某酸奶厂配料罐304不锈钢夹套底部材料的失效分析

某酸奶厂二次配料罐304不锈钢夹套底部出现开裂现象,影响了工厂的正常运行。通过观察裂纹宏观形貌、裂纹金相特征、断口形貌以及断口腐蚀产物能谱分析及应力腐蚀敏感性试验等分析了开裂原因。结果表明:配料罐夹套开裂是由奥氏体不锈钢的应力腐蚀造成的;根据事故发生的原因,提出了返修和消除缺陷的方法。     

某核电机组阀门引漏管开裂原因

某核电机组阀门引漏管发生开裂，采用宏观观察、化学成分分析、金相检验、维氏硬度测试、扫描电镜和能谱分析等方法对引漏管的开裂原因进行分析。结果表明：引漏管开裂的原因为应力腐蚀，腐蚀介质为氯离子，最后提出了相关建议。     

0Cr18Ni9不锈钢换热管应力腐蚀开裂原因分析

某管板式换热器运行不到2个月,换热管进口端即发生开裂。通过宏观分析、化学成分分析、水质分析、金相分析、断口以及能谱分析等方法,对换热管开裂属性及原因进行了分析。结果表明:该换热管开裂为应力腐蚀开裂;循环冷却水中较高含量的氯离子以及换热管进口端处于应力腐蚀敏感温度区导致了应力腐蚀的快速发展。最后,给出了进行焊后热处理和加强循环冷却水处理的建议。     

管线钢的应力腐蚀研究现状及损伤机理

回顾了管线钢的应力腐蚀研究现状,并比较了发生在管道外的“经典型”的高pH应力腐蚀开裂与近十多年来发现和研究的近中性pH应力腐蚀开裂的特征,讨论了它们的影响因素以及开裂机理,最后展望了埋地管道的未来研究方向。     

某电厂300MW锅炉高温过热器管开裂原因分析

某电厂300MW锅炉高温过热器管在进行水压试验时发生开裂,采用宏观观察、化学成分分析、金相检验、硬度测试、拉伸试验、微观分析、X射线能谱分析等方法,对高温过热器管的开裂原因进行了分析。结果表明:该高温过热器管内壁存在明显的脱碳层和腐蚀坑。脱碳层使得管子耐腐蚀能力降低,并且弯管和焊接处存在残余应力,两者共同作用导致管子发生应力腐蚀直至开裂。     

1Cr18Ni9Ti不锈钢输油管道开裂原因分析

通过化学成分分析、宏观检验、金相检验和断口分析等方法对1Cr18Ni9Ti不锈钢液压油输送管道开裂原因进行了分析。结果表明:不锈钢管开裂为应力腐蚀开裂,裂纹起源于管道外壁并逐渐向内壁扩展;产生开裂的主要原因是工业水中氯、硫和氧等腐蚀性物质不断在钢管外壁沉积,在管道压力和腐蚀介质共同作用下,不锈钢管发生应力腐蚀开裂。     

钛制再沸器管板接头焊缝腐蚀开裂的原因及改进措施

钛制再沸器是维尼纶生产厂醋酸精馏系统中的重要设备,使用工况苛刻、复杂,投入使用2年后,发现管板与换热管接头连接处焊缝产生腐蚀开裂.从钛制再沸器的选材、设计、制造、运行状况、使用条件、应力状态等几方面入手,分析管板接头焊缝产生腐蚀开裂的原因是:①工作介质醋酸酐和甲酸含水量低,不能维持钛在沸腾醋酸中的钝态;②在环境介质中,钛制再沸器管板接头焊缝长期受交变应力的作用,导致管板焊缝开裂.提出了避免钛制再沸器管板接头腐蚀开裂的4项措施.     

