BG-SG特殊螺纹接头结构参数对密封性能的影响

BG-SG特殊螺纹接头是一种针对国内页岩气井专门开发的特殊螺纹接头形式,主要由锥面/锥面主密封结构、直角扭矩台肩结构和双段式螺纹连接部分组成,具有高连接强度、高抗扭等优点,适用于大狗腿度下的复杂井况。基于控制变量法的思想,运用有限元数值仿真计算方法分别研究了密封面过盈量(δ)、密封面长度(l)和密封面锥度(ΔD/L)等三个结构参数对接头密封接触压力分布和密封性能的影响。分析结果表明,δ的增大对接头密封性能有正面影响,但过大的过盈量并不能持续增加有效接触长度,且需控制其值不致引起接头结构的塑性变形或黏结;增加l值,可一定程度上增加密封面的有效接触长度,但超过某个特定长度以后则会在密封面中部产生零接触应力区域;ΔD/L对密封面两侧接触点附近的影响有所不同。根据分析结果优化设计了各结构参数,所开发接头顺利通过实物性能试验,验证了有限元分析的有效性。     

计算石油套管特殊螺纹接头e_m值的一种新方法

介绍了API标准中关于石油套管螺纹接头em的计算公式。基于此理念,引导出计算石油套管特殊螺纹接头em值的计算公式,并给予解析说明。应用计算机机械制图法,详细给出了计算em的简单、便捷的一种新方法。该特殊螺纹接头值em的计算求法适用于石油套管行业特殊螺纹接头的生产应用,可供参考使用。     

特殊螺纹接头上扣过程仿真分析

在试验和有限元分析的基础上,介绍了特殊螺纹接头上扣扭矩曲线与接头结构的关系,并完成了宝钢BGT2系列196.85×12.7 mm BG140V BGT2套管气密封特殊螺纹接头的上扣过程的模拟。参照ISO13679(2002)标准要求,针对不同的几何尺寸组合分别建立有限元模型,并分析其上扣过程扭矩曲线变化,探讨了不同尺寸参数对扭矩曲线形状的影响;同时利用有限元模型计算了该规格产品的屈服扭矩和上扣过程接触力变化。通过与实物试验的对比,验证了该分析结果的可靠性,从而为产品开发和使用提供指导。     

螺纹牙形对特殊螺纹接头弯曲性能的影响

为分析特殊螺纹接头弯曲性能,采用有限元方法,对比正角度螺纹、负角度螺纹和齿侧过盈螺纹3种牙形对特殊螺纹接头密封面上密封性能的影响。有限元分析结果表明,负角度螺纹可以提高拉伸性能,而齿侧过盈螺纹有利于提高压缩性能。综合来看,齿侧过盈螺纹有利于弯曲性能。这些结果可为抗弯曲特殊螺纹接头设计提供参考。     

圆螺纹套管的滑脱机理研究

连接接头滑脱失效是圆螺纹套管损坏的主要形式。利用弹塑性有限元法,研究了圆螺纹套管接头发生滑脱失效的过程与机理,然后通过全尺寸试验,分析了这种接头在失效过程中的应变分布及变形情况,并验证了有限元结果。研究表明,圆螺纹套管滑脱失效最先发生在啮合大端的第1、2牙螺纹上,设法提高此处螺纹的承载能力,对提高圆螺纹套管的连接强度具有重要意义。     

API圆螺纹套管接头上卸扣力学性能实验研究

为了深入了解上卸扣工况对套管接头力学性能的影响,给研究套管接头产生粘扣的力学因素提供实验依据,采用在套管接 头内外表面巾应变片的方法,利用全尺寸上卸扣试验机,对套管接头进行了重复上卸扣实验,测量了接头内外表面应变和上卸扣扭矩。通过实验结果分析,确定了影响接头粘扣的主要力学条件和部件,所确定部件与实际操作过程发生粘扣部件相吻合,采用增大接箍螺纹端部锥度,降低端部接触压力的方法,提高了套管的抗粘扣性能     

