X20CrMoV12.1钢长期高温时效的逆回火脆性研究

X2 0CrMoV12 .1耐热合金钢是热电厂主蒸汽管线的主要用材之一。该管材经 16×10 4 h长期高温载荷运行后 ,性能明显退化 ,常温下呈完全脆性状态。试验结果表明 ,管材的脆化是可逆的 ,属于逆回火脆现象。运用透射电镜和俄歇电子能谱等方法对其显微组织结构进行了研究 ,发现晶界碳化物的球化以及有害元素磷在晶界的偏聚是材料性能退化和致脆的原因     

用Larson—Miller参数描述12CrlMoV与15CrMo的老化行为

通过系列温度－时间组合的实验室模拟实验和对大量数据的汇总、分析，证明Larson-Miller(P)参数可以合理描述12CrMoV、15CrMo等主蒸汽管道材料的多种老化行为。结果表明，随着P值的增大，热管材料基体中的合金元素贫化加剧，球化程度逐渐升高，且力学性能显著下降，显示出这两种主蒸汽管道材料的组织和力学性能退化与Larson-Miller参数之间良好的对应关系。     

用Larson-Miller参数描述12Cr1MoV与 15CrMo的老化行为

通过系列温度-时间组合的实验室模拟实验和对大量数据的汇总、分析,证明Larson-Miller(P)参数可以合理描述12Cr1MoV、15CrMo等主蒸汽管道材料的多种老化行为.结果表明,随着P值的增大,热管材料基体中的合金元素贫化加剧,球化程度逐渐升高,且力学性能显著下降,显示出这两种主蒸汽管道材料的组织和力学性能退化与Larson-Miller参数之间良好的对应关系.     

主蒸汽管道材料12Cr1MoVG与ASME SA-335 P22的对比

本项目汽机侧主蒸汽管道采用了12Cr1MoVG材料,因为该材料不是ASME材料,业主质疑设计选型不合格,甚至认为12Cr1MoVG性能低于ASME SA-335 P22.本文从材料应用、化特性和化学成分特点阐述解释了该设计选型的材料是能满足性能要求的.     

转炉连接螺栓断裂分析

分析了炼钢转炉托圈连接螺栓早期断裂的原因。结果表明，开裂起源于加工时变截面过渡圆角的尖刀痕，经短程疲劳扩展后发生脆断。螺栓脆断是由于严重的冶金缺陷及组织不良，导致材料性能恶性。重新热处理后获得了良好的综合性能。     

稠油热采注气管使用后的性能变化

对新疆稠油热采注气管取样管道在常温下的材料性能进行了分析测试，获得了服役5a（年）后的稠油热采管道不同部位的抗拉强度、屈服强度、伸长率、断面收缩率和硬度等力学性能；又通过显微组织观察和力学性能测试，讨论了管道组织变化和性能退化之间的关系，得到了注气管道不同管段处性能退化情况。进而分析了造成管道性能退化的影响因素，对管道性能退化造成的安全隐患提出了相应的防护措施。     

压水堆核电站反应堆压力容器材料概述

反应堆压力容器是核电站重要部件之一,综述了反应堆压力容器材料的发展历程、性能要求、在役辐照脆化、制造现状等,指出A508-Ⅲ钢具有优良的焊接性、较高的淬透性和抗中子辐照脆化性,并具有良好的低温冲击韧性和较低的无延性转变温度等优点.分析了该钢的化学成分、制造工艺与性能之间的关系,对反应堆压力容器材料国产化的实现与未来发展方向的指引有一定的参考作用.     

铁基非晶合金退火脆化与防脆技术

综述了铁基非晶合金退火脆化的影响因素，分析了各种防止退火脆化的方法，认为在电脉冲快速加热的同时外加磁场退火，则是改善铁基非晶合金磁性能、防止其退火脆化的一种较好的方法。     

长期高温服役电站主蒸汽管道的剩余寿命评估

采用金相检验、力学性能测试及高温蠕变持久试验等方法，对某电站主蒸汽管道12Cr1MoV钢管的显微组织和力学性能进行了研究。结果表明：长期高温服役后，12Cr1MoV钢管道组织中出现5级珠光体球化，晶内碳化物析出明显，蒸汽管道内壁、中间、外壁组织的球化程度、晶粒度等级均一致，管道的力学性能下降明显；估算管道的剩余寿命约为4.45 a。     

管线钢焊接热影响区的局部脆化及其对安全性的影响

本文介绍管线钢焊接热影响区的局部脆化研究意义,和多道焊的临界粗品区局部脆化对安全性的影响,得出结论在对管理进行安全分析和评价时,应充分考虑管道材料焊接热影响区的局部脆化问题。而在新建管线的质量控制中应通过焊接工艺的优化来改善焊缝及热影响区性能,     

Damage and Residual Life Assessment of Bends for X20CrMoV12.1 Main Steam Pipe after Long-Term Service

The bent sections from a main steam pipe in a thermal power plant in Shanghai were examined after 165,000 h service at 550 °C under 13.73 MPa pressure. The residual life of the bend sections is determined by evaluation of the service stresses and testing to obtain creep rupture data. Metallographic analysis and tensile, impact, and hardness tests are also conducted. These combined tests show that the properties of the steel deteriorated during service, displaying embrittlement tendencies; the corresponding microstructures exhibit grain boundary weakening and creep damage characteristics. However, considering no evidence of localized damage in the form of creep cavitation or surface cracks was observed in the examined parts, considering the residual life of the bends at service condition, they are adequate for an additional 44,000 h of operation. It is recommended that a health assessment should be taken after 25,000 h service exposure for safety reasons.     