汽轮机抽汽疏水管焊缝开裂原因分析

某电厂汽轮机二级抽汽疏水管在运行过程中于焊缝处发生开裂。采用宏观分析、化学成分分析、金相检验、扫描电镜分析等方法对疏水管焊缝开裂原因进行了分析。结果表明:由于该疏水管直管和弯管对接焊后未进行去应力焊后热处理,焊缝处残余应力较高;在焊接残余应力、工作应力及氯离子的共同作用下,疏水管焊缝内壁萌生裂纹,裂纹由管内壁向外壁不断扩展,最终导致疏水管发生应力腐蚀开裂。     

加氢裂化换热器焊缝开裂失效分析

某换热器管子与管板之间发生焊缝开裂.通过对管板和管子的焊缝渗透检测、化学成分分析、拉伸试验、硬度测试、金相组织检查和用扫描电镜对断口进行观察和能谱的成分测定.结果表明,换热器焊缝开裂的原因是由于在湿硫化氢环境中和焊接残余应力的共同作用下,产生了应力腐蚀开裂.     

某热电厂高温过热器蛇形管开裂原因分析

某热电厂60%的高温过热器蛇形管在安装运行10 h后就发生了开裂失效。采用磁粉探伤检验、化学成分分析、硬度测试、金相检验、拉伸试验等多种手段分析了导致蛇形管早期开裂的原因。结果表明:开裂高温过热器蛇形管原材料由于合金元素钼分布不均匀而存在组织偏析,导致局部区域材料的塑性性能和抗腐蚀性能下降;在高温高压水蒸气和钢管自身强残余应力作用下,最终造成蛇形管由内壁向外壁发生了应力腐蚀开裂。     

弹壳开裂失效分析

对某型H68黄铜弹壳进行检查时发现大量弹壳存在裂纹。通过对弹壳进行宏观和微观观察、能谱分析、金相检验和残余应力测定等,分析了弹壳开裂的原因。结果表明:弹壳的开裂性质为应力腐蚀开裂,其原因是由于收口位置存在一定的残余拉应力,且该位置的晶粒尺寸较大,在外界介质的协同作用下产生了应力腐蚀裂纹。     

节温器开裂原因分析

通过断口分析、金相检验、腐蚀性能测定等方法对节温器壳体开裂的原因进行了分析。结果表明:节温器的开裂属于应力腐蚀开裂。引起应力腐蚀开裂的主要原因是节温器中作用于壳体内侧应力较高和含硫橡胶对黄铜壳体产生腐蚀。     

Analysis and Subsequent Testing of Cracked Brass Connector Housings

This paper details the examination of brass coaxial cable connectors which exhibited cracks in their outer housings. Failure analysis indicated a brittle failure due to stress corrosion cracking. Two common stress corrosion cracking tests for copper materials were conducted on new connectors from the same manufacturing lot. Failure of these connectors confirmed the observed fracture mode. This paper shows that failure analysis can involve testing to duplicate and confirm failure mode in addition to the requisite examination of failed components. This additional testing can be especially helpful in corrosion-related failures.     

H68黄铜弹壳开裂原因分析

通过化学成分分析、裂纹宏观和微观检验、显微硬度测试与微区成分能谱分析等方法,分析了H68黄铜弹壳开裂失效的原因。结果表明：材料本身存在冶金缺陷β相偏析与零件收口处退火不良是造成弹壳开裂失效的原因。     

Failure analysis of the brass tubes in a lubricating oil cooler

Failure analysis was carried out on leaked brass tubes of a lubricating oil cooler. Direct evidences of dezincification and stress corrosion cracking (SCC) were observed by scanning electron microscope (SEM) and energy dispersive spectroscopic (EDS) analysis. It is found that there are many small pits distributed on the fracture surface and EDS analysis revealed the occurrence of dezincification in the small pits. SCC was observed on the cross-sectional plane of the fracture by SEM. Ammonia test has proved the existence of residual stress in the as-received tubes. It is determined that the brass tubes have been suffered from the co-action between dezincification and SCC.     

Failure analysis of brass portions of dielectric unions

Persistent failures (leakage) were observed in the brass portion of dielectric unions after a relatively short service period. Metallographic examination revealed evidence of severe stress-corrosion cracking within the brass as well as dealloying on the surface. Evaluations using stress calculations and the dynamics of freezing water indicated that the unions were not overtightened during installation, and the water passing through the unions did not freeze. The subject copper alloy was shown to have been insufficient for the intended application due to high susceptibility to corrosion.     

