I. N. Shiganov

Laser welding of high-strength aluminium–lithium alloys with a filler wire

Abstract The possibilities of using laser welding with a filler wire for joining sheet materials made of V-1469 and V-1461 high-strength aluminium–lithium alloys are investigated. The optimum conditions of placing the filler wire in relation to the laser beam in the weld pool are determined. The optimum welding parameters resulting in the high-quality formation of the welded joint with equal sagging and excess metal and the absence of porosity and cracks are also determined. The mechanical properties of welded joints are outlined and the microstructure of the welded joint is investigated. The corrosion resistance of the produced welded joints is studied.

Optimization of the shape of nozzles for coaxial laser cladding

The results of mathematical modelling of the flows of powder in nozzles for coaxial laser cladding are presented. The modelling results are used to determine the optimum geometrical parameters of the nozzle used for the construction of appropriate technological equipment. Calculations are carried out to determine the optimum values of the flow rate of powder, the size of powder particles, the geometry of the powder flow and the distance from the outlet of the nozzle to the surface of the components. The resultant values were used in the development of technological processes of cladding with powders of different composition.

Technology of low-frequency vibrational treatment of welded structures in engineering

New equipment and technologies for low-frequency vibrational treatment of components in engineering are examined. The design of new equipment and its technological characteristics are described, the technology of stress relieving after welding, casting, machining, etc. is discussed, and equipment for inspecting the stresses prior to and after treatment is analysed.

Hybrid laser-arc welding of aluminium alloys

Abstract Special features of laser welding of aluminium alloys with laser and arc heat sources are investigated. Advantages and shortcomings of these methods are noted. Experiments were carried out to combine laser and arc heat sources for welding aluminium alloys. Equipment for hybrid welding is described. The technological parameters influencing the external formation of the welded joints are determined. Specific conditions for welding 1424 aluminium alloys with a thickness of 4.0 mm are presented. High-quality welded joints were produced by hybrid laser-arc welding in 1424 alloy with a thickness of 4.0 mm.

Deposition of composite coatings with SiC on the surface of aluminium alloys by laser injection

Abstract Investigations were carried out to determine the technological conditions and the conditions of producing coatings of a composite material based on an aluminium alloy on the surface of aluminium alloys with the addition of SiC particles by laser injection. The dependences of the penetration of the particles into the surface on the preheat temperature, the consumption of the powder, the velocity of movement of the particles and the treatment conditions are determined. The tribological properties of the coatings are determined and advantages of these coatings in comparison with the substrate material and the cast composite material are discussed.

Special features of welding 10KhSND low-alloy structural steel with an oscillating laser beam

Abstract Experimental results confirm that deep penetration welding with oscillations of the laser beam influences formation of the structure, shape and quality of a welded joint. The results of metallographic studies are used to determine the values of the oscillation parameters of the laser beam at which the risk of formation of defects in the welded joint is reduced. The results of mechanical tests and microhardness measurements of the welded joints produced by laser welding with an oscillating beam in 10KhSND steel are presented.

Modelling the process of formation of a composite coating with SiC particles on the surface of aluminium alloys under the effect of powerful laser radiation

Abstract The process of penetration of SiC particles into the surface of an aluminium alloy, melted by the effect of powerful laser radiation, is investigated. The formation of these surfaces greatly increases the wear resistance of components made of aluminium alloys. The physical and mathematical models, describing the technological conditions for the penetration of particles to a depth of up to 1.5–2.0 mm, are investigated. The results of the calculations are confirmed by experimental data.

Development of technology and equipment for ultrasonic shock treatment of welded joints

Abstract New equipment and technology for ultrasonic shock treatment (UST) of components in engineering are described. The design of new equipment and its technical characteristics are outlined. Technology and the results of stress relief after welding, surfacing, pressure working and other operations are presented.

Special features of laser welding of aluminium alloys

Special features of laser welding structures made of aluminium alloys are investigated. The results of investigation of the most promising deformable aluminium alloys are presented.

Metallurgical special features of the production of welded joints in dispersion‐filled metallic composite materials

At present, new requirements determined by the rapid development of science and technology are imposed on structural materials. In particular, this relates to certain special properties. These properties are obtained in conventional structural materials as a result of the effect of alloying elements. In this case, there may be a decrease in or complete loss of the mechanical properties and, in many cases, the required properties cannot be obtained in conventional materials. It is also necessary to take into account the problem of saving energy and materials. Therefore, it is important to produce completely new materials with a set of the required properties. According to experimental results, these materials may be represented by systems based on non-mixing components. The general feature of these composite materials (CM) is the limited solubility of components in the liquid phase. At present, there is already a large number of identical composite materials, and the number of only binary systems of this type is more than 500. However, the application of these composite materials is delayed by the high cost of production, complicated production of large volumes and problems in joining of these materials. Analysis of the production of structures from composite materials and prospects for further application in industry has indicated the need for development of a method of theoretical description of the systems of non-mixing components. Only if the nature of interaction of these components of the composite materials and their mixing is understood will it be possible to develop new methods of production and joining of these materials. In particular, these materials include systems based on Fe-Cu and Fe-Cu-Pb. Special features of the interaction in the Fe-Cu system can be utilised in the development of isotropic and anisotropic magnetically hard materials with a high level of magnetic energy. The most interesting possibilities are offered in the area of heterophase materials based on iron, nature, cobalt and alloys of these elements, in particular ESD magnets. The presence of low-melting ductile elements, in particular lead, in the Fe-Cu-Pb composite together with a strong base and with high heat conductivity, makes it possible to realise the Charpy principle in the production of antifriction alloys operating in the sliding friction conditions. It is also important to note that a strong refractory base in these alloys may be greatly hardened as a result of rational alloying and appropriate heat treatment and the required properties of the low-melting elements may be retained on the initial level. In addition, these composite materials may be used as a basis for the production of high-damping materials, combining this property with a number of other properties, in particular, antifriction and high-strength properties. In the present work, welded joints in the composite materials based on Fe-Cu and Fe-Cu-Pb were produced by automatic argon-arc and laser welding in a continuous CO, laser with a power of 2.5 kW, at a welding speed of 1.7 m/min, and in a Kvant-15 pulsed laser, with a pulse time of 2-3 msec and a pulse energy of 10 J. Cross sections of the welded joints and the weld zone were examined in an optical microscope. According to the thermodynamic analysis of the melt of the Fe-Cu alloy, phase separation of these alloys in the liquid phase is possible. Because the Fe-Cu system is characterised by the dominance of the forces of paired interaction of the atoms of the same type in relation to the phase interaction of the atoms of different types, the repulsive forces of iron and copper are reflected in on the equilibrium diagram in the form of a flat liquidus, indicating a tendency for phase separation. The free energy of the system has the positive sign which, according to the theory of thermodynamics, indicates the phase separation of the system: