隔热油管连接处保温涂层的制备与隔热性能

针对辽河油田稠油开采中隔热油管连接处热损失严重的问题,制备了隔热涂层。采用IMDRG01仪器测试了隔热涂层的外表面温度,采用自制的仪器测试了其导热系数;对涂料的组成、涂层厚度与结构等对涂层隔热性能的影响进行了研究。结果表明:当涂层厚度为4 cm,隔热油管内部温度为350℃时,涂层外表面的温度为46℃;隔热涂料中添加真空球形粒子可有效提高涂层的隔热性能;珍珠岩的添加可在一定程度上提升涂层的隔热性能。辽河油田稠油热采注汽温较高,更适合采用含纤维与不含纤维的复合隔热保温涂料涂层。     

火灾下平行钢丝束温度膨胀及高温蠕变试验研究

采用非接触式应变视频测量系统,对常用于实际工程的1670级平行钢丝束进行了15个温度水平下的温度膨胀试验以及多应力水平下的高温蠕变试验,并对历经2 h高温蠕变试验后冷却至室温的平行钢丝束试件进行了抗拉强度测试,获取了平行钢丝束热膨胀应变历程及高温蠕变应变历程曲线。试验结果表明:平行钢丝束热膨胀应变随着温度升高呈非线性增长,且在750 ℃附近材料微结构发生相变;温度和应力水平对高温蠕变历程均会产生显著影响;蠕变试验温度愈高,应力水平对历经高温后平行钢丝束的剩余抗拉强度的影响愈显著;与1860级预应力钢绞线相比,1670级平行钢丝束具有较小的高温蠕变应变。基于试验数据,建议了平行钢丝束热膨胀系数关于温度的函数式及高温蠕变模型。该文所建议的平行钢丝束热膨胀系数及高温蠕变模型有利于预应力钢结构火灾高温下的力学响应分析。     

粘弹性流体法向力作用下的抽油杆柱横向振动仿真

聚合物抽油机井抽油杆柱在粘弹性流体井筒内偏心运动时，抽油杆柱受到交变粘弹性流体法向力的作用。该文指出了交变粘弹性流体法向力是抽油杆柱横向振动的激励。考虑抽油杆柱所受粘弹性流体法向力与抽油杆柱横向振动位移的耦合关系，建立了受粘弹性流体法向力作用的抽油杆柱在油管内横向振动仿真的力学和数学模型。采用有限差分法和Newmark法实现了对抽油杆柱在油管内横向振动的仿真计算。分析了抽油杆柱在初始偏心和粘弹性流体法向力激励下的横向振动规律。仿真结果表明:抽油杆柱的任何初始偏心都会导致在全井范围内发生杆管碰撞现象；抽油杆柱下冲程杆管碰撞更为剧烈，且泵端附近碰撞力最大；由于粘弹性流体法向力的存在，杆柱与油管壁的接触碰撞更加频繁，加剧了杆管偏磨。所建立的粘弹性流体法向力作用下的抽油杆柱横向振动仿真模型对于聚驱井杆管偏磨分析、扶正器的优化配置具有指导作用。     

Microstructure in the weld region in seam welded and resistance welded Zircaloy 4 tubing

The microstructure of tungsten inert gas (TIG)-arc welding and resistance welding in Zircaloy 4 tubing is described in relation to the phases present. Differences in microstructure between the weld zone and base tubing are discussed in terms of the phase transformations that take place during the very different thermal cycles occurring in both processes and a comparison between them is made. A feature of the weld region is the presence of a coarse grained Widmanstätten structure in the TIG welding while a martensitic-type structure or very fine Widmanstätten structure is present in resistance welding.     

73．0mm EUJ55油管短节断裂原因分析

对断裂油管短节和新油管短节材质进行了对比试验,并对所用吊卡和油管接箍主要配合尺寸进行了测量和分析,发现吊卡磨损之后承载面孔径变大,油管接箍承载面本身偏小。根据尺寸测量结果,推断出了油管断裂时与吊卡的非正常配合状态。对油管断裂时的受力状态分析结果认为油管短节失效过程为：接箍一侧承载面滑入磨损的吊卡承载面内孔里边,管体倾斜与吊卡上活门体下端面内圆弧棱相撞产生裂纹和变形,最后在偏斜拉伸和冲击载荷共同作用下断裂。     

预应力钢绞线温度膨胀及高温蠕变性能试验研究

火灾高温下钢绞线的温度膨胀及高温蠕变性能是影响张拉钢结构抗火能力的重要因素。该文以1860级预应力钢绞线为研究对象,采用非接触式应变视频测量系统,测试了钢绞线在15个温度水平下的热膨胀应变,得到热膨胀应变随温度的变化规律,并拟合出热膨胀系数计算公式。研究发现,大约750℃时钢绞线材料发生相变,导致热膨胀应变突变。通过钢绞线在不同温度及应力水平下的高温蠕变试验,得到蠕变应变与时间的关系曲线,并建议了钢绞线高温蠕变计算公式。高温蠕变试验现象表明,在较高温度及应力水平时,蠕变会导致钢绞线断裂;对经2 h高温蠕变未断裂的钢绞线自然冷却到常温后,进行抗拉强度试验,发现其抗拉强度有一定程度的退化,且经历的蠕变温度越高,应力水平对高温蠕变后试件抗拉强度的退化影响越明显。     

TEM study of the FSW nugget in AA2195-T81

During friction stir welding (FSW) the material being joined is subjected to a thermal-mechanical process in which the temperature, strain and strain rates are not completely understood. To produce a defect free weld, process parameters for the weld and tool pin design must be chosen carefully. The ability to select the weld parameters based on the thermal processing requirements of the material, would allow optimization of mechanical properties in the weld region. In this study, an attempt is made to correlate the microstructure with the variation in thermal history the material experiences during the FSW process.     

Zum Einfluss des Schweißens auf das Kriechverhalten moderner Stähle für die thermische Energieerzeugung

The influence of welding on creep behaviour of modern steels for thermal power generation Un‐ and low alloyed ferritic/bainitic Chromium steels as well as high alloyed ferritic/martensitic 9–12 % Chromium steels are widely used for high temperature components in thermal power generation. Welding in all its variety is the major repair and joining technology for such components. The weld thermal cycle has significant influence on the base material microstructure and its properties. The Heat Affected Zone is often regarded as the weakest link during high temperature service. While weldments of un‐ and low alloyed ferritic Chromium steels can show significant susceptibility to Reheat Cracking in the coarse grained heat affected zone, weldments of high alloyed ferritic Chromium steels generally fail by Type IV Cracking in the fine grained heat affected zone during long term service. In this paper the influence of the weld thermal cycle on the base material microstructure is described. Long‐term creep behaviour of weldments is directly related to the main failure mechanisms in creep exposed ferritic weldments and implications for industries using heat resistant ferritic steels are shown.     

某井油管腐蚀原因分析

对某井油管检查发现,管体内外壁均有不同程度的腐蚀,但是在某些井段腐蚀最严重。对油管管体的化学成分分析、金相显微组织检测和SEM,EDS及XRD的分析结果表明:管体具有正常的化学成分和金相组织,腐蚀坑底部有大量的腐蚀产物堆积,Cl-在腐蚀产物层下富集。油管内壁产物为FeCO3,MgFe(CO3)2,FeO(OH),Mg3Ca(CO3)4和Fe3O4,外壁产物主要有FeCO3,MgFe(CO3)2,CaCO3和FeO(OH)。表明该井油管内壁腐蚀原因为CO2腐蚀,内壁腐蚀穿孔后,腐蚀性的介质和气体由此进入套管和油管的环空造成油管外壁CO2腐蚀。井深3279m处油管处于CO2腐蚀速率最大的温度区间,腐蚀最严重。Cl-的富集是诱发局部腐蚀的主要原因。     

Simulation of microstructure and liquation cracking in 7017 aluminium alloy

Welding in a 7000 series aluminium alloy can lead to the development of a white zone microstructure and liquation cracking in the heat affected zone adjacent to the fusion boundary. A Gleeble 1500 thermomechanical system has been used to study the conditions associated with damage development. A range of simulations has been carried out covering thermal and thermomechanical conditions typically encountered during weld manufacture. Results show that both the white zone microstructure and liquation cracking can be simulated at a sufficient scale to permit full characterisation in laboratory testpieces. Data analysis has defined and mapped the stress and temperature conditions leading to crack initiation. This evaluation demonstrates that the susceptibility for cracking is minimised by increasing the cooling rate following weld manufacture.     