锥面密封油套管特殊螺纹接头密封面过盈量计算

根据厚壁圆筒的弹性力学原理,对油套管锥面密封形式特殊螺纹接头的密封面过盈量设计进行了理论推导,根据第四强度理论,在保证密封面不屈服的条件下,得出密封面理论最大过盈量.利用得到的公式对密封结构参数进行了计算分析,结果表明,密封面角取10°～30°、台肩角取5 °～20°,为接头设计的理想范围.对实际加工接头进行标准试验,对比试验值与计算值,发现实际过盈量为计算最大过盈量的0.7～0.9倍,研究成果为接头密封面设计提供了理论依据.     

API偏梯形套管螺纹接头在上扣与轴向载荷下的有限元分析

针对深井和大位移井中套管存在很大轴向拉伸和压缩载荷的情况,对API偏梯螺纹接头进行有限元分析计算,得出了在不同载荷作用下螺纹接触应力的分布。     

API圆螺纹油管接头连接性能的非线性有限元分析

ＡＰＩ圆螺纹油管在油田有着广泛的应用，在使用过程中，发现油管接头有粘扣甚至滑脱现象。为了探讨ＡＰＩ圆螺纹接头粘扣和滑脱的机理，改善螺纹接头的连接性能，对螺纹接头在机紧过盈，轴向拉伸载荷作用下进行计算机仿真的非线性有限元分析。分析结果表明，啮合螺纹接触应力过高造成螺纹粘扣；管体螺纹接头部分强度刚度较低限制了螺纹接头的连接强度。     

API偏梯形套管螺纹连接的接触应力场研究

随着油气田勘探开发向纵深发展 ,对偏梯形螺纹套管的需求量越来越大 ,深入研究此种套管螺纹连接力学性能显得非常重要。在分析套管螺纹粘扣机理的基础上 ,建立了 API J5 5194 .1m m× 8.33mm偏梯形套管螺纹连接的非线性接触模型 ;研究了此种套管接头在上紧扭矩、拉应力、压应力以及摩擦力等不同载荷作用下内外螺纹接触应力的分布状态 ;同时对内外螺纹锥度的极限配合情况进行了数值模拟 ,并就摩擦因素和锥度对偏梯形螺纹连接应力场分布的影响进行了总结。     

G105反扣钻杆胀扣失效分析

G105反扣直在油田使用过程中发生胀扣失效,为寻找胀扣失效的原因,首先分析了钻杆在服役过程中的载荷情况,然后通过计算机工况仿真得到了钻杆在不同载荷条件下的失效形式,说明钻杆胀和主要是由于工作扭矩超过了钻杆工具接头应有的实际抗扭屈服能力造成的。     

An Assessment of the Machinability of Iron‐Rich Iron‐Aluminium Alloys

Iron‐Aluminium‐Alloys show high potential as a material for automotive and aerospace applications due to their combination of properties. In comparison with other iron‐based alloys the lower density and good mechanical properties lead to a higher specific strength, which makes them interesting for lightweight applications. These alloys also have a good to outstanding resistance to oxidation and sulfidation. Nevertheless their use is restricted because of limited knowledge regarding the machining of these materials. New tool and cutting technologies have to be developed to counteract this situation. For example, a successful industrial introduction of a 10 wt% Al iron‐aluminium alloy would require a cutting tool lifetime 10 to 100 times higher than the currently achievable. For this purpose, the characteristic wear effects at the cutting edge have to be understood and the alternating changes of chip formation by constant process parameters have to be explained. Reasons and remedies are discussed.     

