35t/h炉面式减温器冷却水管裂纹原因浅析

对面式减温器冷却水管产生裂纹原因的分析表明，由于水质含氧和Cl^-离子过高，造成腐蚀，同时由于操作不当，产生温变应力，致使冷却水管腐蚀疲劳产生裂纹。     

TP347H不锈钢管表面裂纹的产生原因

在TP347H不锈钢大小头管生产过程中表面出现了环向裂纹;通过对钢管的化学成分、硬度、夹杂物、晶粒度、显微组织、裂纹处微观形貌和能谱微区成分等进行了分析,找出了裂纹产生的原因。结果表明:不锈钢管的表面裂纹是应力腐蚀裂纹;不锈钢管在成型过程中产生残余应力是裂纹产生的内因,在酸洗过程中带来的氯离子是裂纹产生的外因,晶界碳化铬的析出加剧了应力腐蚀开裂。     

离心式鼓风机叶轮的应力腐蚀

通过对裂纹断口形状和特点的分析，从应力来源、焊接缺陷等方面对应力腐蚀裂纹的影响进行了探讨。从焊后热处理、工艺结构刚性等方面对预防和减少应力裂纹的产生提出相应的解决办法。     

DAO分离器纵缝应力腐蚀裂纹的分析与预防

厚壁容器在组装、预热、焊接和热处理过程中如有不当就会产生较大的残余应力,当具备应力腐蚀3个基本条件时容易产生应力腐蚀裂纹。通过对产生的裂纹机理、容器使用条件、磁粉检测和金相检查结果的分析,提出裂纹的处理方法及预防措施。     

蒸压釜裂纹成因探讨

针对某企业蒸压釜检验时,发现的一台蒸压釜焊缝存在大量网状裂纹的问题,分析了裂纹产生部位和裂纹形貌,探讨了裂纹成因,认为这是一种危险性的应力腐蚀和腐蚀疲劳共同作用下产生的裂纹。     

X60螺旋焊管的应力腐蚀开裂试验研究

通过改进的WOL预裂纹试样应力腐蚀试验，得到了在500，1000ppm的硫化氢水溶液中，X60螺旋焊管的应力腐蚀裂纹扩展速率da／dt，结果表明，随硫化氢水溶液浓度的增加，X60螺旋缝埋弧焊管应力腐蚀裂纹扩展速率增加，焊管抗应力腐蚀的寿命越短。     

聚丙烯聚合釜筒体裂纹的失效研究

分析聚丙稀反应釜裂纹产生和扩展的原因,系属于腐蚀疲劳断裂,具有低周疲劳扩展性质.裂纹的产生是环境因素、操作工况和与结构设计上存在的边缘应力综合影响的结果.下温度计接管下方的焊缝在边缘应力和焊接残余应力共同作用下使交变载荷的应力水平提高,促使焊缝处产生疲劳裂纹,冷却水介质作用下的吸氧腐蚀加剧了裂纹的扩展.根据失效机理,成功地采取了挖补工艺修复方法.     

16MnR钢在硝酸盐环境下应力腐蚀性能试验研究

用楔形张开加载(WOL)预裂纹试样研究了16MnR钢在硝酸盐环境中的抗应力腐蚀性能。测定了16MnR钢母材及焊接接头在硝酸盐环境下的临界应力强度因子KISCC和应力腐蚀裂纹扩展速率；同时研究了缓蚀剂、材质、溶液温度对16MnR钢应力腐蚀开裂的影响，结果表明，缓蚀剂谈明显的降低应力腐蚀敏感性，增加裂纹的孕育时间；焊接接头与母材相比，由于没有元素Ni的不良作用，具有较高的应力腐蚀抗力；16MnR钢的硝酸盐应力腐蚀敏感性随温度升高而降低。     

