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本文主要对石油化工企业中服役设备出现的失效情况进行研究。通过采用扫描电镜、光学显微镜、能谱仪等设备对裂纹的形貌、腐蚀产物进行了分析.结果表明该设备失效的主要原因是材料存在较严重的成分偏析,在介质中的H2S作用下产生了氢诱导阶梯裂纹.焊接残余应力、H2S应力腐蚀加速了裂纹的扩展。 相似文献
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硝酸钠蒸发器应力腐蚀开裂及其对策袁必刚(鄂西化工厂)我厂硝酸钠蒸发器破坏失效是碳素钢、低合金钢在含有氯离子介质中应力腐蚀开裂的实例。该设备结构复杂,在运行过程中除了承受工作应力外,还有结构应力、焊接残余应力、温差应力等。焊接过程还带来材料内部的一系列... 相似文献
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R-2反应器夹套失效分析 总被引:1,自引:0,他引:1
通过宏观及金相检查、材质分析,应用光学显微镜对R-2反应器夹套开裂、渗漏失效原因进行了分析。结果表明,冷作拉应力与焊接残余应力是产生应力腐蚀造成反应器夹套失效的主要因素。由于应力腐蚀裂纹的产生、扩展并穿透内外壁,造成泄漏。 相似文献
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催化烟机入口高温烟气管线发生裂纹,在对此类故障的简短回顾之后,采用应力分析软件对此管道做了分析。根据应力计算结果和可能的失效原因,分析得出了审慎的结论以及一些整改建议。 相似文献
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从某炼油厂的换热器管板裂纹形貌判断该换热器为应力腐蚀失效,对换热器管板的应力状态及应力腐蚀失效机理进行分析,并给出防护措施。 相似文献
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双向应力对失效评定图的影响 总被引:2,自引:0,他引:2
文中通过弹塑性有限元方法探索了双向应力对失效评定曲线的影响,同时比较了弹塑性有限元建立的失效评定曲线与R6选择1曲线。从工程角度出发,单向应力条件下的R6选择1曲线可粗略地作为双向应力下含缺陷结构的失效评定方法,但更精确的评定必须考虑双向应力影响。文中同时还研究了双向应力对J积分守恒性及数值的影响。 相似文献
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Raj N. Singh 《Journal of the American Ceramic Society》1990,73(10):2930-2937
The first-matrix cracking stress and fiber-matrix interfacial shear stress were measured in zircon-matrix composites uniaxially reinforced with either uncoated or BN-coated silicon carbide filaments to study the role of intentional changes in interfacial shear stress on first-matrix cracking stress. The first-matrix cracking stress was measured by mechanical tests performed in either tension or flexure, and the filament-matrix interfacial shear stress was measured by a fiber pushout test. The first-matrix cracking stress was independent of the measured interfacial shear stress and did not conform to the predictions of a number of energy-based micromechanics models. In contrast, the first-matrix cracking stress showed a good correlation with the first-matrix cracking strain, which is hypothesized to be a more realistic criterion for first-matrix cracking in this class of filament-reinforced ceramic-matrix composites. 相似文献
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ABS塑料现实使用中经常出现应力开裂现象。为了解决此问题,本项目对有应力开裂的ABS试样和无应力开裂的ABS试样进行拉伸实验、冲击性能测试、红外光谱分析、热分解实验、扫描电镜和感偶等离子原子发射光谱分析。通过分析比较,找出开裂原因,指导材料的应用。试验结果表明:无应力开裂试样的拉伸强度是有应力开裂试样的约1/3,但断裂伸长率却是有应力开裂试样的约5.6倍;应力开裂试样的抗冲击强度下降了。无应力开裂的试样中无机填料量较少(质量分数约为3.07%)、颗粒较小、且分散均匀;而有应力开裂的试样无机填料质量分数约为5.29%。无应力开裂试样中Ti的质量分数24.33%,有应力开裂试样的Ti的质量分数35.77%,由于Ti的量增大,且颗粒较细,比表面积增大而不易分散均匀,出现团聚现象,形成应力集中。 相似文献
