Corrosion Protection of the Zone of Thermal Action (Zone of Butt of Tubes While Welding) from the Inside When Laying Multifunctional Pipeline Systems

The work is aimed at handling a main problem of corrosion protection of the pipeline s interior section adjacent to a weld butt. It is proposed to execute fastening of elements of the protective system of pipes by application of the pulse-magnetic technology which has essential technical and economical advantages over other methods. Protection of end sections of pipes is performed by pulse-magnetic pressing-in of a bush made from stainless steel or by pulse-magnetic welding of rings from a protective material. Commercial tests of the pipelines produced by the technology being proposed supported good prospects of this technology use

Action of Pulse-Magnetic Fields on Liquid and Crystallizing Metal

Pulsed-magnetic fields are used for execution of a whole complex of technological processes: dividing, forming, assembling, welding and others. In all these technologies half-finished products from sheets, sections and tubes are used as billets. Action of magnetic fields on a cast metal is known in the metallurgy production, for example, casting to an electromagnetic crystallizer. In spite of a high electrical resistance of a melt and owing to low mechanical resistance of a liquid metal the use of high-intensity pulse-magnetic fields (PMF) in technologies of mechanical engineering is of interest. Even the first exploration experiment showed high efficiency of such action. At energy of 1, 2 kJ a portion of the melt under the action of the PMF has flown more than 4 m, spread in the form of a thin film on the ceiling and solidified. The paper presents three basic technological schemes of such action: with influence through a wall of a magneto-transparent crucible; by an immersion inductor; and action from the surface. Factors accompanying such action are: added sources of heat as a result of flowing of induced eddy currents through the melt; force action on the melt responsible for passage of waves of stress and metal flows. Action of these factors is controllable both in intensity and in direction. The temporal action of the pulse-magnetic field on a liquid and crystallizing metal (LCM) is to be matched with a curve of cooling the melt: either on the portion above the crystallization area or on its different portions, that is, at different relationships of solid and liquid phases.Factors of action of the pulse-magnetic field change temperature conditions of crystallization influence on the number of centers of crystallization and, as the consequence, change structure and properties of cast metal. The paper presents results of first studies on action of the pulse-magnetic field on a LCM which testify that such action is real and good. This has determined the prospects for development of new technologies in metallurgy (forming of an ingots structure, stirring of a material, rolling of cast metal and so on) and in mechanical engineering (in casting, stamping, welding and others)

STRUCTURAL CHANGES ORIGINATING IN THE BLANK MATERIAL AT THE MOMENT OF COLLISION WITH TOOLING AND THEIR INFLUENCE ON THE QUALITY OF THE FINISHED WORKPIECE

Cette étude considère les conditions pour générer les changements de structure et leur influence sur le degré de déformation d'un tube avant la collision, sur la vitesse de collision et sur les propriétés physiques et mécaniques du matériau impacté. Les limites supérieures et inférieures pour la vitesse de collision qui permettent de déterminer les changements de structure ont été fixées. On montre l'influence de la vitesse sur la valeur des contraintes résiduelles et les dimensions finales de la pièce.The paper considers the conditions of generating structural changes and their dependence on the degree of tangential structural strain of a blank before the collision, on the collision velocity and on the mechanical and physical properties of the colliding materials. Lower and upper boundaries for the collision velocities determining structural changes are set. The velocities influence upon the value of residual stresses and upon the workpiece final dimensions is shown

Metallic behavior in the center of deformation when pulse-magnetic cropping an allowance of hollow billets

The mechanism of parting of hollow billets when pulse-magnetic loading is the concern of the paper. Much attention is given to investigation of the kinematics of the process of parting under various conditions of loading and different relations of geometrical parameters of a billet, inductor and die. With consideration for results of metallographic investigations the model of metallic behavior in the center of deformation has been proposed, which allows to control knowingly the process of pulse-magnetic cutting with the aim of the attainment of the required quality of products

INFLUENCE OF THE SPREAD IN VALUES OF ALUMINIUM ALLOY DYNAMIC PROPERTIES UPON THE FINAL RESULTS OF MAGNETIC-PULSE STRAIN

Dans cette étude on fournit un modèle mathématique pour un procédé d'expansion de tubes par impulsion magnétique au moyen d'une approximation par la loi puissance de la courbe d'écrouissage dynamique [MATH]. La méthode par éléments finis permet d'analyser les déformations dues aux contraintes du matériau tubulaire dans le procédé d'expansion par impulsion magnétique et d'estimer l'influence de la dispersion des facteurs k et n sur les résultats de la déformation finale. Les limites de la dispersion des facteurs k et n ont été définis tous deux en fonction des résultats de tests dynamiques cités par d'autres chercheurs sur les alliages d'aluminium et les résultats obtenus par les auteurs.The paper provides for mathematical model of magnetic-pulse process for tubular blanks expansion by means of power approximation of the dynamic hardening curve [MATH]. Finite element method allows to analyse stressed strain of the blank material in the process of magnetic-pulse expansion and to estimate the influence of the spread in "k" and "n" factors on final strain results. Boundaries of the spread in "k" and "n" factors were defined both by the results of dynamic tests on aluminium alloys cited by other investigators and by the results obtained by the authors

Magnetic pulse deformation of tubes made of partially polymerised carbon fibre reinforced plastic

The paper describes impulse deformation of tubes made of partially polymerized carbon filled plastic in combination with aluminium rings. A mathematical model is proposed for investigation of two stages of joint deformation. The first stage involves impulse deformation of an aluminium ring combined with carbon filled plastic mass. During the second stage the kinematics obtained at the first stage is used to determine the stress-strain state of a carbon filled plastic tube by the finite-element method. Changes in the stress-strain state due to a number of technological parameters are also described

Pulse-Magnetic Processing Technology when Making Parts and Units of Aerospace Engineering

Experience on using of pulse-magnetic processing of materials (PMPM) at the enterprises of the aero-space industry is presented. The emphasis is on the processes of hollow billets stamping. A complete list of technological processes mastered is available, advantages of these processes are outlined. The paper is illustrated with some examples of the concrete parts and units made with a help of the pulse-magnetic technology.On décrit l'expérience de l'utilisation du formage magnétique dans les entreprises de l'industrie aérospatiale. On parle surtout des processus du formage des piéces brutes creuses. On procéde à l'énumération de tous les processus mis en oeuvre, on décrit leurs avantages. Il y a quelques exemples de piéces et de sons-ensembles concrets fabriqués à l'aide de la technique magnétique