焊缝应力腐蚀裂纹的原因分析及控制措施

发生应力腐蚀时外观无变化,裂纹发展迅速且预测困难,对设备的安全运行带来了威胁,因而更具有危险性。本文介绍了应力腐蚀裂纹的特征、产生原因及防止措施。     

大型构件整体热处理应用实例

高炉工程的热风炉本体在焊接过程中因焊缝金属及热影响区易产生焊接残余应力,且热影响区的淬硬倾向和焊缝中氢的存在均可导致裂纹的产生,特别是当热风炉在高温状态下工作更容易因应力腐蚀而产生晶间应力腐蚀裂纹。因此,     

Review on Stress Corrosion and Corrosion Fatigue Failure of Centrifugal Compressor Impeller

Corrosion failure,especially stress corrosion cracking and corrosion fatigue,is the main cause of centrifugal compressor impeller failure.And it is concealed and destructive.This paper summarizes the main theories of stress corrosion cracking and corrosion fatigue and its latest developments,and it also points out that existing stress corrosion cracking theories can be reduced to the anodic dissolution(AD),the hydrogen-induced cracking(HIC),and the combined AD and HIC mechanisms.The corrosion behavior and the mechanism of corrosion fatigue in the crack propagation stage are similar to stress corrosion cracking.The effects of stress ratio,loading frequency,and corrosive medium on the corrosion fatigue crack propagation rate are analyzed and summarized.The corrosion behavior and the mechanism of stress corrosion cracking and corrosion fatigue in corrosive environments,which contain sulfide,chlorides,and carbonate,are analyzed.The working environments of the centrifugal compressor impeller show the behavior and the mechanism of stress corrosion cracking and corrosion fatigue in different corrosive environments.The current research methods for centrifugal compressor impeller corrosion failure are analyzed.Physical analysis,numerical simulation,and the fluid-structure interaction method play an increasingly important role in the research on impeller deformation and stress distribution caused by the joint action of aerodynamic load and centrifugal load.     

合成氨中置锅炉换热管破裂原因分析

通过宏观检查，化学分析，金相检验等方法对中置锅炉Cr-Ni系奥氏体不锈钢换热管的破裂事故原因进行了分析，确定应力腐蚀是中置锅炉换热管发生破裂的原因。     

Growth simulation for 3D surface and through-thickness cracks using SGBEM-FEM alternating method

An SGBEM-FEM alternating method had been proposed by Nikishkov, Park and Atluri for the analysis of three-dimensional planar and non-planar cracks and their growth. The proposed method is an effective method for fatigue or stress corrosion crack growth simulation. During crack growth simulation, however, an oscillation phenomenon is observed in crack advance or stress intensity factor distribution. If oscillating amplitude in SIF or crack advance does not decrease during next increment steps, the crack growth simulation fails. In this paper several methods are examined to remove the oscillation phenomenon. As a result, it is found that smoothing in stress intensity factor distribution or in crack front geometry can remove or weaken the oscillation phenomenon. Using the smoothing techniques, stress corrosion crack growth simulation is performed for a semi-elliptical surface crack and a through-thickness crack embedded in a plate. Crack front shape and stress intensity factor distribution are obtained after each increment during the crack growth. And the depth and length of a crack are obtained as a function of time. It is noted that the SGBEM-FEM alternating method is a very effective method for SCC growth simulation for a surface crack and a through-thickness crack.     

SPV490Q钢焊接接头在不同浓度硫化氢溶液中的应力腐蚀开裂行为

对SPV490Q钢焊接接头的楔形张开加载(WOL)预裂纹试样在不同浓度硫化氢溶液中进行了应力腐蚀试验,测定了焊缝的应力腐蚀临界应力强度因子KISCC和应力腐蚀裂纹扩展速率da/dt。结果表明:随着H2S浓度的升高,SPV490Q钢焊缝的应力腐蚀临界应力强度因子KISCC下降,应力腐蚀裂纹扩展速率da/dt增大,焊接接头的应力腐蚀抗力降低。     