组合油管对水平井修井管柱下入能力的影响研究

针对修井管柱在大水垂比、长水平段水平井下入困难的问题,采用修井管柱2种规格油管组合下入作业的方式,开展了不同油管长度比例对修井管柱下入能力影响的研究。基于水平井井眼轨迹的特点,综合考虑修井管柱在各井段的受力情况,建立了修井管柱在水平井垂直段、造斜段和水平段下入过程中的载荷计算模型,应用插值法、迭代法及分段判别计算法实现了模型的求解,并编制了相应的计算软件。基于现场数据进行了修井管柱下入能力的实例研究,结果表明：相较于修井管柱主体为单一线重油管和其他不同长度比例的2-7/8和3-1/2两种线重组合油管,组合油管中线重较大的3-1/2油管下入到井斜角为56.3°左右的井深时修井管柱的下入能力最佳。研究结果可为油田水平井修井管柱的安全下入提供指导。     

C和W对低合金Cr-Mo钢焊缝金属组织和冲击韧性的影响

使用OM、SEM、EPMA、EBSD等手段并进行热膨胀和冲击等实验,研究了C和W元素对第四代钠冷快堆用低合金Cr-Mo钢钨极氩弧焊(TIG)熔敷金属微观组织和冲击韧性的影响.结果 表明:多道次焊接热循环使多层多道焊缝金属的组织分布不均匀,分为表层焊缝组织和中间焊缝组织.表层焊缝组织,可分为熔化区(MZ)、粗晶区(CGH...     

Corrosion failure analysis of high strength grade super 13Cr-110 tubing string

The main reasons for corrosion failure of super 13Cr-110 tubing and couplings have been proposed based on the analysis techniques of Optical Microscopy (OM), Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS) and X-ray Diffraction (XRD). The results show that the composition, structure and mechanical properties of the tubing and the coupling were all in accordance with the corresponding parameter requirements of API Spec 5CT standards. Furthermore, corrosion occurring in the inner wall of joint was caused by the combined impacts of CO₂ corrosion, acid corrosion, erosion corrosion, and crevice corrosion, meanwhile, the synergistic effects of crevice corrosion, and sulfate-reducing bacteria (SRB) corrosion resulted in corrosion occurring in the outer wall of the tubing and the coupling. Finally, to check the quality of the tubing string before well completion, increase torque, install a centralizer, and add bactericide and inhibitor were advised to prevent the types of corrosion failure from taking place.     

Effect of post-weld aging treatment on mechanical properties of Tungsten Inert Gas welded low thickness 7075 aluminium alloy joints

This paper reports the influence of post-weld aging treatment on the microstructure, tensile strength, hardness and Charpy impact energy of weld joints low thickness 7075 T6 aluminium alloy welded by Tungsten Inert Gas (TIG). Hot cracking occurs in aluminium welds when high levels of thermal stress and solidification shrinkage are present while the weld is undergoing various degrees of solidification. Weld fusion zones typically exhibit microstructure modifications because of the thermal conditions during weld metal solidification. This often results in low weld mechanical properties and low resistance to hot cracking. It has been observed that the mechanical properties are very sensitive to microstructure of weld metal. Simple post-weld aging treatment at 140 °C applied to the joints is found to be beneficial to enhance the mechanical properties of the welded joints. Correlations between microstructures and mechanical properties were discussed.     

石油储罐钢焊接热影响区模拟研究

采用焊接热模拟技术,研究不同焊接热输入条件下焊接热循环对石油储罐钢焊接热影响区粗晶区(CGHAZ)的组织和性能的影响.结果表明:实验钢在80～100kJ/cm的大热输入下,热影响区仍能够保持良好的低温韧性;随着焊接热输入的增加,实验钢CGHAZ组织变粗大,低温冲击功下降;钢中弥散分布着大量细小TiN粒子,在焊接热循环中...     

Effect of welding wire and groove angle on mechanical properties of high strength steel welded joints

Mechanical properties of high strength steel welded joints strictly depend on the welding process, the filler material composition and the welding geometry. This study investigates the effects of using cored and solid welding wires and implementing various groove angles on the mechanical performance of weld joints which were fabricated employing the gas metal arc welding process. It was found that weld joints of low alloy, high strength steels using low alloy steel cored welding wires exhibited higher tensile strength than that of low alloy steel solid wire and chromium‐nickel steel bare welding wire when the method of gas metal arc welding is employed. The effect of groove angle on the strength and toughness of V‐groove and double V‐groove butt‐joints was investigated. V‐groove joints, with higher tensile strength than double V‐groove joints in the whole range of groove angles, were superior in toughness for small groove angles, but impact toughness values of both joints were comparable for large angles. The effect of heat input and cooling rate on the weld microstructure and weld strength was also investigated by performing thermal analysis employing the commercial software ANSYS. It was concluded that cooling rate and solidification growth rate determined the microstructure of the weld zone which had great consequences in regard to mechanical properties.     

