Fundamentals of the design of welding sealing structures of transmission oil pipelines. Welded connectors and T-bends

Investigations were carried out to determine the stress state of a cylindrical, connector, connectors with unloading rings, used for restoring the load-carrying capacity of sections of transmission oil pipelines with metal losses of different origins, and also a sheltering branch pipe, a branch pipe with a circular strap and a split T-bent, used as repair jackets preventing the unsealing of non-working technological fittings.     

Optimization of the main parameters of resistance butt welding of large pressed profiles made of aluminium alloys

The main parameters of the conditions of resistance butt welding (RBW), influencing the stability of the melting process and the quality of the welded joints, are examined. Criteria for optimization of the RBW conditions are selected. The stability of the optimized conditions of RBW of large pressed profiles of aluminium alloys is analysed.     

Methods of overlapping closed joints in friction stir welding of thin wall structures made of aluminium alloys

Three methods of completing closed (circular and annular) welded joints in welding the 1570C alloy of an Al–Mg–Sc system with a thickness of 11 and 35 mm (using the output wedge, a tool with a moving tip, friction welding) are discussed. The range of double stirring (the beginning to end of the welded joint) has a heterogeneous microstructure and mechanical properties. The distributions of the hardness of the weld metal after the first and second stirring cycle are similar if the working length of the tip is the same, and greatly differ if the working length of the tool used for the second pass is variable (as in welding with a moving tip). The ratio of the tensile strength of the welded joint and the parent metal is not lower than 0.9, which is higher than in arc welding. It is shown that the three methods of completing the closed joints can be used in practice.     

Diffusion welding of components made of creep-resisting alloys: diffusion welding of titanium-based creep-resisting alloys (Part 2)

The efficiency of using diffusion welding for joining components of nickel creep-resisting alloys is confirmed. It is proposed that the mechanical properties can be improved, the extent of plastic deformation of components reduced, and softening of the welded nickel creep-resisting alloys prevented using nickel-based interlayers.     

Dimensioning of welded structures made of strain-hardened aluminium alloys

The progress in the standardization of aluminium-welded structures' calculations leaves much to be desired. This paper presents a fundamental evolution of advanced methods of calculation for the building of structures made of strain-hardened aluminium alloys. It contains calculation procedures consistent with Eurocode 9, which account for the actual development of aluminium structural safety. Qualitative advancement in the analysis of load capacity is explicitly visible in the area of welded aluminium structures that display the thermal penetration effect in heat-affected zones; this phenomenon has a destructive impact on the mechanical properties of the structure. These effects are typical of the majority of aluminium alloys and do not happen in the case of welded steel structures.     

Friction welding of T-joints in sheet structures of aluminium alloys

A special tool is developed for the friction welding of T-joints which produces T-sections with smooth contact between the surfaces of the web and the flange.     

Corrosion resistances of stressed building structures made of aluminum alloys

Propagation of various types of localized corrosion on real stressed building structures was examined. The naturally aged 1915T alloy used in such structures was found to be highly resistant under various atmospheric conditions. It was insensitive to corrosion cracking and exfoliation corrosion, and the pitting depth did not exceed 0.21 mm in both the base metal and weld joints after 20-year tests. A mathematical analysis of experimental data allowed the prediction that even on the Main Exhibition pavilion near the foundry, the maximum corrosion depth should not exceed 0.5 mm after 50 years of operation. Postwelding artificial aging reduced the resistance to corrosion cracking. Because of this, the Sochi Concert hall was attacked by numerous corrosion cracks. However, a decrease in the actual stresses below a threshold level for corrosion cracking prevents further crack propagation. The effects of corrosive components of the atmosphere were studied. Pitting corrosion was found to be mainly promoted by the presence of chlorides and acid discharges from production departments. Various factors that stimulate and inhibit the corrosion of stressed aluminum building structures were revealed. Original Russian Text ? V.S. Sinyavskii, V.D. Kalinin, 2007, published in Zashchita Metallov, 2007, Vol. 43, No. 6, pp. 635–646.     

Diffusion welding of components made of creep-resisting alloys (part 1)

The efficiency of diffusion welding components made of nickel creep-resisting alloys is confirmed. It is proposed that to increase the mechanical properties and decrease the extent of plastic deformation of components and also prevent the softening of the welded nickel creep-resisting alloys welding should be carried out using nickel interlayers.     

