邻近强电线路时埋地管道交流腐蚀的可能性评估

强电线路与埋地管道共用一个走廊时管道上不可避免地产生次生交流干扰。当这一交流干扰电流密度达到一定极限后便会造成管道的交流腐蚀,危及管道设备乃至人身的安全。提出了管道上交流腐蚀的条件及控制指标的新观点,并对管道交流腐蚀的可能性进行评估。     

忠县-武汉输气管道遇到的交直流干扰及防护措施

忠武输气管道部分管段存在着高速公路及铁路的施工工地,其用电设备的接地系统对管道产生了严重的交流、直流干扰;该管道在部分地段还分别与多条强电线路交叉或平行,使管道有受强电冲击的危险,并在一些管段造成高于30 V的交流干扰。针对这些问题提出了通过排流器、电涌保护器、屏蔽线等保护管道的解决措施。     

PCCP供水管道高压线交流干扰及排流措施研究

本文针对PCCP高压线杂散电流交流干扰问题,探讨了杂散电流机理,针对国内某PCCP供水管道提出了相应的交流干扰检测和排流措施。通过对高压线交流干扰监测和有效排流,旨在提高PCCP管道的安全性和使用寿命,同时为相关类似工程提供有效参考。     

埋地管道交流杂散电流的危害与排流

根据埋地天然气管道受到的交流干扰情况,针对性的对长输埋地管道交流干扰及防御问题进行了探讨,参照国内外同行业的交流干扰防护做法,总结了一种新的排流处理方法,实施效果理想。重点阐述了交流干扰的来源,交流干扰的形式、危害,高压输电线路对埋地金属管道的影响及处理措施,并分析了各种排流方法在实际运用中的特点,为近似问题的解决处理提供参考。     

埋地管道交流干扰缓解技术研究现状

阐述了交流干扰缓解技术的发展状况,介绍了目前国内外常用的缓解措施及相关设备,并对交流干扰缓解技术未来发展方向进行了展望。     

苏南成品油管道交流杂散电流干扰检测及防护措施

以苏南成品油管道为研究对象,对交流杂散电流干扰进行测试,表明有5个管段存在明显的交流干扰。确定了各管段的交流杂散电流的干扰程度和干扰源,得到了不同杂散电流干扰源造成的交流干扰电压波动规律。对苏南成品油管道提出了交流干扰防护措施,并根据现场的模拟试验和计算,确定了排流地床参数。     

埋地管道交流干扰有效检测技术及风险评价方法最新研究进展

综述了交流干扰相关参数(如交流干扰电压、交流电流密度以及管道阴保电位)有效测试技术及交流干扰风险评价方法的最新研究成果,指出了目前交流干扰相关参数测试过程中存在的误区和交流干扰风险评价过程中应注意的问题,以期提高对交流干扰参数测试和交流干扰风险评价的认识,最后展望了该领域的发展趋势。     

固态去耦合器交流干扰缓解效果检测

某原油输送管道在交流干扰严重区段采用了固态去耦合器接地的交流干扰缓解措施。通过现场干扰程度调查与测试、防护效果检测评价、固态去耦合器运行参数测试等工作,获得了详细的现场数据,对固态去耦合器产品的性能与应用效果进行了评价总结,为埋地钢管交流干扰缓解工程的固态去耦合器的选型与应用提供参考。     

埋地钢质管道交流干扰测试与评价

高压交流输电线路及交流电气化铁路对与其临近铺设的埋地钢质管道会引起交流干扰,产生交流腐蚀,并对阴极保护系统的安全运行带来不利影响。因此,埋地钢质管道中交流干扰的检测与评估是必要的。国内外对于埋地金属管道受交流干扰的测试与分析,主要围绕交流干扰电压、交流电流密度、腐蚀速率等参数的测试来开展。在交流干扰及阴极保护有效性评价方面,国外以交流电流密度及交/直流电流密度比为主要参量。本工作通过对交流干扰下的管地电位信号时频特征研究,得出管地电位信号时频特征与交流干扰源频率存在一致性,为检测和判定埋地钢质管道上的交流干扰提供了一定的依据。     

埋地油气管道交流干扰腐蚀及防护研究进展

分析了交流干扰腐蚀的机理、特点和对埋地油气管道的不利的影响,介绍了国际上埋地管道交流干扰危险性新的分类标准和先进的交流干扰测试方法,阐述了国内外对存在交流干扰时阴极保护标准的研究现状,并提出了自己的见解.同时对国内外在埋地管道交流干扰腐蚀防护新技术和新方法上的研究进行了总结评述.基于国内外交流干扰腐蚀及防护的最新研究进...     

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).     

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.     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.