U75V轨道钢线性摩擦焊工艺研究

目的 提高及改善目前轨道连接与修复的质量。方法 采用线性摩擦焊（LFW）的方法,对高碳轨道钢（U71Mn）在不同参数下进行了焊接试验,并对其微观组织和力学性能进行了表征。结果 焊接参数对接头质量起着决定性的作用。根据焊后接头的微观组织差异,可将其分为4个部分：焊缝中心区（WCZ）、热力影响区（TMAZ）、热影响区（HAZ）和母材（BM）。BM为珠光体和上贝氏体的混合组织,TMAZ由珠光体和少量马氏体组成。在WCZ中,由于受到的热力耦合作用的增强和更高的冷却速率,该区域马氏体含量进一步增加。在拉伸试验中,所有试样均在WCZ处发生断裂,接头的最大抗拉强度达到BM强度的86.6%。此外,WCZ中存在大量马氏体,在增加焊缝显微硬度的同时也降低了焊缝的冲击韧性。结论 采用LFW的方法可以得到焊接质量优良的轨道钢接头。     

Microstructure characterization and properties of carbon steel to stainless steel dissimilar metal joint made by friction welding

Dissimilar metals of 1045 carbon steel and 304 stainless steel are joined successfully by friction welding. The microstructure variation and mechanical properties are studied in detail. The weld interface can be clearly identified in central zone, while the two metals interlock with each other by the mechanical mixing in peripheral zone. On carbon steel side, a thin proeutectoid ferrite layer forms along weld interface. On stainless steel side, austenite grains are refined to submicron scale. The δ-ferrite existing in stainless steel decreases from base metal to weld interface and disappears near the weld interface. Severe plastic deformation plays a predominant role in rapid dissolution of δ-ferrite compared with the high temperature. Carbide layer consisting of CrC and Cr₂₃C₆ forms at weld interface because of element diffusion. Metastable phase CrC is retained at room temperature due to the highly non-equilibrium process and high cooling rate in friction welding. The fracture appearance shows dimple fracture mode in central zone and quasi-cleavage fracture mode in peripheral zone. Further analysis indicates that welding parameters govern tensile properties of the joint through influencing the thickness of carbide layer at weld interface and heterogeneous microstructure in thermo-mechanically affected zone on carbon steel side.     

高压气井完井管柱系统的轴向流固耦合振动研究

目前针对石油完井管柱的研究没有考虑瞬变流诱发的管柱运动,而实际的管柱与管内流体存在相互影响、相互作用。对完井管柱系统流固耦合振动响应进行了初步分析与探索,给出了适用于气井完井管柱流固耦合分析的数学模型,提供了采用特征线法对耦合模型进行解耦以及采用插值方法进行数值求解的具体过程,并以现场数据为例,预测分析了天然气不稳定流动引起的流体压力、管柱应力、管柱振动速度的耦合响应过程。研究结果表明：天然气不稳定流动使管柱处于交变应力状态,并诱发管柱往复运动,这将加剧完井管柱结构的疲劳破坏与磨损破坏。该结果对预防完井管柱先期实效有实际工程意义     

Residual stress driven cracking in superalloy weldments

Superalloy weldments are normally given post weld heat treatments to homogenize the weld metal microstructure, relieve residual stress, and precipitate strengthening phases. The relationship between microstructure and post weld heat treatment is easily studied; it is less straightforward to study the effects of post weld heat treatment on residual stress relaxation. Using a self-restrained testing procedure, a relatively simple approach was used to investigate the effects of microstructure and post-weld heat treatment on cracking during residual stress relaxation. Candidate superalloys for Advanced Ultra Supercritical steam plants were studied. It was found that cracking due to residual stress relaxation is primarily dependent on grain size, and in cases of intermediate grain size, intragranular precipitation is a controlling factor. These results are in agreement with traditional stress relaxation cracking theories.