某电厂TP304不锈钢换热管裂纹分析

某电厂汽轮机汽封加热器的TP304换热管出现裂纹,对已泄漏的换热管取样分析,TP304不锈钢管的化学成分和力学性能都符合技术条件要求,有应力腐蚀倾向,裂纹附近有较大拉应力,裂口表面含有Cl离子和Na离子等腐蚀介质,TP304管是由于应力腐蚀引起的开裂。     

X80管线钢焊接接头的硫化氢应力腐蚀试验研究

采用X80管线钢焊接接头制作楔形张开加载（WOL）试样，在硫化氢介质中进行恒位移应力腐蚀试验，分别测得母材、焊缝和热影响区的临界应力强度因子KISCC和裂纹扩展速率da／dt。试验结果表明，热影响区的‰最小，裂纹扩展速率最大，具有较差的抗应力腐蚀开裂的能力，是应力腐蚀开裂的薄弱环节。且通过对X80管线钢焊接接头的显微组织观察和基本力学性能研究，对影响X80钢应力腐蚀影响因素提供了试验依据，并对试验结果予以验证。     

控制棒驱动机构管座法兰母材性能评估

针对控制棒驱动机构（CRDM）下部Ω环的热电偶（TC）管座母材在水压试验后出现缺陷的问题,参照 CRDM／TC 管座法兰母材的采购技术规范要求,对管座母材进行材质分析,比较了业主与制造厂提供的同批次材料性能差异。分析结果显示,业主提供的部分批次理化检验余料除晶粒度不符合采购技术规范外,内部还有较大尺寸夹杂,但材料的其他性能指标均满足采购规范技术要求。原材料内部存在混晶现象,材质性能分布不均匀。为此,结合材料失效机理研究了母材应力腐蚀裂纹扩展性能,试验结果表明,在一回路高温高压水环境下,超标夹杂的存在未对材料的应力腐蚀裂纹扩展速率产生明显影响。     

高压涡轮盘榫齿裂纹分析

对某发动机涡轮盘的榫齿裂纹断口、材质和受力进行综合分析,结果表明,榫齿裂纹为起始应力较大的疲劳裂纹,盘片材料热膨胀不协调以及存在叶片共振是导致涡轮盘榫齿裂纹的主要原因。另外,GH2036材料在高温燃气环境易发生沿晶腐蚀,是导致涡轮盘提前失效的诱发因素。     

Corrosion fatigue characteristics in the weld of multi-pass welded A106 Gr B steel pipe

In order to investigate the corrosion fatigue characteristics in the weld of multi-pass welded A106 Gr B steel pipe, corrosion fatigue tests were performed under the various stress ratios and 3.5 wt% NaCl solution at room temperature. The corrosion fatigue characteristic curves were represented using crack closure concept. The obtained results are as follows ; when the load frequency is 1.0 Hz, the crack opening point is transited in the region of K_max=20-32 MPa-msu1/2. In the low stress intensity factor range, the crack opening point is higher than that in air. However, in the high stress intensity factor range, it is lower than that in air. In the cases of 0.1 Hz and 0.01 Hz, the crack opening point gradually decreases to K(min) with K_max increase.     

AISI4340高强钢在含氧和/或Cl-高温水中的应力腐蚀行为

采用慢拉伸应力腐蚀试验与应力腐蚀裂纹扩展试验,对AISI4340钢在含饱和氧和/或0.1 mol·L^-1的100℃水中的应力腐蚀行为进行研究。结果表明:100℃水中存在的氧或C一均可以增大AISI4340钢的应力腐蚀倾向,但在含Cl^-并除氧的100℃水中的应力腐蚀倾向不显著,慢拉伸断口依旧保留部分韧性断裂特征,而在含饱和氧的高温水中AISI4340钢发生完全脆性断裂,应力腐蚀倾向显著;氧或Cl^-均可提高AISI4340钢在100℃水中的应力腐蚀裂纹扩展速率,氧与Cl^-之间存在交互作用,二者共存显著提高了应力腐蚀倾向,并导致开裂后裂纹快速扩展。