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Prediction of the residual stress-strain state of butt and tee joints of Al-Mg-Mn aluminium alloy produced by consumable electrode pulse-arc welding

Gao Shiyi, Korzhyk Volodymyr, Liu Zhe, Khaskin Vladyslav, Zhao Yunqiang, Illiashenko Yevhenii, Alyoshin Andriy, Kvasnytskyi Viktor, Perepichay Andrii, Prokhorenko Odarka

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 4

311--328

EN

Assessment of the residual stress-strain state (SSS) at MIG welding of aluminium alloys structures is relevant, because of the need to predict formation of residual stresses and strains, which may lead to lowering of fatigue strength of such a structure. Therefore, the research is devoted to determination of the influence of the mode of pulse-arc (MIG) welding of 1561 aluminium alloy of Al-Mg-Mn system (4 mm thickness) on the thermal cycle of the process and prediction of the influence of rigid restraint of the welded specimens in the assembly-welding fixture on the residual SSS of butt and tee welded joints. For this purpose, a finite element model of calculation of the temperature fields and SSS was created on the base of the conduced technological studies, which ensured up to 10% accuracy, that is an acceptable result for technological calculations. This model was used to determine the longitudinal and transverse tensile stresses and displacements, equivalent strains and stresses, out-of-plane displacements of the welded joint of Al-Mg-Mn aluminium alloy. It was found that rigid restraint of the specimens leads to formation of maximal equivalent stresses at MIG welding: for the butt joint - up to 190 MPa, forming in the points of transition from the weld to the base metal on the face surface; for the tee joint - ~250-260 MPa, forming in the weld area in the flange. Out-of-plane displacement after unfastening of the welded specimens from the assembly-welding fixture was equal to: for butt joint – up to 0.1 mm; for tee joint – up to formation of a plastic zone in the flange ~1.7 times larger than in the web, and out-of-plane bending of the web by 1.31 mm.

2

Microplasma spraying of coatings from wire of heat-resistant nickel alloy Inconel 82 with laser melting

Korzhyk Volodymyr, Gao Shiyi, Khaskin Vladyslav, Bernatskyi Artemyi, Kislitsya Oleksandr, Voinarovych Sergii, Kuzmych-Yanchuk Yevhenii, Kaluzhnyi Sergyi, Hu Yanchao, Guirong Guirong

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 7

164--178

EN

The work is devoted to studying the technological capabilities of the processes of microplasma spraying of wires from heat-resistant nickel alloy Inconel 82 with further laser melting of the sprayed layers to produce narrow-path coatings during restoration of worn end faces of ribbed parts, used in nuclear engineering, aerospace and textile industry, etc. Numerical modeling by finite element method was applied to select the parameters of the modes of microplasma wire spraying and further laser melting of sprayed layers of Inconel 82 alloy. This made it possible to select the parameters of the modes with an accuracy of up to 20% (current 30-40 A at voltage 40 V, deposition speed 100 mm/min; radiation power 3.0 kW, defocusing spot 3 mm, remelting speed 750 mm/min). The value of the parameter of coating growth rate during microplasma spraying of Inconel 82 alloy wire was determined (it was equal to 1 mm of coating height / 1 cm of narrow path length / 1 min of spraying process duration). The work shows for the first time that the useful area of the microplasma spraying spot is close to the defocused laser radiation spot, ensuring unique possibilities for deposition of narrow paths and their laser remelting without hard phase burnout. This is experimentally confirmed by ~17% (290-350 HV) increase in the hardness of sprayed Inconel 82 layer (200-240 HV) during its remelting by radiation with power density of ~4.3·104 W/cm2. It was also determined that the features of structure formation during laser remelting of Inconel 82 alloy promote an enhancement of its corrosion resistance up to 1.5 times and increase in wear resistance by 20-40%, compared to sprayed coatings.

3

Influence of speed and heat input of the pulsed-arc welding process on the structure formation of Al-Mg-Mn aluminum alloy joints

Korzhyk Volodymyr, Gao Shiyi, Khaskin Vladyslav, Illiashenko Yevhenii, Grynyuk Andrii, Alyoshin Andriy, Bushma Oleksandr, Wang Xinxin, Hu Yanchao, Guirong Guirong

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 8

313--331

EN

This paper establishes the trends in structure formation of 4 mm thick 1561 aluminum alloy welded joints, depending on changes in the parameters of the MIG welding mode on a steel substrate (specifically, the speed and heat input of the process). Welding modes were selected based on the criterion of satisfactory seam formation, and the optimal welding mode was determined based on the criteria of minimizing porosity, grain refinement, and improved mechanical properties. Technological studies have shown that, based on the criterion of satisfactory seam formation with a quality level ranging from C to B according to ISO 10042, it is advisable to select a welding speed between 380 and 600 mm/min with a heat input between 217 and 240 J/mm. Metallographic studies have shown that increasing the MIG welding speed promotes weld grain refinement, decreases their shape factor, and simultaneously increases the number of pores while reducing their size. Mechanical tests demonstrated that increasing the welding speed enhances the mechanical properties of welded joints. Therefore, when using MIG welding of aluminum alloys in industry, it is recommended to increase the speed to 600 mm/min and higher.