Special features of magnetic-pulsed welding of thin sheet stamped-welded structures

The problem of reducing the weight and screening on-board cable systems of space equipment against radio interference is solved. To solve the problem, a method of producing lightweight stamped-welded screening casings of connectors by magnetic–pulsed welding–forming (MPWF) has been developed. The results of theoretical analysis and experimental studies of the MPWF process are used to determine the mechanism of formation of welded joints, the energy parameters of the process and the geometrical parameters of assembling, influencing the quality of the welded joints and the degree of deformation in forming. The experimental results are used to design and manufacture a welding–forming installation with induction coils for MPWF of the lightweight screening casings.     

Finishing works after welding of structures made of rust-resistant,high-alloy steels

In this paper, problems that occur when working with welds formed of high-alloy steels to restore their passive layers, damaged as a result of temperature impact, are discussed. Particular attention was paid to the procedures concerning aggressive etching agents during and after completion of the passivation processes (waste neutralization and utilization).     

Technological and constructional features of welding titanium alloys for marine structures

The methods of welding marine titanium alloys do not differ greatly from the commercial methods of welding titanium ensuring reliable protection against the environment. Welding is carried out either in inert gases or in vacuum. Nevertheless, there are a number of technological and constructional special features of welded joints associated with the working conditions of marine structures in the actual service conditions which are discussed in this article.     

浅论镍铬钼合金接管堆焊焊接技术的应用

本文简要介绍了镍铬钼合金接管堆焊焊接工艺及注意事项。     

Some special features of fracture in large semifinished products made of aluminum alloys

The load-bearing structure of modern airframes requires monolithic members that are produced from large forged and rolled aluminum-alloy semifinished products. These members are designed in accordance with the principle of “safe service life,” and critical parts are designed in accordance with the principle of “safe vulnerability to damage.” For this reason, the charactersitics of static crack resistance (K _1c, RGFC, σ _cr ^net , and others) have become very important and some of them are used as control parameters in standard documentation. These parameters characterize the operating capacity of the material of a structure with a crack and take into account the magnitude and direction of the applied load. If the crack front deviates from the given direction to another plane (for example, from a transverse plane to a heightwise plane), the process of crack propagation becomes unpredictable and uncontrollable. The present paper is devoted to the special features of fracture in large semifinished products made of aluminum alloys. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 2–7, March, 1997.     

钛/铝异种金属搅拌摩擦焊搭接接头的组织结构

采用搅拌摩擦焊对TC1钛合金和LF6铝合金异种金属进行了搭接连接,研究了接头的微观组织结构.结果表明,当搅拌头旋转频率为1 500 r/min、焊接速度为60mm/min时,能获得焊缝成形良好、无孔洞和裂纹等缺陷的搭接接头,搭接处铝合金和钛合金充分混合,形成焊核区.焊核两侧进入铝合金中的钛合金在搅拌针的挤压下发生了弯曲...     

Computer modelling of residual welding strains in technological design of welded structures

The proposed automated program takes into account changes in the geometrical parameters during drawing, the mechanical properties and the contact friction conditions along the length of the deformation zone, and also the conditions of plastic deformation of the shell and the fracture parameters of the shell. It is shown to be possible to produce defect-free flux-cored wires at the minimum number of passes.     

基于计算机控制的自动焊接系统在长距离油气管道焊接中的应用

长距离油气管道的焊缝为环形,在焊接过程中需要采用仰焊、立焊、平焊等几种焊接方式。由于每一种焊接工艺都有各自不同的操作要领,因此长距离输送管道的焊接较难实现自动化。并且长距离油气管道一般在野外现场焊接,工作环境复杂,对焊接系统的稳定性要求较高。鉴于此,设计研发了一种基于计算机控制的全位置自动焊接系统。该系统采用自保护药芯焊丝,除了能够满足仰焊、立焊和平焊等不同焊接工艺的要求,还具有电弧稳定、焊透性和焊渣剥离性良好、无需保护气体等诸多优点。基于X-80管线钢的焊接实验表明:自动化焊接系统的使用明显提高了焊接过程的连续性和稳定性,确保了焊接接头的内在品质和外观成形,降低了焊接工作强度,且降低了管道焊接的成本。