The paper considers the results of modeling the cable system of the above-water cable-stayed transition of the main gas pipeline using a laboratory installation and computer modeling using finite element methods. The main characteristics of materials and structural elements used to create a computer and laboratory model are given. Various modes of tension of the cable system affecting the further operation of the model under consideration, allowing to determine the service life of the object, are studied. It is shown that with a slight weakening of the tension of one of the cables, in the cable system, the occurrence of stresses in the pipe body is observed, the magnitude of which, under certain conditions, greatly exceeds the operating values. A small imbalance of effort leads to a redistribution of effort and a distortion of the entire structure, which, under cyclic loads, can lead to a premature exit from the standing of the object in question.

Keywords: cable-stayed transition, effort, stress-strain state, cable system, finite element method, model, load, force.

The application of the results of hardness measurements and its modeling in CAD as a 3D model is considered. Different welding modes were applied and electrodes CT-15, OZL-8 and CL-11 were used as consumables. The test material is a hot-rolled pipe with a diameter of 159 mm made of corrosion-resistant steel 12X18N10T with a thickness of 6 mm. The electrodes were fused to half its length and removed from the electrode holder, after cooling the remainder of the electrode, it was reused. For scanning measurement of microhardness of samples with a load of 100 g, the scanning step was applied 0.5 mm. The use of modern software was able to more accurately simulate the test results on a 3D model. The samples are welded with CT-15 electrodes at a maximum current of 100 A. the hardness is over 450-550 HV, regardless of what the passage was. Similarly, when welding with OZL-8 brand electrodes, but only at low currents, the hardness exceeds 450 HV. In both electrodes, the hardness is increased. When using OZL-8 electrodes, samples welded at high currents have less hardness than at low currents. When welding with these electrodes, it is possible to use them in certain passages, for example, when surfacing the root layer of the seam. In the case of full penetration in high-current modes with CT-15 electrodes, the result differs little as in low modes.

Keywords: steel 12X18N10T, multi-pass welding, welding of austenitic steels, pipe, coated electrodes, welding modes, mechanical properties, macrostructure. Excel, Autodesk Inventor, CT-15, OZL-8, CL-11, amperage

The use of laser radiation for welding aluminum alloy AD33 can improve the quality of welded joints and process performance. At the same time, most of the welded structures in production are performed using automatic laser welding installations, which allow ensuring the necessary quality of welded joints, including due to the constancy of the technological process modes. However, there are a number of industries where manual laser welding installations are indispensable and in high demand. At the same time, a distinctive feature of the manual laser welding process is the problem of ensuring the constancy of the duration of exposure to laser radiation on the surface of the workpiece when the speed of the laser beam changes. The paper presents the results of a comparative study of the dependence of the quality of the AD33 aluminum alloy welded joint on the change in the speed of the laser beam for manual and automatic laser welding conditions.

Keywords: aluminum alloy, laser radiation, welding, welding bath, technological process, microstructure, AD33, laser beam, manual laser welding, Al–Mg–Si, aluminum thermal deformation coefficient, vacuum chamber, pulsed laser