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Stress cracking is one of the most frequent causes of premature failure of polymers, affecting also engineering polymers like PET. In this work, the stress cracking behavior of injection moulded PET was investigated using sodium hydroxide (NaOH) aqueous solutions in various concentrations as active fluids. The application of mechanical load to the sample bars was done in a tensile testing machine, using the ordinary tensile test and also a relaxation procedure. The results showed that all NaOH solutions were aggressive stress cracking agents for PET, reducing mechanical properties and causing catastrophic failure with a significant surface damage. The occurrence of hydrolysis reactions was also observed when NaOH solutions were applied in combination with tensile loads, causing a reduction in molar mass of PET molecules. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
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韩健;韩冬雪;刘春太;陈静波;申长雨 《中国塑料》2010,24(4):76-79
研究了不同注塑工艺下成型的聚碳酸酯(PC)平板制品的环境应力开裂行为。结果表明:在四氯化碳浸渍下,在制品侧壁位置出现分层开裂;熔体温度升高可以提升PC制品的耐环境应力开裂性;保压压力较大时,制品开裂现象较为明显。在分析分子取向和残余应力与制品环境应力开裂行为关系的基础上,探讨了注射成型工艺对PC注塑制品环境应力开裂行为的影响机理。 相似文献
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碳酸饮料聚酯包装瓶应力开裂解决方法 总被引:2,自引:0,他引:2
通过对应力开裂机理进行研究和讨论,找出了影响碳酸饮料包装瓶应力开裂的因素,提出了解决思路和方法,并在生产实践中对制瓶工艺进行优化,最终解决了碳酸饮料包装瓶的应力开裂技术难题。 相似文献
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HDPE耐环境应力开裂性能的研究及改进 总被引:1,自引:0,他引:1
对HDPE的耐环境应力开裂性能进行了研究。试验表明:采用共混及化学改性的方法,HDPE的耐环境应力开裂性能有了很大提高,为解决HDPE树脂在制作管材时出现的短时间内应力开裂问题提供了依据。 相似文献
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介绍了脱水塔的开裂情况,通过采用光学显微镜、扫描电镜、能谱仪等设备对裂纹的形貌、腐蚀产物进行了分析,结果表明该设备产生裂纹的主要原因是应力腐蚀(碱脆),并提出一些有效的防治措施. 相似文献
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聚酯瓶应力开裂解决方法 总被引:4,自引:2,他引:2
通过对应力开裂机理进行研究和讨论,找出了影响聚酯(碳酸饮料)瓶应力开裂的因素,提出了解决思路和方法,并在生产实践中对制瓶工艺进行优化,最终解决了应力开裂技术难题。 相似文献
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针对气气换热器壳侧膨胀节发生开裂的问题,通过对设备的结构、工作参数及膨胀节的制造情况等相关数据进行收集和分析,再结合对开裂膨胀节取样进行的一系列实验室检测检验,最终判断膨胀节开裂原因为其长期工作在有湿硫化氢介质的环境下,存在湿硫化氢应力腐蚀,而奥氏体不锈钢膨胀节在冷加工成型过程中,由于加工硬化产生了大量的形变马氏体,进... 相似文献
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Different types of coatings were characterised for: swelling by moisture, moisture permeability, elastic modulus and extensibility. These data were used to calculate maximum internal stress. Internal stress was also measured directly whilst changing temperature and humidity. The stress data were compared to cracking and flaking results in both natural and accelerated weathering tests. Results showed that high levels of stress occur if there is a difference in swelling between coating and wood. In most cases stress relaxation took place rapidly. Comparing maximum stress, extensibility and cracking, a good correlation between these data was found. The ratio between maximum stress and extensibility appeared to be a very good predictor for crack formation. 相似文献