4

Features of the process of formation and dispersion of a liquid layer and formation of powder particles in plasma-arc atomization of current-conducting solid and flux-cored wire

Gao Shiyi, Kryvtsun Ihor, Korzhyk Volodymyr, Strohonov Dmytro, Burlachenko Oleksii, Demіanov Oleksii, Tereshchenko Oleksii

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 5

58--72

EN

The paper gives the results of mathematical modeling and experimental studies of the processes of formation and fragmentation of the liquid layer and formation of powder particles in plasma-arc atomization of current-conducting solid stainless steel AISI 316L wire and flux-cored Fe-Al wire. Mathematical modeling showed that initial fragments of size d0 = 670–780 μm form at plasma-arc atomization of the above-mentioned wires, where after their separation from the tip of the atomized wire their multiple disintegration in the plasma jet takes place, which ends at the distance of ~ 120 mm with formation of fine spherical fragments (powders) with the average diameter of 105–125 μm. Experimental studies on determination of the initial size of the drops, forming at metal drop separation from the liquid layer, using high-speed filming, showed that their size is d0 = 720–815 μm, and size of atomization products (powder) determined using the sieve analysis method are equal to 119–142 μm. Comparison of the obtained experimental and calculated data showed that that for atomization of both the solid stainless steel AISI 316L wire and flux-cored wire of Fe-Al system the main fraction of powder particles is 1–300 μm, which makes up 96–99 wt. % in both the cases, the error between the theoretical and experimental data being not higher than 7–32 %, depending on powder fraction, allowing application of the mentioned mathematical complex model to determine the optimal modes of plasma-arc atomization process with a wide range of wire materials. The study of the shape parameters and structure of AISI 316L and Fe-Al powders showed that most of the particles have a regular spherical shape with a sphericity coefficient close to 0.8–0.9, the microstructure of which is characterized by the absence of pores and voids.

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Evaluation of the possibility of obtaining spherical powders of titanium alloy Ti 6Al 4V by supersonic reverse polarity plasma torch for use in additive manufacturing

Gao Shiyi, Korzhyk Volodymyr, Strohonov Dmytro, Tereshchenko Oleksii, Demіanov Oleksii, Ganushchak Oleg

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 8

434--448

EN

This work demonstrates the possibility of producing spherical Ti-6Al-4V Grade 5 alloy powders with superior technological properties compared to those obtained through conventional industrial gas atomization methods for additive manufacturing, by utilizing plasma atomization of a 1.0 mm diameter solid wire. The process employs supersonic plasma jets generated by a DC reverse polarity plasma torch with vortex arc stabilization. The plasma torch has a copper hollow electrode anode and a special diffusive nozzle cathode. Analysis of the particle size distribution of the powder showed the main fraction of -140 μm 96 %wt., and the amount of the finely divided fraction of -63 μm is up to 55-60 %wt. Also, using subsonic jet had been give fraction -250 μm, which is 97 %wt., and the amount of the finely-divided fraction -63 μm does not exceed 30 %wt. The study of the shape and structure properties of Ti 6Al 4V Grade 5 powder showed that the sphericity coefficient reaches up to 0.9, the number of defects in the form of satellites and irregular particles does not exceed 1 %wt. In terms of technological characteristics, Ti 6Al 4V Grade 5 powder obtained by the adopted technique is on par with the industrial method of producing spherical powders for additive manufactuing by the direct polarity plasma torches.

6

Investigation of Spectral Parameters of Constricted arc Plasma for Controlling Welding Processes and Related Technologies

Chernyak Valeriy, Korzhyk Volodymyr, Gao Shiyi, Khaskin Vladyslav, Voitenko Oleksandr, Illiashenko Yevhenii, Wang Xinxin, Grynyuk Andrii, Konoreva Oksana, Sviridova Iryna

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no. 7

250--263

EN

The paper is devoted to investigation of spectral parameters of constricted arc plasma, as a foundation for further development of basic approaches to intellectual controlling of plasma-arc technologies of material treatment and welding. The relevance of application of spectrometric analysis of the welding arc consists in obtaining the possibility of sufficiently accurate control of its temperature and energy input into the product being welded, recording initiation of weld defects (including internal pores), determination of atmospheric oxygen ingress into the weld pool, etc. The spectral composition, temperature and concentration of the constricted welding arc plasma were determined in the paper to more precisely define its physical characteristics at 80 and 100 A currents, in order to establish the further applicability of dynamic spectral analysis of a constricted plasma arc in control of welding processes. As modern spectrometers with CCD-detectors of the spectral range of 200÷1100 nm have the resolution of the order of 0.35 nm, which 2-3 times exceeds the quantization step by the measured wavelength, and may lead to considerable errors, an approach is proposed to increase the accuracy of spectrometric measurements to acceptable values. Radiation spectra of the constricted welding arc measured in the wavelength range of 650÷1000 nm allowed within the model of local thermodynamic equilibrium calculating the excitation temperature of the main spectral range components: Ar I and O I. It was established that the excitation temperature of electron levels of Ar atoms in the welding arc plasma only weakly depends on the discharge current, and it is equal to 13500 ± 500 K. Excitation temperature of O I electron levels was equal to 10000 ± 500 К at arc current of 100 A and to 7200 ± 500 К at 80 A current. Electron density of high-current welding arc plasma was measured by Stark broadening of Ar I lines (696.543; 772.4; 912.3 nm). It was found that with the rise of current of the constricted welding arc by 20%, an increase of charge concentration in the arc plasma by 1.5 times and of its temperature by 1.2 times are observed.