Influence of Tool Offsetting on the Structure and Morphology of Dissimilar Aluminum to Copper Friction-Stir Welds

In this work, a systematic analysis of the effect of tool offsetting on the morphological, structural, and mechanical properties of 6082-T6 aluminum to copper-DHP friction-stir welds was performed, enabling full understanding of Al-Cu bonding structure and failure mechanisms. Important relations between tool positioning and the thermomechanical phenomena taking place during welding were established. Tool offsetting was revealed to be an effective way of solving one of the most important concerns in Al/Cu friction-stir welding, i.e., the formation of large amounts of intermetallic-rich structures, which deeply influence the final strength and surface morphology of the welds. Actually, for welds produced without tool offsetting, it was found that the formation of fluidized intermetallic-rich structures promote the formation of internal decohesion areas inside the nugget, which have a detrimental effect on weld strength. For welds carried out with tool offsetting, intermetallic formation is almost suppressed, but important metallurgical discontinuities in the vicinity of large copper fragments, dispersed over the nugget, and at the nugget/copper interface were also found to have a detrimental effect on weld strength.     

The Effects of Borides on the Mechanical Properties of TLPB Repaired Inconel 738 Superalloy

The transient liquid phase diffusion bonding (TLPB) method was used to repair an artificial crack in Inconel 738, which was notched by a femtosecond laser. Mixed ratios of BNi-1a:DF-4B were investigated at the bonding temperature of 1373 K (1100 °C) for 2 to 36 hours. The effect of borides on the mechanical properties of TLPB repaired joints was studied through analysis of the microstructure, fracture path, and morphology observations. The borides formation, morphology, distribution, and joints strength were studied in detail. The results showed that the diffusion of B can either increase or decrease the joint strength, depending on its distribution and morphology. The amount of large blocky Ni-B compounds in the precipitate zone were reduced with increasing holding time, which resulted in an increase in joint strength. Nevertheless, further increasing the holding time led to a decrease in joint strength because of the formation of continuous acicular borides in the diffusion-affected zone. The fracture modes of TLPB joints were also discussed on the basis of the microstructure and fractography.     

球罐用BP460钢板及焊接接头断裂韧性试验研究

宝山钢铁(集团)公司为了满足宝钢三期工程贮氧球罐的需要,自行研制新的高强度压力容器用钢板.经过大量的试验研究工作之后,决定采用正火 回火的工艺路线,按照德国DIN EN10028—92标准生产球罐用BP460钢板.本文对宝钢生产的46mm厚BP460钢板(宝钢命名为BP460)、焊接接头及焊后热处理的钢板进行全面力学性能试验,以便根据试验结果对钢板性能进行综合评价.     

Cavitation erosion behavior of CLAM steel weld joint in liquid lead-bismuth eutectic alloy

The cavitation erosion of weld joint and base metal of China low activation martensitic(CLAM)steel in liquid lead-bismuth eutectic alloy(LBE)at 550°C was investigated to simulate the cavitation erosion of the first wall and the nuclear main pump impeller in the accelerator driven sub-critical system(ADS).A suit of ultrasonic cavitation facility was self-designed to study the cavitation erosion.By studying the surface micro topography,roughness and mean pit depth of the tested specimens,it was found that some crater clusters and large scale cracks appeared on the tested specimen surface after the formation of numerous single craters,and the base metal exhibited much better cavitation erosion resistance than the weld bead due to the difference in their mechanical properties and microstructures.In addition,by comparing the results of static corrosion and cavitation erosion,it could be concluded that the cavitation erosion and the dissolution and oxidation corrosion in liquid LBE would accelerate mutually.     

An Assessment of Vacuum‐Heat‐Treated H11 Hot‐Work Tool Steel using the KIc/HRc Ratio

