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The technology of manufacture of live steam lines and hot reheat lines at FINOW Rohrsysteme GmbH are discussed. These pipelines are designed for high-performance CCGT units and are made from high-chromium martensitic steel X10CrMoVNb9-1 (P91). The principles of certification and evaluation of conformance of thermal and mechanical equipment made from new construction materials with the TRCU 032-2013 technical regulation of the Customs Union are detailed. The requirements outlined in Russian and international regulatory documents regarding the manufacture of pipes and semifinished products for pipeline systems are compared. The characteristic features of high-chromium martensitic steel, which define the requirements for its heat treatment and welding, are outlined. The methodology and the results of a comprehensive analysis of metal of pipes, fittings, and weld joints of steam lines are presented. It is demonstrated that the short-term mechanical properties of metal (P91 steel) of pipes, bends, and weld joints meet the requirements of European standards and Russian technical specifications. The experimental data on long-term strength of metal of pipes from a live steam line virtually match the corresponding reference curve from the European standard, while certain experimental points for metal of bends of this steam line and metal of pipes and bends from a hot reheat line lie below the reference curve, but they definitely stay within the qualifying (20%) interval of the scatter band. The presence of a weakened layer in the heat-affected zone of weld joints of steel P91 is established. It is shown that the properties of this zone govern the short-term and long-term strength of weld joints in general. The results of synthesis and analysis of research data support the notion that the certification testing of steam lines and other equipment made from chromium steels should necessarily involve the determination of long-term strength parameters. 相似文献
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The nature of and reasons for weld joint failure in the hot reheat (HRH) steam lines of an 800-MW power unit are analyzed. It is shown that the weld joint destruction happened in the softened area and is typical for the weld joints operating for a long time under creep conditions. Numerical simulation demonstrated that the weld joint exhausted its lifetime due to the impact of equivalent stresses that exceeded design values, this being the reason for the failure. 相似文献
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为优化焊接工艺,解决水冷壁T23接头焊缝在运行中容易出现裂纹的问题,测试了T23接头在4种不同工艺(不预热、焊后不热处理,不预热、焊后热处理,预热、焊后不热处理,预热、焊后热处理;预热温度为150 ℃,焊后热处理工艺为740 ℃、0.5 h)下的硬度和冲击韧性,并观察了显微组织的变化。研究结果表明,预热对T23接头硬度的影响不大,但增大晶粒尺寸和过热区的宽度,对焊缝和热影响区(HAZ)的韧性均有不利影响;焊后热处理明显降低焊缝和HAZ的硬度,虽然对HAZ韧性影响很小,但可改善焊缝的韧性。建议预热温度不超过150 ℃或取消预热,进行焊后热处理以保证接头的长期服役性能。 相似文献
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基于电厂汽轮机末级动叶片水蚀损伤机理,对受损叶片进行手工钨极氩弧焊(GTAW)修复,并对焊接接头的组织性能进行试验。结果表明,焊缝硬度满足使用要求,焊接接头力学性能优良,焊接接头抗高周疲劳性能满足叶片工况要求。为了提高叶片抗水蚀性能,延长叶片使用寿命,对比分析了叶片超音速火焰喷涂NiCr和WC-Co金属陶瓷2种不同涂层的组织结构、机械性能、热震性能、磨粒磨损及冲蚀磨损性能。与WC-Co涂层相比,NiCr涂层具有优异的耐磨性能及抗冲蚀性能,可作为耐水蚀涂层应用在汽轮机末级动叶片上。 相似文献
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针对某电厂1 000 MW超超临界塔式锅炉T23钢管焊接接头发生泄漏的问题,对接头裂纹进行了宏观检查和微观组织分析。分析表明,水冷壁管焊缝附近裂纹的形成原因主要是由焊接残余应力和焊接结构本身的拘束应力共同作用造成的。 相似文献
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对超超临界压力机组锅炉贮水罐焊接接头进行无损探伤和硬度检查,发现在贮水罐焊接接头及母材中存在硬度不均现象,为此,对焊接接头进行复型金相检验,发现焊缝高、低硬度和母材区域组织异常。指出主要原因是局部热处理温度控制不均导致焊接接头出现Ostwald熟化异常组织,冷却速度太慢使焊接接头形成回火索氏体,处理方法是把整个贮水罐退厂更换。 相似文献
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P92钢是制造1 000 MW 超超临界压力发电机组的重要钢种之一,对其焊接性进行了研究.比较了P92钢和P91钢的裂纹敏感性和焊接工艺要求,通过电厂实例分析了P92钢焊接头易出现的问题,如裂纹、焊口根部氧化及成型不良、焊缝硬度及组织异常等,指出P92钢焊接质量控制要点是预热温度、层间温度、焊接热输入量、热处理温度以及... 相似文献
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A. B. Popov 《Thermal Engineering》2012,59(4):289-294
The stressed and strain state of sector-type pipeline elbows is analyzed using the finite element method. Features in which
sector elbows of pipelines differ from circular elbows are revealed. Formulas for determining the maximal equivalent stresses
in sector elbows are presented. 相似文献
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目前不少水电站因为管道漏水等问题而取消伸缩节 ,在取消伸缩节时最后一条焊缝的焊接环境温度选择是非常重要的。针对这个问题 ,本文结合万家寨水利枢纽工程 ,采用三维有限元模型 ,详细分析了在各种焊接环境温度条件下钢管的应力状态 ,提出了合适的焊接环境温度范围。研究表明以 5月份作为焊接时间是合适的 相似文献
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以AgCdO电接触复合材料为触点材料,黄铜为底板,通过电阻钎焊实现触头和底板的焊接。采用JTUIS-IV超声成像无损检测仪、金相显微镜、扫描电子显微镜(SEM)等测试手段,研究焊料种类及焊缝显微形貌对钎着率的影响。结果表明,不同焊料在焊接过程中会表现出不同的作用效果;钎着率较高的工件中仍然存在裂缝、夹杂等微观缺陷,且该缺陷主要存在于铜与焊料的结合层;第二相石墨的加入会明显降低钎着率并极大地损害材料的焊接性能;采用Ag25CuP和无银焊剂焊接后,焊缝过渡层均呈现树枝状晶体组织,但形貌差异较大。 相似文献
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对P91钢在发电机组应用中容易出现的接头脆化和裂纹等问题,采取了相应的焊接工艺,并通过冲击、拉伸和弯曲试验检测其焊接性能。结果表明,采用相应的焊接工艺,P91钢焊接接头可以获得良好的韧性和强度。此外,弯曲试验后试件也未发现裂纹,保证了P91钢的安全使用。 相似文献
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