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The results of an experimental study of laser cutting of aluminum-lithium alloys using a repetitively pulsed CO2 laser with Q-switching under conditions of intense material evaporation are presented. The dependence of cut quality on the assisted gas pressure is determined. It is shown that a high-quality cut with a sheet thickness of 1.5 mm can be obtained at a gas pressure of 0.5–0.6 bar, which is significantly less compared to cutting with a continuous laser power. This makes it possible to reduce the assisted gas consumption. The dependence of cut surface roughness on the pulse repetition rate is measured. [ABSTRACT FROM AUTHOR]

In this study, a new surface treatment method was applied to laser welded joints of a high-strength VT6 titanium alloy. After welding, the welded joints were exposed to high energy electric pulse treatment in combination with ultrasonic forging. Ultrasonic forging creates a high-defect structure with high curvature of the crystal lattice in the surface layer, as evidenced by the appearance of extinction contours. The total number of cycles to failure is 8,700 for the samples untreated after welding and 29,400 for the treated samples, which indicates a significant increase in the fatigue life of the welded joint. [ABSTRACT FROM AUTHOR]

The paper presents a series of experimental works for the optimization of the thermal post-treatment process (quenching and artificial ageing) of the laser welding joints of aluminum-lithium alloy 1420 (the system Al-Mg-Li) by the temperature and time characteristics, in order to find the breaking stress, yield limit and ultimate tensile strain approaching to the respective characteristics of the main alloy, or equal to them. Low-cycle tests have been done with the thermally-treated welding joints for the pulsing stretching at various loading amplitudes at the temperatures of –60, +20, +85°С. The surface structure of ruptured welding joints with and without thermal treatment has been studied after low cycle tests at various loading amplitudes at the increased and decreased temperatures. [ABSTRACT FROM AUTHOR]

The paper presents the investigations of the shape of single tracks formed by the laser cladding method and distribution of ceramic particles in them. The laser effect on the powder mixture was optimized, which resulted in the formation of pore-free clad tracks. We have found that the initial concentration of ceramics in the powder mixture influences intensively on the track geometrical shape. It is demonstrated that at the higher ceramics concentration in the clad powder, ceramic particles are oriented over the track edges. [ABSTRACT FROM AUTHOR]

The characteristics of a mechanical shutter in a repetitively pulsed CO2 laser with a self-filtering resonator and Q-switching have been investigated. It is shown that the turning on of Q-factor and the formation of the resonator mode occurs in a time much shorter than the shutter response time. The ability to generate high-power pulses with a front duration of about 130-150 ns with a high quality laser beam, which allows the formation of a pulsating optical discharge in atmospheric air, is demonstrated. [ABSTRACT FROM AUTHOR]

In the paper, the influence of heat treatment on the mechanical characteristics of welds obtained by laser welding is investigated. Changes in the microstructure and strength properties depending on various modes of heat treatment of the welds are investigated. As a result, full heat treatment provides a 1.5 times increase in the tensile strength of the weld in comparison with the strength of the alloy as delivered from the factory. [ABSTRACT FROM AUTHOR]

The results of experimental study of laser welding of alloys based on aluminum and titanium using an intermediate composite Al+Ti insert obtained by explosion, with nanopowder additives and plastic deformation of the aluminum seam, are presented. Morphologically high-quality welds have been obtained in the welding of both the aluminum plate and the titanium one with the corresponding parts of the insert. It was found that the collapse of the joint in the tensile test occurred along the aluminum part of the insert, which had a lower tensile strength than that of the titanium one. The use of a nanomodifier without plastic deformation increases the strength of the welded joint by about 10% compared to the unmodified compound. The use of nanomodifying and strain hardening can significantly increase the tensile strength, the value of which is more than 97% of the strength of the AD1 alloy. The experiments on laser butt welding of plates made of aluminum alloy 1424 followed by their plastic deformation confirm the effectiveness of strain hardening of welded joints of aluminum alloys. [ABSTRACT FROM AUTHOR]

Characteristics of craterlike structures on the laser cut surface and their dependence on surface roughness are experimentally studied for sheet thickness of 3-16 mm. The crater size and the number of craters increase with the sheet thickness. The dependence of the number of craters on the cutting velocity is nonmonotonic and has a peak. This peak is observed at an optimal cutting velocity, which ensures the minimum roughness of the cut surface. A qualitative explanation of the observed phenomena is proposed. [ABSTRACT FROM AUTHOR]

The paper deals with the optimized laser welding of heterogeneous materials based on titanium and aluminum-lithium alloys. The tensile strength of resulting joints has been measured. The micro-structure of the surface of welded joint fracture has been studied. The tensile strength of the welded joint reaches 250 MPa. [ABSTRACT FROM AUTHOR]

The paper is devoted to the analysis of the Mg influence on welded joint properties. The laser welding of aluminum alloys with the quite equivalent content of the alloying element Mg has been studied comparatively. Under study are the mechanical properties, the X-ray structural analysis of resulting welded joints has been performed. It is shown that the strength of the welded joints of Mg-containing aluminum alloys is 0.8 - 0.95 of the basic material strength. The X-ray analysis demonstrated the variation of the parameters of the welded joint lattice as compared to the basic alloy. [ABSTRACT FROM AUTHOR]