜(SEM)和透射电镜(TEM)对弹坑截面不同深度处的微观组织进行观察分析,得到由塑性变形引起晶粒细化的结论。首先,低能量位错结构(LEDS),如高密度位错墙(DDWs)和位错缠结(DTs)的形成将原始晶粒分割为交错的层状结构;随着应变的增大,DDWs和DTs演化为具有低取向差的亚晶界并将层状结构分割为细小胞状结构;亚晶界转变为高角度晶界,最终导致超细晶的形成。对动态再结晶过程中,由冲击波作用下产生的高应变和高应变率导致的超细晶的形成进行了讨论。 相似文献
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Φ127mm×9.19mm IEU S-135钻杆腐蚀失效分析 总被引:1,自引:0,他引:1
对发生管体刺穿、外壁腐蚀的Φ127mm×9.19mm IEU S-135钻杆进行了失效分析。结果表明,钻杆的化学成分、金相组织、机械性能均符合API标准及订货技术条件。钻杆管体刺穿是由于内壁发生严重H_2S腐蚀+氧腐蚀造成的。钻杆管体外壁腐蚀是由氧腐蚀引起的。 相似文献
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为了同时减少钻杆接头和对磨套管的磨损,采用超声表面加工技术和硫氮共渗技术对钻杆接头材料35CrMo钢进行复合处理。利用光学三维形貌仪、扫描电子显微镜、EDS能谱仪、显微硬度计和X射线衍射仪分别研究了试样的表面形貌、粗糙度、成分、硬度和相结构,并在水基钻井液润滑条件下采用环块磨损试验机考察了35CrMo钢和套管对磨副的磨损性能。结果表明,超声表面加工可以使35CrMo钢和硫氮共渗复合处理改性层的表面粗糙度均显著降低,进一步提高硫氮共渗改性层硬度,显著改善35CrMo钢的耐磨性能,并使对磨副套管的磨损率明显降低,钻杆接头和套管的磨损表面形貌也得到显著改善。 相似文献
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某焦化厂煤调湿蒸汽回转干燥机管束在运行过程中发生开裂.采用化学成分分析、金相显微镜、扫描电子显微镜以及EDS能谱等手段对失效钢管进行取样分析.根据宏观和微观断口形貌、显微组织、钢管的腐蚀坑及力学性能测试结果,确定了钢管失效原因为应力腐蚀开裂.裂纹起源于钢管表面的点蚀坑,应力来自于钢管承受冷热交替时产生的热应力. 相似文献
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某焦化厂煤调湿蒸汽回转干燥机管束在运行过程中发生开裂。采用化学成分分析、金相显微镜、扫描电子显微镜以及EDS能谱等手段对失效钢管进行取样分析。根据宏观和微观断口形貌、显微组织、钢管的腐蚀坑及力学性能测试结果,确定了钢管失效原因为应力腐蚀开裂。裂纹起源于钢管表面的点蚀坑,应力来自于钢管承受冷热交替时产生的热应力。 相似文献
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Microstructure of the surface zone in a heat-treated cermet material 总被引:17,自引:0,他引:17
J. Zackrisson U. Rolander G. Weinl H.-O. Andren 《International Journal of Refractory Metals and Hard Materials》1998,16(4-6):315-322
The microstructure of a Ti(C, N)-(Ti, W)(C, N)-(Ti, Ta)(C, N)-WC-Mo2C-Co cermet with a heat-treatment induced surface gradient has been studied. The post-sintering heat-treatment was performed at 1200 °C in a nitrogen atmosphere and the resulting microstructure was compared to that of the as-sintered material. The microstructures were characterised with optical microscopy, X-ray diffraction, electron microprobe analysis, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, electron energy-loss spectroscopy and energy-filtered transmission electron microscopy. It was found that a 50-μm deep nitrogen-rich surface zone was introduced by the heat treatment. η-phase was observed in the surface zone. The nitrogen gradient caused diffusion of titanium towards the surface, thereby forcing the cobalt-rich binder to be transported inwards. The composition of the binder phase and outer rim of the carbonitride grains showed only minor changes with depth. The variations in binder composition may be a direct consequence of the heat treatment, but are also likely to be influenced by the formation of η-phase. A nitrogen-rich phase was present in the surface zone of the heat-treated material both as thin layers (≈ 70 nm) surrounding the carbonitride grains and as small parts of some carbonitride grains. In addition, the Ti(C, N) cores in the surface region were found to have different N/(C + N) ratios. 相似文献
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本论文用腐蚀漏磁检测仪、超声波测厚仪等仪器及X射线能谱(XRD)等方法,在对新疆某油田一输油长输管线出站36km管段现场开挖、检测验证和实验室试验分析研究的基础上,主要针对该输油管道腐蚀穿孔失效的特点、影响因素、机理及其防护措施进行了全面分析研究。经分析研究发现:管道外表面均光滑、平整,未见明显异常腐蚀点,而地势相对低洼管段的管道内壁发生了严重局部腐蚀,管道钢材自身不存在质量问题,管线较大高程差,起伏多变的地形,引起的管道底部沉降水、泥沙、其他腐蚀性介质(Cl^-、Ca^2+、Mg^2+)及低pH值(5.84)酸性环境等是该管道腐蚀失效的主要影响因素;输送介质中水质的高矿化度和高含量Cl^-,也是腐蚀穿孔失效的重要因素。 相似文献
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The oxides formed on the surface of the alloy 690 in hydrogenated supercritical water at 400℃ for 1000 h were investigated using scanning electron microscopy,transmission electron microscopy,scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy.The oxides on me surface of the alloy 690 exhibited multi-layer structure:an outer layer consisted of granular crystallites(NiO and NiFe_2O_4) and a compact inner layer(spinel and Cr_2O_3).Chemical analysis indicated that the outer layer was enriched in nickel but depleted in chromium,whereas the inner layer was enriched in chromium and iron but depleted in nickel.The inner layer was also characterized as layered structure by Fe-rich spinel on top of continuous Cr_2O_3 layer.Besides,Cr_2O_3 nodules were readily observed at the oxides/alloy interface. 相似文献
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通过结构分析、断口检查、硬度测试、抗拉试验、显微组织观察及能谱分析,对电厂高温再热器SA-213TP347H钢管进行裂纹原因分析。结果表明:高温再热器在运行中容易晃动,裂纹处于管夹挤压的凹坑;裂纹处管材的拉伸性能、硬度均符合ASME A213/A213M对SA-213TP347H钢的要求;显微组织为奥氏体和沿晶界分布的含Cr碳化物,裂纹是沿晶裂纹,由管外壁向管内扩展;裂纹处腐蚀产物均含有O、S等非金属元素。分析表明:产生裂纹的原因是由于管夹挤压管道,同时管道结构易晃动,增加了挤压变形处的应力,促进了含Cr碳化物沿晶界析出,形成贫Cr区而导致晶界弱化,并在腐蚀性介质的作用下,导致晶间应力腐蚀开裂。 相似文献