绿色气相缓蚀剂的复配及其缓蚀性能研究

目的 为解决单组分绿色气相缓蚀剂缓蚀性能差的问题,复配一种绿色复合气相缓蚀剂,探究其对碳钢和黄铜金属试样的缓蚀作用。方法 采用腐蚀质量损失、接触角、电化学等试验测试分析复合气相缓蚀剂对碳钢、黄铜的缓蚀效果与成膜耐久性。结果 复合气相缓蚀剂对10号钢、H62黄铜的缓蚀效率分别为84.71%、91.67%,缓蚀性能显著优于单组分气相缓蚀剂;复合气相缓蚀剂在10号钢、H62黄铜表面均形成了缓蚀膜,H62黄铜表面形成的缓蚀膜较10号钢的更具耐久性。结论 与单组分气相缓蚀剂相比,该复合气相缓蚀剂对碳钢、黄铜均具备良好的缓蚀作用,为绿色气相缓蚀剂的防锈包装应用提供支撑。     

Stress corrosion cracking of leaded brass in a sulphuric acid environment

Free-cutting leaded brass is commonly used as sleeve fittings (also termed clamping ferrules) on polytetrafluoroethylene-lined flexible hoses for the filling and distribution of compressed gases, e.g., oxygen, nitrogen and carbon dioxide, for various industrial and medical applications. Some of the gas-filling and gas distribution facilities are located in the proximity of highly industrialized areas for the convenience of transportation, application and customer service. Therefore, the gas-filling and gas distribution gears are frequently exposed to the environment containing various chemical substances, which in the presence of ambient moisture and under the influence of mechanical and residual stresses in the material can effect an undesirable material degradation reaction. Stress corrosion cracking (SCC) has been identified to occur in C36000 Cu–Zn–Pb leaded brass ferrules under the synergistic reactions of a sulphuric acid production environment in a sustained tensile stress environment. The tensile stress was imparted to the material by the mechanical crimping process applied on the ferrules, and superimposed by cyclical high-pressure gas-cylinder-filling operations. The chemical species responsible for the SCC originated from the gaseous vapours and/or ionic derivatives of S-containing substances emitted from a neighbouring sulphuric acid production plant, which reacted with water and moisture condensates on the brass ferrule surfaces and effected the chemical corrosion reaction(s). SCC of the leaded brass ferrules gave rise to predominantly intergranular failures with fracture surfaces heavily decorated by corrosion products of various configurations. Most corrosion products were found to have embedded on the grain-boundary planes of the fracture surfaces, suggesting that grain-boundary short-circuit diffusion may have served as a viable mechanism for the SCC of C36000 leaded brass under the operating conditions of this case study.     

球罐应力腐蚀开裂研究与安全性分析

对球罐应力腐蚀开裂的原因和主要影响因素进行了分析.针对16MnR和SPV50Q球罐用钢,在分析湿硫化氢环境下应力腐蚀开裂形式的基础上,通过改进的WOL预裂纹试样的应力腐蚀开裂试验,对不同球罐用钢、不同硫化氢浓度、不同焊接状态条件下的应力腐蚀开裂进行了研究,并对设备的安全性能进行了分析,进而提出了防止应力腐蚀开裂的对策.     

陕西土壤模拟液中3种典型接地金属材料的腐蚀行为

为了弄清3种典型接地金属材料(H62黄铜、Q235钢、镀锌钢)在陕西土壤中的腐蚀情况,采用失重法(外加电流浸泡)、电化学测试、扫描电镜(SEM)和X射线衍射(XRD)研究了其在陕西中部土壤模拟液中的腐蚀行为和电化学规律。结果表明:在有外加电流的模拟液中浸泡,随浸泡时间延长,Q235钢腐蚀速率逐渐变慢,镀锌钢表面镀锌层腐蚀较快,H62黄铜的腐蚀速率变化不大;Q235钢、镀锌钢、H62黄铜的腐蚀产物分别主要为α-FeOOH、β-FeOOH、Fe3O4,ZnO、Zn(OH)2、FeOOH、Zn5(CO3)2(OH)6和Cu2O、CuO、CuCl2;在含相同NaCl浓度的模拟液中,H62黄铜的耐腐蚀性能最好,镀锌钢的次之,Q235钢的最差。