600MW主蒸汽管道温度套管漏泄的原因分析及处理方法

分析了某电厂主蒸汽管道不锈钢材料的温度测点套管泄漏的原因，阐述了主蒸汽管道温度套管改进的安装及焊接工艺。     

Life extension technology for steam pipe systems—II. Development of life prediction methodology

Part II of this paper addresses the development of a fracture mechanics based life prediction methodology of steam pipes which operate at elevated temperatures but in the sub-creep temperature range. Elastic-plastic fracture mechanics concepts were employed to establish the remaining life prediction methodology and inspection criteria of steam pipes. Leak-before-break analyses were utilized to determine the flaw inspection criteria. Both tension and bending type loading conditions were considered in the life prediction analysis. The life assessment technology is concerned with the fatigue crack growth life of circumferential cracks in a pipe. The material properties of the A106B steam pipe steel reported in Part I of this paper were used to predict the fatigue life of steam pipes. The effects of operating parameters (e.g. stress and temperature), pipe size, and material properties on the remaining life and inspection intervals of steam pipes can be quantitatively evaluated.     

Hydrogen embrittlement in power plant steels

In power plants, several major components such as steam generator tubes, boilers, steam/water pipe lines, water box of condensers and the other auxiliary components like bolts, nuts, screws fasteners and supporting assemblies are commonly fabricated from plain carbon steels, as well as low and high alloy steels. These components often fail catastrophically due to hydrogen embrittlement. A brief overview of our current understanding of the phenomenon of such hydrogen damage in steels is presented in this paper. Case histories of failures of steel components due to hydrogen embrittlement, which are reported in literature, are briefly discussed. A phenomenological assessment of overall process of hydrogen embrittlement and classification of the various damage modes are summarized. Influence of several physical and metallurgical variables on the susceptibility of steels to hydrogen embrittlement, mechanisms of hydrogen embrittlement and current approaches to combat this problem are also presented.     

某稠油井用高温蒸汽注汽管爆裂失效分析

通过对某油田稠油井发生爆裂的高温蒸汽注汽管进行宏观分析、化学成分分析、金相检验、力学性能测试以及扫描电镜断口分析,找出了该管爆裂失效的原因.结果表明:该高温蒸汽注汽管线的爆裂性质为脆性开裂,开裂起源于管表面的两处机械损伤;导致其爆裂失效的主要原因是该管在服役过程中由于水击作用发生了胀径,使注汽管壁厚不均匀;同时管表面存...     

The effect of physical aging on the embrittlement of steam-sterilized polycarbonate

Polycarbonate is known to suffer from dramatic reductions in ductility upon exposure to hot, humid environments, such as during steam sterilization. Two phenomena have been proposed to be the main causes of this embrittlement: hydrolysis and microcavity formation. The present study focuses on a third phenomenon, whose contribution to the embrittlement has until now been considered insignificant: (physical) aging. By studying the influence of steam sterilization on the tensile deformation behavior of polycarbonate, it is shown that aging actually is one of the dominant factors in the embrittlement.     

使用21年后主蒸汽管道的性能变化及其安全评估

对某石化热电厂材质为１０ＣｒＭｏ９１０,服役时间超过１０万ｈ的主蒸汽管道进行全面检测与安全评估,对１１７个现场测定的硬度值进行统计分析,介绍了新管材、旧管母材及焊缝的常温和高温拉伸试验结果,－６０～５５０℃影响各温度下冲击功值,以及由试验定的韧脆性转变温度,并评价了长期服役对韧脆性转变温度的影响。     

过热器管不同运行时态爆管分析与测试

过热器管在运行过程中要十分注意控制运行温度,若温度偏高,则会造成短期超温爆管和长期过热爆管,前者断裂过程类似于高温拉伸快速断裂,后者类似于蠕变断裂,故在实际生产中,必须严格控制其使用温度,以避免爆管事故的发生。     

超临界锅炉高温过热器T91钢管爆管分析

通过化学成分、显微组织、力学性能、硬度和内壁沉积物检查等手段对某电厂超临界锅．炉高温过热器出口T91钢管爆裂的原因进行了分析。结果表明：由于该钢管内壁氧化皮脱落堆积,管内蒸汽流通面积减小,造成了钢管过热,从而引起了钢管在薄弱区域爆裂失效。