Charpy V‐notch (CVN) impact‐test values are widely used in toughness specifications for AISI H11 hot‐work tool steel, even though the fracturing energy is not directly related to the tool design. K_Ic, the plain‐strain stress‐intensity factor at the onset of unstable crack growth, can be related to the tool design; however, K_Ic test values are not widely used in toughness specifications. This is surprising since to the designer K_Ic values are more useful than CVN values because the design calculations for tools and dies of high‐strength steels should take into account the strength and the toughness of materials in order to prevent the possibility of rapid and brittle fracture. An investigation was conducted to determine whether standardized fracture‐toughness testing (ASTM E399‐90), which is difficult to perform reliably for hard materials with a low ductility, could be replaced with a so far non‐standard testing method. A particular problem is that the manufacture of the fatigue crack samples is difficult and expensive, and this has promoted the search for alternative fracture‐toughness testing methods. One of the most promising methods is the use of circumferentially notched and fatigue‐precracked tensile specimens. With this technique the fatigue crack in the specimen is obtained without affecting the fracture toughness of the steel, if it is obtained in soft annealed steel, i.e., prior to the final heat treatment. The results of this investigation have shown that using the proposed method it was possible to draw, for the normally used range of working hardness, combined tempering diagrams (Rockwell‐C hardness ‐ Fracture toughness K_Ic ‐ Tempering temperature) for some AISI H11 hot‐work tool steel delivered from three steel plants. On the basis of the combined tempering charts the influence of the processing route on the mechanical properties was investigated. In the same way, vacuum‐heat‐treated tool steels were assessed and their properties expressed as a ratio of the fracture toughness to the hardness (K_Ic/HRc).     

Strengthening and Toughening Effect of Yttrium on Al2O3/TiCN Ceramic Tool Material

Modern ceramic cutting tool materials with their excellent physical, mechanical properties and cutting performances promote greatly the development of metal cutting technology.Therefore, they are one of the most promising cutting tool materials in the coming Zlst century["'l. however, the intrinsic brittleness is a fatal weakness for ceramic tool materials. In order to reduce the brittleness and to increase the strength and the fracture toughness of the cutting tool materials, various research…     

Influences of Manufacturing-Related Microstructural Variations on Fatigue in Carbide-Rich Tool Steels

In cold-work applications, tool steels with high carbide contents are used as cutting and stamping tools. The tool service life is limited by wear resistance and fatigue strength. The relationship between manufacturing-related microstructural influences and fatigue strengths of tool steels has not yet been adequately investigated. To investigate these influences on high-cycle fatigue (HCF) strength (N_G = 10⁷), rotating bending tests are performed on AISI D2 and AISI M2/M3. Raw materials are produced by conventional ingot casting and subsequent hot working (HW) as well as in a powder metallurgy (PM) process with hot isostatic pressing (HIP) and forging. Herein, a statistically validated correlation of process-related defect size and the resulting fatigue strength is presented. Both PM steels show significantly higher HCF strength than the HW steels. Critical defects in PM appear to be exclusively small oxide inclusions. In contrast, fatigue cracks in HW are typically initiated by the fracture of large, blocky eutectic carbides. The main factor influencing HCF strength is defect size. Other critical features of the microstructure include matrix hardness, circularity, and defect type. Improvements in fatigue strength can be obtained by reducing the size of fracture mechanical defects, inclusions for PM, and eutectic carbides for HW microstructures.     

旋转速度对（WC+B4C）p/6063Al复合材料搅拌摩擦焊接头力学性能和微观组织的影响

搅拌摩擦焊的旋转速度对接头焊缝形貌、微观组织和力学性能均有较大的影响。采用搅拌摩擦焊方法对5 mm厚的(WC+B4C)p/6063Al复合材料进行焊接试验,固定焊接速度为100 mm.min-1,旋转速度分别为900,1100,1300和1500 r.min-1,焊后观察焊缝宏观形貌和各种缺陷,并对接头的微观组织和力学性能进行了分析。焊缝宏观缺陷研究结果表明,随着旋转速度的升高,焊接热输入量增大,金属流动性得到改善,飞边、沟槽等宏观缺陷显著增多,焊缝形貌越来越粗糙;接头微观组织研究表明,由于搅拌头的搅拌作用,相比于母材,在焊核区增强相颗粒分布更加均匀,更多增强相颗粒发生破碎,且随着旋转速度的增加,这种趋势增强。对接头的抗拉强度研究表明,在1300 r.min-1以内时,随着旋转速度增加,接头抗拉强度随之增加,最大值为166 MPa,进一步增加到1500 r.min-1时,强度又有所降低,为154 MPa。