混输高矿化度气田水集输管道绝缘接头附近非保护端管线内腐蚀分析及解决方案

集输管道外防腐多采用防腐层外加强制电流阴极保护或牺牲阳极保护。但实际使用中发现,由于管道内存在矿化度高的导电介质,导致了对绝缘接头附近非保护端管线严重内腐蚀。本文针对四川某含高矿化度气田水气藏阴极保护绝缘接头附近非保护端管线内腐蚀现状,分析了内腐蚀原因;提出了初步解决方案:将绝缘接头改为地面竖直安装;对绝缘接头非保护端加强测厚监测(以便对有问题的管段及时更换);对符合条件的采用绝缘接头跨接等。     

卤水管道绝缘接头整改方案探讨

输送卤水的管道经常发生绝缘接头非保护侧管道内腐蚀穿孔事故,本文根据某采输卤管道绝缘接头非保护侧经常腐蚀泄漏的具体情况,论证了将绝缘接头更换为绝缘短管以及将绝缘接头跨接两种方案对于减缓绝缘接头非保护侧管道腐蚀泄漏的可行性。     

低温过热器受热面管焊接接头断裂失效分析

过热器是提高发电锅炉循环热效率的关键部件,其部件一旦失效会造成巨大的经济损失。通过力学性能测试、微观形貌及成分能谱分析、 X射线衍射物相分析及金相分析等方法,对ASH低温过热器受热面管焊接接头的断裂原因进行了分析。结果表明:该焊接接头的断裂形式为高温疲劳和应力腐蚀共同作用后的断裂,应力腐蚀所产生的点蚀是造成裂纹启裂的原因,断口形貌具有碱性断裂的特征,同时结合锅炉水pH值8.57和腐蚀产物分析,该断口为碱性腐蚀断裂。采用有限元分析软件ABAQUS对受热面管在运行过程中的应力分布进行了模拟,验证了其在运行过程中焊接接头位置应力集中的存在。为了防止碱脆断裂,应对锅炉用水进行充分软化处理,同时管道焊接应控制焊缝成形,提高焊接质量,焊后进行去应力退火处理。     

TC4钛合金耳片断裂原因分析

分析了由TC4钛合金材料制造的飞机减速板接头耳片在使用中发生断裂的故障。作动筒通过螺杆与该减速板接头耳片相连接并驱动减速板工作。通过对断裂件进行外观检查,断口宏、微观观察、能谱分析,金相组织检验等手段,确定了减速板接头耳片的断裂性质及失效原因。结果表明:该减速板接头耳片的断裂性质为疲劳断裂,其断裂源是由耳片内孔与连接螺杆之间接触所产生的微动磨损引发的;产生微动磨损的原因是由于耳片与连接作动筒的螺杆之间配合间隙不当和润滑不良所致。     

焊接电压对绝缘铜线微电阻热压焊接头的影响

采用微电阻热压焊工艺来焊接耐高温微细绝缘铜线,研究了不同焊接电压下接头的外观形貌、截面微观组织、拉断力和形成过程. 结果表明,当焊接时间为20 ms、电极压力为12 N、焊接电压大于2.05 V时,该工艺可在一个输出脉冲内完成绝缘铜线的除漆和焊接,无需预先除漆. 随着焊接电压的增加,接头长度基本不发生变化,接头宽度和拉断力一直增大;接头失效形式依次表现为界面剥离、前端断裂和中部断裂. 接头的演变过程包括预压塑性变形、接头弱连接、热辅助下的压陷、接头强连接和熔融金属挤出5个阶段.     

化工管道用超低碳微合金管线钢焊接接头的微观组织和冲击性能研究

采用光学显微镜、扫描电子显微镜、透射电镜和冲击试验机对化工管道用超低碳微合金管线钢焊接接头的微观组织和冲击性能进行研究。结果表明,超低碳微合金管线钢焊接接头焊缝区和热影响区的显微组织明显不同,且与母材的微观组织也存在差异。在温度为-10℃时,超低碳微合金管线钢焊接接头的冲击功为177 J,断裂方式为韧性断裂。     

一种改进的绝缘接头防爆测试箱

油气管道中所用的绝缘接头是管网的薄弱环节,绝缘接头防爆测试箱质量好坏对绝缘接头的检测及运行有重要影响,本文针对测试箱存在的经常打开带来的密封不良、接线腐蚀等缺陷,从石油天然气行业安全角度出发,提出了一种改进的绝缘接头防爆测试箱。通过改造,绝缘接头防爆测试箱可以在不打开测试箱的情况下完成绝缘接头的测试,改善了测试箱容易腐蚀生锈,接触不良故障,同时有效提高测试效率,保证绝缘接头运行安全。     

漏电导致阴极保护绝缘接头内腐蚀失效的有限元分析

对漏电导致阴极保护绝缘接头内腐蚀失效问题,建立了绝缘接头有限元计算模型,开展了绝缘接头漏电电流密度大小与分布数值计算,并讨论了管道绝缘接头两侧电位差,输送介质电阻率和绝缘接头内涂层缺陷对绝缘接头漏电电流密度大小与分布的影响规律.模拟计算结果与油田现场失效绝缘接头内腐蚀现象一致,并给出了相应的防护建议.     

含工艺缺陷PE管道热熔焊接接头力学性能测试分析

通过拉伸和冲击试验对聚乙烯(PE)管道的拉伸性能及冲击性能进行分析,利用环境电子显微镜对断口进行微观分析。结果表明,拉伸性能的整体趋势相似,得出5种拉伸-位移曲线类型,对应5种断裂形式;不同工艺参数下热熔接头的冲击强度和冲击韧性整体都比正常接头低,呈先上升后降低的趋势。并通过扫描电镜观察总结出4种典型的断口形貌,对含工艺缺陷PE燃气管道热熔接头的力学性能进行全面评价。     

600MPa级高Al冷轧双相钢点焊接头断裂方式

通过拉伸剪切试验以及对拉剪断口的微观组织和扫描电镜分析,研究了高Al冷轧双相钢点焊接头的断裂方式,并分析了接头断裂方式对接头力学性能的影响规律.研究结果表明,高A1冷轧双相钢的点焊接头主要有3种断裂方式,即:母材撕裂的焊点拔出、沿熔核边界的焊点拔出及界面断裂.3种不同的断裂方式分别代表了3种不同的裂纹萌生和扩展方式.此...     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。